DATA COLLECTION AND ANALYSES PERTINENT TO EPA'S
DEVELOPMENT OF GUIDELINES FOR PROCUREMENT OF HIGHWAY CONSTRUCTION
PRODUCTS CONTAINING RECOVERED MATERIAL
                Vol. II
                   1981

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           Q&TA. COLLECTION AND ANALYSES PERTINENT
             TO EPA'S DEVELOPMENT OF GUIDELINES
      FOR PROCUREMENT OF HIGHWAY CONSTRUCTION PRODUCTS
               CONTAINING RECOVERED MATERIALS

                         Volume II
               Technical Data and Appendices
      This report (ms. 2096) describes work performed
for the Office of Solid Waste under contract no. 68-01-6014
     and is reproduced as received from the contractor.
    The findings should be attributed to the contractor
            and not to the Office of Solid Waste
                   and Emergency Response
            U.S.  ENVIRONMENTAL PROTECTION AGENCY
                            1981

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This report was prepared by Franklin Associates, Ltd., Prairie Village, Kansas,
and Valley Forge laboratories, Inc. of Devon, Pennsylvania, under contract no.
68-01-6014.

Publication does not signify that the contents necessarily reflect the views
and policies of the U.S. Environmental Protection Agency, nor does mention
of commercial products constitute endorsement by the U.S. Government.

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                                  PREFACE
          This report was prepared as a joint venture with Franklin Associates,
Ltd. of Prairie Village, Kansas, and Valley Forge Laboratories, Inc., of Devon,
Pennsylvania.  Franklin Associates was prime contractor on the project.   The
study was performed for the U.S. Environmental Protection Agency,  Office of
Solid Waste, under Contract No. 68-01-6014.

          This report has been separated into two volumes because of its size.
Volume One is the "Issues and Technical Survey."  Volume Two is "Technical Data
and Appendices."  It contains the full technical reports authored by Valley
Forge Laboratories, as well as appendices which contain support documentation
for the entire report.

          This project relied heavily on interviewing people knowledgeable
about the procurement process, and about the issues relevant to this project.
We are indebted to the numerous people who contributed to this project.   They
include people in state, local, and Federal government service, suppliers of
highway construction material, contractors, trade associations, and others.
Special recognition  is made to the American Association of State Highway
Transportation Officials (AASHTO) who put forth substantial effort to secure
information for  this project.

          Finally, appreciation is due William Kline who served as the EPA
project officer, and to John M. Heffelfinger and Penelope Hansen who provided
general guidance for the study.

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                             TABLE OF CONTENTS
Part I - POWER PLANT ASH                                         1-1

     INTRODUCTION                                                1-1
     FLY ASH                                                     1-1
          Production and Handling                                1-1
          Physical and Chemical Properties                       1-7
          Utilization of Fly Ash in Highway Construction         1-11
               Structural Fill and Backfill                      1-13
               Engineering Properties of Fly Ash as Fill
                 Material                                        1-13
               Frost Susceptibility                              1-13
               Moisture-Density Characteristics                  1-15
               Shear Strength                                    1-17
               Compressibility                                   1-20
               Permeability and Leaching Characteristics         1-22
               Capillary Action                                  1-28
               Slope Stability                                   1-28
               Handling Characteristics                          1-28
               Examples of Fly Ash Utilization in Highway
                 Embankment Construction                         1-29
               Motorway M.5 - Bristol and Somerset, England      1-30
               Alexandria By-Pass - Dumbarton, Scotland          1-30
               Clophill By-Pass, Motorway A.6 - Bedfordshire,
                 England                                         1-30
               U.S. Route 250 - Fairmont, West Virginia          1-30
               Melvin E. Amstutz Expressway - Waukegan,
                 Illinois                                        1-31
               Route 7 and 148 - Powhatan Point, Ohio            1-32
               Overall Technical Assessment                      1-32
          Lime-Fly Ash-Aggregate Bases and Sub-Bases             1-34
               Description of Pozzolanic Reaction                1-34
               History of Lime-Fly Ash-Aggregate Base            1-35
               Materials and Mixture Proportions                 1-38
                    Lime                                         1-38
                    Fly Ash                                      1-38
               Aggregates                                        1-39
               Mix Proportions                                   1-40
               Moisture Content                                  1-42
               Engineering Properties                            1-43
                    Compressive Strength                         1-43
                    Flexural Strength                            1-45
                    Modulus of Elasticity                        1-45
                    California Bearing Ratio                     1-45
                    Autogenous Healing                           1-45

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          Fatigue Properties                           1-46
          Dimensional Stability                        1-46
          Durability                                   1-48
          Permeability                                 1-51
     LFA Pavement Thickness Design Considerations      1-51
     AASHTQ Structural Equivalency Method              1-51
     Other Pavement Thickness Design Approaches        1-57
     Applications and Limitations of LFA Materials     1-57
     Durability and Late Season Construction           1-59
     Strength Development and Construction Cutoff
       Dates                                           1-59
          Mechanical Stability                         1-62
     LFA Use in Highway Construction Projects          1-65
          Illinois                                     1-65
          Ohio                                         1-67
          Pennsylvania                                 1-69
          Other States                                 1-73
     Federal Aviation Administration                   1-74
          Newark Airport Project                       1-75
          Toledo Express Airport                       1-79
          Economic Evaluation of LFA Base              1-84
     Overview of LFA Usage                             1-93
          LFA Use by State Highway Agencies            1-93
          Marketing Considerations                     1-97
     Overall Technical Assessment of LFA Materials     1-99
          Advantages and Disadvantages                 1-99
     Institutional Barriers and Related Factors        1-102
Cement-Stabilized Fly Ash Bases and Sub-bases          1-103
     History of Cement-Stabilized Fly Ash              1-103
     Pozzolanic Nature of Cement-Stabilized Fly Ash    1-104
     Mixture Proportions                               1-105
     Engineering Properties                            1-107
          Compressive Strength                         1-107
          Moisture Density                             1-111
          California Bearing Ratio                     1-111
     Pavement Thickness Design Considerations          1-111
     Late Season Construction                          1-113
     Assessment of Performance in Specific Projects    1-116
          Harrison Power Station - Haywood, West
            Virginia                                   1-116
          Philip Sporn Plant - New Haven, West
            Virginia                                   1-116
          Virginia County Road 665 - Carbo, Virginia   1-117
     Economic Evaluation of Cement-Stabilized Fly
       Ash Base                                        1-117
          Bituminous Wearing Surface on Cement-
            Stabilized Fly Ash Base Courses            1-118

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                    Full Depth Asphalt                           1-119
                    Bituminous Wearing Surface on Crushed
                      Aggregate Base Course                      1-119
                    Reinforced Concrete Pavenent on Crushed
                      Aggregate Sub-base                         1-119
               Overall Technical Assessment                      1-121
          Mineral Filler in Bituminous Pavements                 1-121
               Research on Use of Fly Ash as Mineral Filler      1-122
               Utilization of Fly Ash as Mineral Filler          1-130
               Review of Specification Requirements              1-132
     BOTTOM ASH                                                  1-135
          Production and Handling                                1-135
          Physical, Chemical, and Engineering Properties         1-136
          Utilization of- Power Plant Aggregates                  1-140
               Power Plant Aggregates in Base Courses            1-145
                    Unstabilized Bases                           1-145
                    Stabilized Bases                             1-149
          Assessment of Poser Plant Aggregate Use as Base
            Course Material                                      1-156
     POWER PLANT AGGREGATES IN BITUMINOUS PAVING MIXTURES        1-157
          Research Investigations                                1-157
               West Virginia University                          1-157
               Ohio State University                             1-160
                    Material Characterization                    1-160
                    Gradation                                    1-160
               Los Angeles Abrasion and Sodium Sulfate
                 Soundness                                       1-161
               Specific Gravity and Absorption                   1-161
                    Bottom Ash-Bituminous Mixtures               1-162
                    Bottom Ash-Aggregate-Bituminous Mixtures     1-162
          Use of Power Plant Aggregates in Bituminous Paving     1-172
          Assessment of Power Plant Aggregates Use in
            Bituminous Paving                                    1-178
     REFERENCES                                                  1-183

Part II - USE OF CEMENT KILN DUST AND LIME KILN DUST IN
            HIGHWAY CONSTRUCTION                                 II-l

     INTRODUCTION                                                II-l
          Cement Kiln Dust  (CKD)                                 II-l
          Lime Kiln Dust  (LKD)                                   II-l
     MANUFACTURING PROCESS                                       II-l
     QUANTITIES AVAILABLE                                        II-6
          Cement Kiln Dust                                       II-6
          Lime Kiln Dust                                         II-8

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     USE OF WASTE KILN DUSTS IN HIGHWAY CONSTRUCTION             II-8
     COMMERCIAL AVAILABILITY OF PRODUCTS CONTAINING KILN DUST    11-10
          Amounts and Locations of Cement Kiln Dust              11-10
          Amounts and Locations of Lime Kiln Dust                11-10
          Locations of Past and Present Producers of Kiln Dust-
            Fly Ash-Aggregate Compositions                       11-11
          Locations of Potential Producers of Kiln Dust-Fly
            Ash-Aggregate Compositions                           11-11
     TECHNICAL ASSESSMENT                                        11-11
          Laboratory Investigation - Cement Kiln Dust            11-12
               Compressive Strength                              11-12
               Durability                                        11-21
               Autogenous Healing                                11-21
          Laboratory Testing - Lime Kiln Dust                    11-21
               Compressive Strength                              11-21
               Durability Tests                                  11-26
          Field Installation                                     11-26
               Cement Kiln Dust                                  11-26
               Lime Kiln Dust                                    11-32
     SUMMARY ASSESSMENT                                          11-32
     REFERENCES                                                  11-35

Part III - USE OF ASPHALT-RUBBER IN HIGHWAY CONSTRUCTION         III-l
     INTRODUCTION                                                III-l
     APPLICATIONS                                                III-l
          Crack Control                                          III-3
          Waterproofing                                          III-4
          Crack or Joint Sealant                                 III-4
     COMMERCIAL AVAILABILITY OF PRODUCTS
     Availability of Recycled Rubber                             III-5
     CHARACTERISTICS OF THE RUBBER USED IN ASPHALT-RUBBER
       MIXTURES                                                  III-8
     AVAILABILITY OF  THE ASPHALT-RUBBER MIXTURE (INCLUDING
       AVAILABILITY OF EQUIPMENT)                                III-8
     AVAILABILITY  OF EXPERIENCED PERSONNEL TO INSURE PROPER
       CONSTRUCTION                                              III-9
     INDUSTRY DEMAND FOR ASPHALT-RUBBER                          III-9
     COST OF ASPHALT-RUBBER AND COMPARISON WITH COMPETING
       SYSTEMS                                                   111-10
     SPECIFICATIONS                                              111-12
     RESEARCH NEEDS - ASPHALT-RUBBER                             111-14
     CORPS OF ENGINEERS EXPERIENCE WITH A-R                      111-15
     SUMMARY ASSESSMENT                                          111-18

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     ASPHALT-RUBBER AS A CRACK AND JOINT FILLER                  111-19
          Filler Materials                                       111-20
               Source                                            111-20
               Preparation                                       111-20
               Properties                                        111-21
          Potential Quantity Consumption                         111-21
          Economic Evaluation                                    111-21
          Advantages and Disadvantages                           111-22
          Advantages                                             111-22
          Disadvantages                                          111-23
     CONCLUSIONS                                                 111-23
     REFERENCES                                                  111-24

Part IV - USE OF INCINERATOR RESIDUE IN HIGHWAY CONSTRUCTION     IV-1

     INTRODUCTION                                                IV-1
     BACKGROUND                                                  IV-1
     QUANTITIES OF MATERIALS                                     IV-2
     DESCRIPTION OF MATERIAL                                     IV-11
     PRINCIPAL USES                                              IV-18
          Bituminous Base Courses                                IV-20
          Wearing Surfaces                                       IV-25
          Stabilized Bases  and Sub-bases                        IV-38
          Fused Aggregate                                        IV-42
     TECHNICAL ASSESSMENT OF USES                                IV-45
          Stabilized Base and Sub-base                           IV-47
          Wearing Surfaces                                       IV-48
          Bituminous Base Mixes                                  IV-49
     ENVIRONMENTAL FACTORS                                       IV-51
     ECONOMICS                                                   IV-53
     OTHER APPLICATIONS                                          IV-53
     MISCELLANEOUS                                               IV-54
     SUMMARY                                                     IV-55
     REFERENCES                                                  IV-57

Appendix A - SUPPORT DOCUMENTATION - POWER PLANT ASH             A-l

     MEMORANDUM:  USE OF FLY ASH (FEDERAL HIGHWAY ADMINIS-
       TRATION                                                   A-2
     MEMORANDUM:  USE OF FLY ASH IN PORTLAND CEMENT CONCRETE
       AND STABILIZED BASE CONSTRUCTION  (FEDERAL HIGHWAY
       ADMINISTRATION)                                           A-4
     CIRCULAR LETTER:  CHANGES TO PAVEMENT DESIGN CRITERIA
       (COMMONWEALTH OF PENNSYLVANIA DEPARTMENT OF TRANS-
       PORTATION)                                                A-8
     STATE AND/OR FEDERAL SPECIFICATIONS                         A-12
     STATE OF ILLINOIS - DEPARTMENT OF TRANSPORTATION -
       SPECIAL PROVISION FOR POZZOLANIC BASE COURSE, TYPE A      A-13

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     STATE OF ILLINOIS - DEPARTMENT OF TRANSPORTATION -
       SUPPLEMENTAL SPECIFICATION FOR SECTION 804 POZZOLANIC
       AGGREGATE MIXTURE EQUIPMENT                               A-23
     STATE OF OHIO - DEPARTMENT OF TRANSPORTATION -
       SUPPLEMENTAL SPECIFICATION 835 AGGREGATE LIME-FLY
       ASH BASE                                                  A-26
     STATE OF PENNSYLVANIA - DEPARTMENT OF TRANSPORTATION -
       AGGREGATE-LIME-POZZOLAN  BASE COURSE                      A-29
     FEDERAL AVIATION ADMINISTRATION - NEWARK AIRPORT PROJECT -
       LIME-CEMENT FLY ASH STABILIZED FILL SAND BASE             A-34
     FEDERAL AVIATION  ADMINISTRATION - TOLEDO AIRPORT PROJECT -
       ITEM P-305 AGGREGATE-LIME-FLY ASH SUBBASE OR BASE COURSE  A-44
     APPENDIX VII:  PERMEABILITY TESTS                           A-58

     PATENTS                                                     A-72
          2,564,690 Hydrated Lime-Fly Ash-Fine Aggregate
            Cement                                               A-73
          2,698,252 Lime-Fly Ash Compositions for Stabilizing
            Finely Divided Materials Such as Soils               A-79
          2,815,294 Stabilized Soil                              A-84
          2,937,581 Road Building Method                         A-88
     ASTM STANDARD SPECIFICATIONS AND STANDARD TEST METHODS      A-92
     POZ-0-BLEND - THE SECOND GENERATION OF POZ-0-PAC            A-93
Appendix B - SUPPORT DOCUMENTATION - KILN DUST                   B-l

     PATENTS
          4,018,617 Mixture for Pavement Bases and the Like      B-2
          4,038,095 Mixture for Pavement Bases and the Like      B-13
          4,101,332 Stabilized Mixture                           B-20

Appendix C -  SUPPORT DOCUMENTATION - ASPHALT RUBBER             C-l

     ARIZONA DEPARTMENT OF TRANSPORTATION - SPEC 4010821 -
       STRESS-ABSORBING MEMBRANE (SEAL)                          C-2
     ARIZONA DEPARTMENT OF TRANSPORTATION - SPEC 4010721 -
       STRESS-ABSORBING MEMBRANE (INTERLAYER)                    C-ll
     PENNSYLVANIA DEPARTMENT OF TRANSPORTATION - OPEN
       GRADED RUBBERIZED ASPHALT FRICTION COURSE (SRL-H
       RECLAIMED)                                                C-18
     ARIZONA REFINING COMPANY - SPECIFICATION FOR ARM-R-
       SHIELD (TM)                                               C-22
     ARIZONA REFINING COMPANY - CONSTRUCTION SPECIFICATION
       FOR ARM-R-SHIELD (TM) STRESS ABSORBING MEMBRANE
       INTERLAYER                                                C-26

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     ARIZONA REFINING COMPANY - CONSTRUCTION SPECIFICATION FOR
       ARM-R-SHIELD (TM) SURFACE TREATMENT                       C-33
     SAHUARO PETROLEUM & ASPHALT CO. GUIDE SPECIFICATIONS FOR
       ASPHALT RUBBER FOR STRESS ABSORBING TREATMENTS (SAM OR
       SAMI)                                                     C-40
     ARIZONA REFINING COMPANY - SPECIFICATION FOR ARM-R-
       SHIELD-CF                                                 C-50
     GENSTAR CONSERVATION SYSTEMS INC. - DESCRIPTION OF
       GENSTAR TIRE RECYCLING PROCESS                            C-51
     ARM-R-SHIELD CUTS RESURFACING COSTS IN HALF, SAVES ENERGY,
       CONSUMES OLD TIRES                                        C-55

Appendix D - DATA AND CALCULATION - ESTIMATES OF ENERGY AND
       ENVIRONMENTAL IMPACTS OF SELECTED HIGHWAY CONSTRUCTION
       PRODUCTS AND INSTALLATION                                 D-l

     INTRODUCTION                                                D-l
     STABILIZED AND AGGREGATE BASE COURSE ALTERNATIVES           D-2
     ASPHALT BASE COURSE ALTERNATIVES                            D-6
     ASPHALT RUBBER AS STRESS ABSORBING MEMBRANE INTERLAYER
       (SAMI) OR SEAL COAT                                       D-6
     FLY ASH AS FILL MATERIAL                                    D-8
     DATA AND CALCULATIONS                                       D-9
     FOREWORD                                                    D-10
     INDIVIDUAL COMPONENTS                                       D-ll
     LIMESTONE MINING                                            D-ll
     LIME MANUFACTURE                                            D-12
     CRUSHED STONE                                               D-13
          Crude Oil Production                                   D-15
          Asphalt  Cement Refining                               D-16
          Emulsified Asphalt Cement Production                   D-17
     ASPHALT AGGREGATE                                           D-18
     SAND MINING                                                 D-18
     PORTLAND CEMENT                                             D-19
     FLY  ASH/BOTTOM ASH                                         D-21
     LIME/CEMENT KILN DUST                                       D-23
     INCINERATOR RESIDUE                                         D-24
     GROUND RUBBER                                               D-25
     PRODUCT MIXTURES                                            D-32
     SPECIFIC APPLICATIONS OF PRODUCTS  FOR  HIGHWAY  AND  ROAD
        CONSTRUCTION                                             D-32
     BATCHING, SPREADING, AND COMPACTING                         D-33

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                                                                 Page

     STABILIZED BASE COURSE                                      D-35
     ASPHALT BASE COURSE                                         D-43
     ASPHALT SEAL COATS                                          D-48
     STRESS ABSORBING MEMBRANE/INTERLAYER                        D-53
     REFERENCES                                                   D_58


Appendix E - LEACEAIE EXTRACTION AND EVALUATION                  E-l

     METHOD FOR LEACHING OF HIGHWAY CONSTRUCTION PRODUCTS
       CONTAINING RECOVERED MATERIALS                            E-2
          EP Toxicity Test Procedure, Federal Register/
            Volume 45, No. 98/Monday, May 19,1980/Rules
            and Regulations/ p. 33127                            E-7
          Results of Leachate Tests (Letter from R. Collins
            to W. Kline)                                         E-12

Appendix F - SUMMARY OF QUESTIONNAIRE RESPONSES                  F-l

     ASSESSMENT OF RECOVERED MATERIAL USE BY STATE               F-2
     SUMMARY OF RECOVERED MATERIALS QUESTIONNAIRE                F-3

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                              LIST OF TABLES
1-1       Production of Power Plant Ash in The United States
            Since 1970                                           1-2
1-2       Quantities of Utility Coal Burned and Total Ash
            Produced in 1978 by State                            1-5
1-3       Normal Range of Chemical Composition of Fly Ashes
            from Different Types of Coals                        1-11
1-4       Physical Properties of Fly Ash from Different Sources  1-12
1-5       Development of Shear and  Compressive Strength
            Characteristics of Compacted Fly Ash Over Time       1-21
1-6       Summary of Laboratory Test Results from Leachate
            Extraction Analyses of Fly Ash Samples               1-27
1-7       Comparison of Fly Ash Embankments with Conventional
            Soils                                                1-29
1-8       Estimated Annual Production of Lime-Fly Ash-Aggregate
            Base Material in the United States                   1-37
1-9       Aggregate Specification Requirements for Lime-Fly Ash-
            Aggregate Base Course Mixtures Used by Various State
            Transportation Agencies and the Federal Aviation
            Administration                                       1-41
1-10      Recommended Minimum Thicknesses for Asphalt Surfaces
            Using Different Base Course Materials in Different
            Applications                                         1-56
I-11      Three State Comparison of Flexible Pavement Thickness
            Designs                                              1-58
1-12      Summary of Bid Prices for Base Course Alternates
            in Illinois                                          1-86
1-13      Three-State Comparison of Pavement  Base Course Costs  1-92
1-14      States Having Potential or Actual Use of Lime-Fly
            Ash-Aggregate                                        1-96
1-15      Engineering Characteristics of Cement-Stabilized
            Fly Ash Mixes Using Different Fly Ash Sources        1-109
1-16      Physical Properties of Mineral Fillers                 1-128
1-17      Marshall Design Criteria                               1-129
1-18      Results of Marshall Tests on Bituminous Mixtures
            Containing Various Mineral Fillers                   1-131
1-19      Comparison of Fly Ash Characteristics with Appli-
            cable Specification Requirements for Mineral
            Filler in Asphalt                                    1-133
1-20      Annual  Production of Power Plant Aggregates in the
            United States Since 1970                             1-137
1-21      Chemical Analysis of Selected Bottom Ash and
            Boiler Slag Samples                                  1-138
1-22      Summary of Engineering Properties of Selected
            Bottom Ash and Boiler Slag Samples                   1-142

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          Standard Aggregate Test Properties of Selected
            Bottom Ash and Boiler Slag Samples                   1-143
          Utilization of Bottom Ash and  Boiler Slag             1-144
          Comparison of West Virginia Department of Highways
            Requirements for Class 2 Crushed Aggregate Base
            Course with Typical Properties of Fort Martin
            Bottom Ash                                           1-146
1-26      Comparison of West Virginia Department of Highways
            Requirements for Class 1 Crushed Aggregate Base
            Course with Typical Properties of Blended Mitchell
            Bottom Ash - Blast Furnace Slag                      1-148
1-27      Cost Elements of Comparative Base Systems              1-154
1-28      Cost Comparison for Some Equivalent Base Systems
            16' Wide                                             1-155
1-29      Marshall Test Data for Power Plant Aggregate
            Prepared by Drop Hammer or Kneading Compactor        1-159
1-30      Comparison of Marshall Test Results for Selected
            Bottom Ash Samples Prepared by Drop Hammer or
            Kneading Compactor                                   1-163
1-31      Different Types of Mixes and the Optimum Asphalt
            Content of Each Mix                                  1-164
I-31A     Comparison of Boiler Slag-Aggregate Wearing Sur-
            face Mixtures to West Virginia Department of
            Highways Wearing Course III Requirements             1-175
1-32   .   Cost Comparison Wet Bottom Boiler Slag Seal Coats
            Vs. 5/8" Crushed Lime Stone Seal Coats               1-176

II-l      Chemical Composition of Cement Kiln Dust               II-2
II-2      Particle Size Analysis of a Typical Cement Kiln Dust   II-3
II-3      Chemical Composition of Lime Kiln Dust                 II-4
II-4      Particle Size Analysis of a Typical Lime Kiln Dust     II-5
II-5      Cement Producing Plants in the United States           II-8
II-6      Commercial Lime Plants in the United States            II-9
II-7      Laboratories and/or Consultants that Contributed
            Laboratory Data on Kiln Dust Compositions            11-13
II-8      Sources of Cement Kiln Dust Used in Laboratory
            Testing                                              11-14
II-9      Compressive Strengths of CKD-Fly Ash-Aggregate
            Compositions Showing Curing Temperature Effects      11-18
11-10     Freeze-Thaw Resistance of CKD Compositions as
            Measured by the Compressive Strength of Vacuum
            Saturated Specimens                                  11-22
11-11     Autogenous Healing of Laboratory Specimens
            Containing CKD                                       11-24
11-12     Compressive Strengths of LKD-Fly Ash-Aggregate
            Compositions                                         11-25

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Table                                                            Page

11-13     Freeze-Thaw Test Data                                  11-27
11-14     Data on Field Installations - CKD Road Base
            Compositions                                         11-29
11-15     Compressive Strength of Specimens from Field
            Installations                                        11-30
11-16     Compressive Strengths of Field Samples                 11-31

III-l     History of the  Development of Asphalt-Rubber          III-2
III-2     Comparison of Asphalt-Rubber Products                  III-6
III-3     Summary of Performance of Field Test Sections -
            Corps of Engineers Waterways Experimental Station    111-16

IV-1      List of Currently Operating Municipal Incinerator
            Plants - 1980                                        IV-4
IV-2      List by State of Quantities and Type of Residue,
            Operating Plants                                     IV-13
IV-3      Tabulation of Quantities of Types of Residues Produced IV-14
IV-4      Design Gradation for Philadelphia Test Section Paving
            Mix in Percent Passing by Weight                     IV-28
IV-5      Design Gradation for Harrisburg Test Section Paving
            Mix in Percent Passing by Weight                     IV-31
IV-6      Design Gradation for Delaware County Test Section
            Paving Mix                                           IV-3 5
IV-7      Field Density Test Results - Demonstration Site        IV-41
IV-8      Summary of Skid Resistance Values Philadelphia Test
            Section                                              IV-50

D-l       Stabilized and Aggregate Base Course Alternatives      D-3
D-2       Asphalt Base Course Alternatives                       D-7
D-3       Stress Absorbing Membrane Interlayer  (SAMI)
            Alternatives                                         D-7
D-4       Data for Mining 1,000 Pounds Limestone                 D-12
D-5       Data for the Manufacture of 1,000 Pounds Lime          D-13
D-6       Data for Production and Installation of 1,000
            Pounds of Crushed Stone                              D-14
D-7       Data for the Production of 1,000 Pounds Crude Oil      D-15
D-8       Data for Refining 1,000 Pounds of Asphalt Cenent       D-16
D-9       Data for 1,000 Pounds of Emulsified Asphalt Cement     D-17
D-10      Data for Production of 1,000 Pounds of Asphalt
            Aggregate                                            D-18
D-ll      Data for Mining 1,000 Pounds Sand                      D-19
D-12      Data for Production of 1,000 Pounds of Portland
            Cement                                               D-21
D-13      Data for Conditioning and Transporting 1,000 Pounds
            of Fly Ash                                           D-22
D-14      Data for 1,000 Pounds Dry Bottom Ash or Boiler Slag    D-23
D-15      Data for Delivering 1,000 Pounds of Lime or Cement
            Kiln Dust                                            D-24

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          Data for Processing and Delivering 1,000 Pounds of
            Incinerator Residue                                  D-25
D-17      Data for Producing 1,000 Pounds of Granulated Rubber   D-26
D-18a     Detailed Air and Water Pollutants Resulting from
            the Production of Highway Road Construction
            Materials                                            D-27
D-18b     Detailed Air and Water Pollutants Resulting from
            the  Production of Highway Road Construction
            Materials                                            D-28
D-18c     Detailed Air and Water Pollutants Resulting from
            the Production of Highway Road Construction
            Materials                                            D-29
D-18d     Detailed Air and Water Pollutants Resulting from
            the Production of Highway Road Construction
            Materials                                            D-30
D-18e     Detailed Air and Water Pollutants Resulting from
            the Production of Highway Road Construction
            Materials                                            D-31
D-19      Data for Batching, Spreading, and Compacting 1,000
            Pounds of Pozzolanic Mixtures                        D-33
D-20      Data for Batching.1,000 Pounds Asphalt Concrete        D-34
D-21      Data for Batching 1,000 Pounds Asphalt Rubber          D-35
D-22      Energy and Environmental Profiles Summary              D-36
D-22a   .  Energy and Environmental Profiles for 24,000
            Square Feet of Stabilized Base Course Materials      D-38
D-22b     Energy and Environmental Profiles for 24,000 Square
            Feet of Stabilized Base Course Materials             D-40
D-22c     Energy and Environmental Profiles for 24,000 Square
            Feet of Stabilized Base Course Materials             D-41
D-22d     Energy and Environmental Profiles for 24,000 Square
            Feet of Stabilized Base Course Materials             D-42
D-23      Energy and Environmental Profiles Summary              D-44
D-23a     Energy and Environmental Profiles for 24,000 Square
            Feet of Asphalt Base Course Materials                D-46
D-23b     Energy and Environmental Profiles for 24,000 Square
            Feet of Asphalt Base Course Materials                D-47
D-24      Energy and Environmental Profiles Summary              D-49
D-24a     Energy and Environmental Profiles for 24,000 Square
            Feet of Seal Coat Materials                          D-51
D-24b     Energy and Environmental Profiles for 24,000 Square
            Feet of Seal Coat Materials                          D-52
D-25      Energy and Environmental Profiles Summary              D-54
D-25a     Energy and Environmental Profiles for 24,000 Square
            Feet of Stress Absorbing Membrane Materials          D-56
D-25b     Energy and Environmental Profiles for 24,000 Square
            Feet of Stress Absorbing Membrane Materials          D-57

-------
                              LIST OF FIGURES

Figure

1-1       Locations of power plant ash                           1-3
1-2       Total 1978 ash production according  to state           1-4
1-3       Particle size distribution of fly ash                  1-8
1-4       Chemical composition of bituminous coal fly ash        1-9
1-5       Particle size distribution of fly ash compared with
            gradation limits of normally frost-susceptible
            soils                                                1-14
1-6       Moisture-density relationships for western Pennsyl-
            vania bituminous coal fly ashes                      1-18
1-7       Moisture-density relationships for Michigan bitum-
            inous coal fly ashes                                 1-19
1-8       Comparison of consolidation rates of fly ash and
            silty clay soils                                     1-23
1-9       Compressive strength development of  a lime-fly ash-
            aggregate mixture in the Chicago area                1-44
1-10      Flexural fatigue behavior of lime-fly ash-aggregate
            material                                             1-47
1-11      Standard freeze-thaw cycle for Illinois                1-50
1-12      Residual strength concept for lime-fly ash-aggregate
            mixtures                                             1-60
1-13      Projected compressive strength developments of lime-
            cement-fly ash-aggregate composition at Newark Air-
            port project                                         1-77
1-14      Compressive  strength vs. degree-days for LFA mix
            at Toledo Airport project                            1-83
1-15      Most probable areas of lime-fly ash-aggregate base
            course commercialization                             1-95
1-16      Variation in 7-day compressive strength developments
            with cement content for cement-stabilized fly ash
            mixtures using different sources of fly ash          1-110
1-17      Moisture-density relationships of design mixes         1-112
1-18      Base course thickness design chart                     1-114
1-19      Relationship between initial and adjusted base
            course thicknesses for cement-stabilized fly ash
            base materials                                       1-115
1-20      Comparison of alternative pavements                    1-120
1-21      Typical particle size distribution for selected
            bottom ash samples                                   1-139
1-22      Typical particle size distribution for selected
            boiler slag samples                                  1-141
1-23      Marshall curves for Mitchell plant surface course
            mixtures                                             1-165
1-24      Relationship between ash content and Marshall
            properties, Mitchell plant sufrace course mixtures   1-166

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Figure                                                           Page

1-25      Marshall curves for Rockdale ash surface course
            mixtures                                             1-167
1-26      Relationship between ash content and Marshall
            properties, Rockdale ash surface course mixtures     1-168
1-27      Marshall curves for Mitchell plant base course
            mixtures                                             1-170
1-28      Relationship between ash content and Marshall
            properties, Mitchell plant base course mix           1-171

II-l      Compressive strength of cement dust-fly ash-
            aggregate mixtures                                   11-16
II-2      Compressive strength of pozzolanic mixtures
            containing cement kiln dust, fly-ash & aggregates    11-17
II-3      Report of Proctor curve                                11-20
II-4      Compressive strength vs. age at test                   11-23
II-5      History of cylinders with 10 percent fly ash and
            8 percent lime (precipitator dust)                   11-28

IV-1      Location of currently operating municipal incin-
            erator plants                                        IV-3
IV-2      Particle size distribution of "as received" incin-
            erator residues                                      IV-17
IV-3      Average particle size distribution of graded
            incinerator residues                                 IV-19
IV-4      Particle size distribution of littercrete base used
            in Houston test section                              IV-22
IV-5      Particle size distribution of mix design used in
            Washington, D.C. test section                        IV-24
IV-6      Particle size distribution of mix design used in
            the Baltimore, Maryland test section                 IV-26
IV-7      Particle size distribution of wearing surface mix
            used in Philadelphia test section                    IV-29
IV-8      Particle size distribution of wearing surface mix
            used in Harrisburg test section                      IV-32
IV-9      Particle size distribution of wearing surface mix
            used in Delaware County test section                 IV-36
IV-10     Gradation range of weekly samples from 39th & Iron
            St. incinerator, Chicago, Illinois                   IV-40
IV-11     Particle size distribution of wearing surface mix
            used in Harrisburg fused aggregate test section      IV-44

D-l       Materials and process flow diagram for the manu-
            facture of 1,000 pounds of portland cement           D-20
D-2       Materials flow for stabilized or aggregate base
            course alternatives                                  D-39

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Figure                                                           Page

D-3       Materials flow for asphalt base alternatives           D-45
D-4       Materials flow for seal coat alternatives              D-50
D-5       Materials flow for SAM or SAMI                         D-55

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                                  Part  I

                              POWER PLANT  ASH
INTRODUCTION

          The residual materials collected from the burning  of  coal at  electric
utility plants are referred to as power plant ash.   These materials are produced
in two forms:  fly ash and bottom ash.   Fly ash is  the fine-grained dusty mater-
ial from the combustion of ground or powdered coal  that is recovered from boiler
flue gases by means of electrostatic or mechanical  collection systems.   Bottom
ash is the granular material which, after coal combustion, collects in  the ash
hopper at the base of the boiler unit.

          The relative amounts of fly ash and bottom ash produced at a  partic-
ular power plant location are determined mainly by  the design of the boiler
units.  However, as a general rule, 70 percent or more of all power plant ash
is fly ash.  Although fly ash and bottom ash are collected separately,  at many
power plants these materials are mixed together for storage  or disposal.

FLY ASH

Production and Handling

          The production of fly ash  has increased tremendously over the past
15 years as more  coal-burning power plants come on line and ash collection
methods improve.  Ash collection and utilization statistics compiled by the
National Ash Association show that fly ash production has tripled between 1966,
the first year the association began collecting data, and 1979.  In 1966, 17.1
million tons of fly ash was collected, while in 1979, the most recent year that
statistics are available, a total of 57.5 million tons of fly ash was collected
(Reference I-l).as shown in Table 1-1.

          Fly ash is currently being produced at a total of 380 coal-burning
power plants located in 39 states.  The locations of all existing coal-fired
power plants in the United States are shown in Figure 1-1.  Estimated quanti-
ties of total ash produced in 1978 in each state are shown in Figure 1-2.
These quantities were determined based on 1978 consumption of coal by electric
utility companies in each state, as shown in Table 1-2.  No attempt was made
to further determine amounts of fly ash produced in each  state because the
respective quantities of fly ash and bottom ash at each plant vary depending
on plant design, operation, and other factors.  From Figure 1-2, it is evi-
dent that half of all ash which is now being generated in the United States
is found in the six largest ash-producing states (Ohio, Pennsylvania, Illinois,
Indiana, Kentucky, and West Virginia).
                                     1-1

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                                 Table 1-1

                     PRODUCTION OF POWER PLANT ASH IN


THE UNITED
STATES SINCE 1970
(Millions of tons)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
Fly
Ash
26.5
27.8
31.8
34.6
40.4
42.3
42.8
48.5
48.3
57.5
Bottom
Ash
9.9
10.1
10.7
10.8
14.3
13.1
14.3
14.1
14.7
12.5
Boiler
Slag
2.8
5.0
3.8
3.9
4.8
4.6
4.8
5.2
5.1
5.2
Total
Ash
39.2
42.9
46.3
49.3
59.5
60.0
61.9
67.8
68.1
75.2
Note:  In 1978, a total of 8.4 million tons of fly ash was utilized,
       representing 17.4 percent of the 48.3 million tons of fly ash
       produced.  This is the highest percentage of ash utilization
       in any one year so far.  Replacement of portland cement in
       concrete mixes is the largest single use of fly ash.
                                     1-2

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I
CO
                                                                  TEXAS
             Figure 1-1.  Locations of power plant ash.

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                                                        Table  1-2

                       QUANTITIES OF  UTILITY  COAL  BURNED  AND  TOTAL ASH PRODUCED IN  1978  BY  STATE
Ul
                State
 1.  Alabama         9
 2.  Arizona         2
 3.  Colorado        9
 4.  Delaware        2
 5.  Florida         6
 6.  Georgia         8
 7.  Illinois       27
 8.  Indiana        26
 9.  Iowa           22
10.  Kansas          6
11.  Kentucky       19
12.  Maryland        5
13.  Michigan       24
14.  Minnesota      18
15.  Mississippi     2
16.  Missouri       18
17.  Montana         3
18.  Nebraska        4
19.  Nevada          2
20.  New Hampshire   1
(Thousands of tons)
Number
of
Plants
Utility
Coal
Burned
Total
Ash
Produced
Number
of
State Plants
Utility
Coal
Burned
Total
Ash
Produced
17,100
7,560
5,680
1,170
8,630
15.620
35,780
29,280
6,730
6,350
26,880
4,230
25,190
12,400
1,450
21,750
1,720
2,220
5,140
750
2,394
1,058
795
162
1,208
2,187
5,009
4,100
942
890
3,763
592
3,527
1,736
203
3,045
241
311
719
105
21.  New Jersey      4
22.  New Mexico      2
23.  New York       10
24.  North Carolina 13
25.  North Dakota    5
26.  Ohio           32
27.  Oklahoma        1
28.  Pennsylvania   27
29.  South Carolina  9
30.  South Dakota    3
31.  Tennessee       8
32.  Texas           6
33.  Utah            4
34.  Vermont         1
35.  Virginia        6
36.  Washington      1
37.  West Virginia  12
38.  Wisconsin      18
39.  Wyoming       	5.
2,220
8,820
6,350
21,690
8,020
53,310
600
40,340
6,860
2,360
21,700
9,780
2,490
10
4,830
5,410
27,740
11,310
11,380
311
1,235
890
3,037
1,123
7,463
84
5,648
960
330
3,038
1,369
349
2
676
757
3,884
1,583
1,593
                                                                    TOTAL
                                                                             380
                               480,850
67,319
         Note:  Fly  ash  (fly   ash and  bottom ash)  quantities determined by assuming 14  percent  ash content  for  all
                utility  coal burned.

-------
          According to the most recently published figures, a total of 255
new coal-fired power plants are expected to come on line in the United States
by  1987.  Of  this total, 164 plants are expected to be completed by 1985.
These 164 plants will be built in 36 states, including 4 states (Arkansas,
California, Louisiana, and Oregon) that do not presently have any coal-fired
plants (Reference 1-2).  Based on projected new plant construction and planned
conversions from oil to coal, it is estimated that the total amount of fly ash
that  will be generated in 1985 will be 90 million tons (Reference 1-3).

          Not all fly ash is the same.  The quantity and quality of fly ash is
influenced by the source of the coal burned, the basic design of the coal-fired
boiler, and the means used to collect the fly ash.  Most of the coal mined and
burned in the United States is bituminous coal, but ashes from anthracite coal
tend to have higher carbon content, while ashes from lignite and sub-bituminous
coals have a much higher percentage of calcium oxide.  The physical and chem-
ical characteristics of fly ash are discussed in greater detail in the follow-
ing section of this report.

          There are three basic types of coal-burning boilers:  stoker-fired,
cyclone-fired, and pulverized coal-fired units.  Stoker-fired units generally
produce a comparatively coarse fly ash, the amount varying depending on whether
the stoker is a traveling grate or spreader type.  With cyclone or slagging
boilers, from 0 to 65 percent of the fly ash is released into the flue gases
and collected.  Most of the fly ash produced in cyclone units melts and is
collected with the bottom ash as a slag at the base of the furnace.  In pul-
verized coal-fired units, finely ground coal is burned in suspension, causing
the fly ash to enter the stream of flue gases for eventual removal either by
mechanical collectors or electrostatic precipitators (Reference 1-4).

          After collection, the quality of fly ash is further influenced by
the techniques used at the power plant for ash handling and storage.  To some
extent, ash handling and storage techniques are related to power plant design,
but are also influenced by utility practice and available land.  Basically,
ash handling and storage is accomplished either by wet or dry methods.  At
least 50 percent of all ash currently produced is handled dry.  Dry methods
involve short-term storage of fresh ash from the precipitator in hoppers or
long-term storage of the dry ash in silos.  Dry ash can be discharged through
gates or pneumatically into  transport vehicles.

          Wet handling of fly ash involves adding a certain quantity of water
to the fly ash, which puts it in either a conditioned or ponded form.  Con-
ditioned fly ash results from the addition of small amounts of water (20
percent or less by  weight) sufficient to prevent dusting of the fly ash and
enable it to be stockpiled in large quantities. Ponded fly ash results from
the  addition of large amounts of water to produce a slurry and enable trans-
port of the ash by pipeline to settling ponds or lagoons.  At many power
plants, fly ash and bottom ash are collected and disposed of together in the
same lagoon, although a power plant may employ more than one means of ash
collection and storage (Reference 1-5).
                                     1-6

-------
Physical and Chemical Properties

          Not only are there differences in the fly ash from different coal
sources and power plants, but  there is also a certain amount of variability
in the ash from a single power plant.  Normally, fly ash is gray in color,
although the color can range from cream to light tan, through various shades
of  gray, to dark brown and nearly black.  The cream color is usually indica-
tive of high calcium oxide content.  The tan color is usually attributed to
the presence of iron oxide, while the darker colors are most often associated
with an increasing presence of carbon.

          Fly ash is composed of fine particles that are predominantly
spherical in shape, solid or hollow, and of a glassy or amorphous nature.
The carbon content in ash is composed of angular particles.  The particle
size distribution of most bituminous coal  fly ashes, as shown in Figure 1-3,
lies essentially within the range of a silt (Reference 1-6).  Particle sizes
for glassy spheres in bituminous fly ash vary from 10 to 300 microns (Ref-
erence 1-7).  In general, lignite  and sub-bituminous coal fly ashes are
coarser than bituminous coal fly ashes.

          The specific gravity of fly ash usually ranges from 2.1 to 2.6,
while Elaine fineness values vary2from 1,700 cm2/gm for fly ashes from
mechanical collectors to 6,400 cm /gm for fly ashes from electrostatic
precipitators.  As a general rule, fly ash from mechanical collectors is
normally coarser than fly ash from electrostatic precipitators.  The water
soluble content for bituminous fly ash is from 1 to 7 percent.  The leachate
from most fly ashes is alkaline with  a pH ranging from 6.2 to 11.5.  Com-
pacted dry densities of fly ash are generally from 70 to 95 pounds per cubic
foot, with the lower densities often attributable to higher carbon content
(Reference 1-8).

          Chemically, the principal components of bituminous coal fly ash are
silica, alumina, iron oxide, lime, and magnesia, with varying amounts of car-
bon, as measured by loss on ignition. Figure 1-4 shows the range of chemical
constituents found in typical bituminous coal fly ashes (Reference 1-9).  The
composition of fly ashes from the western (lignite and sub-bituminous) coals,
or fly ashes produced from limestone or dolomite injection processes, are
often significantly different from bituminous fly ashes.  Lignite and sub-
bituminous fly ashes are characterized by higher concentrations of calcius
and magnesium oxide and reduced percentages of silica and iron oxide, as veil
as a lower carbon content.  Modified fly ash from limestone and dolomite in-
jection processes, as expected, have significantly higher lime and magnesia
content.  The western and the modified fly ashes also have a much higher water
soluble content than bituminous fly ashes (Reference 1-10).
                                     1-7

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 Cleor Square
Openings, inches
 3
                                Number US. Standard     Time, mirutes
                                      Series
                                     a040_8020pl_4j6_60_BO_l«40
                   )   «**»•	1
                   lCOk«CI  fiK  I'
                                     1.0       0.1       0.01
                                     Portide Diotneter, mm
                                      S*MO      1  SIT AND CL«T
                                              0.001
      O.OOOI
       I^FIK lCO»«£ I MEDIUM TFWe
CLAY
Figure 1-3.   Particle size distribution of  fly ash.
                                             1-8

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•)
«n


O
o
a
o



v
CoO




MgO




SO.
   NQjO
   OTHER



   LOSS-ON

   IGNITION

                                                               LEGEND
                              3O     40    SO     60    70



                                  Concentrofion, Percenf
                                                            80
9O
100
  Figure 1-4.   Chemical composition of bituminous  coal  fly ash.
                                         1-9

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          Table 1-3 compares the normal range of chemical composition of
bituminous coal fly ash with that of lignite and sub-bituminous coal fly
ashes.  From this table, it is evident that lignite and sub-bituminous
coal fly ahses have much higher free lime content and lower loss on ig-
nition characteristics than fly ashes from bituminous coals (Reference 1-11).

          Although the use of fly ash in portland  cement concrete is not
being considered in this report, classification of fly ash for this purpose
may be of some use in identifying basic chemcial differences between fly
ashes from different types of coal.  There are three different classifica-
tions of fly ash, according to ASTM C618-80, "Fly Ash and Raw or Calcined
Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete,"
which is included in the Appendix of this report.  These classifications are
defined in the specification as follows:

          1.  Class N - raw or calcined natural pozzolans that
              comply with the applicable requirements for the
              class, such as some diatomaceous earths, opaline
              cherts and shales; tuffs and volcanic ashes or
              pumices, any of which may or may not be processed
              by calcination; and various material requiring
              calcination to induce satisfactory properties,
              such as some clays and shales.

          2.  Class F - fly ash normally produced from burning
              anthracite or bituminous coal that meets the ap-
              plicable requirements for this class.  This class
              of fly ash has pozzolanic properties, which will
              be explained later in this report.

          3.  Class C - fly ash normally produced from lignite
              and sub-bituminous coal that meets the applicable
              requirements for this class.  In addition to having
              pozzolanic properties, Class C fly ash also has
              some cementitious properties.  Some Class C fly
              ashes may contain lime contents higher than 10
              percent.

          The chemical requirements for these three classes of fly ash are
presented in ASTM C618 as follows:
     Chemical Composition
SiO.
         23
                     - min. ,
Sulfur trioxide (SO,) - max.,  %

Moisture content - max., %

Loss on ignition - max., %
Mineral Admixture Class


70.0      70.0     50.0

 4.0       5.0      5.0

 3.0       3.0      3.0

10.0      12.0      6.0
                                     1-10

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                                 Table 1-3

                  NORMAL RANGE OF CHEMICAL COMPOSITION OF
                  FLY ASHES FROM DIFFERENT TYPES OF COALS
                    Bituminous     Sub-bituminous     Lignite

Si02                 20 to 60         40 to 60        15 to 45

A1203                 5 to 35         20 to 30        10 to 25

Fe?0                 10 to 40          4 to 10         4 to 15
  te -J

CaO                   1 to 20          5 to 25        15 to 35

MgO                   0 to 5           1 to 6          3 to 10

SO.                   0 to 4           0 to 2          0 to 10

Na 0                  0 to 4           0 to 2          0 to 6

L.O.I.                0 to 20          0 to 3          0 to 5
(Loss on Ignition)
          In terms of quality control for use in highway construction, the
most significant fly ash properties are  fineness, as measured by the -325
mesh sieve, and loss on ignition.  Also of importance are the specific grav-
ity and surface  area, although  the latter is no longer part of ASTM C618.
Table 1-4 summarizes these physical properties for a number of bituminous
and western coal fly ash samples.

Utilization of Fly Ash in Highway  Construction

          Over the years, fly ash has proven an extremely useful material.
Its principal use at the present time is a partial replacement for portland
cement in  the production of concrete and concrete block.  Fly ash has also
been used in substantial quantities as a highway construction material.  Its
main applications have been as a road fill material, as a stabilization agent
for highway and parking lot base courses, and as a filler in asphalt paving
mixes.
                                     1-11

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                      Table 1-4




PHYSICAL PROPERTIES OF FLY ASH FROM DIFFERENT SOURCES
Plant Source:

Location:

Ash Type:
Physical
Properties
Ignition
Loss (Z)
Specific
Gravity
Ft. Martin

Maldsvllle,
W. Va.
Bltlainous



1.2

2.39
Albright

Albright,
W. Va.
Bituminous



2.0

2.12
Hat field' s
Ferry
Mason town,
Pa.
Bituminous



3.1

2.34
Hawthorn

Kansas City,
Mo.
Bituminous



2.6

2.57
Meramec

St. Louis,
Mo.
Bituminous



2.6

2.43
Leland
Olda
Stanton,
N.D.
Lignite



0.3

2.77
Four
Corners
Fruit land,
N.M.
Sub-bit.



0.2

1.67
Big
Brown
Falrfleld,
Tx.
Lignite



0.4

2.44

Mohave
Laughlin,
He.
Sub-bit.



0.7

2.24
Hoot
Lake
Fergus
Falls
Lignite



1.9

2.58
J.E.
Corette
Billings,
Mt.
Sub-bit.



0.5

2.48
Percent Retained
0325 Mesh Sieve
Surface Area
(cm2/cm3)
15.9

2,404
18.9

1,980
12.0

2,456
20.8

2,470
15.2

3,701
27.7

2,606
44.9

1,777
19.2

2,101
10.0

9,115
12.7

6,435
11.2

7,802

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          This section of the report discusses in detail the quantities of
fly ash used in these applications, the properties of fly ash that make it
suitable for each use, technical factors associated with such uses, and the
performance of selected highway projects in which fly ash has been used in
these applications.

          Structural Fill and Backfill.  The earliest documented use of fly
ash as a structural fill material occurred in Great Britain during  the late
1950s.  After repeated field trials, the use of fly ash, or pulverized fuel
ash, as it is known in England, has become more or less standard practice
on British highway projects.  Over the years, a number of other European
countries (such as France, Germany,  Poland) have also begun utilizing sig-
nificant portions of their fly ash in the construction of roadway fills and
embankments.

          In the United States, however, there has to date been very limited
use of fly ash for highway fill material, despite the comparatively large
quantities of fly ash that exist in many parts of this country.  This is
probably due in large part to the lack of familiarity many highway engineers
possess concerning fly ash and some of its unique engineering properties.

          Engineering Properties of Fly Ash as Fill Material.

               Frost Susceptibility.  As noted previously, fly ash is pre-
dominantly a silt-size non-plastic material.  As such, its particle size
distribution falls essentially within normally recognized limits for frost-
susceptible soils, as shown in Figure 1-5 (Reference 1-12).  This apparent
frost susceptibility of fly ash may be one of the principal reasons why most
highway engineers in the United States are reluctant to use fly ash as a fill
material.  However, this objection can be overcome by restricting the use of
fly ash in embankments to depths below that normally expected for frost pene-
tration and covering the fly ash with non-frost  susceptible soil.  Alterna-
tively, fly ash within the frost penetration zone can be stabilized with
either lime or cement to inhibit the effects of damaging frost action.

          Despite the fact that fly ash falls within the grain size of a
frost-susceptible material, particle size distribution alone is not  a fully
reliable indicator of frost susceptibility.  Other factors such as pore size,
permeability, and mineralogy also influence the response of a material to
frost.  Although no frost susceptibility criteria have been established in
the United States, the Road Research Laboratory in England has developed a
test method to evaluate frost susceptibility.  The test method involves sub-
jecting a compacted 6-inch high specimen to freezing temperatures which
simulate actual field conditions.  The test is run over a 250-hour time
period and then the total amount of frost heave of the specimen is measured.
                                     1-13

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                 100
                     LMITS OF
                     FROST SUSCEPTIBLE
                     SOILS.
                                 OJ            00'
                                PARTICLE SEE-MILLIMETERS
                                                             0001
Figure 1-5.   Particle size distribution of fly ash  compared with gradation
              limits of normally frost-susceptible soils.
                                       1-14

-------
          The following criteria have been adopted by the Road Research
Laboratory for the frost susceptibility test:

          1.   Materials considered to be essentially non-frost
               susceptible exhibit a heave of 0.5 inches or less.

          2.   Marginally frost susceptible materials heave be-
               tween 0 . 5 and 0 . 7 inches .

          3.   Frost susceptible materials heave 0.7 inches or
               more (Reference 1-13) .

          Results of frost heave tests performed on a number of fly ash
samples by the Road Research Laboratory have shown that some fine-grained
fly ashes have performed satisfactorily with respect to their frost-heave
characteristics, despite the fact that their particle size distribution is
indicative of frost susceptibility.  However, the fact remains that some
fine-grained fly ashes are frost susceptible and that testing of a partic-
ular source of fly ash prior to its intended use is the only reliable way
to identify the extent of frost susceptibility.  A copy of the Road Research
Laboratories' Frost Susceptibility test method is included in the Appendix
of this report.

          In summary, the possible frost susceptibility of compacted fly ash
for use as borrow or embankment fill material is not as serious a problem as
most engineers are led to believe.  In the first place, the depth of frost
penetration varies with geographical location and is not a major consideration
in some ash-producing regions of the United States.  Secondly, the resistance
of fly ash to frost heaving can be substantially increased by the addition of
cement or lime in moderate amounts (5 to 15 percent by weight) .  Such stabi-
lization increases the tensile strength of the compacted ash, providing added
resistance to heave pressure from ice lenses, and reduces fly ash permeability,
allowing less water to penetrate the ash for later frost formation.  Finally,
objections to the use of fly ash as compacted fill within the frost depth can
be overcome simply by substituting a non-frost susceptible soil for fly ash
within the frost zone.  In Great Britain, for example, the use of frost sus-
ceptible materials is not allowed within 450 mm (approximately 18 inches) of
the road surface (Reference 1-14).
               Moisture-Density Characteristics.  One of the most
considerations of a material to be used in a fill or embankment is proper
compaction.  Fly ash is somewhat of a unique engineering material in terms
of its compaction characteristics.  In dry form, fly ash is cohesionless and
is generally considered a dusty nuisance.  When saturated, it becomes an
unmanageable mess.  But, as with most fine-grained soils, it can be easily
handled and compacted at more intermediate moisture contents, and does ex-
hibit some cohesion.  Conditioned fly ash tailgated over the slope of an
embankment can have a dry density as low as 40 to 50 pounds per cubic foot.
However, when it has been well compacted at an optimum moisture content
(usually between 18 and 30 percent) , the dry unit weight of fly ash may be
in excess of 85 pounds per cubic foot.
                                     1-15

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          The objective of any compacted fill ±s  to achieve the highest
practical densification at a reasonable cost.  In this respect, fly ash
offers some distinct advantages compared to conventional soils, insofar
as it possesses a lower compacted density, thereby reducing the applied
loading and resultant settlement to the supporting subgrade and allowing
for  greater usage of an equivalent amount of fly ash.

          The compaction characteristics of a fill material are defined
by the results of moisture-density tests performed in the laboratory using
standardized testing methods.  The two moisture-density tests used  by Amer-
ican engineers are the standard and modified proctor test methods.  Both
tests involve the compaction of material into a standard size steel mold 4
inches (10.16 cm) in diameter by 4.6 inches  (11.68 cm) high.  The standard
proctor test (ASTM D698 or AASHTO T-99) involves the compaction in three
equal layers using a 5.5 pound (2.5 kg) hammer and a drop of 12 inches, with
a total of 25 blows for each layer.  The modified proctor test (ASTM D1557
or AASHTO T-180) also involves compaction in three equal layers with a total
of 25 blows for each layer, but specifies the use of a 10 pound (4.5 kg)
hammer and a drop of 18 inches.

          A copy of each test method is included in the Appendix.  For each
test method, material is compacted at different moisture contents and the
dry density is determined.  For most materials, there is a level of moisture,
termed the optimum moisture content, at which the compacted dry density
achieves a maximum value.  At moisture levels above or below the optimum,
the dry density is reduced.

          Because of the basic differences in the composition and prpperties
of different fly ashes, there may be considerable variation in the moisture-
density characteristics of fly ashes from different power plants, or even
different samples of fly ash from the same power plant. Such variations are
attributable to changes in compactive effort and the behavior of fly ash to
compaction at different moisture levels.  Consequently, both laboratory and
field compaction tests are recommended for use of any fly ash source as fill
material in order to define the anticipated  range of moisture contents and
dry density values.

          Since fly ash may be delivered to  the field over a wide range of  .
moisture  (depending  upon whether it has been handled in a dry, conditioned,
or ponded state), it is necessary to determine the practical  range of density
values which are associated with such levels of moisture.

          Dry fly ash should be conditioned  to within 4 percent of optimum
moisture content prior to being delivered to  the job site.  Conditioned fly
ash that has been stockpiled may  exhibit considerable variability in mois-
ture  content, depending on its relative location within the stockpile.
Ponded ash  should have a moisture content as close as possible to optimum
following excavation from the  lagoon, especially since ponded fly ash has a
characteristically flat moisture-density curve  (Reference 1-15).
                                      1-16

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          Figure 1-6 shows a range of modified Proctor moisture-density
curves developed from a National Ash Association study of engineering
properties of seven western Pennsylvania bituminous coal fly ashes for
use as structural fill materials (Reference 1-16).  Each ash sample had
a different particle size distribution and specific gravity.  From this
figure, it can be seen that the maximum density of compacted fly ash
varied from 89.0 pounds per cubic foot at an optimum moisture content of
19 percent  to a low of 76.7 pounds per cubic foot at an optimum moisture
content of 29 percent.  Further study of Figure I-'6 shows that compaction
characteristics are not directly related to specific gravity, since the
fly ash with the highest maximum dry density in this study also had the
lowest specific gravity.

          The use of the modified Proctor compaction curves in Figure 1-6
serve to establish approximate limits of a compaction envelope for fly ash.
The area within the compaction envelope defines ranges of achievable density
at corresponding unit weights for a modified Proctor compactive effort, which
is attainable in the field using modern compaction equipment.  Such informa-
tion is of practical value in the field since it is not always possible to
adjust the moisture content of delivered fly ash at the job site.  Using
such a compaction envelope enables an engineer to control the method of
placement and compaction of fly ash in the field to achieve more uniform
density results and achieve a desired percentage of the maximum compacted
density value.

          Figure 1-7 shows modified Proctor moisture-density curves for
four samples of Michigan fly ash.  The maximum dry density values for these
samples ranged from 74 to 96 pounds per cubic foot, while optimum moisture
contents varied from 18 to 32 percent (Reference 1-17).

               Shear Strength.  Development of  shear strength is an essen-
tial characteristic of embankment and fill materials.  The shear strength of
a material is determined by means of the undrained triaxial compression test
(ASTM  D2850 or AASHTO T-234-74).  Shear strength tests conducted on freshly
compacted fly ash samples show that fly ash derives most of its shear strength
from internal friction (Reference 1-18).

          The shear strength of fly ash is affected by the density and mois-
ture content of the test sample.  Remolded triaxial test specimens may be
prepared at any predetermined density and moisture content and, if required,
may also be soaked prior to testing.  Undrained shear strength has been
found to decrease significantly in fly ash samples compacted on the wet side
of optimum moisture content (Reference 1-19), or to less than maximum dry
density.

          Generally, it is not practical nor possible to compact a material
to 100 percent of its maximum dry density in the field.  In most cases, a
minimum compaction of 90 to 95 percent is specified as a more realistic com-
paction limit in the field.  According to  the FHWA Fly Ash Users Manual,
recommended reductions in the laboratory test values for shear strength, ap-
parent cohesion, and angle of internal friction with associated reductions
in compacted density of fly ash are as follows:
                                    1-17

-------
             s _
Figure 1-6.  Moisture-density relationships for western Pennsylvania
             bituminous coal fly ashes.
                                    1-18

-------
              95-
              90-
                   10        IS        20
                    Water content (*)
                            10       20     X      40
                                  Water content (%)
              9C •
              85-
                                             95
15
                           20
                         content

                      ST. C1AI»
                                    25
  IS       20
Water content [TO

TRENTOM
                                                                       25
Figure  1-7.  Moisture-density relationships for Michigan bituminous
              coal  fly ashes.
                                        1-19

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                                      Percentage of Value
                                      at Maximum Density
                                                        Angle of
Percentage of Maximum          Shear         Unit       Internal
	Dry Density	         Strength     Cohesion     Friction

         85                      60           70           80
         90                      75           70           80
         95                   90 to 95        70           80
          One distinct advantage of using fly ash as a fill or embankment
material is its  self-hardening or age-hardening ability.  The age-harden-
ing of fly ash can best be correlated with the amount of free lime present
in the ash.  Most self-hardening fly ashes contain at least 4 to 6 percent
free lime.  Fly ashes tkat have been ponded prior to compaction exhibit much
less age-hardening than conditioned fly ashes.  This is probably because the
water used to convey ash to the lagoon results in agglomerations, uneven dis-
tribution of internal moisture, and largely dissipates the chemical reactions
responsible for age-hardening of fly ash.

          Not all fly ashes possess age-hardening properties.  Most eastern
coal fly ash is not self-hardening, while western coal fly  ash is.  But even
in those fly ashes with little or no age-hardening, there is still an ap-
parent cohesion due to capillary forces produced by pore water (Reference
1-20).  However, this apparent cohesion can be destroyed either by saturation
or complete drying.  Fly ashes possessing self-hardening properties develop a
cohesion resulting from the cementing action which occurs between the fly ash
particles and which increases with age (Reference 1-21).

          The shear strength and compressive strength characteristics of com-
pacted fly ashes have been found to increase over time, particularly if the
fly ash is self-hardening.  Table 1-5 presents data from British fly ashes
used as compacted fill, which clearly shows cohesion and compressive strengths
which double or triple within a three month period (Reference 1-22).

          In the case of western fly ashes, high free lime contents often
necessitate that such ashes be conditioned and stockpiled for a period of
time prior to use to reduce their reactivity.  Neverthelesss, such reactive
fly ashes, even after conditioning and stockpiling, may exhibit age-harden-
ing properties.

               Compressibility.  An embankment or fill material should possess
low compressibility in order to minimize roadway settlements or differential
settlements between structures and adjacent approaches and to maintain to
the maximum extent possible a smooth riding surface.  Available data reported
to date show that settlements within fly ash embankments, either with or with-
out age-hardening properties, have been within acceptable limits and have pro-
vided satisfactory performance.
                                     1-20

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                                                         Table  1-5
                                           DEVELOPMENT OF  SHEAR AND COMPRESSIVE
H

10
H
Age (Days)


     1


     7


    28


    91


   182


   371


   749


 1,230

(3.4 years)
STRENGTH CHARACTERISTICS OF COMPACTED
FLY ASH OVER TIME
Source of Fly Ash

Unit
Cohesion
11
29
32
38
40
42
51
79
Barony
Friction
Angle
38
41
42
42
42
42
45
41
Braehead
Compressive
Strength
45
127
144
171
180
189
246
346
Unit
Cohesion
9
29
32
35
39
43
45
70
Friction
Angle
34
39
41
42
41
40
39
40
Compressive
Strength
34
122
140
157
171
185
189
300
Unit
Cohesion
13
17
20
22
24
25
25
29
Portobello
Friction
Angle
35
41
43
43
43
43
46
44.5
Compressive
Strength
50
75
92
101
111
115
124
138
            Note:   All ash sources  are  located in Great  Britain.   Data initially reported by Sutherland, H. B. (Reference
                   22).   Unit  cohesion  and  Compressive strength data are experienced in pounds per square inch.

-------
          The compressibility of fly ashes with no self-hardening character-
istics is basically similar to the compressibility of a typical cohesive soil.
The compressibility of a material is determined by means of a laboratory con-
solidation test (ASTM D2435), wherein a sample (2-inch diameter by at least
0.5 inch high) is subjected to a series of incremental pressures and the change
in height of the sample is measured after full consolidation at each loading.
The void ratio of the sample is then determined at each pressure.  The slope
of the resultant curves is called the compression index and is a measure of
the compressibility of the material.  A copy of the ASTM consolidation test
method may be found in the Appendix.

          Figure 1-8 shows that consolidation occurs more rapidly in compacted
fly ashes than in clay soils because fly ash has a greater permeability than
clay.  Although a number of factors affect the compressibility of fly ashes
which do not self-harden, the predominant factor in determining the overall
compressibility of such ashes is the initial compacted density (Reference I-
23).

          For fly ashes with self-hardening properties, the time-dependent
phenomena of age-hardening can reduce the time rate of consolidation, as
well as the magnitude of the compressibility.  The results of a study of
the compressibility of compacted fly ashes with age-hardening properties
show that the overall magnitude of settlements in these materials is less
than that which would occur in ordinary soils and is a function of the hard-
ening characteristics of the ash material and the age at which loading is
applied to the compacted material.  This study also indicates that partly
saturated, fly ashes, regardless of whether or not they are self-hardening,
tend to be less compressible than fully saturated samples (Reference 1-24).

               Permeability and Leaching Characteristics.  The permeability
of fly ash which has been compacted to its maximum dry density in accordance
with the standard Proctor method (ASTM D698 or AASHTO T99-74)  has been found
to range from 4x10"^ cm per second to 5x10"^ cm per second (Reference 1-24).
These values were determined by means of the falling head permeability test,
described in U.S. Army Corps of Engineers Manual 110-2-1906, Appendix 7,
Section 4, which is included in the Appendix.

          Despite air void ratios ranging from 8 to 14 percent, these values
represent relatively low permeability rates, comparable to those of a clay
or silty clay soil  (Reference 1-25).  The permeability of a compacted fly
ash embankment material is a function, of the degree of compaction, the ex-
tent of age-hardening of the fly ash, and the grain size distribution of
the material.

          ASTM Subcommittee E-38.06.05 task group on process wastes had
developed a Recommended Practice for Use of Process Waste in Structural
Fill.  This recommended practice describes the physical characteristics
of and procedures for the use of certain process wastes (inorganic by-
                                      1-22

-------
                       (10)
                                                   40
                    AVERAGE
                    CONSOLIDATION OWE
                    STIFF SILTY CLAY
                                                              u
                                                             O
                                                       VERY
                                                       LOOSE
                                                       LOOSE  5
                                          "c
. . 'MEDIUM
'iDENSE
TDENSE  J?
  "VERY
                                                       DENSE
            (00)    0000)    (0,000)

Consdidotion Pressure,  tsf (kPa)
Figure 1-8.   Comparison  of consolidation rates of fly ash and
              silty  clay soil.
                                        1-23

-------
products such as coal combustion wastes, including fly ash) in structural
fill  and similar applications.  This practice also describes structural
and engineering properties of such in-place materials related to structural
integrity and protection of ground and surface water, as well as test pro-
cedures to be used in determining these properties.

          The Recommended Practice has a special provisions section dealing
with handling leachate from process wastes where leachate concentrations ex-
ceed certain levels.  The Special Provisions of the Recommended Practice,
which is found in the Appendix, are:

          •    Materials having an in-place permeability of
               greater than 1 x 10"^ cm/sec. should have an
               appropriate underdrain and permeate collection
               and disposal system.

          •    Materials having an in-place permeability of
               1 x 10" ^ cm/sec, or lower do not require per-
               meate collection systems.

These provisions apply only to process wastes having leachate concentrations
in excess of 100 times Drinking Water Standards.

          The criteria for the Drinking Water Standards and the testing pro-
cedures used in producing and analyzing the leachate for comparison with
these criteria are discussed in  the following paragraphs.

          In order to simulate leachate production, laboratory techniques
have been developed to combine water and waste materials such as ash for a
specific contact period and degree of agitation, separate the ash and water,
and then analyze the water for the presence of trace elements.

          An extraction procedure  (EP) was developed by the U.S. Environ-
mental Protection Agency (EPA) as a means of generating leachate from a
particular material so that the leachate could be analyzed for toxicity as
defined by the hazardous waste regulations of the Resource Conservation and
Recovery Act (RCRA).  A waste material is considered hazardous  if the extract
from the EP has a concentration of any substance listed in The- National In-
terim Primary Drinking Water Standards that is greater than or equal to dme
hundred times that standard.  The following inorganic chemicals and permis-
sible concentrations are listed in the Drinking Water Standards:

                                             Drinking Water Level
               Contaminant                       (mg/l. or ppm)

               Arsenic                                 0.05
               Barium                                  1.00
               Cadmium                                 0.01
               Chormium                                0.05
               Lead                                    0.05
               Mercury                                 0.002
               Selenium                                0.01
               Silver                                  0.05
                                      1-24

-------
          The basic steps involved  in the EPA extraction procedure are
detailed in the hazardous waste guidelines and regulations that were first
published in the December 18, 1978 issue of The Federal Register  and re-
cently updated in the May 19, 1980 issue of The Federal Register.  A copy
of the updated extraction procedure is included in the Appendix.  The ex-
traction procedures involves the following:

          •    A minimum 100 gram sample of the waste material
               is separated in liquid and solid phases by means
               of a filter or a centrifuge.

          •    The liquid portion is refrigerated between 1° and
               5° Centigrade (34° to 41° Fahrenheit) until the
               analysis is performed.

          •    The solid portion must be ground so that it will
               pass through a 3/8 inch (9.55 mm) sieve.

          •    The solid portion of the sample, after grinding,
               is added to 16 times its own weight of deionized
               water.  The solution is adjusted to a pH of 5 and
               the mixture is agitated for 24 hours, using an
               approved shake or extractor apparatus.  During the
               24-hour agitation period, the solution must be
               maintained at a pH of 5 by adding 8.5N acetic acid
               and the sample temperature must be kept between 20°
               and 40° Centigrade (68° to 104° Fahrenheit).

          •    After the 24-hour extraction procedure is completed.
               the sample is again filtered to separate the liquid
               and solid phases.  The second liquid phase is di-
               luted with more deionized water and mixed with the
               original liquid phase which has been  refrigerated.

          •    The liquid extract is then analyzed for the  sub-
               stances listed in the Primary Drinking Water Stan-
               dards.  Appropriate methods for analyzing the
               leachate generated by the extraction procedure
               are listed in "Methods for Chemical Analysis of
               Water and Wastes," published by the U.S. Environ-
               mental Protection Agency  (Reference 1-26).

          A collaborative interlaboratory testing program was  performed
during 1979 under the joint sponsorship of the U.S. Department  of  Energy's
Laramie Energy Technology Center and the American Society  for  Testing and
Materials (ASTM).  A total of 18 laboratories participated  in  the  testing
program.  Nineteen fossil energy materials were  tested,  including  various
fly ashes, bottom ash, boiler slag, and other combustion by-products.  Each
material was tested using three different extraction procedures,  including
the Environmental Protection Agency's procedure, although  not  all materials
were tested by each laboratory.
                                      1-25

-------
          Table 1-6 presents a summary of the test results for those labora-
tories participating in leachate extraction testing of fly ash samples using
the EPA extraction procedure.  A total of five fly ash samples were analyzed—
three bituminous coal fly ashes, one lignite, and one sub-bituminous coal fly
ash.  There were a total of 39 extraction tests performed, each involving analy-
sis of concentrations for eight different inorganic chemicals, or a total of
312 separate analyses.

          From Table 1-6, it can be seen that from the total of 312 analyses,
there were 29 test values which exceeded 10 times drinking water standards,
but only one in excess of 100 times drinking water standards.  This involved
the selenium concentration tested by one of the 16 laboratories analyzing
bituminous coal fly ash sample number 1.  Leachate concentrations exceeding
10 times drinking water standards included 13 selenium analyses, 9 arsenic,
3 cadmium, 2 chormium, 1 mercury, and 1  lead.  Bituminous coal fly ash sample
number 3 had no test  values in excess of ten times drinking water standards
(Reference 1-27).

          Although more extensive leachate testing of coal combustion by-
products will be conducted in the future, the preceding test results, while
performed on a small number of samples, indicate that fly ashes, when used
in an embankment or fill situation, do not typically leach hazardous concen-
trations of inorganic chemicals.  Further discussion of the environmental
impacts of fly ash use is presented in Volume One of this report.

          Actual field experience with fly ash embankments to date has shown
that very little water has been observed to percolate through such embank-
ments.  This is probably due not only to the comparatively low permeability
of compacted fly ash, but also to the gradual cementing action resulting from
self-hardening of the ash.

          Because of relative impermeability and alkalinity, the danger of
pollution to underlying ground water or to surface waters in the vicinity of
a fly ash embankment is minimal, particularly if the entry of surface water
is well controlled and the fly ash is capped with an envelope of natural
soil.  As noted earlier, the permeability of compacted fly ash can also be
substantially reduced by chemical stabilization with lime or portland cement.
Another advantage of low permeability is that construction operations are not
adversely affected by inclement weather.

          Because of the relatively low permeability of compacted fly ash,
unprotected side slopes are  subject  to a high degree of runoff.  Therefore,
side  slope protection in the form of natural soil and topsoil covering with
vegetation, or at the very least a bituminous seal coating, is required to
prevent erosion.
                                      1-26

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                                                       Table 1-6
                                       SUMMARY  OF LABORATORY TEST  RESULTS  FROM
                                   LEACHATE EXTRACTION ANALYSES OF FLY ASH SAMPLES
H
       Sample  Description
1.   Bituminous Coal
    Fly  Ash No. 1
    (From  2% sulfur
       coal)

2.   Bituminous Coal
    Fly  Ash No. 2
    (From  4% sulfur
       coal)

3.   Bituminous Coal
    Fly  Ash No. 3
    (From  2% sulfur
      coal)

4.   Lignite Coal
    Fly  Ash
    (From  less than
      sulfur coal)

5.   Sub-bituminous
    Fly Ash
    (From  less than
      sulfur coal)
n Power Company
Pennsylvania Electric
Company
Ohio Power Company
i
Monongahela Power
Company
•
Minnkota Power
i 1%
Coal Commonwealth
Edison Company
i 1%
No. of Tests
by
Plant Location Labs
Keystone Station 16
Shelocta, Pa. .
Kammer Plant 5
Captina, U. Va.
Harrison Station 7
Haywood, U. Va.
Milton Young Plant 7
Center, N.D.
Waukeegan Plant 4
Waukeegan, 111.
TOTAL 39
Total Values Elements
Exceeding Exceeding
10 x DWS 10 x DVIS
17 8 Se
7 As
1 Pb
1 Hg
7 3 Cd
2 Cr
1 As
1 Se
- -
4 3 Se
1 As
1 1 Se
29 6 out
of 8
possible
elements
Total Values
Exceeding
100 x DWS
1
(Se)

-
-
-
1

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               Capillary Action.  Water has been  observed to rise by capil-
lary action in some compacted conditioned fly ash embankments.  Capillarity
can cause saturation and resultant instability in embankments or  fills less
than 2 feet (0.6 meters) in thickness.  The phenomenon of capillary rise is
not reduced or materially affected by self-hardening or the increase in shear
strength of the compacted fly ash over time.  An effective means of prevent-
ing capillary rise  in fly ash embankments and fills is the placement of a
drainage layer of full-draining granular material at the base of the embank-
ment to a height of at least 18 inches above the ground water level (Reference
1-28).  The ASTM Recommended Practice for Use of Process Waste in Structural
Fill notes that such material should be placed a minimum of 5 feet above the
historical high water table.

               Slope Stability.  An average slope of two horizontal to one
vertical should provide a minimum safety factor against sliding based on an
effective internal friction angle of 33° and zero cohesion.  This is felt
to be a conservative estimate of the safety factor of a fly ash slope be-
cause the beneficial effects of apparent cohesion and age-hardening of the
fly ash were not included in the analysis  (Reference 1-29).

               Handling Characteristics.  The moisture content of fly ash
brought to the field for use as a fill or embankment material can present
certain difficulties above and beyond those normally encountered in place-
ment and  compaction of conventional soils.  First, the handling of dry
or silo stored ash creates in many cases a severe dusting problem when the
material is dumped and spread, especially on hot, windy days.  The following
precautions are advised to minimize the dusting problem:

          1.   Wet the material with water to bring its moisture
               content up to the optimum range.

          2.   Have a water truck with  a spray bar attachment
               available for additional wetting of the surface
               after placement and rolling.

          3.   Keep traffic off the surface of the fill after
               rolling unless placing an additional layer.

          4.   Seal the exposed surface at the end of each day's
               work.

          When stockpiles of conditioned or ponded ash are used, lumps of
hardened ash  are  sometimes encountered.  These must be broken up by con-
struction equipment prior to using the  ash for embankment or fill purposes.
The  effects of lensing  (the formation of small, shallower, transverse shear
cracks) and crusting  of the surface can be avoided by using discing or till-
ing  equipment to  agitate the loose lift and the surface of the preceding
compacted lift  (Reference 1-30).
                                      1-28

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          One of the principal advantages of using fly ash as a fill material
is that, unlike conventional soils, fly ash can be placed throughout the win-
ter months.  Table 1-7 presents a comparison of the advantages and disadvan-
tages of fly ash embankments with those of conventional soils.

                                 Table 1-7

                     COMPARISON OF FLY ASH EMBANKMENTS
                          WITH CONVENTIONAL SOILS

ADVANTAGES OF FLY ASH

          Lighter compacted unit weight, resulting in lower settlements and
          ability to place fill on soft or marginal ground.

          Self-hardening properties for many fly ashes ultimately result in
          higher cohesion and shear strength than most conventional soils.

          Low compressibility when properly compacted with negligible re-
          sultant settlement.

          Fly ash can be placed throughout the winter because it does not
          freeze like conventional soils.

DISADVANTAGES OF FLY ASH

          Most fly ashes are frost susceptible, requiring either chemical
          stabilization or substitution with suitable natural soils in
          frost prone areas.

          Sensitivity to moisture, necessitating that compaction be done
          very close to, and preferably below, optimum moisture content.

          Subject to capillary action, requiring underlayment with a drain-
          age layer of granular material directly above the ground water
          table. Some clay and soil borrow  materials also are subject to
          capillary action.

          Subject to dust generation during placement.
               Examples of Fly Ash Utilization in Highway Embankment Con-
struction.  There are numerous examples of the use of fly ash in the con-
struction of highway fills or embankments throughout the United Kingdom.
A few of the more outstanding projects are cited herein to dramatize the
advantages of fly ash, or pulverized fuel ash, use for embankment purposes.
                                     1-29

-------
               Motorway M.5 - Bristol and Somerset, England.  A section of
motorway M.5 two miles in length was constructed on a highly compressible
alluvium layer up to 40 feet thick.  Embankment heights of up to 7 feet
were built along the ^ai^ road with interchange road fills up to 20 feet
high.  The embankments were constructed of pulverized fuel ash because of
the relatively light unit weight of the ash in comparison to locally avail-
able borrow material.  In addition, potential settlement problems at 14
bridges and 2 interchanges were alleviated by using the lighter ash over
the compressible alluvium subgrade.  When sufficient amounts of ash could
not be obtained from the nearest generating station, over 1 million tons of
additional ash was transported to the job site from another power station 80
miles away by rail so that the unique properties of the ash could continue to
be utilized (Reference 1-31).

               Alexandria By-Pass - Dumbarton, Scotland.  The construction of
the Alexandria By-Pass included a bridge over the River Leven with very high
approach embankments due to clearance requirements for navigational purposes.
The use of a lightweight fill material was  warranted because of poor subsoil,
in this case a saturated silt.  Construction of the facility in two stages
involved placement of nearly 670,000 cubic yards of pulverized fuel ash in
the embankments, which reached a maximum height of 39 feet.  Two years after
completion of the project, the total settlement of the embankment was only
10 inches, which is considered quite satisfactory (Reference 1-31).

               Clophill By-Pass, Motorway A.6 - Bedfordshire, England.  During
1975, approximately 20,000 cubic yards of pulverized fuel ash was used to con-
struct an 8-foot high roadway embankment over a 16 foot thick layer of highly
compressible peat on a section of the A.6 Motorway.  In addition, the ground
water table in the area was essentially at ground surface, making it almost
impossible to operate construction equipment.  In order to minimize settle-
ments, pulverized fuel ash was used for construction of the embankment. The
total settlement of the embankment is  6 inches, which is less than the pre-
dicted settlement (Reference 1-31).

          Despite numerous projects utilizing fly ash as fill material for
construction of highways in Europe, only five documented instances of such
use  in the United States have been determined from available literature.
Three projects are described in this report.

               U.S. Route 250 - Fairmont, West Virginia.  Approximately 5,000
tons of fly ash were utilized in the repair of an embankment along a section
of U.S. Route 250 in Fairmont, West Virginia.  The repair work resulted from
a slide failure caused by poor drainage.  The slide mass was removed, sub-
surface drainage installed, and the slide material that had been removed was
replaced with fly ash.  The embankment had an average height of 25 feet with
1-1/2 to 1 side slopes.
                                      1-30

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          Fly ash was hauled to the site in open trucks with no dusting
problems during hauling or placement.  The ash was tailgated and spread
in 9-inch thick  lifts and compacted by a rubber-tired vibratory roller
to a density of 97 percent or more of Standard Proctor (ASTM D698 or
AASHTO T-99) density values.  Upon completion of compaction operations,
the exposed surface of the fly ash embankment was sealed with a coat of
hand-sprayed road tar (Reference 1-32).

               Melvin E. Amstutz Expressway - Waukegan, Illinois.  The Melvin
E. Amstutz project (Federal Aid Route 437, Section 8) in Lake County, Illinois
involved the construction of a fill embankment for a four-lane divided highway
with a 42-foot wide median between Grand and Greenwood Avenues  in Waukegan,
Illinois, some 40 miles north of Chicago.  This is probably the most outstand-
ing example of fly  ash use in highway embankment construction thus far in the
United States.

          A total of 246,000 cubic yards of embankment material were required
for this job.  Fly ash was selected as an alternate because a nearby Common-
wealth Edison power plant offered an available source of material at a poten-
tial cost savings.  Alternate bids indicated that construction of a fly ash
embankment would result in a savings of approximately $62,000 compared to an
earth embankment (Reference 1-33).

          Prior to placement of the fly ash, unsuitable in-place soils were
removed and replaced with granular fill to a. height of 2 feet above the ground
water table.  The average height of the fly ash embankment was 3.5 feet, al-
though 18 to 20 foot  embankments were built in ramp areas.  The fly ash em-
bankment was covered by 8 feet of earth fill on the outside slopes and by 2
feet of earth fill in the median areas.

          Fly ash was trucked to the site either from stockpiles located out-
side the power plant or from closed storage silos and placed in 6 inch layers.
Each layer was compacted by means of a 10-ton vibratory single steel drum
roller to densities in excess of 85 percent of the maximum dry density at op-
timum moisture levels of 25 percent.

          The contractor added water where necessary to obtain the desired
density.  Side slopes of 2 to 1 were maintained and are performing satis-
factorily.

          The fly ash placed in this embankment is stronger than most natural
soils because of its age-hardening characteristics.  The material was work-
able and stable with  excellent compaction characteristics, provided the proper
construction methods and equipment are utilized.  The use of fly ash enabled
work to proceed under wet conditions when it might not have been possible to
work with conventional soils.  Moreover, the lighter weight fly ash was found
to be advantageous in bridging over weak subsoils  (Reference 1-33).
                                     1-31

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               Route 7 and 148 - Powhatan Point, Ohio.  Nearly 6,000 tons
of fly ash from the Burger Station of Ohio Edison Company were used as back-
fill material around a concrete bridge over a railroad at the intersection
of state routes 7 and 148 in Powhatan Point, Belmont County, Ohio, which is
located in the southeastern part of the state.  The conditioned ash was placed
between  the Fall of 1979 and March of 1980.

          At its deepest point, the ash embankment is 27 feet high and ex-
tends longitudinally about 80 feet.  The material was compacted in 12  inch
lifts except near the top, where 6 inch lifts were used.  Compaction opera-
tions were monitored by a field representative of the Ohio Department of
Transportation, who verified that all layers of fly ash were compacted to at
least 95 percent of Standard Proctor density.  Prior to placement of the com-
pacted ash fill, the surfaces of the bridge  abutment were coated with an
asphalt preparation.  In addition, a base of steel mill slag was placed and
overlain with a celanese filter cloth.

          According to the contractor on the project, the amount of ash used
on the project worked out closer in planned quantity than any other material
he had ever used and did not demonstrate the shrinkage one normally expects
with  dirt or gravel.  He also felt that there was no way he could have
achieved the same degree of compaction with an earthen fill in that situation
without a lot of hand tamping.

          Throughout the winter construction period, there was no shutdown
time while placing the fly ash embankment.  Whenever the ash began to dry
out, the' contractor simply ordered a load of wet ash, which he blended with
the dry ash and corrected the problem.  However, the contractor did feel that
he would not recommend ash placement in temperatures below 30 degrees Fahren-
heit simply because he had experienced problems getting the ash out of the
truck bed at those temperatures.

          Exposed slopes were capped with a soil cover.  Rail traffic was
maintained at all times during construction of the embankment.  Little or
no settlement has been observed in the fill since the sub-base and wearing
surface was placed and the road was opened to traffic in the Spring of 1980
(Reference 1-34).

         Overall Technical Assessment.  It is evident from the review of
available literature pertaining to fly ash use as an embankment or struc-
tural fill material that fly  ash is unquestionably suitable for such use
and, in addition, provides certain unique and beneficial properties when
utilized in such applications.  Of particular advantage is the relatively
low density of the material combined with substantial shearing strength
and long-term  strength gaining characteristics.  Moreover, compacted fly
ash has a low permeability, particularly if it is self-hardening, and indi-
cations thus far are that the material does not leach potentially hazardous
concentrations of inorganic chemicals.
                                      1-32

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          Prospective users of fly ash must be aware of the potential for
frost susceptibility of this material.  Furthermore, the placement of fly
ash in a fill or embankment must be accomplished above the anticipated high
water table and the material must be underlain by a. drainage blanket or open-
graded granular material.  Precautions must be made to keep the fly ash suf-
ficiently moist while spreading and compacting in order to avoid excessive
dusting and all exposed sloping surfaces of the fly ash must be covered with
soil to protect against erosion.

          In spite of the preceding precautions, an objective engineering
assessment of the use of fly ash for embankment and structural fill purposes
leads to the conclusion that this material is well suited for such purposes.
Indeed, fly ash has been used extensively and successfully as highway fill
and backfill material througout much of Great Britain for many years and its
excellent performance in many British highway projects has been repeatedly
documented.  In  those few instances where fly ash has been used as highway
fill material in the United States, its record of performance has also been
outstanding.

          Duriag April 1980, a questionnarie was circulated to all state
highway departments by The American Association of State Highway and Trans-
portation Officials (AASHTO).  The questionnaire requested information on
uses, extent, performance, and attitudes related to different recovered
materials in highway construction in each state.  Results of this question-
naire indicate that a total of 8 states have made, or are making, use of fly
ash in an embankment or structural fill.  These states are Arizona, Illinois,
Minnesota, New York, Ohio, West Virginia, Wisconsin, and Wyoming.  All of
these states rated the material's performance in this application as either
acceptable, good, or excellent.  Each of these states plans to make further
routine use of flv ash as an embankment or structural fill material, except
that Minnesota feels that more field study should be made in connection with
such use.

          Aside from lack of knowledge about the usefulness of fly ash and
some of its unique characteristics, perhaps the biggest obstacle to more
widespread use as highway fill material in this country is logistics.  Most
highway construction projects are designed so that there is practically a
balance between cuts and fills and as little borrow material as possible is
required.  Except for those occasional situations where a large stockpile
of  ash may be located relatively close to a highway project, in most in-
stances, the use of excavated earth from the project site will be more con-
venient, available, and economical.  Moreover, there will most likely be
less future opportunities to utilize fly ash as a highway embankment or
fill material  because fewer new highway facilities will be constructed com-
pared to reconstruction, widening, and resurfacing of existing facilities.


                                     1-33

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          For these reasons, development of procurement guidelines  for  the
use of fly ash as a structural fill do not appear to be warranted.  However,
further efforts should be made to educate highway engineers, road-building
contractors, and other interested parties concerning the advantages offered
by fly ash in the construction of fills and embankments so that, when oppor-
tunities to make use of this material do arise in the future, fly ash will
receive favorable consideration and not be discriminated against because it
is unlike soil.  The relative economics and logistics of each site-specific
situation should be the determining factors in deciding whether fly ash use
as highway fill material is most suitable and advantageous for  a particular
project.

Lime-Fly Ash-Aggregate Bases and Sub-Bases

          One of the most successful and promising applications for the use
of fly ash in highway construction is in lime-fly ash aggregate (LFA) base
or sub-base mixtures.  These mixtures are blends of commercial lime, fly ash,
and mineral aggregates, combined with water in the proper proportions and
compacted to form a dense, stable mass.  Mixtures of lime, fly ash,  and ag-
gregate and in some cases additional portland cement are often referred to
as pozzolanic pavements.  These mixtures may also involve substitution  of
kiln dusts in place of lime or cement, which is discussed in another section
of the report.

          Description of Pozzolanic Reaction.  A pozzolan is defined as a
siliceous or aluminous and siliceous material which is in itself chemically
inert, and  possesses little or no cementitious value, but, when in a finely
divided form and in the presence of water, will react with calcium  hydroxide
at ordinary temperatures to form compounds possessing cementitious  properties
(Reference 1-35).  The term pozzolan is derived from the Latin word "pozzuo-
lana," which referred to a volcanic ash found near the town of Pozzuoli, Italy,
where the mixing of volcanic ash with a crude lime was first discovered in 350
B.C. and used as a matrix for Roman building materials.

          The most commonly available pozzolan in use in the United States at
this time is fly ash.  Because of basic variations in coals from different
sources, along with design differences in coal-fired boilers, not all* fly
ashes are the same.  While there are differences in fly ashes from  one  plant
to another, day to day variations in the fly ash from a single plant are
usually quite predictable, provided plant operation and coal source remain
constant.  It should  also be pointed out that fluctuations in the  chemical
composition of fly ash are far less critical for use in LFA base materials
than in portland cement concrete.

          To determine whether a particular source of fly ash is suitable for
use in a pozzolanic pavement, the pozzolanic reactivity of the fly  ash  must
be determined in accordance with the procedures outlined in ASTM C593,  "Standan
Specification for Fly Ash as a Pozzolan for Use with Lime," a copy  of which is •
included in the Appendix of this report.
                                     1-34

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          Although it is not necessary to understand the mechanisms by which
cementitious compounds are formed in the pozzolanic reaction, some awareness
of the basic chemistry involved is useful.  It should be recognized that the
chemistry of pozzolanic reactions, which is closely related to cement chemis-
try, is an extremely complex subject which has been extensively researched for
many years.

          Essentially, what occurs in a pozzolanic reaction is that calcium
from the lime and silica from the pozzolan (normally fly ash) react in the
presence of water to form a gelatinous calcium-silicate compound, which pro-
vides a cementitious binder for the aggregate particles in the mix.  The
pozzolanic reaction is time and temperature dependent, so that different
compounds may be in varying stages of formation, depending on the length of
time the reaction has been progressing or the temperature conditions to which
the component materials have been exposed.

          In cases where dolomitic limes are used, the presence of magnesium
in these limes will cause other cementitious compounds to be produced, gen-
erally at a slower rate and over a longer period of time than the calcium-
silicate compounds, thus resulting in an even more complicated reaction
mechanism.  Analysis of aged pozzolanic products has also indicated the
formation of crystalline compounds at later stages of the reaction.  The
chemical interaction of calcium ions on the surface of the silica, along
with later crystalline growth, are both involved in the pozzolanic reaction
(Reference 1-36).

          Most western (lignite and sub-bituminous) coal fly ashes contain
higher concentrations of free lime (CaO) and sulfate  (803), resulting in
the formation of other cementitious reaction products such as ettringite
(calcium sulfo-aluminates).  Such reactions are related to portland cement
chemistry and offer opportunities to use higher fly ash dosages in LFA
mixtures (Reference 1-37).

          History of Lime-Fly Ash-Aggregate Base.  The initial  discovery of
a pozzolanic reaction between fly ash and lime and its subsequent use in the
stabilization of fine-grained soils was made by Jules E. Havelin and Frank
Kahn, engineers from the Special Tests Branch of the Philadelphia Electric
Company during the mid-1940s.  This discovery subsequently became the basis
for three patents on the stabilization of soils using lime-fly ash reactions.
Copies of these patents are included in the Appendix of this report.

          As a followup to this work, Dr. L. John Minnick of the G. and W. H.
Corson Lime Company, under the sponsorship of Philadelphia Electric Company,
began research on the use  of lime-fly ash pozzolanic reactions with aggre-
gates and soil-aggregate mixtures.  Much of this early lime-fly ash-aggregate
work in the laboratory was performed during the late  1940s and early 1950s at
the  University of Pennsylvania under the direct supervision of Richard H.
Miller of the Civil Engineering Department.
                                     1-35

-------
          The earliest known field installation involving the use of lime-
fly ash-aggregate as a base course material was in November of 1950 on a
temporary by-pass road along the New Jersey Turnpike in Swedesboro, New
Jersey.  The test section was several hundred feet long and involved the
blending of fly ash and boiler slag on a 1:3 ratio  with a 3 percent lime
content.  The materials were mixed in place and compacted.  The road base
remained in very good condition and provided excellent performance for two
years, at which time the new construction was completed and the by-pass was
removed.

          Three more experimental projects using LFA were placed in 1951,
one each in Pennsylvania, New Jersey, and Maryland.  Later samples were ex-
tracted from each of these locations and compressive strengths were found
to range from 2,090 to 4,315 psi (Reference 1-38).  On the basis of these
and other early successful installations, a patent was  granted for lime-
fly ash-aggregate mixtures in road base construction.  A  copy of the orig-
inal patent for lime-fly ash-aggregate compositions (marketed under the
trade name of Poz-0-Pac) can be found in the Appendix of this report.

          With the issuance of a patent for "Poz-0-Pac," and the establish-
ment of a licensee arrangement for the production of the material, pozzo-
lanic base materials were eventually produced and placed in construction
projects in at least a dozen states.  The most frequent use of LFA mater-
ials has been in the states of  Illinois, Ohio, and Pennsylvania.  A later
section of this report will focus on the extent of LFA base course use in
several of these states.

          Recently, the "Poz-0-Pac" patents have expired, although there
are still a number of pozzolan producers in many of these states that con-
tinue to sell pozzolanic base course materials.  Throughout the years, it
is estimated that approximately 25 to 30 million tons of LFA or pozzolanic
base course materials have been produced and placed in the United States.

          Table 1-8 presents estimated quantities of pozzolanic base course
materials produced on an annual basis in the United States since 1970.  For
comparison purposes, annual production figures from the Chicago area are
also included in this table.  Table 1-8 clearly shows that for the past
ten years the Chicago area has produced approximately 80 percent of the
LFA base course materials  used in the country.  Since 1956, it has been
estimated that over 12 million tons of LFA base materials have been pro-
duced in the Chicago area  (Reference 1-39).

          Also evident from this table is the steadily declining production
of these materials.  To some extent, this decline can be attributed to dras-
tic reductions in state  highway construction programs occasioned by infla-
tion and declining gas tax revenues in key fly ash producing states, such
as Ohio and Pennsylvania.
                                     1-36

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                             Table 1-8
               ESTIMATED ANNUAL PRODUCTION OF
            LIME-FLY ASH-AGGREGATE BASE MATERIAL
                    IN THE UNITED STATES
                          (Thousand tons)
          Total LFA
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
TOTAL
Production



1,050
778
610
801
736
755
738

LFA Production
In Chicago Area
 Percent -
Production
In Chicago
                                                   62.9

                                                   84.8

                                                   82.0

                                                   84.9

                                                   85.6

                                                   86.1

                                                   81.3
NOTE:  Poz-O-Pac patents expired in  1979.

SOURCE:  I U Conversion System, Inc., Horsham,  Pennsylvania
         and American Fly Ash Company, Chicago, Illinois
                                1-37

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          There is, however, potential for a considerable increase in the
amount of fly ash which could be used for pozzolanic base course construc-
tion in many states because of the economic and environmental benefits to
be derived from using such materials.

          Materials and Mixture Proportions.  The key to successful pavement
performance with lime-fly ash-aggregate (LFA) mixtures is good mix design
and sound construction techniques.  The quality of the principal constituents
of these mixtures must also be assured in order to design an acceptable mix.

               Lime.  The term lime, when used in reference to LFA mixtures,
can include various chemical and physical forms of quicklime, hydrated lime,
or hydraulic lime.   The most commonly used forms of lime in LFA mixtures
have been monohydrated  high calcium and dolomitic hydrated limes.  However,
in recent years, increasing demand for lime products, plus the escalating
cost of lime production, have resulted in localized lime shortages or the
periodic unavailability  of commercial lime for use in the LFA base market.
To alleviate such shortages, certain lime producers, such as Marblehead Lime
Company in the Chicago area, have combined lime stack dust with their regular
hydrated lime, with additions of the stack dust being as high as 80 percent,
and marketed this product under the name "polyhydrate."  This is considered
an acceptable source of lime where it is available in the State of Illinois
(Reference 1-40).

          In  other states, such as Ohio, the shortage of lime in some areas
has become so severe that there is not a sufficient quantity of lime to blend
with stack dust for polyhydrate.  Consequently, stack dusts from lime and
cement kilns are presently being evaluated as an alternative source to lime.
A more detailed discussion of the potential for utilization of lime and ce-
ment kiln dusts in road  base compositions is presented in  another section
of this report.

               Fly Ash.  Quality requirements for the use of fly ash and
other pozzolans with lime in plastic mortars and non-plastic mixtures are
contained in ASTM C593-76a, "Standard Specification for Fly Ash and Other
Pozzolans for Use with Lime."  To be considered acceptable for use in LFA
mixtures, fly ash must meet the following physical requirements:

          Water soluble fraction, maximum percent      10.0
          Fineness, amount retained when wet sieved:
            No. 30  (.60 mm) sieve, max. percent         2.0
            No. 200 (.075 mm) sieve, max. percent      30.0
          Lime-pozzolan strength, or minimum
            compressive strength, psi:*
          Plastic mixes
            At 7 days, 130 + 3°F. (54 + 2°C.)          600
            After additional 21 days, 73 4- 38F.
               (23 + 2°C)                               600
          Non-Plastic Mixes
            At 7 days, 100 + 3°F. (38 + 2°C.)          400
            psi indicates pounds per square inch.
                                     1-38

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          In addition  to the above requirements, many state and Federal
transportation agencies also specify that the fly ash have a minimum loss
on ignition value of 10 percent when determined in accordance with the pro-
cedures of ASTM C311.  Although ASTM C593 has set no limit on the loss on
ignition value for a pozzolan when used with lime, such a provision would
be very desirable.

          The Illinois Department of Transportation requires that the mois-
ture content of dampened pozzolan shall not exceed 35 percent.  The Ohio
Department of Transportation specifications do not require that fly ash
meet the criteria of Section 7 of ASTM C593 for plastic mixes.  The Pennsyl-
vania Department of Transportation specifications require only that pozzolan
comply with  ASTM C593.  In addition, the Federal Aviation Administration
(FAA) does not require that the water-soluble fraction of the fly ash be
determined, and states that the requirements of ASTM C593 may be waived if
it can be demonstrated that a mix  of comparable quality and reliability
can be produced with lime and/or fly ash that do not meet specified quality
criteria (Reference 1-41).

          The pozzolanic reactivity or lime-pozzolan strength of fly ash is
the best indicator of  its ability to form cementitious compounds in LFA mix-
tures.  The pozzolanic reactivity of fly ashes is dependent on the following
factors:

          1.   Fineness—the larger the percentage passing the
               -325 mesh sieve, the greater the surface area
               and pozzolanic reactivity.

          2.   Silica  and alumina content—the higher the silica,
               or the  silica and alumina, the more reactive the
               fly ash.

          3.   Loss on ignition and carbon content—the lower
               the loss on ignition, the  higher the pozzolanic
               reactivity of the fly ash.

          4.   Alkali  content—the higher the alkali content,
               the more reactive the fly  ash. (Reference 1-7).

               Aggregates.  Since the major proportion of an LFA mixture is
composed of aggregate, the quality of the final product is dependent to a
large extent on the aggregate used.  A wide variety of aggregate types and
gradations have been used successfully in LFA compositions.  These include
crushed stones, sands, gravels, bottom ash, boiler slag, and several types
of ferrous slags.  Whatever the type and source of aggregate used, the gra-
dation of the aggregate should be such that, when mixed with lime, fly ash,
and water, the resultant mixture is mechanically stable and capable of being
densely compacted in the field.  Furthermore, any aggregate used in LFA base
mixtures should consist of hard, durable particles and be free from any dele-
terious chemicals or organic substances that could interfere with the desired
pozzolanic reactions within the mixture.
                                     1-39

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          In general, aggregates with a relatively high percentage of fines
(-200 mesh sieve) tend to produce mixtures with somewhat greater durability
than the more  coarse graded aggregates, although LFA mixtures containing
coarser aggregate gradations have usually been more mechanically stable and
may possess higher  strengths at an earlier age.  Over time, however, LFA
mixtures containing fine graded aggregates ultimately develop strengths
equal to or in excess of mixtures with coarser aggregates.  In assessing
the relative suitability of different aggregates for use in LFA mixtures,
it must be recognized that ultimate strength development appears to be more
dependent on the lime-fly ash matrix than on the aggregate (Reference 1-42).
However', the key to good performance is the use of  a well-graded aggregate.

          Most, if not all, state and Federal transportation agencies that
specify LFA mixtures also specify the quality requirements and range of
acceptable  gradations for aggregates to be used in such mixtures.  Table
1-9 compares the gradation and other physical requirements of aggregates
for use in LFA mixtures in the states of Illinois, Ohio, and Pennsylvania,
as well as the Federal Aviation Administration.  From Table 1-9, it can be
seen that there are basic similarities in these aggregate specification
requirements.

               Mix Proportions.  The relative proportions of each constituent
(lime, fly ash, and aggregate) used in LFA mixtures may vary, depending on
the materials used and the design criteria to be satisfied.  Generally, lime
and fly ash contents are designated as a percentage by dry weight of the total
mixtures, not including water  (Reference 1-43).  Acceptable mixtures have been
used in which the lime content has been as low as 2 percent or as high as 8
percent:  Fly ash contents have been found to range from a low of 8 percent
to as high as 36 percent.  Typically, LFA mixtures contain from 2-1/2 to 4
percent lime and from 10 to 25 percent fly ash.  In some cases, small quan-
tities  (from 0.5 to 1.5 percent) of Type I portland cement have  also been
added to LFA mixtures in order to accelerate the initial strength gain of
the mix (Reference 1-44).

          For mix design purposes, LFA iaix proportions are developed by
determining the lime te fly ash ratio and the lime plus fly ash content.
The ratio of lime to fly ash is important because it affects the quality
of the matrix in the mix.  Lime to  fly ash ratios generally are in the
range of from 1:10 to 1:2 with ratios of 1:3 to 1:5 being most common.
Lime  content is established by trial batch procedures to provide for de-
sired strength and durability characteristics of the mix.  Factors that
tend to increase the amount of lime required are increased aggregate fines
(-200 mesh sieve), higher plasticity index of the aggregate particles
passing the -40 mesh sieve, and fly ash  with a relatively high pozzolanic
reactivity.
                                      1-40

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                            Table 1-9

AGGREGATE SPECIFICATION  REQUIREMENTS  FOR LIME-FLY ASH-AGGREGATE
          BASE COURSE MIXTURES  USED BY  VARIOUS STATE
TRANSPORTATION AGENCIES  AND THE FEDERAL AVIATION ADMINISTRATION

               AGGREGATE GRADATION REQUIREMENTS
(Percent Passing)
Sieve Size
2" (50.0mm)
1-1/2" (38.1mm)
1" (25.0mm)
3/4" (19.0mm)
1/2" (12.5mm)
3/8" ( 9.5mm)
f4 (4.75mm)
#8 (2.36mm)
116 (1.18mm)
#40 (0.425mm)
#50 (0.300mm)
#100 (0.150mm)
#200 (0.074mm)


Illinois
	
100
90-100
	
60-100
	
40-70
	
	
0-25
_ —
	
0-10
(Gravel)
0-15
(Crushed stone or
Ohio Pennsylvania
100 100 100
	 	 	
75-100 	 	
	 52-100 70-100
50-85 	 	
	 36-70 58-100
35-60 24-50 45-80
15-45 	 	
10-35 10-30 25-50
	 	 	
3-18 	 	
	 15 max 6-20
1-7 0-10 	


slag)
FAA*
100
	
75-100
	
50-85
— _
35-60
15-45
10-35
	
3-18
	
1-12



*Gradation for LFA material used in Toledo Airport Project.

Property
Sodium Sulfate
Soundness
OTHER TYPICAL
Illinois
25% max.

Los Angeles Abrasion 45% max.
Liquid Limit
Plasticity Index
	
9 max.
AGGREGATE REQUIREMENTS
Ohio Pennsylvania
15% max. 20% max.

	 55% max.
	 25 max.
	 6 max.
*
FAA
12% max

	
25 max
6 max
                               1-41

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          The ratio of the lime plus fly ash to the aggregate determines the
amount of the matrix which is available to fill the void spaces between ag-
gregate particles.  The matrix helps to produce a mix of optimum density and
maximize the contact between the cementitious matrix and the aggregate par-
ticles.  Normally, lime plus fly ash contents in LFA mixtures range from 12
to 30 percent.  However, fine graded aggregates generally require a higher
percentage of lime, plus fly ash to provide satisfactory strength development
than well graded'aggregates. Also, aggregates with an angular particle shape
and rough surface texture require larger quantities of lime plus fly ash than
aggregates with rounded and smooth particles (Reference 1-45).

          The state of Illinois has recently adopted a mix design procedure
for lime-fly ash-aggregate compositions as part of its laboratory evaluation
program for approval of such mixtures.  A copy of this mix design procedure
is included in the Appendix.

               Moisture Content.  Lime-fly ash-aggregate base course mixtures
are mixed with water at  an optimum moisture content to assure  a mix of moist,
nonplastic consistency that can be compacted in the field to a maximum density
by means of conventional spreading and rolling equipment.  The optimum mois-
ture content of a particular LFA mixture is determined in the laboratory by
the moisture-density test procedures such as outlined in ASTM C593.

          Most state and Federal transportation agencies specify some form of
modified compactive effort  (10 pound hammer, 18 inch drop) as part of their
moisture-density test procedures for LFA mixtures.  Pennsylvania is a notable
exception, since the PennDOT specification requires a standard compactive ef-
fort  (5.5 pound hammer, 12 inch drop) to determine the moisture-density re-
lationship of LFA mixtures.

          The following table compares the moisture-density test procedures
used By the states of Illinois, Ohio, and Pennsylvania, as well as the Fed-
eral Aviation Administration, in determining the optimum moisture content
for LFA.

                      MOISTURE-DENSITY TEST PROCEDURES
                  USED FOR LIME-FLY ASH-AGGREGATE MIXTURES
                              IN  VARIOUS STATES
Name  of  Agency

Illinois DOT
Ohio  DOT
Pennsylvania  DOT
Federal  Aviation
 Administration
Procedure

ASTM C593
ASTM C593
PTM 106

FAAT611
Hammer
Weight
(Ibs.)

  10
  10
   5.5

  10
 Hammer
  Drop
(inches)

   18
   18
   12

   18
Number
  of
Layers

  3
  3
  3
 Number
of Blows/
 Layer

  25
  25
  25

  25
                                      1-42

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          Engineering Properties.  Knowledge of the engineering properties
of lime-fly ash-aggregate mixtures is important with respect to mix propor-
tioning and pavement structural analysis.  The most important of these prop-
erties are strength and durability.  The properties of LFA mixtures are af-
fected by the characteristics of the lime and/or ash, mix proportions, com-
pacted density, and the curing conditions (time, temperature, and moisture)
to which the materials are exposed.

          This report discusses significant engineering properties of these
mixtures.  Since most, if not all, of these properties vary for a given mix-
ture depending on curing conditions, it is necessary to define the curing
conditions when reporting data.

               Compressive Strength.  The most widely used criterion for the
acceptability of a pozzolanic base material is the compressive strength test.
As a general rule, the higher the compressive strength, within limits, the
better is the quality of the stabilized material, provided excessive early
strengths are not developed.  LFA base materials have the unusual character-
istic of developing compressive strength over an extended period of time,
depending also on temperature conditions.

          The compressive strength development of LFA compositions is most
frequently determined in the laboratory by means of the curing procedures
outlined in ASTM C593 (7 days at  100°F or 38°C).  Typical well-designed
LFA mixtures generally develop compressive strengths ranging from  500 to
1,200 psi under these curing conditions.  Use of a lignite or sub-bituminous
fly ash, which has a relatively high.calcium content, may even result in
higher 7-day strength values.  A minimum compressive strength value of 400
psi is specified in the ASTM C593 procedure.

          Actual compressive strength development of LFA base course materials
in the field is time and temperature dependent.  As the temperature increases,
the rate of strength gain also increases.  Below 40°F, the pozzolanic reac-
tion, virtually ceases and the mixture does not gain strength.  However, once
temperatures exceed 40°F, the reaction again continues.  In this way, LFA
compositions in the field, although they gain no strength during the winter,
continue to increase in compressive strength  at other times of the year for
a  long, indefinite period.  Compressive strengths in excess of 4,000 psi
have been recorded for  core specimens taken from LFA base course mixes af-
ter several years in the field.

          Figure 1-9 shows the compressive strength development of a typical
LFA base course mixture placed in the Chicago area.  This figure shows that
approximately half of the strength of this mixture  was developed prior to
the first winter.  During the second and third years, additional strength
gains were reported during the summer months as temperatures increased.
After the third year, the mix exhibited a compressive strength of approxi-
mately 2,000 psi (Reference 1-45.) , although it does not yet appear to have
reached its ultimate strength.
                                     1-43

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                  2000
                        Strength
                        development
                        2nd and 3rd
                                    Strength
                                   developmen
                                              f   Dormant
                                              T~~ /*/ winter
                                      Initial
                                     strength
                                   development
                                 Sept  construction
                                         IOO      IOOO  IO.OOO
                                     Age in days
Figure  1-9,   Compressive strength development of  a lime-fly ash-aggregate
               mixture in   the Chicago area.
                                          1-44

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          It should be noted that  the compressive strengths  of LFA mixtures
produced in the Chicago area are generally higher than the strength of com-
parable mixtures produced elsewhere.  The principal reason for this is that
most coal-fired power plants in the Chicago area burn sub-bituminous coal,
which  results in a more reactive fly ash than that of eastern bituminous
coals.

               Flexural Strength.  Many engineers believe that measurement
of the flexural strength of LFA mixtures may be a better indicator of the
effective strength of the material than compressive strength.  Although flex-
ural strength can be determined directly from tests, most agencies estimate
the flexural strength of LFA mixtures by taking a ratio of the material's
compressive strength.  The ratio of flexural strength to compressive strength
for most LFA mixtures is between 0.18 to 0.25.  An average value of 20 percent
of compressive strength is considered to be a fairly accurate estimate of the
flexural strength  of LFA mixtures (Reference 1-47).

               Modulus of Elasticity.  The modulus of elasticity is a measure
of the stiffness or bending resistance of a material.  Theoretically, the mod-
ulus of elasticity is the ratio of the change in stress divided by the change
in strain for a given stress increment.

          For materials such as pozzolanic base mixtures, the relationship
between stress and strain is not linear and, therefore, it is  not possible
to determine a constant value for the  modulus of  elasticity.  Moreover,
the modulus is different depending on whether it is derived from compressive
or flexural testing procedures.  Since the flexural modulus is recommended
for use in pavement design calculations, and since this value is lower than
the compressive modulus, the modulus of eleasticity is based on the flexural
modulus.  For LFA mixtures, the modulus of elasticity is in the range of 1.5
x 106 Psi to 2.5 x 106 psi (Reference 1-48).

               California Bearing Ratio.  The California bearing ratio (CBR)
test (ASTM D1833) is often used as a way of measuring the comparative strength
of  soils used as a subgrade for highway and airfield pavements.  Because of
the  high strength of LFA mixtures compared to conventional soils, it  is dif-
ficult to obtain meaningful values  from CBR tests performed on these mixtures.
In fact, CBR values of several hundred are not unusual when testing cured LFA
specimens.  The CBR test is much more applicable for evaluating the improvement
in soil bearing characteristics when treating the soil with lime and fly ash
(Reference 1-49).

               Autogenous Healing.  One of the most unique characteristics
of LFA base course compositions is their inherent ability  to heal or rece-
ment cracks within the material by means of a self-generating mechanism.
This phenomenon is referred to as  autogenous healing and results from the
continuing pozzolanic reaction between the lime and the fly ash in LFA
mixtures.
                                     1-45

-------
          Laboratory tests and field observations have confirmed that auto-
geneous healing does occur and that cracking of LFA mixtures in the field
can be corrected to a significant extent.  The degree to which autogenous
healing occurs depends on the age at which cracking occurs, the  degree of
contact of the fractured surfaces, curing conditions, the strength of the
pozzolanic reaction, and available moisture.  Because of the autogenous
healing, LFA mixtures are not as susceptible to deterioration under repeated
wheel loadings as other materials which do not possess this property.  In
addition, autogenous healing enables LFA base materials to be more resilient
and better able to resist attack from the elements (Reference 1-50).

               Fatigue Properties.  All engineering materials are subject to
failure caused by progressive fracture under repeated loading.  The flexural
fatigue  properties of LFA base course materials are important in pavement
design  analysis.  A study of these fatigue properties was made at the Uni-
versity of Illinois by applying loads on beam specimens of LFA materials on
a continuous basis at the rate of 450 load applications per minute.  Figure
1-10 summarizes the results of these tests and relates the number of load
applications to failure with the ratio of applied stress to the modulus of
rupture of  the material.

          In analyzing fatigue properties  of LFA mixtures, the relationship
of strength gain with time must also be recognized.  The flexural strength
of LFA mixtures, like the compressive strength, increases with time, while
the stress level (ratio of applied  stress to the modulus of rupture) de-
creases. . Therefore, as the time required to accumulate the number of load
applications to failure increases, the actual number of load applications
needed for failure also becomes greater.  If the gain in strength of the LFA
material is sufficiently rapid, or if the applied stress is small, the ma-
terial may never fail in fatigue  (Reference 1-51).

          Because of the autogenous healing, LFA mixtures are even less
susceptible to fatigue failure than other conventional paving materials.
This was confirmed by tests conducted on pozzolanic base course materials
at the University of Illinois Pavement Test Track Facility.  During these
tests, it was discovered that if the pozzolanic materials did not fail un-
der the action of repeated loads after only a few load applications, then
fatigue failure was not attained during the remainder of the testing pro-
gram  (Reference 1-52).

               Dimensional Stability.  The main causes of volume changes in
LFA base materials are variations in moisture, temperature changes, and
frost action.  For most LFA materials, the  first two factors are of greater
significance than frost action with respect to dimensional stability.
                                      1-46

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                  I
                      1.00
                      .75
                      '50
                      .25
                                              I     r
                                           •• I.OOO-.3I6 log x
                         i    10    io*  la3   io4   ios   io6 to7

                                I, Number of Cjfdtl to fa Hurt
Figure  1-10,  Flexural  fatigue  behavior of  lime-fly ash-aggregate
               material.
                                        1-47

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          The change in volume caused by temperature change is expressed as
the coefficient of thermal expansion.  It is expressed in terms of inches
per  inch per degree Fahrenheit.  Miller and Couturier investigated the
thermal expansion for these compositions ranged from approximately 5  to 7 x
10-6 inches per °F. These values are comparable to those of concrete at the same
moisture content.  Moreover, the coefficient of thermal expansion increased
with the dry density of the mix.  Larger percentages of lime and fly ash also
tended to increase the coefficient of thermal expansion for LFA mixtures
(Reference 1-53).

          There is no published information on moisture-related volume changes
in LFA mixtures.  However, it is known from field experience that LFA mixtures
exhibit drying shrinkage tendencies  (Reference 1-54).  This is particularly
evident when LFA mixtures attain high early strengths and then are exposed to
lower temperatures and internal moisture reductions.

               Durability.  The durability of LFA mixtures is the single
property which most affects its performance in the field.  Durability re-
fers to the ability of a  material to maintain its structural integrity
under the in-service environmental conditions to which it is exposed.  Cyc-
lic freezing and thawing is the major durability factor that must be con-
sidered when evaluating LFA mixtures.

          The extent to which an LFA base material will be exposed to cyclic
freeze-thaw action is influenced by geographic location, variability in cli-
mate, location of the LFA material within the pavement structure, and the
design characteristics of the pavement.  The major concern of producers and
users of LFA mixtures is that the material be durable enough to withstand
the effects of the first winter of cyclic freezing and thawing.

          During the early development and use of LFA mixtures, the dura-
bility of pozzolanic materials was evaluated by a freeze-thaw test patterned
after an existing procedure that had been developed for evaluating the hard-
ening of soil-cement compositions  (ASTM D658).  Essentially, the freeze-thaw
test  procedure for LFA mixtures involved making triplicate cured specimens,
exposing them to 12 cycles of freezing and thawing (24 hours of freezing at
-10°F and 23 hours of thawing at 738F), wire brushing each specimen 25 times
after each cycle, and recording the loss in weight after brushing.  This
freeze-thaw test procedure was incorporated into ASTM C593 and the acceptance
criteria required a  maximum 14 percent weight loss after 12 freeze-thaw
cycles.

          Over the years, a substantial amount of laboratory test data was
collected which correlated compressive  strength development for many dif-
ferent LFA compositions with performance in the ASTM C593 wire brush freeze-
thaw test.  With few exceptions, these data clearly established the fact that
compacted LFA mixtures which were  cured in the laboratory for 7 days at 100°F
and which developed average compressive strengths in excess of 400 psi were
able to pass the freeze-thaw test  with less than the maximum allowable 14
percent weight loss.  As a result, a minimum  compressive strength require-
ment of 400 psi after 7 days curing  at 100°F was introduced into the ASTM
C593 specification.
                                      1-48

-------
          The principal objections to the ASTM C593 wire brush freeze-thaw
test procedure were:

          1.   The 24-hour freeze cycle at -10 °F and the 23-hour
               thaw cycle at 73°F were not truly representative
               of actual freeze-thaw conditions which LFA ma-
               terials were exposed to in the field.

          2.   A total of 12 cycles of freezing and thawing may
               or may not be indicative of the actual number of
               freeze-thaw cycles to which a road base material
               will be exposed during a typical winter.

          3.   The use of a wire brush to administer 25 strokes
               across the exposed face of the cylindrical test
               specimen after each freeze-thaw cycle seemed an
               arbitrary and unnecessarily  severe measure of
               the LFA material's  ability to withstand freezing
               and thawing.

          A stabilized base materials durability study, funded by the Federal
Highway Administration (FHWA) and the Illinois Department of Transportation
(TDOT), was undertaken at the University of Illinois in 1972 to evaluate these
objections.  Some of the findings of this comprehensive investigation are:

          1.   A standard Illinois freeze-thaw cycle was developed
               for use in durability testing of stabilized mater-
               ials.  This standard cycle is shown in Figure 1-11,
               which also shows that pavement temperatures within
               a base course can  vary  by as much as 3°F, depend-
               ing on pavement design (Reference 1-55).

          2.   An automatic programmable freeze-thaw curing cab-
               inet was built to provide for exposing LFA test
               specimens to any desired range and variation of
               temperature.

          3.   A heat transfer model was developed to compute
               actual pavement temperatures at different loca-
               tions within an LFA base in relation to air temp-
               erature and pavement layer thicknesses.

          4.   A vacuum saturation test procedure was found to
               correlate very well with the compressive strength
               of LFA road base test specimens after 5 and 10
               standard Illinois freeze-thaw cycles in the pro-
               grammable curing cabinet (Reference 1-56).
                                     1-49

-------
                                                    T*mo»ratittt Oifft'tnct » 5 F
Figure  1-11.  Standard freeze-thaw cycle  for Illinois.
                                        1-50

-------
          Based on  the  findings of these studies, ASTM Committee C7.07 in
1976 revised ASTM C593  to replace the freeze-thaw test with the vacuum sat-
uration test procedure, with the additional stipulation that the minimum
acceptable compressive  strength after vacuum saturation must be 400 psi.
The vacuum saturation test procedure is described in ASTM C593-76 and found
in the Appendix.

               Permeability.  LFA mixtures containing normal hydrated lime
have an initial permeability in the range of 3.5 x 10~5 centimeters per
second, as measured by  the falling head permeability tests.  This initial
permeability decreases  rapidly over the first several days of curing, ap-
proaching 3.5 x 10~6 cm/sec after 5 days of curing and 2.5 x 10~6 cm/sec
after 13 days of curing.  It has been reported that a special LFA blend
containing high-early strength additives was evaluated in the laboratory
by the Corson Lime  Company in 1971 and found to have a permeability af
7 x 10~° cm/sec after 7 days of curing (Reference 1-57).

          Although  these data are somewhat sketchy, they are illustrative
of the low  permeability of LFA base materials and the fact that the perme-
ability of the material continues to decrease over time as the pozzolanic
reaction takes place.   The permeability of  LFA base is especially low when
compared to that of crushed stone base and is also considerably lower than
bituminous base.

          LFA Pavement  Thickness Design Considerations.  The thickness design
of pavements with LFA   (or LCFA) base course mixtures is based on the struc-
tural layer equivalency concepts developed from the AASHTO Road Test, as
well as recognized  structural design methods.  In those states where a con-
siderable amount of experience and performance history is available  for
LFA base materials, such as Illinois, Ohio, and Pennsylvania, the equiva-
lency approach is used  and is quite adequate for pavement design.  A total
of 34 states make use of structural layer coefficients in pavement design
(Reference 1-58).   In other states where experience and familiarity with
the materials is not as  extensive, a more rigorous approach using theo-
retical pavement design analysis is used.

               AASHTO Structural Equivalency Method.  The AASHTO Road Test
sponsored by the American Association of State Highway  Officials* was con-
ducted in Ottawa, Illinois between 1958 and 1960 and involved the testing
of six  specially constructed roadway loops using either rigid or flexible
pavement.  The flexible pavements were underlain with either crushed stone,
gravel, cement-treated base, or bituminous-treated base.  No lime-fly  ash-
aggregate base was  used in the AASHTO Road Test. During the 25-month test
period, over 1.1 million total vehicle axle loads were applied to the test
pavements and bridges.
                                     1-51

-------
          One of the objectives of the AASHTO Road Test was to determine the
relationships between the number of repetitions of different axle loadings
and configurations with the performance of different types of pavement and
different thicknesses of bases and sub-bases.  A serviceability rating sys-
tem on a scale of 0 to 5 was developed and correlated with axle loadings
and pavement characteristics such as pavement profile, rutting, cracking,
and patching.  By means of mathematical models and regression analysis,
pavement performance was related to axle loadings and an empirical struc-
tural number was developed for layered flexible pavement systems (Reference
1-59).

          A more comprehensive discussion of the findings of the AASHTO Road
Test and the theory involved in development of the findings of the AASHTO
Road Test and the theory involved in development of pavement performance
equations may be found in Report 5 of the AASHTO Road Test (Reference 1-60).

          The structural number, which relates pavement layer thickness to
pavement performance is given by the following equation:

               SN = Vl + a2D2 + a3D3


where

          SN = structural namber or structural capcity of
               the pavement

          D., D-, and D_ are the thicknesses of the surface
               Base, ana sub-base, respectively.

          a., a., and a, are the equivalency values or structural
               coefficients for each layer.

          The structural number for a flexible pavement is a function of
the anticipated  traffic loading, subgrade, and environmental conditions,
and required performance level.  Nomographs have been developed to relate
these factors and determine the required structural number for a given set
of conditions.   The value of the structural number  (SN) generally ranges
from 1.0 to  6.0.  The design  methodology for pavement systems based on the
structural equivalency method developed from the AASHTO Road Test is con-
tained in the AASHTO Interim Guide for Pavement Structures (Reference 1-67).

          The acronym AASHTO refers to the same organization, which is now
known as the American Association of State Highway and Transportation Of-
ficials.  At present, 32 states make use of the AASHTO Interim Guide, either
in their entirety or with some modification.
                                      1-52

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          The fundamental premise for selection of values for structural
coefficients a^, &2>  an<^ a3 *s that there is a ratio of thicknesses be-
tween different materials such that pavements constructed in a similar
manner will have identical performance records.  However, this assumption
is not necessarily valid  under all conditions (Reference 1-62).

          From the AASHTO Road Test, the following structural coefficients
were determined:
          a. Bituminous  concrete wearing surface            0.44

          a» Bituminous  stabilized base                     0.30-0.35

          a2 Portland cement stabilized base                0.30-0.35

          a  Crushed stone base                             0.13-0.14

          a  Gravel sub-base                                0.11

          Since the AASHTO Road Test did not evaluate the performance of
pozzolanic base course materials, the University of Illinois, which had
begun its research on LFA materials in 1956, undertook a pavement test
track study in 1960.  This test track study, sponsored by the National
Lime Association, involved a comparison of the performance of crushed
stone and LFA bases.  A  circular test tract, with a 16' centerline dia-
meter, was housed in a 40 by 60 foot quonset-type building on the Uni-
versity's campus.  Dynamic wheel loadings were applied to the test track
by two rubber tired wheels mounted on a rotating loading frame.  The test
track was also equipped with water level control, provisions for varying
the loading and speed of the wheel frame, and electronic deflection gauges
mounted in the test pavement.

          In all, a total of six test sets were run, three for each base
type.  Each test set comprised six separate pavement sections.  Crushed
stone base thicknesses were varied from 4 to 12 inches.  Pozzolanic base
sections were varied from 4 to 6 inches.  Various surface materials, in-
cluding chip seal coat and asphaltic concrete, were used.  The number of
dynamic wheel load applications generally ranged from 100,000 to 400,000
for crushed stone bases  to in excess of 1 million for pozzolanic bases.

          Based on the comparative performance of pozzolanic and crushed
stone base materials from the University of Illinois Test Track Study,
and using a structural coefficient of 0.14 for the crushed stone base,
Ahlberg and Barenberg (Reference 1-62) recommended the following struc-
tural coefficients for pozzolanic base materials, assuming adequate cured
strength at time of loading:
                                     1-53

-------
                                Compressive            Recommended
                               Strength, psi           Structural
Quality                      (7 days @ 100°F)          Coefficient

High                        Greater than 1,000          a. = 0.34

Average                        650 to 1,000             a. - 0.28

Low                            400 to 650               a.- = 0.20


          Pozzolanic base course materials have been used to a greater extent
in Illinois, Ohio, and Pennsylvania than in any of the other states.  Each of
these three states makes use of structural coefficients in the design of lay-
ered flexible pavements.  However, because of differences in environments,
traffic, and construction practices from one state to another, each state
establishes layer coefficients applicable to its own practices and based on
its own experience.  The structural coefficients for LFA base course mixtures
in each of these states are:

               Illinois              0.28
               Ohio                  0.28
               Pennsylvania          0.40

          Until 1976, the structural coefficient for LFA base materials in
Pennsylvania had been 0.30.  However, at that time the Pennsylvania Depart-
ment of Transportation changed its structural coefficients for LFA and ag-
gregate-ceaent base materials from 0.30 to 0.40, which is equivalent to bit-
uminous concrete base course.

          These changes resulted from the findings of a two-year pavement
test track study initiated in 1972 at Penn State University.  The purpose
of the study was to investigate the structural coefficients of four sta-
bilized base materials used in Pennsylvania, as a logical followup to the
AASHTO Road Test.  A total of 17 test sections were constructed on a one-
mile long oval with two tangent sections, one in cut and one in fill.  Among
the 17 test sections were two sections using LFA base materials, each of
which was 8 inches in thickness.  The material for these test sections was
supplied by a commercial producer with a pugmill plant in Lancaster County,
Pennsylvania and consisted of 3 percent lime, 15 percent fly ash, and 82
percent crushed limestone aggregate.

          Over 1 million equivalent 18 kip wheel load applications were ap-
plied to each of the pavement test sections during the two-year loading
period.  It is important to recognize  that this type of loading is equiva-
lent to that normally applied on interstate facilities and is far in excess
of the wheel loadings experienced on most other facilities.  The pavement
serviceability of  all test sections was monitored throughout the test per-
iod by means of several different surface profile measurements, together
with  an evaluation of cracking and rut depths.  The study concluded that


                                     1-54

-------
aggregate-cement provided the best pavement performance, with LFA and bit-
uminous concrete base being about equal  (but not performing quite as well
as aggregate-cement), and aggregate-bituminous base providing the least
performance of the four alternatives  (Reference 1-63).

          When using the  AASHTO equivalency method of design it is essen-
tial to keep in mind that, in addition to equivalent  thickness values for
various pavement layers, certain specified minimum thicknesses must also
be provided.  These minimum thickness values are based on the layer thick-
nesses required to support the heaviest anticipated wheel loadings for
different  pavement uses without inflicting any structural damage to the
pavement layers.  M-ttn'mimi asphalt surface thicknesses are recommended by
the Asphalt Institute  and are also contained in design manuals used by-
different state transportation agencies.  Table 1-10  summarizes recommended
pavement surface thicknesses, as suggested by the Asphalt Institute (Ref-
erence 1-64).  These minimum surface thicknesses are  used in computation
of alternative base thicknesses for economic evaluation.

          In order to assess the relationship of using different structural
coefficients for different base course materials, the required thickness of
crushed stone, LFA, and bituminous concrete base materials have been com-
puted for different structural numbers using structural coefficients from
Illinois, Ohio, and Pennsylvania.  These comparative thicknesses form the
basis for an economic comparison of LFA and other base course alternatives,
which is presented later in this report.

          The following is a sample computation using a structural number
of 4.00 with Illinois structural coefficients of 0.13 for crushed stone
base, 0.28 for LFA base, 0.33 for bituminous base, and 0.40 for bituminous
surface.  According to Table 1-10 a minimum of 3 inches of bituminous sur-
face material is required when using either a bituminous base or a pozzo-
lanic base.  A minimum of 5 inches of bituminous surface material is required
when using a crushed stone base.  In this sample  computation, no sub-base
material was used.

          The  various thicknesses of the three road base alternatives for
this example are computed as follows:

          SN = a D  + a.D2 + a D  where SN = 4.00 and both a  and D  = 0

Bituminous Base:  4.00 = (.04) (3.00) + (.33) (D );   .33 D  = 2.80;

                  D, =  8.5 inches


Pozzolanic Base:  4.00 = (.40) (3.00) + (.28) (D2);   .28 DZ = 2.80;
                  D- = 10.0 inches


Crushed Stone Base:  4.00 = (.40) (5.00) + (.13) (D2);  .13 DZ = 2.00;
                     D  = 15.4 inches
                                     1-55

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                                              Table 1-10


                                   RECOMMENDED MINIMUM THICKNESSES  FOR
                                 ASPHALT SURFACES* USING DIFFERENT  BASE
                                COURSE  MATERIALS  IN DIFFERENT  APPLICATIONS
APPLICATION
Very Heavy Duty
Heavy Duty
Medium Duty
Light Duty
DESCRIPTION
Interstate
routes
Major through-
fares
Truck Terminals
Residential
streets
Commercial
drives
Auto parking
Driveways
STRUCTURAL
NUMBER
4.0 and
above
3.0 and
above
2.0 to
3.0
Less than
2.0
MINIMUM SURFACE
BITUMINOUS
BASE
4
3
2
1-1/2
THICKNESS (INC.)
STABILIZED
AGGREGATE
BASE
4
3
2
1-1/2
BASE COURSE TYPE
UNBOUND
AGGREGATE
BASE
6
5
4
2-1/2
*The term asphat surface includes  the  combined  thickness  of  both  the wearing surface and the binder
 or leveling course.
NOTE;  The Pennsylvania Department of  Transportation revised their minimum surface thickness require-
       ments on February  20,  1980 to  require that a minimum of 3-1/2 inches of asphalt surface
       (2 inch binder and 1-1/2 inch Wearing  surface)  be placed over all non-bituminous base materials

-------
       Table 1-11 summarizes the results of similar computations performed
for pavement structural numbers ranging from 2.0 to 6.0 for Illinois, Ohio,
and Pennsylvania flexible pavement designs.

            Other Pavement Thickness Design Approaches.  In situations where
performance data and/or experience with LFA materials are not available, the
pavement thickness design should be based on the anticipated strength of the
pozzolanic base at the time of loading.   Since LFA materials continue to
gain strength over time, fatigue due to repeated wheel loadings is generally
not a factor.  Instead, the number of wheel load applications to be carried
during the first winter and the early strength of the base material are more
critical to the analysis of the pavement.

       The structural capacity of pavements with LFA base materials can be
calculated from the  material properties and relative layer thicknesses by
means of the Westergaard Slab Theory, the Elastic Layered System Theory, or
Meyerhof's Ultimate Load Theory.  Since procedures have not been standardized
for using any of these more theoretical analytical methods for design of LFA
pavements, the details of these methods are not discussed in this report.

       Applications and Limitations of LFA Materials.  Over the past twenty-
five or more  years, LFA materials have been used in a wide variety of pave-
ment applications.  As with all  paving materials, LFA is most effective when
properly designed, mixed, and handled and should only be used under the proper
conditions.

       LFA mixtures have been successfully used as base and sub-base material
in flexible pavement systems and as a sub-base for rigid pavements.  How-
ever, it is important that the time interval between placement of LFA base
and the installation of a bituminous wearing surface or rigid pavement not
be too long or else the surface of the LFA base should be sealed with a tar
or asphalt to protect the surface from the long-term  effects of traffic,
weather, or water.  Generally, it is advisable to place a bituminous sur-
face over the LFA base the day after the base has been installed.

       Besides its successful use as a base and sub-base, LFA has also been
used as a shoulder material.  In some areas, LFA use as a shoulder material
has met with limited success.  This is probably due to several reasons.  One
is that shoulders are normally covered with a  thinner layer of stone chips
or bituminous wearing surface than a base course.  This affords less protec-
tion from freezing and thawing, not to mention the effects of occasional
heavy  truck traffic.  Secondly, in northern states like Illinois, shoulders
often receive a heavy dose of road salts during the course of a winter  and
exposure to such salts has sometimes had deleterious effect on the material
(Reference 1-65).
                                  1-57

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                       Table  I-11
THREE STATE COMPARISON OF FLEXIBLE PAVEMENT THICKNESS DESIGNS

                ILLINOIS                   OHIO                    PENNSYLVANIA
Structural
Number
(SN)
2.0
2.5
3.0
T
in
00 3.5
4.0
4.5
5.0
5.5
6.0
Asphalt
Wearing Surface
Ohio 111. Pa.
.35 .40 .44
1.5"
2.5"
2.0"
4.0"
2.0"
4.0"
3.0"
5.0"
3.0"
5.0"
3.0"
5.0"
3.0"
5.0"
4.0"
6.0"
4.0"
6.0"
Aggregate
Sub -Base
(.11)
0
0
0
0
0
0
0
0
0
0
6"
6"
8"
8"
8"
8"
10"
10"
Aggre-
gate
Base
(.13)
7.7"
6.9"
10.8"
11.5"
15.4"
14.2"
16.3"
17.1
19.2°
Bitu-
minous
Base
(.33)-
4.25"
5.15"
6.7"
7.0"
8.5"
8.0"
8.9"
9.2"
10.0"
Pozzo-
lanic
Base
(.28)
S.O"
6.1"
7.9"
8.2"
10.0"
9.4"
10.4"
10.8"
11.8"
Aggre-
gate
Base
(.14)
8.0"
7.9"
11.4"
12.5"
16.1"
14.9"
17.0"
18.0"
20.0"
Bitu-
minous
Base
(.35)
4.25"
5.15"
6.6"
7.0"
8.4"
8.0"
8.8"
8.7"
10.0"
Pozzo-
lanfc
Base
(.28)
5.3"
6.45"
8.25"
8.75"
10.5"
10.0"
11.0"
11.5"
12.5"
Aggre-
gate
Base
(.14)
6.4"
5.3"
8.9"
9.3"
12.9"
11.7"
13.7"
14.2"
16.2"
Bitu-
minous
Base
(.40)
3.4"
4.1"
5.3"
5.5"
6.7"
6,3"
7.0"
7.2"
7.9"
Pozzo-
Tanic
Base
(.30)
4.5"
.5.4"
7.1"
7.3"
9.0"
8.4"
' 9.31'
9.5"
10.5"
(.40)
3.4"
4.1"
5.3"
5.5"
6.7"
6.3"
7.0"
7.2"
7.9"

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       Aside from proper mix design and blending, the key to good per-
formance with LFA pavements is in adequate field compaction.  Most field
problems attributed to LFA base over the years seem to have been the re-
sult of improper compaction during placement,  inadequate moisture control
at the mixing plant, placement of the material on. a poorly prepared sub-
grade, or placing the material under adverse weather conditions (Reference
1-66).

            Durability and Late Season Construction.  Durability is the
most important single property related to the performance of LFA mater-
ials, particularly resistance to cyclic freezing and thawing.   There
are two schools of thought with respect to late season construction using
LFA materials.  One holds that unless  the pozzolanic material is able to
develop a certain level of cementing action and resultant strength, it will
be unable to withstand the disruption forces associated with the initial
winter freeze-thaw cycle.  Since cementing action and strength development
is time and temperature dependent, it is felt that material placed beyond
a certain cutoff period during the construction season may be unable to
develop the strength (and durability) needed for freeze/thaw resistance
(Reference 1-33).

       The other school of thought concerning late season  construction
holds that, regardless of cementing action, as long as the LFA mix is
placed above a certain minimum temperature, contains a well-graded ag-
gregate, and is placed to a sufficient depth to support anticipated wheel
loadings, the mechanical stability of the base material will be adequate
to support wheel loadings until the following spring.  At that time,
strength development can proceed as normal (Reference 1-68).  It should
be pointed out that this premise is not necessarily applicable to facil-
ities carrying medium to  heavy traffic loadings.

       Each of these two schools of thought are discussed in greater detail
in terms of how they affect late season construction using LFA materials.

            Strength Development and Construction Cutoff Date.  During the
durability study program performed at the University of Illinois, Thompson
and Dempsey  evaluated the late season construction for LFA materials in
terms of a residual strength concept.   The residual strength is the
strength of a stabilized material at the conclusion of the first winter
of cyclic freezing and thawing.  According to Thompson and Dempsey, some
residual strength, greater than a minimum tolerable strength, is needed to
assure satisfactory pavement response, in terms of durability.  Figure 1-12
illustrates the  residual strength concept and the relationship of residual
strength to minimum tolerable strength.
                                  1-59

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S1
QJ
O>
k.

3
                            •Cured Strength
                          Residual Strength   |
                                                                      t
                  Minimum Tolerable  Strength
                       y
         initial  Curing ^  {First Winter-Cyclic^ |     Curing-Year  2     I

            v>-_.i     "  I r~" -	^-i__r^      I                         '
            Year  I
j Freeze-Thow Damage j


i	I
i
                                Time




      Figure 1-12.   Residual  strength concept  for lime-fly ash-aggregate mixtures,
                                    1-60

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       To assure a sufficient cured strength by the onset of the first
freeze-thaw cycle, strength development was correlated with degree-days
of curing. Since strength development ceases at temperatures below 40°F,
degree-days are sometimes computed with a 40°F base temperature.  Although
degree-days of curing can be related to compressive strength in the labor-
atory, field curing occurs at varying temperatures.  It must also be recog-
nized that degree-days of curing at higher temperatures results in higher
strength than with   the same number of degree-days at lower temperatures.

       By analyzing local weather records, the number of degree-days from
any particular date can be determined, using a selected base temperature.
Normally, this is based on the coldest late season temperature or  earliest
winter over  a twenty-year period of time.  These degree-days represent cur-
ing according to air temperatures and not pavement temperatures.  However,
this type of analysis does enable an engineer to select a construction cut-
off date, after which no LFA base material is usually installed without
special permission.  This concern over late season construction definitely
limits the period of time during which LFA base materials can be placed on
State and Federally funded highway projects.

       State transportation agencies  using LFA do specify certain construc-
tion cutoff dates, beyond which placement of LFA materials is not permitted
unless authorized in writing.  In Illinois, LFA is allowed to be placed
after September 15th only if test specimens are able to attain the follow-
ing laboratory compressive strengths:

                                  REQUIRED COMPRESSIVE STRENGTH (psi) -
                                  14 DAY CURE AT 72%	

TRANSITION DATE                   NORTHERN ZONE           SOUTHERN ZONE

September 15                           700                     650
October 1                              850                     700
October 15                             950                     850

       The above transition dates must be verified by samples of LFA
material, representative of July production, submitted to IDOT for lab-
oratory testing by August 15.  Approval of a particular transition date
is based on consideration of cured strength characteristics determined
from test results and predicted during degree-days.

       In Ohio, the construction cutoff date is September 15th on pave-
ments to be opened to traffic during the summer, fall, and winter months
of  the construction year.  On pavements which are to be opened the fol-
lowing spring, LFA base may be placed later than September 15th but, af-
ter that date, a bituminous curing coat and a minimum of one overlying
pavement  course must be constructed within 72 hours of final compaction
of the base.  In no case shall LFA be placed during rain or when the
temperature is below 40°F in the shade.  The material is not allowed to
remain uncovered during the winter months.
                                  1-61

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          According to Pennsylvania DOT specifications, LFA is permitted
to be placed  on State highways only between April 15 and September 21.
The late season cutoff date of September 21 was established for selected
engineering districts in Pennsylvania where LFA is available as a result
of a special study performed by several Penn DOT materials engineers in
1975.  This study developed a failure criterion for LFA mixtures and sta-
tistically evaluated actual temperature data in certain areas of the State
in order to determine failure problems for given placement locations and
dates.

          The failure criterion for this study was based on a correlation
between the results of the wire brush freeze-thaw test and the double punch
tensile test method developed at Lehigh University (Reference 1-69).  A
total of 231 LFA samples were tested to develop a relationship between
double punch tensile strength and freeze-thaw failure (14 percent weight
loss within 12 freeze-thaw cycles).  From this relationship, a probability
of failure was determined for various tensile strength ranges.

          Tensile strength development was then related to curing at several
different temperatures to establish a tensile strength vs. degree-day cor-
relation.  Then 26 years of temperature data from first order weather sta-
tions from the Philadelphia, Harrisburg, and Pittsburgh areas were statis-
tically analyzed by computer.  Air temperatures were correlated to reflect
base  course temperatures and a theoretical frequency of occurrence for var-
ious  temperatures was established.

          A family of curves was developed relating projected tensile strength
to frequency of occurrence for different dates. September 21 was selected as
a cutoff date because the probability of failure is only one percent on that
date  (Reference 1-70).

          Regardless of the method used, there seems to be a reasonably close
correlation among the northern states which are principal LFA users, as far
as construction cutoff dates are concerned.  Despite cutoff dates, it is al-
ways  possible to make use of additives, such as portland cement, to increase
the  rate of strength development during the later stages of the construction
season.  At present, Illinois appears to have the best system for evaluation
and  possible approval of late season compositions and extension of the con-
struction cutoff date.

               Mechanical Stability.  A study was performed in 1975 to
evaluate LFA pavement base thickness for residential streets in Toledo,
Ohio  as a function of accumulated service time.  The purpose of the study
was  to determine whether a pozzolanic base placed during the latter part
of the construction season could reasonably be expected to have sufficient
strength to withstand traffic loads during  the ensuing winter and before
spring temperature rises could develop significant strength-gaining reac-
tions in the mix.
                                      1-62

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          The study involved the following steps:

          •    Developing an estimate of travel demand per
               dwelling unit for a planned 90 unit residential
               subdivision.

          •    Apportioning the travel demand in terms of ve-
               hicle types and axle load groupings.

          •    Estimating the number and types of vehicles
               associated with residential construction and
               translating this estimate into equivalent  18
               kip single axle loads.

          •    Simulating the average daily traffic on a typical
               subdivision street during construction and after
               complete development.

          •    Generating an estimated accumulation of 18 kip
               single axle loadings as a function of time.

          •    Using equations derived from the AASHTO Road Test
               for a given subgrade condition, determine the re-
               quired structural number (SN) for the pavement
               as a function of accumulated pavement service time.

          •    Compute the required thickness of pavement layers
               from the pavement structural number and from struc-
               tural coefficients accepted by the City of Toledo.

          Based on calculations for design traffic number, accumulations of
equivalent 18 kip single axle loadings for 6 months increments, and an as-
sumed soil GBR value of 3, the pavement structural number (SN) was related
to allowable wheel load repetitions, based on the AASHTO Road Test equation.
For each six-month increment, the required percentage of total pavement SN
was computed.  Assuming a 2-inch asphalt wearing surface and an LFA design
coefficient of 0.28, the required thickness of LFA base course for each time
increment was also computed.

          It was concluded from  this study that a six-inch thick layer poz-
zolanic base can withstand the traffic service requirements placed on it dur-
ing the first year, even without any cementing action.  Essentially, the
uncemented LFA base was considered as structurally equivalent to a crushed
stone base during the first year of service.  Computations of the required
thickness of crushed stone base showed that a six-inch stone layer was ade-
quate for support of anticipated wheel loadings during the first year (Ref-
erence 1-71).
                                     1-63

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          This is significant because a substantial percentage of LFA base
material is placed during late season due to awarding of contracts and sched-
uling of work.  One LFA producer in northern Ohio has reviewed his annual LFA
tonnage figures for the past five years and discovered that approximately 50
percent of all LFA base material from his plant is produced after September
1st and 32 percent is produced after October 1st.  Therefore, enforcement of
a construction cutoff date of September 15th in Ohio results in a loss of
approximately 40 percent of LFA tonnage each year on State projects  (Reference
1-72).  In many instances, this carries over to municipal work, where State
highway specifications are often adopted verbatim by local officials.

          One exception is the City of Toledo, Ohio, which is now a  regular
user of LFA base.  The City of Toledo has a supplemental specification for
Item 835 Aggregate-Lime-Fly Ash Modified Base.  This is essentially  the  same
material specification as that of the Ohio Department of Transportation  (ODOT).
A copy of the City of Toledo supplemental specification is in the Appendix.
There is, however, one notable difference between the City of Toledo and the
ODOT specification with respect to the construction season.  The City of To-
ledo specification states  that Aggregate-Lime-Fly Ash Base Modified shall
be placed between April 1 and November 1 and only when the temperature in
the shade is 40°F or higher.  Placement of the material prior to April 1 or
after November  1 must be authorized in writing by the Commissioner  of Engi-
neering and Construction of his authorized representative.  To date, the City
of Toledo has experienced no problems with LFA base material placed  after
ODOT September 15th cutoff date and even LFA base installed November 1st (if
temperatures permit) has performed acceptably  (Reference 1-73).  The City
does insist that the LFA base be overlaid with asphalt as quickly as possible
and, during late season construction, efforts are sometimes made to  keep
traffic off newly paved projects.

          Another municipality using LFA base is the City of Lancaster,
Pennsylvania.  When State funds are involved, the City does not place LFA
base after the Penn DOT September 21st cutoff date.  If no State funds are
involved, LFA base has been placed as  late as December 1st with no  subse-
quent problems, provided the compacted surface is wet down and covered with
black top the following day.  It was also felt that restraining the  LFA  base
between curbs results  in better performance  (Reference 1-74).

          Although there are numerous examples of successful LFA base place-
ment after State construction cutoff dates, acceptable pavement performance
depends on a combination of freeze-thaw resistance and support of accumulated
wheel loadings.  Therefore, on heavier traffic facilities, adherence to  es-
tablished cutoff dates would appear to provide an adequate margin of safety
to  assure desired performance, while extension of such dates may be  warranted
on  more lightly traveled facilities.
                                      1-64

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          LFA Use in Highway Construction Proj ects.  Although lime-fly ash-
aggregate (LFA) road base materials have been produced and used to some ex-
tent in over a dozen states, the particular states in which the largest quan-
tities have been used in highway construction for the longest period of time
are Pennsylvania, Ohio, and Illinois.  In each of these states, the product
is often referred to by its trade name (Poz-0-Pac).  LFA is also referred to
by different names in state specifications.  The material has also been used
by the Federal Aviation Administration (FAA) in several airport paving pro-
jects.

          This section of the report focuses on the quantities of LFA materials
used, the types of projects in which these materials have been used, specifi-
cations, bidding procedures, and overall product performance in each of these
three states, as well as in other selected highway and airport projects.

               Illinois.  Over the past twenty-five years, the largest tonnage
use of LFA road base materials has probably occurred in the State of Illinois,
and particularly in the Chicago metropolitan area.  The reasons for this are:

          1.   There is a large amount of comparatively high
               quality fly ash produced by utilities in the
               Chicago area.

          2.   The  fly ash broker in the Chicago  area has
               developed and maintained a product-oriented
               quality control program with .the local utility
               company.

          3.   Marketing of construction products using this
               fly ash  has been conducted in an aggressive
               and yet professional manner.

          The first known use of Poz-0-Pac, or pozzolanic aggregate mixtures
(PAM), as they are known in Illinois, was in the summer of 1955 using a lime-
fly ash-boiler slag mix on a Park District project for the City of Chicago.
Approximately 800 tons of base material was mixed-in-place on this project.
Although this was a crude beginning, the job held up well.

          In 1956, the O'Brien Paving Company began operating the first Poz-
0-Pac mixing plant in Illinois, located on Chicago Avenue.  A total of 25,000
tons of material was produced that first year, with double that quantity the
following season.  In 1958, the first  public road project in Illinois using
PAM  was installed for the  Cook County  Highway Department.  This was a 3/4
mile section of a county road on the northern edge of Chicago.  Installation
of the PAM material was overseen by Professor George Hollon of the University
of Illinois Civil Engineering Department, who was at that time very active in
the research of lime stabilization.  The success of this installation prompted
Cook County to place yet another PAM base project the following year, this
time using the County's own road forces.  It was also during 1959 that the
first supplemental specification for pozzolanic aggregate material was pre-
pared by the Cook County Department of Highways (Reference 1-75).
                                     1-65

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          In 1960, the first PAM mixes using gravel aggregate were produced.
Up until  that time, the only aggregate used in the lime-fly ash-aggregate
mixtures in the Chicago area had been boiler slag because it was plentiful,
inexpensive and  was a clean, uniform material which produced a well-graded,
high strength, high quality base mix (Reference 1-76).  During 1960, the
first County contract that involved contractor bids was let using PAM.  The
low  bidder for that project also purchased a mixing plant and began produc-
ing the material.  The following year, another contractor was low bidder on
a Cook County road project using PAM, and he also purchased a plant and also
became a producer.  By 1964, the Illinois Department of Highways had compiled
a design manual on the use of PAH in municipal road construction throughout
the entire state (Reference 1-77).

          The first use of PAM on a State highway in Illinois was during
1957 on a secondary road project in Chicago.  The mix used on this project
consisted of 5 percent lime, 35 percent fly ash, and 60 percent boiler slag.
Core specimens taken from the base material placed on this project ultimately
exceeded 4,000 psi in compressive strength, with some cores approaching 5,000
psi (Reference 1-78).  After monitoring and sampling this project for a three-
year period, Illinois Department of Transportation (IDOT) engineers concluded
that PAM could be used as a base course material.

          Although PAM has been used extensively on local road projects and
in dozens of secondary road projects for IDOT in the Chicago area over the
past 25 years, the use of PAM during that time had not been permitted on the
IDOT primary road system, except for a project using PAM in the shoulders of
Interstate 55 near Chicago.  However, during that time the Department has
spent over half a million dollars for research involving lime-fly ash mixtures.

          Recently, IDOT has developed a new policy allowing PAM to bid as
an optional base material on 12 selected primary road projects in Illinois
during 1980.  Of six projects already let, PAM was low in five bids.  Each
of the primary  road projects was to have a structural number of 5.00 or
less and the performance of PAM on these projects is to be carefully  moni-
tored  (Reference 1-79).

          On each of these contracts, the low bidder would be given the option
of which base course alternate to use on the project and a substitution could
be made at a later date prior to installation of the base.

          The first construction specification for PAM use on State highways
in Illinois was developed in November 1961 and has since been revised eight
times.  The most recent material specification for PAM was published in April
1980 as a special provision and is not yet included in the Illinois Department
of Transportation's Standard Specifications for Road and Bridge Construction.

          The new 1980 PAM  specifications in Illinois consist of the following:
                                      1-66

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          •    Special Provision for Pozzolanic Base Course,
               Type A

          •    Supplemental  Specification for Section 218.
               Stabilized Sub-base

          •    Supplemental Specification for Section 804.
               Pozzolanic Aggregate Mixture Equipment

          •    Pozzolanic-Aggregate Mixture (PAM) Laboratory
               Evaluation/Design Procedure

          These specifications were developed through the efforts of a six-
man task force over an 18-month time period.  The task force consisted of
two representatives each from IDOT and the University of Illinois Civil
Engineering Department, and one representative each from the PAM producers
in northern Illinois and the ash marketing agency supplying these PAM pro-
ducers.  The task force reviewed previous stabilized base research studies,
including late-season construction cutoff date procedures, as well as data
from IDOT studies of field variability of PAM materials and performance data
from previous PAM projects.  A copy of each of these specifications is in-
cluded in the Appendix.

          According to the Special Provision for Pozzolanic  Base Mixtures,
Type A, and the Supplemental Specification for Section 218, Stabilized Sub-
Base, the composition of the mixture must be such that test cylinders cured
for 14 days at 72°F will have a minimum compressive strength of 600 psi and
a minimum lime content of 3.5 percent.  A minimum compressive strength of
600 psi is high by comparison with other states using LFA materials, such as
Ohio or Pennsylvania.

          One of the reasons for the higher strength criterion was because
IDOT engineers over the years had observed a difference in strength between
laboratory and field mixed PAM specimens.  The difference was such that
field strengths for the same mixes under very similar curing conditions
were approximately 70 percent of comparable laboratory strengths.  There-
fore, in order to attain 400 psi compressive strength in the field, IDOT
engineers now require 600 psi strength in the laboratory to take into ac-
count field variability (Reference 1-80).

               Ohio.  In Ohio, aggregate-lime-fly ash has been used on a
limited basis in State highway construction as a base course for asphaltic
concrete pavement and continuously  reinforced portland cement pavement.
Aggregate-lime-fly ash is seldom bid as an alternate base material in Ohio
because State officials believe that designing for different pavement thick-
nesses causes a big problem in terms of expense.  The legality of optional
bids in Ohio is considered questionable.
                                     1-67

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          To date, this supplemental specification has not been included
in the Ohio Department of Transportation's  (ODOT) Construction and Ma-
terial Specifications, sometimes  referred  to as the Blue Book.  Until
now, it has been decided to allow only a supplemental specification for
the material because it had once been covered by a patent and a license
was required for its manufacture.

          Ten years ago, there were four different producers of aggregate-
lime-fly ash in Ohio.  As of this time, only one producer in the Toledo area
is still supplying this material.  The other producers in Ohio stopped mar-
keting the material a number of years ago for several reasons.  The principal
reason was economics.  Until the Arab oil embargo of 1973, the price per square
yard for pozzolanic base was not substantially different from black base and
there was little or no incentive on the part of ODOT to use the material.  In
addition a number of areas in the State were experiencing shortages of lime,
which at times severely hampered the production of aggregate-lime-fly ash
base (Reference 1-81).

          The initial use of aggregate-lime-fly ash base material on a State
highway in Ohio took place in 1960 on State Route 727 in Clermont County.
The project was considered experimental and involved 2.5 miles of flexible
pavement using various design sections including aggregate-lime-fly ash base.
A detailed report on this project was prepared by the ODOT Construction Bureau
in 1970, reporting satisfactory performance.  At that time, the surface of the
road was in excellent condition and samples of the base were very hard.  No
additional information is presently available.

          From'1969 to  1972, aggregate-lime-fly ash was used as a base ma-
terial on three projects involving continuously reinforced portland cement
concrete pavement.  One of these pavements  is still in excellent condition.
The other two projects show a considerable  amount of transverse cracking in
the surface of the concrete pavement.  Because of general problems encountered
by ODOT with continuously reinforced concrete pavements, the cause of the
cracking could not be attributed solely to  the base material.  Although the
aggregate-lime-fly ash base was not considered the cause of the cracking, a
decision was made to discontinue the use of continuously reinforced pavement
in Ohio.

          Between 1969 and 1972, aggregate-lime-fly ash base was specified
in the original bid plans on two projects,  one on a two-lane road and one
on a heavily traveled section of four-lane  road.  The pavement of each of
these projects is still in good condition after nearly ten years, with only
isolated signs of cracking and/or rutting.
                                      1-68

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          Since 1972, aggregate-lime-fly ash has been permitted to be bid
as an  alternate to 301 bituminous-aggregate base on a total of seven pro-
jects.  The aggregate-lime-fly ash was used on only two of these projects
and not the other five either because the contractor did not elect to use
the aggregate-lime-fly ash alternate or because the bid cost of the pave-
ment design using the aggregate-lime-fly ash alternate was higher than the
design for the bituminous-aggregate alternate.  On one project, constructed
in 1973, the aggregate-lime-fly ash was bid as an alternate using a struc-
tural layer coefficient of 0.35.  To date, the material  has performed ex-
cellently at  this project location.  On the other project, built in 1977
aggregate-lime-fly ash was bid as an alternate using a structural layer
coefficient of 0.28.  To date, there have been no known problems with this
installation (Reference 1-82).

          Aggregate-lime-fly ash base has only been used on eight primary
State highway projects in Ohio.  The material has been used more extensively
in secondary and non-state work, especially in northern Ohio.  In general,
this material has provided good to excellent performance on the projects in
which it has been used and is considered an acceptable base course material
by design and construction personnel of the Ohio Department of Transporta-
tion (Reference 1-83).

          Aggregate-lime-fly ash base materials have been used to a greater
extent  in municipal projects in northern Ohio than on State projects.  The
material has been used in dozens of road and street projects in the City of
Toledo over the years and"not a single failure has been reported.  Most in-
stallations have been made during summer months.  In such cases, the material
has performed excellently and city officials have been quite pleased.  A few
projects using aggregate-lime-fly ash have extended as far into the season as
mid-November, but still the material did not fail after the first winter.

          Over the past several years, aggregate-lime-fly ash base has cap-
tured the low bid in 80 percent of all the reconstruction projects in the
Toledo area in which it has been bid as an alternate to bituminous base.
Although city officials consider aggregate-lime-fly ash to be more economical,
each project is designed and evaluated separately and only if substantial cost
savings seem possible are alternate bids taken.  According to the Construction
Engineer for the  City of Toledo, their only reservation to the use of aggre-
gate-lime-fly ash is during late season construction in temperatures below
50°F (Reference 1-84).

               Pennsylvania.  Over the past 25 years, LFA or aggregate-lime-
pozzolan (ALP) base has been used in over a hundred state highway projects
in Pennsylvania, not to  mention many miles of local roads and streets in
municipalities throughout the state.
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          Since 1966, there has been a standard specification for aggregate-
lime-pozzolan (ALP) base material in Pennsylvania, which is contained in Sec-
tion 322 of the Pennsylvania Department of Transportation (Penn DOT) Form 408
Specifications.  A copy of this specification is included in the Appendix.
It has been carried forward in the Penn DOT Form 408 Specifications in an
essentially unchanged form since that time.  The only specified material
testing requirements for the mixture are that the liquid limit of the mix-
ture not exceed 25, the plasticity index not exceed 6, and the durability
of the mixture meet the requirements of the Pennsylvania Testing Method (PTM)
110, which is basically the wire brush freeze-thaw test that was formerly part
of ASTM C593.

          In the preparation of Proctor size (4 inch of 101.6 mm diameter by
4.6 inch or 116.8 mm height) freeze-thaw test specimens, however, the moisture-
density test procedures described by PTM 110 for evaluating ALP compositions
differ from those used in other states.  Pennsylvania is the only state using
the standard Proctor density test (5.5 Ib. hammer - 12" drop - 3 layers - 25
blows per layer).  This procedure has been used for many years by Penn DOT on
construction materials such as dense graded aggregate, soil-cement, and cement-
treated base and was also chosen as the criterion for ALP base.

          Usually, ALP compositions placed in the field are almost always com-
pacted to densities greater than 100 percent of standard Proctor density and
that field densities often approach 100 percent of modified Proctor density
(10 Ib. hammer - 18" drop - 3 layers - 25 blows per layer).  This is the pro-
cedure used by other states and the Federal Aviation Administration to prepare
ALP specimens for. strength and durability testing.

          The initial reaction to the question of density is that it does not
seem to make much difference.  However, in designing a base mix, the density
of test specimens directly affects both the compressive strength and durability
of the specimens, which in turn governs the amount of lime required to achieve
acceptable test results.  If too much lime must be added to a field mix, overly
high strengths may develop soon after placement, resulting in shrinkage crack-
ing.  It is, therefore, important to test specimens in the laboratory which
approximate field compaction conditions as closely as possible.

          Since the expiration of the Poz-0-Pac patents, there is no longer a
licensee arrangement for the production and sale of aggregate-lime-pozzolan
base.  At the time the patents expired, there were at least six Poz-0-Pac pro-
ducers in the state of Pennsylvania.  These production facilities are primarily
located in the  southeast part of the state, although there is at least one
producer from the Pittsburgh area.  These producers have supplied Poz-0-Pac
using a variety  of aggregate types, from blast furnace slag in western Penn-
sylvania to limestone, traprock, and even some sand and gravel in the Phila-
delphia area.
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          The first experience with the use of aggregate-lime-pozzolan (ALP)
base  on a state highway in Pennsylvania occurred in 1954 when the material
was used as a base for the construction of the shoulders along the west side
of Germantown Pike (U.S. Route 422) in Plymouth Meeting, west of Philadelphia.
The ALP material was mixed in place and compacted to a six-inch thickness.
The shoulder was placed too late in the season to allow the material to attain
its normal pozzolanic set.  The long-term performance of the ALP shoulder was
compared with that of an 8-inch crushed stone shoulder material placed directly
across the street.  Both shoulders were overlaid  with a bituminous wearing
surface.  Within one year, the conventional shoulder exhibited definite signs
of early deterioration while the shoulder with the ALP base" showed no evidence
of distress (Reference 1-85).

          One of the most outstanding examples of ALP use in Pennsylvania is
the reconstruction of Susquehanna Road between York Road and Tennis Avenue
in Abington Township, northwest of Philadelphia.  The reconstruction of Sus-
quehanna Road was a major construction project on a heavily traveled suburban
arterial route.  Part of the project was two lanes and part was four lanes
undivided.  The project was constructed in several sections, which were com-
pleted between 1964 and 1965.  In one section of the project, the ALP base
material was placed as a ramp for trucks to cross a concrete bridge deck.
Because of equipment running over this ramp, the material was compacted so
hard, it could not be dug, but instead had to be sacrificed.

          During construction, a number of Penn DOT engineers who were un-
familiar with Poz-0-Pac witnessed the spreading and compaction of the ma-
terial.  All were very impressed with the ease of operation, uniformity, and
quality of the product.  Many of them admitted that they had been previously
misinformed about the nature of this material and had formulated many wrong
ideas about it, such as it being difficult to work with.  At the intersection
of Susquehanna Road with Fitzwatertown Road, there was a striking comparison
between the condition of the pavements for these two roads.  The wearing sur-
face  over the stone base for Fitzwatertown Road was badly ravelled due to
truck traffic, while the paving over the ALP base on Susquehanna Road was in
excellent condition (Reference 1-86).

          Aggregate-lime-pozzolan base materials have been placed-in literally
hundreds of jobs in Pennsylvania, ranging from small access roads and streets
for municipal, industrial, and residential and apartment developments to huge
parking lots for shopping centers.  Over ten years ago, thousands of tons of
Poz-0-Pac were placed as the base course for all parking facilities at the
Philadelphia sports complex, which includes the Philadelphia Spectrum and
Veterans Stadium.

          Typical of the many municipal-scale installations in Pennsylvania
in which ALP has been used over the years is the approach roadway to the
Penllyn Pike bridge in Montgomery County, northwest of Philadelphia.  This
bridge was relocated in June of 1965 and the approaches on both sides of the
new bridge were built with ALP base and an asphaltic concrete wearing surface.
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This was the first roadway application using this material that was done by
the Montgomery County highway department.  The base course work was completed
in two days.  However, some material that was not spread the first day was
stockpiled overnight.  Heavy rainfall occurred that night, but the stockpiled
material, although overwet, was still able to be worked and compacted.  During
construction, the hot, humid weather provided excellent curing conditions.

          In October 1965 cores were taken from each side of the bridge.  The
ALP base material, after being in place for only four months, had already
achieved compressive strengths  of 1,880 to 2,340 psi.  The lime content of
the mix used on this job ranged from 3.1 to 3.5 percent (Reference 1-87).

          Since 1976,  when the layer coefficients for ALP and aggregate-
cement (AC) base materials were made equal to that of bituminous concrete
base course (BCBC), flexible pavement projects in engineering districts 6
(Philadelphia), 8 (Harrisburg), 11 and 12 (Pittsburgh) were to be bid on an
alternate basis.  Over the past four years, however, very few alternate bids
were actually received in any of these four engineering districts.  In the
first place, Penn DOT has experienced a severe budgetary cutback during this
period due to a combination of inflation and past bond indebtedness.  Conse-
quently, a sharply reduced number of new construction or reconstruction con-
tracts were let for bid.  Most of the projects being awarded over  the past
two years, at least in the district 6 (greater Philadelphia) area,  have in-
volved resurfacing, safety improvements, and intersection reconstruction
work.  In addition Penn DOT policy is that, when reconstruction projects in-
volve maintenance of traffic, bituminous base is used instead of the aggre-
gate-lime-pozzolan or aggregate-cement alternates.  For these reasons, there
have been comparatively few opportunities for ALP to bid as an alternate.

          During 1979, a decision was made by Penn DOT to discontinue adver-
tising for alternate bids because all of the jobs were going to bituminous
base.  This decision was also made in order to reduce operating costs because
of the extra costs that had been involved in preparing plans and proposals
for alternate bidding  (Reference 1-88).

          Overall, the performance of ALP base materials on state highways
in Pennsylvania has been acceptable to very  good.  Out of more than a hun-
dred state projects using APL, only three have involved serious problems
considered by Penn DOT engineers to be over and above those associated with
normal maintenance.  All three projects were in the Philadelphia area, were
supplied by the same plant, and involved limited amounts of material being
shipped to the job site with  moisture contents nearly double that of the
optimum  value.  Clearly, the main source of the problem in each case was
poor quality control at the mixing plant, along with inadequate field
inspection.
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           For  the most  part,  the field  problems on ALP projects in Pennsyl-
vania have taken the  form of  longitudinal  cracks, alligator cracks, or pot-
holes in the road surface.  These problems were usually  investigated and
discussed  with the  Penn DOT engineer  assigned to the particular project.
Most, if not all, of  these problems were again found to  be related to a lack
of proper  plant or  field control and  could not be attributed to the material
itself.

           In addition to state highway  work, which has diminished drastically
during the past five  years, ALP  base  materials have received rather wide-
spread use in  private and municipal work,  especially in  southeastern Pennsyl-
vania.  Although there  have been many instances of ALP use in township roads,
residential streets,  and parking lots,  the City of Lancaster is perhaps the
best example of ALP use in a  municipality.  The city has been using the ma-
terial for many years,  with annual usage averaging 10,000 to 12,000 tons.

           The  city  usually prepares alternate bids for either ALP base or
bituminous base, but  always selects ALP when it is bid because it costs ap-
proximately half of what the  bituminous base costs.  In cases where ALP base
in one block abuts  bituminous base of equivalent pavement structural number
in an adjacent block, there has  been  no visible difference in the performance
of the two pavements  under  virtually  the same traffic conditions.

           City officials in Lancaster have been very favorably impressed with
both the economics  and  the  performance  of ALP base.  Where possible, the city
uses its own forces to  place  the material.  On a number of occasions, ALP has
been placed after the PennDOT cutoff  date on non-state projects.  If the
weather permits, it has even  been placed after December 1st, but an asphalt
surface was always  installed  the following day.  Thus far, there have been
no failures of an   ALP  project in the City of Lancaster  (Reference 1-89).

           Other States.  Although the majority of LFA base course used in
state highway  projects  has  been  in the  three states discussed previously,
there has  been some use of LFA materials in other states that is also de-
serving of mention.  In the State of  Maryland, approximately 22 miles of
shoulders   on  both  sides of Interstate  95 north of the Susquehanna River
were constructed using  LFA base  material.  A layer of stone chips embedded
in an asphalt  seal  coat was placed over the LFA base.  The roadway was
opened in  the  spring  of 1963.

           Eighteen  months later,  a thorough inspection was made of the shoul-
ders along  the  entire stretch of  I-9S from the Delaware-Maryland state line
to the bridge  over  the  Susquehanna River.  The shoulder not underlain by LFA
base was constructed using  a  soil-cement base.  During the inspection, there
was very obvious rutting and patching of the shoulder underlain by soil-ce-
ment, along with settlement next  to the edge of the roadway and numerous
cracks.   The shoulders  with the  LFA base were far superior in terms of dura-
bility,  rideability, and overall performance (Reference 1-90).  These shoul-
ders remained  in service for nearly ten years, but were removed when the
roadway was widened from two lanes to three lanes in each direction.
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          Another good example of LFA utilization in highway construction
outside of Illinois, Ohio, and Pennsylvania is its use in the Kansas City
area.  City Wide Asphalt Company markets LFA  in Kansas and Missouri under
trademark names of Poz-0-Pac or Poz-0-Blend.  The company purchased the
right to use these trade names from IU Conversion Systems, Inc. in Phila-
delphia.  Since 1977, City Wide Asphalt has produced approximately 600,000
tons of LFA material, most of which has been used in commercial and muni-
cipal work.

          Most of the LFA base produced in the Kansas City area is pre-
blended; that is, the lime and fly ash are blended first, then the addi-
tive (lime and fly ash) is later blended with the aggregate.  Typically,
the pre-blend of lime and fly ash contains 6 to 10 percent lime.  In  the
final Poz-0-Blend product, the additive comprises 12-1/2 to 15 percent,
the remainder being aggregate, which is a combination of limestone and
limestone dust, a by-product of quarrying.  The cost of a ton of Poz-0-
Blend F.O.B. plant in Kansas City is presently $12.00 per ton.  The seven-
day compressive strengths of Poz-0-Blend mixes in the Kansas City area
normally range from 800 to 1,100 psi.  Ultimate strengths generally exceed
1,800 psi and some cores have produced compressive strengths of 5,000 psi
or more.

          The reason why the  strengths of Poz-0-Blend in the Kansas City
area are consistently high is because City Wide Asphalt has invested a large
sum of money on modern plant equipment and product quality control.  They
receive most of the fly ash used in the product from the Hawthorn Station
of Kansas City Power and Light Company and have constructed laboratory facil-
ities at that location.  A full-time chemist is employed at the laboratory
and every load of fly ash is tested at the plant before it is accepted and
put into a mix.

          Until recently, no EFA material was used on state highway projects
around Kansas City in either Kansas or Missouri.  However, the first state
highway project in the area  (Route 33 in Carney, Missouri) which allowed
alternate bids for LFA material was recently bid.  On this project, which
is secheduled to begin next  spring, the LFA base was bid at $6.00 per square
yard, while the bituminous base was bid at $9.00 per square yard for the
same base thickness.  Similar cost savings have been realized when the Poz-
0-Blend material was bid against bituminous base on proj ects for the City of
Kansas City  (Reference 1-91).

          Federal Aviation Administration.  There are at least four known
locations where the Federal  Aviation Administration has been involved to
some extent with the use of  LFA compositions as base course materials for
the  construction of runways  and/or taxiways.  These locations are the Newark
Airport, the John F. Kennedy Airport, the Portland Airport, and the Toledo
Airport.  Two of these projects are discussed in some detail in this report.
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               Newark Airport Project.  The largest single project ever in-
volving the combined use of lime and fly ash in base and  sub-base construc-
tion was the building of runways, taxiways, and aprons at the Newark Airport
in Newark, New Jersey.  On this project, approximately 2 million square yards
of pavement were placed over compressible organic silts and peaty soils that
were once a tidal marsh.  The existing soil surfaces were surcharged and pre-
consolidated using some 20 million cubic  yards of hydraulically placed sand
fill.

          Because of the economics and subsurface conditions, the use  of a
flexible pavement system was decided upon by the Port Authority of New York
and New Jersey at the outset of the project.  Prior to designing the runway
pavements, the validity of current airfield flexible pavement design theories
was reviewed for application to the heavier anticipated wheel loadings associ-
ated with jumbo jet aircraft.  A $500,000 test program was conducted to de-
velop pavement design criteria for jumbo jet aircraft based on :  1) the
interaction of pavement roughness and aircraft response; and 2) the rate of
permanent deformation of the  pavement surface under repeated jumbo jet wheel
loadings.

          A test strip 30 feet wide and 1,200 feet long was constructed, con-
sisting of sixteen 75-foot long sections, each having different thicknesses
and compositions.  Materials investigated included conventional crushed stone
aggregate, cement-stabilized base, asphalt-treated base, and a mixture of lime,
cement, fly ash, and sand.  Test equipment included an extensive network of
in-pavement gauges and a 187,000 pound instrument vehicle, borrowed from the
Army Corps of Engineers, to simulate the main gear of a Boeing 747 aircraft.
The test vehicle was placed in round-the-clock service amounting to 5,000
passes in three months or an equivalent of two years of actual runway use.
Every three days, measurements of rutting, cracking, and pavement surface
deflections were made.  Analysis and interpretation of the test data con-
firmed the validity of the theoretical design approach used by the Port
Authority.  This approach was based on maintaining subgrade deformations
within elastic limits reduction of load stresses in the overlying pavement
sections to insure acceptable pavement surface  roughness and related air-
craft vehicle response.

          The field tests performed by the Port Authority showed that layered
mixtures of hydrated lime, portland cement, fly ash, and crushed stone would
be able to stabilize the uniformly graded hydraulic sand surcharge material
and that these stabilized material layers could be used as a suitable base
for new pavements.  The portland cement was introduced as an additive in the
mixes to accelerate the development of the normal chemical  reaction between
the lime and fly ash.  A copy of the Port Authority specification for the
lime-cement-fly ash stabilized fill sand base material used in the Newark
Airport project is found in the Appendix of this report.
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          The compressive strengths of the lime-cement-fly ash-aggregate
(LCFA) mixtures used on the project were directly related to the chemical
reaction of the lime-cement-fly ash binder, which in turn was affected by
the curing temperature.  Three basic mix designs were used on the project:
          Mix A - 4 percent lime and cement, 10 percent fly ash,
                  30 percent crushed stone, 56 percent sand.
              B - 3.5 percent lime and cement, 12 percent fly
                  ash, 84.5 percent sand.
              C - 3 percent lime and cement, 12 percent fly ash,
                  85 percent sand.
Mix B

Mix
          From the results of Port Authority tests, the projected  strength
development of these base course mixes is shown in Figure 1-13.  From  this
figure, it is noted that the long-term (5-year) strength of Mix A  is 2,000
to 2,600 psi; the strength of Mix B will range from 1,200 to 1,800 psi; and
Mix C will be from 800 to 1,200 psi.  All three mixes were used in each sec-
tion of pavement; Mix A was placed closest to the pavement surface and Mix C
placed directly above the subgrade.

          The thickest pavement sections were constructed at the terminal
gates and holding pads.  These areas  consist of five layers which  were built
to a total  thickness of 36 to 40 inches.  The next thickest sections  were
the middle  portion of the runway ends (34 inches) and the center  strip of
taxiways  (32 inches).  Relatively thin pavement sections  (26 inches) were
designed  for the sides of all runways and taxiways and for the midlength
portions  of runways.  All pavement base was constructed of three layers of
lime-cement-fly ash-aggregate and overlaid with 4 inches of asphalt concrete
wearing surface to protect the base course from weathering and wheel abrasion.

          Port Authority engineers recognized a tremendous economic advantage
when comparing the 1973 estimated costs for in-place 34-inch thick compacted
lime-cement-fly ash-aggregate pavement at $10.88 per square yard with  that of
equivalent performance 43-inch full-depth asphalt at $21.45 per square yard.
The cost  of the pavement using stabilized LCFA base material amounted  to ap-
proximately half that of the full-depth asphalt, or a cost savings of  $10.57
per square yard.  The total projected cost savings for the entire  project,
involving about 2 million square yards of pavement, is an astonishing  $21
million  (Reference 1-92).

          A more direct comparison of the costs vs. strength of competitive
materials is also revealing.  A cubic yard of LCFA material costs  about $3.80
from the  plant.*  A cubic yard of crushed stone commonly used in  road con-
struction costs from  $5.00 to  $6.00.* A cubic yard of lean concrete,  3-sack
mix costs about $12.00.*  If the compressive strength of each material is
judged on the basis of the strength developed per cubic yard, the  following
comparison is made:
 * These figures are based on 1968 costs in the New York City area.
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  2400
  2000
  1600
  1200
   800
  400
                                        30          40

                                  Time,  Months
                                                   50
60
Figure 1-13.
Projected compressive strength development of lime-cement-fly
ash-aggregate composition at Newark Airport project.  See text
for explanation.
                                   1-77

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          LCFA                       500 psi per $1.00*
          Crushed stone               30 psi per $1.00*
          Lean concrete              250 psi per $1.00*

For  this reason, the Port Authority believes that LCFA is stronger per dol-
lar than any pavement material now in use (Reference 1-93).

          The runway paving on this project began in the spring of 1968.
First, a 1,200 ton per hour mixing plant, largest of its kind, was erected
for the mixing of the base materials.  Fly ash was initially supplied free
of charge by the Consolidated Edison Company, followed by conditioning with
16 percent water at the power plant.  Before the fly ash was fed into the
hopper belt system at the plant, it was  passed through a shredder to break
up some of the clumped ash.  Sand for the base mixes was taken directly from
paving surcharge areas and hauled directly to the mixing plant.  The hydrated
lime and portland cement were stored in silos and charged to the main feeding
belt separately.  A storage bin added at the discharge end of the pugmill al-
lowed the mixing plant to be operated continuously.

          Sprading and grading of the base materials was accomplished by an
automatic grading machine.  Each machine pass was about 25 feet wide.  The
compaction of each of the LCFA layers was done by four to  eight passes with
a pneumatic roller.  The finished surface of the pavement base was fine graded
to a tolerance of 1/8 inch in 10 feet.

          Labor and equipment costs were reduced because of the slow initial
set of the LCFA base material.  There was no need to finish the paving work
on the same day that the LCFA material was mixed and spread.  The slow curing
time, with little accompanying heat of hydration, together with low moisture
contents in the base materials, also minimized the curing shrinkage and cracking

          In December,  1968, well after the first paving season had concluded,
the Shell dynamic pavement tester was brought to the airport site to measure
the behavior of pavement under simulated loading conditions of moving traffic.
These test results were deemed highly favorable and the LCFA paving concept
has since been used successfully at Kennedy Airport (Reference 1-94).

          The Newark Airport expansion project, with its LCFA paving system,
was recognized as an Outstanding Civil Engineering Achievement for 1978 by
Civil Engineering magazine.  Reports of cracks that had developed in the sur-
face of the original LCFA runway prompted recent correspondence between a
member of the American Pozzolanic Concrete Association, a group representing
producers  of pozzolanic base materials, and the New York Port Authority.
The Port Authority's response has clarified the status of the LCFA paving
at Newark Airport.

          In his letter, the chief engineer for the Port Authority has stated
clearly that the Port Authority is "still very strongly in favor of the use
of LCFA base courses."  He goes on to mention that a maintenance contract was
   These  figures  are based on 1968  costs  in  the New York City area.


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let in the summer of 1979 to improve the smoothness of the asphalt on the
main LCFA runway.  At that time, a paving mix using a harder grade of as-
phalt was used "in order to limit deflection caused by the proposed 747
aircraft."  Some pavement grooving was also done at that time to facilitate
surface drainage.  The grooves in the pavement "remained straight and hori-
zontal up to the day of removal" in a subsequent maintenance contract (Ref-
erence 1-95).

          Unfortunately, "the harder asphalt was subject to a greater degree
of cracking," with water penetrating through the cracks in the runway pave-
ment.  Therefore, it became necessary to "remove the center keel section of
the runway and replace it with a softer penetrating asphalt."  No replacement
of any of the LCFA pavement was done, nor is any such replacement necessary.

          At no time did the Port Authority consider this work to be anything
except normal runway maintenance, nor has the Authority ever  attributed the
cracked asphalt surface to  a possible base failure (Reference 1-94).

               Toledo Express Airport.  The Toledo Airport project is a clas-
sic example of the kind of problems that can result from bureaucratic inertia
(resistance to change) and the lack of knowledge or familiarity with a con-
struction project.  Early in  1980, the Federal Aviation Administration (FAA)
announced its intention to advertise for bids for the overlay of existing run-
way 7-25, taxiway A at the Toledo Express Airport.  This overlay was initially
designed for a full-depth asphalt pavement.  In February, 1980, prior to bid-
ding, the Toledo-Lucas County Port Authority, which administers the Toledo
Airport, requested that FAA consider the use of a lime-fly ash-aggregate (LFA)
base as an alternate to  bituminous base for this overlay.

          The rationale for the request stemmed from the fact that during the
summer of 1978, approximately 500 tons of LFA material was placed as an ex-
perimental base course for the overlay of a commercial ramp adjacent to the
airport terminal building.  Since its installation, this ramp pavement has
performed satisfactorily with no apparent problems. Core specimens were taken
from the LFA base of the ramp in late March. 1980 and tested for unconfined
compressive strength.  The average strength of the four core specimens was
1,455 psi, with one core achieving 1,810 psi.

          The initial request for consideration of the LFA alternative was
turned down by the FAA's district office in Detroit in late February 1980
on the grounds that, at the time, the FAA had no approved specification for
the material.  The correspondence also advised the Toledo-Lucas County Port
Authority that LFA was not identified in the appropriate sections of the FAA
design manual as an equivalent stabilized material for construction of run-
ways, taxiways, or apron areas (Reference 1-96).

          During the next two months, a considerable amount of technical
information related to LFA base materials, including the results of strength
tests on core specimens taken from the Toledo Airport ramp, was forwarded to
various representatives of FAA.  Despite FAA claims that there was no speci-
fication for LFA materials, a copy of FAA specification P-305, entitled
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"Aggregate-Lime-Fly Ash Subbase or Base Course  (Central Plant Mixed)" was
provided by the National Ash Association and submitted to FAA officials
for their review.  Information pertaining to the LCFA base at the Newark
Airport project, which the FAA district people  apparently had not known
about, was also transmitted.

          A representative of the Port Authority, who is familiar with LFA
materials and technology, personally visited the FAA central engineering
office in Washington, D.C., in early April and  discovered, to his great
surprise, that the FAA engineers did not even know what LFA base course
was.  Their concept of the material was that it involved a combination of
lime, fly ash, and clay soil.  This misconception came about from their
previous exposure to the work of the Army Corps of Engineers with lime-fly
ash stabilization of highly plastic clay soils.

          After clarification of the nature of  the proposed alternate,
authorization to advertise for bids was given to the Port Authority by
FAA on April 29, 1980, although the correspondence specifically stated
that  the proposed LFA alternate was still being reviewed.

          On May 15, 1980, bids were received,  in which the LFA alternate
was $22,000 lower than the original black base  design, a savings of 10 per-
cent.  Based on the results of the bidding, FAA approval was then given to
the use of LFA as an alternate on a portion of  taxiway "A" measuring approx-
imately 1,475 feet long by 60 feet wide,  subject to a number of conditions,
including the following:

          1. . The thickness of LFA was to be based on a ratio
               of 5 inches of LFA to 4 inches of bituminous base.

          2.   The LFA  base must have transverse joints every
               50 feet.

          3.   Fly ash must conform to the requirements of ASTM
               C618,  "Fly Ash and Raw or Calcined Pozzolans for
               Use in Portland Cement Concrete."

          4.   Placement  of the wearing surface shall not be per-
               mitted until the LFA material has achieved a com-
               pressive strength of at least 750 psi.  This must
               be accomplished within the specified contract time
               period of  23 calendar days  (Reference 1-97).

          In  response to  these conditions, LFA  producer representatives and
associated engineering  consultants responded with the following points:

          1.   The thickness ratio of 5 inches  of LFA to 4 inches
               of bituminous base was in accordance with established
               pavement design coefficients presently being used by
                the Ohio Department of Transportation for these ma-
                terials  and was considered acceptable  (Reference 1-98).
                It should  be noted that even with the greater thick-
               ness, the  LFA alternative still  cost less.
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          2.   Jointing of stabilized base materials is normally
               considered of questionable value. However, since
               the LFA material was being used as an overlay,
               the jointing should match that of the existing
               pavement (Reference 1-98).

          3.   The proper specification for fly ash quality
               control for use in a stabilized  base material
               is ASTM C593, "Fly Ash and Other Pozzolans for
               Use with Lime;" and not ASTM C618, which is ap-
               plicable only to the use of fly ash in concrete
               (Reference 1-98).

          4.   It is best to apply an asphalt overlay the fol-
               lowing  day or within a week after placement
               of LFA base to reduce moisture loss to a mim'mum.
               A requirement for minimum strength of base ma-
               terials placed over an existing concrete pavement
               is not a realistic criteria.  Most strength cri-
               teria are for the purpose of limiting flexural
               stresses in the base, but, since there are  no
               flexural stresses in this application, such a
               requirement seems redundant (Reference 1-99).

                 Furthermore, compaction of the wearing surface
               material is influenced by the degree of compac-
               tion of the underlying layers, not by their
               strength.  In a large number of construction
               projects in which a bituminous surface has been
               placed immediately after completion of the LFA
               base, all surface courses have successfully met
               contract requirements.  It has  also been ob-
               served that LFA pavements gain strength through
               pozzolanic reaction at a faster rate than wheel
               loads can accumulate (Reference 1-100).

          Soon-thereafter, the Port Authority formally requested that the
750 psi strength requirement be waived by FAA and that the wearing surface
be placed as soon as practical after completion of the LFA base.  On July 8,
1980, the FAA finally agreed to the early placement of the wearing surface,
but insisted that no aircraft traffic be permitted on the pavement until
field cores were taken  to verify that an average compressive strength of
750 psi was attained.  The FAA further required a minimum 98 percent com-
paction of the bituminous surface course, subject to penalties on a sliding
scale for lower average compaction values.

          From August 6 through August 11, 1980, a total of 7,200 tons of LFA
base material was placed on the Toledo Airport Taxiway "A" project.  The com-
pacted thickness of the LFA base varied, but averaged approximately 14 inches.
The mixture used consisted of 3.5 percent by weight hydrated lime, 11 percent
                                     1-81

-------
fly ash, and 85.5 percent limestone aggregate.  The gradation of the material
was within specified limits and all base materials were compacted as specified
to at least 100 percent of maximum dry density, as determined by the modified
Proctor  test (ASTMD1557).

          Laboratory mix design tests were performed on the 3.5-11-85.5 mix
to determine its compressive strength characteristics prior to placement in
the field.  The average compressive strength of three specimens after 7 days
curing at 70°F was 351 psi.  The average compressive strength of three speci-
mens after 7 days curing at 100°F was 904 psi  (Reference 1-101).

          Between August 4 and 11, 1980, a total of 21 test specimens were
prepared in the laboratory using LFA materials obtained from each day's pro-
duction at the mixing plant.  Each of these specimens was also cured for 7
days at 100°F.  Compressive strength values after curing ranged from 540 to
860 psi, with an average compressive strength of 681 psi, well above the 400
psi specification requirement (Reference 1-102).

          In order to predict the field curing time needed to develop the
required 750 psi  strength in the LFA base, laboratory degree-day studies
were performed at the University of Illinois to determine the rate of strength
development for various curing temperatures in similar base materials.  The
findings of these degree-day studies are presented in Figure 1-14.  This fig-
ure shows that 750 psi can be attained on 600 degree-days (30 days with an
average curing temperature of 75°F,  in the pavement) using a 55°F base
 (Reference 1-103).

          The first five cores were taken from the pavement on September 8,
1980, which was 29 days after the base material had been placed.  Normally,
cores are not taken for several months after placement of stabilized base
materials.  The average compressive strength of these cores was 1,145 psi,
considerably higher than the required 750 psi strength.

          Thermocouples were installed at two  locations within the LFA base
material during its placement.  Periodic temperature measurements were re-
corded on a twice daily basis after construction of the base course.  Air
temperatures were also recorded during the same time period.  During the
29-day period  between placement and initial coring, pavement temperatures
fluctuated between 69°F and 96°F, with an average pavement temperature of
81°F over that time  (Reference 1-104).  Using a 55°F base temperature, an
81°F average temperature represents 780 degree-days.  From Figure 1-14,
this corresponds to a strength development of approximately 900 psi from
the University of Illinois data and 1,050 psi using the Toledo Testing
Laboratory data.

          Throughout all the lengthy discussions concerning the approval of
an LFA alternate and the conditions under which this material could be
placed, it is ironic that FAA engineers had to be practically coerced into
accepting a material which exhibited excellent strength gain characteristics,
                                      1-82

-------
-H

CO
 D
 C
 OJ
 u
4J
w

 0)

•H
 to
 n
 0)
 ^
 a

 §
        0   200
     Figure 1-14.
400   600   800  1000  1200 1400 1600  1800 2000

       Degree-Days, 55°F Base


Compressive  strength vs. degree-days for LFA mix at Toledo
Airport project.
                                        1-83

-------
has a proven service record in the State of Ohio and elsewhere, reduced the
total project cost by 10 percent, and conserved nearly 90,000 gallons of
petroleum by avoiding the installation of bituminous base.  Despite all
these advantages, the FAA representatives stated clearly that approval of
the LFA alternate for the Toledo Airport project did not constitute an ap-
proval of the material on  any other FAA-funded projects in the future
(Reference 1-75).

          It should be further noted that FAA has insisted on extensive moni-
toring of the LFA material and its strength development in order to prove
that this product works.  This monitoring expense has not only eliminated the
entire $22,000 cost savings attributed to the LFA base, but has caused the
overall cost of the project to exceed that of the original black base bid by
$12,000.  To make matters worse, the FAA also insists that the cost overrun,
resulting from their own directives, be paid by the Toledo-Lucas County Port
Authority (Reference 1-106).

               Economic Evaluation of LFA Base.  In this section, the relative
economics of using lime-fly ash-aggregate (LFA) base materials are compared
with the  costs of using competitive base course materials in the states of
Illinois, Ohio, and Pennsylvania.  The competitive base course materials studied
are bituminous concrete base and crushed stone base.  Comparisons are made be-
tween actual bid prices for each type of base.  The bid price data were obtained
from Department of Transportation  (DOT) personnel in each of these three states.

          To analyze these comparative costs in each state, a  pavement design
example was developed assuming a structural number of 4.00 in order to deter-
mine design thicknesses for each of the three pavement options.  Relative
pavement thicknesses for each state are given in Table 1-11.  Based on the
required thickness of each material and its compacted density, a square yard
price was then determined for each wearing surface and base course material
combination in a given state.  The following compacted densities are assumed
for each of the paving materials used:
                                               3
          Wearing surface            150 Ibs/ft-j
          Bituminous base            145 lbs/ft,
          Pozzolanic base            140 lbs/ft_
          Aggregate base             125 Ibs/ft

          The three pavement alternatives are compared in terms of estimated
total in-place costs.  Cost comparisons  are discussed for each of the three
individual states.  An overall comparison is then made of costs from each of
the three states.

          1.  Illinois

          For a pavement structural number of 4.00, use of Illinois flexible
pavement design  coefficients and AASHTO recommended minimum wearing course
thicknesses results in the following basic designs:
                                      1-84

-------
 Bituminous Base          Pozzolanic Base          Aggregate Base

 3"   Wearing Surface      3" Wearing Surface       5"   Wearing Surface
 8.5" BAM* Base           10" PAM** Base           15.4" Stone Base
11.5" Total Pavement      13" Total Pavement       20.4" Total Pavement

  * BAM refers to bituminous aggregate mixture.
 ** PAM refers to pozzolanic aggregate mixture.

           Illinois DOT officials have furnished the following in-place cost
 figures, based on average of five comparative alternate bids received during
 1980 on primary projects in District 1 (Chicago) area:

           Wearing surface            $55.80 per cubic yard
           Bituminous base (BAM)      $54.50 per cubic yard
           Pozzolanic base (PAM)      $39.20 per cubic yard
           Aggregate base             $20.45 per cubic yard (Reference 1-107)

           Converting these prices to square yard costs, based on the design
 thickness and compacted density of each material, results in the following:

           Wearing surface            $4.64 per square yard (3" thick)
                                      $7.74 per square yard (5" thick)
           Bituminous base (BAM)      $12.87 per square yard (8.5" thick)
           Pozzolanic base (PAM)      $10.87 per square yard (10" thick)
           Aggregate base             $8.75 per square yard (15.4" thick)

           Using the above figures, the total estimated cost per square yard
 for each of the three Illinois pavement alternatives is:

                Bituminous Base    Pozzolanic Base    Aggregate Base
 Surface           $ 4.64             $ 4.64             $ 7.74
 Base               12.87              10.87               8.75
 Total Cost        $17.51             $15.51             $16.49

           From the above cost data,  it appears that pozzolanic or LFA base
 is the least expensive of the three  alternatives, being $2.00 per square yard
 less than the bituminous base in the Chicago area.   For a two-lane road 24-
 feet wide, the projected cost savings attributed to LFA base using these cost
 figures would be $28,160 per mile less than bituminous base.

           During the Illinois Pozzolanic Concrete Association Seminar,  held
 in Chicago in April of 1980, a paper was presented outlining the actual cost
 benefits realized over a four-year period due to the use of pozzolanic base
 materials (PAM)  in the Chicago area.   These PAM materials were bid as alter-
 nates to black base (BAM),  cement-treated base (CAM), or portland cement  con-
 crete base on a total of 15  public paving projects let between April 1976 and
 the time of the seminar.  Table 1-12 summarizes the bid prices received for
 the base course paving alternates on each of these 15 projects.
                                      1-85

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              Table 1-12
         SUMMARY OF BID PRICES
FOR BASE COURSE ALTERNATES  IN  ILLINOIS
Letting
Date
4/27/76
7/13/76
3/19/77
5/18/77
6/B/77
7/20/77
£ 8/9/77
Awarding
Authority
Village of
Schaumburg
Village of
Schaumburg
Village of
Frankford
Cook County Hwy.
Cook County Hwy.
Cook County Hwy.
Village of
04 Schaumburg
3/1/78

5/26/78

6/7/78

7/19/78

4/11/79

6/30/79

7/19/79
City

Kane

Cook

Cook

City

I DOT

of Jollet

County Hwy.

County Hwy.

County Hwy.

of Elgin



Project Description
Base Course
Quantity
American Lane 9,318
Martingale Road 6,950
Colorado Avenue 8,182
Central Ave. - Vollmer to 183rd 36,683
Thornton/Blue Island Road
155th - 169th 47,168
115th & Harlem 14,921
Woodfleld Road
Plalnfleld Rd (US- 30) 1-55

Randall Road

Harlem & Steger Roads

167th - Will/Cook Road

Big Timber & N. McLean Roads

Houbolt Rd - Jollet

15,950
22.282

23.311

17,840

17,871

16,173

47,038

SY
SY
SY
SY
SY
SY
SY
SY

SY

SY

SY

SY

SY

Village of
Boll Ingb rook


3/28/80




I DOT







111th Street at Rte 153


Randall Rd - Big Timber to
Highland - Elgin

38,104


39,124

*
SY


SY


Bid Prices
PAM
9"
4.28
9"
4.00
9"
6.75
9"
3.85
10"
5.00
10"
5.15
9"
4.09
16"
7.92
12"
5.95
10"
5.00
8-1/2"
6.40
15"
8.25
9"
9.67
12"
7.26


12"
7.05

BAM
9"
8.33
9"
8.30
8-1/2"
9.22
8"
5.65
9"
6.30
9"
7.00
9"
7.50
15"
12.99
10"
9.49
9"
9.00
8"
8.20
12"
13.45
8-1/2"
13.83
11"
15.53


10"
13.00
TOTAL
Other


9" PCC
14.50
14" CAM
8.12








14" CAM
11.40
8" PCC
22.00


SAVINGS:
Cost Savings &
% of PAM Price
37
27
20
66
61
27
55

112

50

86

32

84

195

157



232
T.247
,700
.800
,210
,029
,318
,604
.200

,970

.600

.046

.168

,100

,678

.378



,787
.588
95%
108%
27t
32%
21% .
26%
83%

39«

35%

53X

22%

63%

30%

362



84%


-------
          As seen in this table, cost savings resulting from the use of the
PAM base alternate ranged from $20,000 to $232,000 per project.  Overall, a
total of $1,247,588 was saved for these fifteen projects  (Reference 1-107),
or an average of $83,172 per project.  This is in addition to the savings of
10 to 15 percent less aggregate, as well as many thousands of barrels of oil
from not using a base with an asphalt binder.  Furthermore, it was noted in
this study that the total cost for asphalt and cement stabilizing agents is
increasing at a greater rate than the total cost of lime and fly ash.  Another
added cost for the bituminous base or BAM alternative is the cost of fuel con-
sumed to dry and heat aggregates and asphalt cement in the dryer (Reference
1-108).

          2.  Ohio

          For a pavement structural number of 4.00, use of Ohio flexible pave-
ment design coefficients and AASHTO recommended minimum wearing course thick-
nesses results in the following basic designs:

Bituminous Base          Pozzolanic Base          Aggregate Base

 3"   Wearing Surface     3"   Wearing Surface     5"   Wearing Surface
      (404)                    (404)                    (404)
 8.4" Black Base         10.5" Pozzolanic Base    16.1" Stone Base
	  (301)              	  (835)              	  (304)
11.4" Total Pavement     13.5" Total Pavement     21.1" Total Pavement

          It was noted by ODOT engineers that, even though the design example
shows a 3-inch wearing surface over the pozzolanic base, a minimum thickness
of 4 inches  of asphalt concrete over the 835 base provides a more efficient
and durable pavement.  Some failures were experienced when using less than a
4-inch thick asphalt layer over a pozzolanic base.  Therefore, ODOT has rec-
ommended a 4-inch wearing surface and 9.5 inches of pozzolanic base (Reference
1-109).

          Ohio DOT officials also furnished a summary of the costs per square
yard for the various materials in this design example, which was based on a
1979 summary of awarded contracts.  These cost figures are:

          Wearing surface (404)      $4.52 per  square yard (3" thick)
                                     $6.03 per  square yard (4" thick)
                                     $7.53 per square yard  (5" thick)
          Bituminous base (301)      $11.19 per square yard (8.4" thick)
          Pozzolanic base (835)      $7.29 per square yard (9.5" thick)
          Aggregate base (304)       $9.08 per square yard (16.1" thick)
                                     1-87

-------
          Using the above figures, the total estimated cost per square yard
for each of the three Ohio pavement alternatives is:

               Bituminous Base     Pozzolanic Base     Aggregate Base
Surface           $ 4.52              $ 6.03              $ 7.53
Base               11.19                7.29                9.08
Total Cost        $15.71              $13.32              $16.61

          From the above cost data, the pozzolanic or LFA base alternative
is the least expensive, and is approximately $2.40 per square yard less than
bituminous base in  Ohio.  For a two-lane road 24-feet wide, the projected
cost savings attributed to LFA base using these cost figures is $33,792 per
mile.

          An illustration of the actual cost savings that were actually rea-
lized on a  project where alternate base course bids were received occurred
during August 1979 when the City of Toledo accepted two bids for reconstruc-
tion of a portion of Heatherdowns Boulevard.  The bid summary sheet shows
three alternates for base course:  1) bituminous-aggregate base; 2) aggre-
gate-lime-fly ash base; and 3) aggregate base.  The summary of bids for the
alternate base items, in costs per cubic yard of material in place, were as
follows:

                                          Bidder No. 1            Bidder No. 2
                                      cost per   total cost   cost per   total cost
Base Alternate                       cubic yard    of base   cubic yard    of base

Bituminous-aggregate                   $42.00     $383,712     $37.00     $338,032
Aggregate-lime-fly ash                 $23.00     $278,803     $26.00     $314,364
Aggregate base                         $11.65     $388,604     $12.50     $367,444

          The lowest cost alternate was the aggregate-lime-fly ash price of
$278,803 from bidder number 1.  When compared to the low price of $338,032
for bituminous-aggregate base, this represents a cost savings of $59,229 or
a 21.2 percent reduction in base course cost by using aggregate-lime-fly ash
instead of bituminous-aggregate.  When compared to the low price of $367,444
for aggregate base, a cost savings of $88,641 or 31.8 percent can be realized
by using the aggregate-lime-fly ash base.

          The total bids for  this project were as follows:

Base Alternate           Bidder No. 1     Bidder No. 2     Difference

Bituminous-aggregate      $1,685,884       $1,632,843      + $53,041
Aggregate-lime-fly ash    $1,580,975       $1,609,176      - $28,201
Aggregate base            $1,690,776       $1,662,255      + $28,521
                                      1-88

-------
          The job was awarded to Bidder Number 1 using the aggregate-lime-
fly ash alternate.  This alternate saved $51,868, or 3.3 percent of the
entire job, compared to bituminous-aggregate.  The aggregate-lime-fly ash
alternate cost $81,280, or 5.1 percent, less than aggregate base.

          3.  Pennsylvania

          For a pavement structural number of 4.00, use of Pennsylvania flex-
ible pavement design coefficients and AASHTO recommended minimum wearing course
thicknesses initially resulted in the following basic designs:

          Bituminous Base          Pozzonlanic Base          Aggregate Base

          3" Wearing Surface       3" Wearing Surface        5" Wearing Surface
          6.7" BCBC*               6.7" ALP** Base           12.9" CABC***

  * BCBC refers to bituminous concrete base course
 ** ALP refers to aggregate-lime-pozzolan base course
*** CABC refers to crushed aggregate base course.

          The above designs were reviewed by the PennDOT Bureau of Design.
As a result of this review, several changes were proposed to conform to the
PennDOT design manual, by taking into account minimum pavement depth, frost
design requirements, and the use of sub-base material.  Based on these changes,
the resultant designs were as follows:

Bituminous Base          Pozzolanic Base          Aggregate Base

 1.5" Wearing Surface     1.5" Wearing Surface     1.5" Wearing Surface
   6" BCBC                2"   Binder Course       2"   Binder Course
  10" Sub-base            5"   ALP                 8"   CABC
	                      6"   Sub-base           10"   Sub-base
17.5" Total Pavement     14.5" Total Pavement     21.5" Total Pavement

          Analysis of the above designs indicates that the resultant struc-
tural numbers for each alternative are slightly different.  The BCBC pavement
has a structural number of 4.16; the ALP pavement has a structural number of
4.20; and the CABC pavement has a structural number of 4.08.

          Pennsylvania transportation officials have furnished the following
in-place cost figures, derived from the most recent weighted average of all
awarded contracts statewide, as published in PennDOT Bulletin 50:

          1-1/2" wearing surface     $3.30 per square yard
          2" binder course           $3.00 per square yard
          6" BCBC                    $9.20 per square yard
          5" ALP base                $8.85 per square yard
          8" CABC                    $8.00 per square yard
          6" sub-base                $3.75 per square yard
          10" sub-base               $4.15 per square yard (Reference 1-110).
                                     1-89

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for
     Using the above figures, the total estimated cost per square yard
each of the three Pennsylvania pavement alternatives is:
Surface
Binder
Base
Sub-base
Total Cost
          Bituminous Base
             $ 3.30

              10.20
               4.15
             $17.65
Pozzolanic Base
   $ 3.30
     3.00
     8.85
     3.75
   $18.95
Aggregate Base
   $ 3.30
     3.00
     8.00
     4.15
   $18.45
          In seeking to verify these unit prices from the latest Bulletin 50
(March 1980), it was discovered that no bid price has  been tabulated in Bul-
letin 50 for the ALP alternate during the past several years.  Apparently,
the unit price for the 5" ALP base was determined by taking a 1974 bid price
from Bulletin 50 and factoring it to 1980 at an inflation rate of 10 percent
per year.  Furthermore, crushed aggregate base course is rarely used by PennDOT,
hence  cost data on this item are very limited (Reference 1-111).

          A July 1979 cost summary of material costs for short projects (less
than 1,000 feet) in PennDOT district 6 (Philadelphia area) indicates that bid
prices for 5" ALP base on such projects averaged $4.53 per square yard.  Dis-
trict 6 engineers have been using an annual escalation figure of 7.5 percent
per year compounded for projecting increased material costs.  On this basis,
the unit price of 5" ALP base would be $4.89 per square yard at this time.

          In order to verify the in-place cost of LFA base, the costs of a
total of six of the most recent ALP projects in District 6 were reviewed.
These jobs dated from 1976 and involved quantities ranging from 1,600 to
100,000 square yards of base material.  A weighted average cost was deter-
mined from the costs of these six projects.  This cost figure was also ad-
justed to take into account variations in the thickness of the ALP base on
these different projects.  This weighted cost turned out to be $5.97, so the
estimated cost of installing a 5" thick layer of ALP base in Pennsylvania was
taken as $6.00 instead of $8.85 per square yard.

          A figure of $6.00 per square yard for 5 inches of ALP base course
does not seem unreasonable when compared to a cost of $6.60 per square yard
for 9.5 inches of LFA base in Ohio and $10.87 per square yard for 10 inches
of PAN base in Illinois.

          Using the revised ALP cost figure, the total estimated cost per
square yard for each of the three Pennsylvania pavement alternatives is:
 Surface
 Binder
 Base
 Sub-base
 Total Cost
          Bituminous Base
              $  3.30

              10.20
                4.15
              $17.65
Pozzolanic Base
    $ 3.30
     3.00
     6.00
     3.75
    $16.05
Aggregate Base
   $ 3.30
     3.00
     8.00
     4.15
   $18.45
                                      1-90

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          From  these data, it appears that the pozzolanic or ALP base is
actually the least expensive alternative, being $1.60 less than bituminous
base per square yard.  For a two-lane road, 24-feet wide, the project cost
savings attributed to ALP base using these cost figures would be $22,528
per mile less than bituminous base.

          Additional comparative cost information on  ALP base and bituminous
base prices was obtained from the City Engineer for the City of Lancaster, who
usually asks for alternate bids for all street reconstruction work.  Recent
bid prices for pavement designs consisting of 1-1/2 inches of asphalt wearing
surface, 6 inches of bituminous base, and 6 inches of sub-base have been rang-
ing from $20.40 to $23.80 per square yard in place, which is considerably higher
than the $17.65 per square yard estimate based on PennDOT Bulletin 50 cost
figures.  Recent bid  prices for  pavement designs consisting of 1-1/2 inches
of asphalt wearing surface, 2 inches of bituminous binder, 5 inches of ALP
base, and a 6 inch sub-base have been  ranging from $14.00 to $17.00 per square
yard (Reference 1-112), which corresponds well with the estimated cost of $16.05
per square yard given above.  The actual installed price for 5-inch thick ALP
base in Lancaster during 1980 was $4.50 per square yard (Reference 1-113).
All the above costs  are based on prevailing wage rates, making the costs for
these projects equivalent to those of PennDOT projects.

          On the basis of these costs, reflecting actual bids received during
1980 in the City of Lancaster, it would appear that even more substantial
savings, on the order of $5.00 to $6.00 per square yard of pavement, can be
realized by use of the pozzolanic base alternative.  When analyzing the com-
parative costs of ALP and BC3C out of the plant it is evident why ALP is the
less costly alternative.  Bituminous base in the Philadelphia area presently
sells for approximately $20 per ton F.O.B. plant, while ALP sells for $9.50
per ton F.O.B. plant (Reference 1-114).  In Pennsylvania, these two materials
are structurally equivalent.

          4.  Three State Cost Comparison

          The estimated costs for all three pavement alternates in Illinois,
Ohio, and Pennsylvania for a flexible pavement with a structural number of
4.00 are compared in Table 1-13.  These cost figures reflect actual bid costs
for all materials and, as such, constitute an accurate current comparison of
the cost of alternative pavement systems in each state.

          The first and most obvious observation from Table 1-13 is that the
pozzolanic base material is consistently the lowest cost alternative in all
three states, with bituminous base second, and aggregate base third.  The
cost differential between pozzolanic base and bituminous base ranges from
$1.50 to $3.00 per square yard.  This difference represents potential cost
savings of approximately $20,000 to $40,000 per mile of two-lane road.
                                     1-91

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                     Table 1-13
THREE-STATE COMPARISON OF PAVEMENT BASE COURSE COSTS

               BASIC PAVEMENT DESIGNS
              (STRUCTURAL NUMBER = 4,0)

BAN
3" wearing
8.5" base
11.5" total
BAM
$ 4.64
12.87
$17.51
ILLINOIS
PAM
3" wearing
10" base
13" total
ILLINOIS
PAM
$ 4.64
10.87
$15.51
(LOW)

STONE
5" wearing
15.4" base
20.4" total
STONE
$ 7.74
8.75
$16.49

BIT
3" wearing
8.4" base
11.4" total
BIT
$ 4.52
11.19
$15.71
OHIO
POZ

STONE
4" wearing 5" wearing
9.5" base 16.1" base
13.5" total 21.1" total
COST COMPARISON
OHIO
POZ
$ 6.03
6.60
$12.63
(LOW)
STONE
$ 7.53
9.08
$16.61

BCBC
1.5" wearing
6" base
10" subbase
17.5" total
BCBC
$ 3.30
10.20
4.15
$17.65
PENNSYLVANIA
ALP
1.5" wearing
2" binder
5" base
6" subbase
14.5" total
PENNSYLVANIA
ALP
$ 3.30
3.00
6.00
3.75
$16.05
(LOW)

CABC
1.5" wearing
2" binder
8" base
10" subbase
21.5" total
CABC
$ 3.30
3.00
8.00
4.15
$18.45

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          A study of Table 1-13 also shows that total pavement costs in
Illinois and Pennsylvania are basically quite similar,  while comparative
costs for the same materials in Ohio are somewhat lower, particularly the
cost of the pozzolanic base.  This simply points out the number of variables
that must be taken into account when comparing cost figures for  the same
material from different areas.  The most significant of these variables are
labor, transportation costs, productivity at the project site, and avail-
ability of materials.  Despite these variables, the cost comparisons dis-
cussed in this section of the report reflect a trend toward significant
savings in cost from use of pozzolanic base materials in areas where such
materials are available and can be supplied in sufficient quantity to pro-
spective users.

          Overview of LFA Usage
               LFA Use by State Highway Agencies.  The findings of a question-
naire on recovered material usage,  which was circulated by AASHTO to all state
highway materials and construction engineers during April 1980, show that a
total of 14 states have at some time used lime-fly ash-aggregate (LFA) compo-
sitions in base course or shoulder applications.  Six of these 14 states
presently include LFA in their state specifications.  One state (West Virginia)
used to have a special provision in its state specifications for lime-fly ash-
aggregate base, but reports that it was discontinued due to lack of interest
by the contracting industry.  Instead, West Virginia uses a lot of cement-
treated base (Reference 1-115).

          States indicating some use of LFA base materials are:

               Arizona               New Jersey*
               Colorado*             North Dakota*
               Illinois*             Ohio*
               Maryland              Oklahoma
               Massachusetts         Pennsylvania*
               Michigan              Texas
               Missouri              West Virginia

          * States which have a specification for lime-fly ash-aggregate.

The only states reporting routine use of LFA are Illinois, Ohio, and Pennsyl-
vania.  Most of the remaining 11 states report that LFA base has been used in
state projects only on a limited field basis (less than six projects) or as a
field experiment  (one or two small test sections).  Generally speaking, LFA
materials have been used to a greater extent on local facilities than state
highways.

          In addition to the 14 states, noted above, at least four other
states are presently evaluating LFA compositions in the laboratory.  These
states are Georgia, Mississippi, New York, and North Carolina.  Of these
four states, only North Carolina felt that LFA behaved poorly in the lab
because "the strength of lime-fly ash stabilization of aggregate base at 7
days was 12 percent of the aggregate base with 3 percent cement and 3 times
as expensive (Reference 1-116).
                                     1-93

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          A review of technical reports and promotional literature on sta-
bilized road base materials confirms that LFA mixtures have also been placed
in several other states, including Delaware, Indiana, New York, South Dakota,
and Virginia.  Since none of the DOT personnel in these states has indicated
use of this material in their questionnaire responses, it is assumed that LFA
use in these states  has been confined to local roads and/or private projects,
with no use in state or Federally funded highway construction.

          Of the 14 states reporting LFA use, 10 consider the performance of
the material to have been either acceptable, good, or, in the case of three
states, excellent.  These three states are Ohio, Texas, and West Virginia.
Reasons cited for excellent performance are the pozzolanic activity of lime
and fly ash, strength gain with age, and good mixing and compaction in the
field.  Three states (Maryland, Massachusetts, and Missouri) have experimented
with LFA materials on a very limited basis in the field and felt that more
study was necessary before being able  to evaluate the performance of the ma-
terial.  One state, Michigan, considered  that LFA base performed poorly on a
job because the material showed "temperature and moisture sensitivity for cure,
frost susceptibility, poor drainability, and was more expensive than conven-
tional aggregate mixtures (Reference 1-117).

          Figure 1-15 is a map of the United States showing the locations of all
coal-fired power plants and all commercial lime plants.  All areas within a 50-
mile radius of both a coal-fired power plant and withn a 200-mile radius of a
commercial lime plant are shaded in on the map and considered as potential use
areas for LFA base material usage.

          Portions of 39 states have been shaded in on this map, indicating
areas where supplies of LFA component materials (lime and fly ash) are avail-
able within a reasonable hauling distance.  Considering the 14 states that
have reported LFA use by the AASHTO questionnaire, plus five additional states
where local or private use of LFA material can also be verified, LFA base ma-
terials have been used to some extent in at least 19 states.  This total rep-
resents approximately half of all states which could possibly be using this
material.  Table 1-14 lists the 39 states where there is some potential for
use of LFA base materials from the standpoint of lime and fly ash availability
and also indicates those 19 states where there has been known use of these
materials.

          Of these 19 states, there are probably only three (Illinois, Ohio,
and Pennsylvania) that are familiar enough with the characteristics and per-
formance of LFA base that they would be able to award more contracts using
this material without first requiring extensive laboratory testing and field
monitoring of the material.  With few exceptions, most of the remaining 20
states would probably need to spend some time in further evaluation of LFA
base before feeling ready to proceed with a substantially higher degree of
LFA use in state highway construction.
                                      1-94

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   • Power Plant Fly Ash
   o L1me Plants .
Figure 1-15. Most probable areas of Hme-fly ash-aggregate base course commercialization.

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                              Table 1-14


                  STATES  HAVING POTENTIAL OR ACTUAL
                     USE OF LIME-FLY ASH-AGGREGATE
        State

 1.   Al abama
 2.   Arizona
 3.   Arkansas
 4.   Colorado
 5.   Connecticut
 6.   Delaware
 7.   Florida
 8.   Georgia
 9.   Illinois
10.   Indiana
11.   Iowa
12.   Kansas
13.   Kentucky
14.   Maryland
15.   Massachusetts
16,   Michigan
17.   Minnesota
18.   Mississippi
19.   Missouri
20.   Nevada
21.   New Hampshire
22.   New Jersey
23.   New York
24.   North Carolina
25.   North Dakota
26.   Ohio
27.   Oklahoma
28.   Oregon
29.   Pennsylvania
30.   South Dakota
31.   Tennessee
32.   Texas
33.   Utah
34.   Vermont
35.   Virginia
36.   Washington
37.   West Virginia
38.   Wisconsin
39.   Wyomi ng
          Extent of  LFA  Use to  Date

"Potential  use due to  logistics
 Experimental  field  use
 Potential  use due to  logistics
 Limited field use - specified
 Potential  use due to  logistics
 Some prior field use
 Potential  use due to  logistics
 Laboratory investigation
 Routine use - specified
 Some prior field use
 Potential  use due to  logistics
 Potential  use due to  logistics
 Potential  use due to  logistics
 Limited field use
 Experimental  field  use
 Limited field use
 Potential  use due to  logistics - bad  climate
 Laboratory investigation
 Experimental  field  use
 Potential  use due to  logistics
 Potential  use due to  logistics
 Some prior field use
 Laboratory investigation - some field use
 Laboratory investigation
 Limited field use
 Fairly routine use  -  specified
 Experimental  field  use
 Potential  use due to  logistics
 Routine use until 1976  - specified
 Some prior field use
 Potential  use due to  logistics
 Limited field use
 Potential  use due to  logistics
 Potential  use due to  logistics
 Some prior field use
 Potential  use due to  logistics
 Very limited field  use
 Potential  use due to  logistics
 Potential  use due to  logistics
                                  1-96

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               Marketing Considerations.  After reviewing and evaluating the
utilization of LFA base, and differences that exist in the event of its use
from one state to another, it is evident that the level of use of LFA base
(or any other construction product) is definitely related to the sales ef-
fort applied on its behalf.  It must be understood that  sales of all construc-
tion materials (asphalt, concrete, aggregate, etc.), are dependent to some ex-
tent on periodic visits to users and specifiers by sales representatives, as
well as spokesmen for material producers lobbying associations.  In this re-
gard, it is virtually impossible for advocates of LFA materials to provide a
sales effort that can even remotely compare with that of the more recognized
and established- construction material industries.

          There are, no doubt, many instances in which too aggressive a market-
ing approach on behalf of an unfamiliar material, such as LFA, may have been
more detrimental than infrequent sales visits.  In addition, most engineers
are dissuaded from further use of a material when a marketing representative
makes undocumented claims about it or when the material is unable to perform
up to its advertised expectations.

          A sales representative for a Chicago-based ash marketing firm,
which has sold more fly ash for use in LFA base than any other firm any-
where else in the United States,  recommends that the following steps be
take to assure success in the marketing of line-fly ash-aggregate:

          1.  Cooperation between the utility company and the
              potential ash vendor on such vital matters as
              quality control, material availability, and load-
              ing hours.  Without such cooperation, and a sin-
              cere interest on behalf of the utility company,
              marketing of quality LFA material is doomed to
              failure.

          2.  Promote and think in terms of a plant-mixed pro-
              duct.  Production plants should have a capacity
              of at least 400 tons per hour.  Contractor-owned
              blacktop plants can be adapted for LFA production
              at a probable cost of $250,000 to $300,000 for an
              additional silo and feeding equipment.

          3.  Sell the product through contractor-owned market-
              ing outlets, using trained and qualified sales
              and engineering representatives.

          4.  Draw on the talents of paving experts to evaluate
              the  product, develop promotional literature, and
              provide technical consultation where needed.

          5.  Develop attractive and technically accurate pro-
              motional literature.
                                     1-97

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          6.  Conduct informal seminars on the properties and
              uses of the product.  Rely on experts where needed,
              emphasizing a direct and honest approach.

          7.  Invite potential producers and users to tour pro-
              duction facilities and project sites where the LFA
              material is being mixed and placed or where it has
              been in service.

          8.  Make frequent personal calls, again using the di-
              rect, honest sales approach.  Display cores of the
              material in addition to sales literature (Reference
              1-118).

          Audio-visual aids are an  excellent example of the use of profes-
sional marketing tools for product promotion.  In 1979, the Federal Highway
Administration, in cooperation with the National Ash Association and the
American Pozzolanic Concrete Association, developed a 20-minute narrated
slide-tape presentation entitled "Lime-Fly Ash Stabilized Bases and Subbases."
This presentation consists of 78 color slides which discuss and explain the
following aspects of LFA base materials:

              LFA components  (lime, fly ash, and aggregate)
              Fly ash production, composition, and handling
              Laboratory testing procedures  (ASTM C593)
              Plant-mixing of LFA materials
              Construction equipment used for LFA placement
              and compaction
              Engineering properties of LFA materials
              Advantages of using LFA materials

          A 20-page script of this slide-tape presentation has also been
prepared by the Federal Highway Administration and is included in this re-
port.  The  Federal Highway Administration disseminates this document to
district offices and other interested parties as part of its information
exchange program.  However, it is noted in the script that the contents of
the presentation do not necessarily reflect the official views or policy of
the government, which does not endorse products or manufacturers.

          It must be understood that any product with which state highway
engineers are not faimiliar cannot sell itself.  Due to the inherently con-
servative nature of the highway engineering profession and its reluctance
to deviate  from the use of familiar and established construction products,
a professional marketing effort must be applied by reasonable, technically
oriented organizations in order to advance the usage of a product such as
LFA base. Even with such an effort, it should be further recognized that
complete acceptance and routine use of any material, with which there is
little familiarity on the state level, probably involves a minimum five-
year time period.
                                      1-98

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          Overall Technical Assessment of LFA Materials.  The technology of
lime-fly ash-aggregate  (LFA) use in base and sub-base construction has been
well documented and implemented to various degrees in more than a dozen states
over the past 20 or more years.  It has been estimated that, since the mid-
1950s, from 20 to 25 million tons of LFA materials have been produced and
placed in different parts of the United States.  There is a large amount of
published literature and unpublished data on composition, characteristics,
and performance of LFA mixtures.  There are hundreds of sections of roadway
that have been placed using LFA base materials and which have provided highly
satisfactory performance for many years.  These projects are testimony to the
fact that LFA materials are indeed suitable for use as road base compositions
on primary and secondary highways, as well as in the construction of airfields.

              Advantages and Disadvantages.  The use of LFA materials in areas
where they are available offers the prospective user a number of advantages.
The principal advantages of these products are:

          1.  The most obvious benefit of LFA compositions is
              cost.  All other factors being equal, these ma-
              terials are nearly always less expensive than
              alternative or competitive base materials such
              as bituminous concrete or crushed aggregate.  In
              these times of inflation and tight budgets, sig-
              nificant cost savings from the use of LFA bases
              are not only possible, but have been documented
              on numerous occasions in many areas of the country.

          2.  A pozzolanic reaction occurs in these compositions,
              resulting in gradual, long-term strength develop-
              ment over time.  This strength development can be
              controlled and designed into the mixture by alter-
              ing the formulation during mix design.

          3.  Ultimate strength development of LFA base is com-
              parable to that of low-strength concrete.  There
              have been many examples where the ultimate strengths
              of LFA materials have exceeded 3,000 psi and in some
              instances have even achieved 5,000 psi or higher
              strengths.  In terms of cost per psi of strength de-
              veloped, LFA provides more strength for the dollar
              than any other paving material.

          4.  LFA  base materials are relatively easy to install
              and can be placed and compacted with conventional
              construction equipment.  There is no need for any
              exotic hardware or fancy procedures when mixing or
              laying LFA materials.

          5.  In states  where LFA has been most frequently used,
              the structural design coefficients for the material
              are equal, or nearly equal, to bituminous base and
              substantially higher than crushed aggregate.
                                     1-99

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          6.   The use of LFA base provides an excellent oppor-
              tunity to utilize a material that is considered
              a disposal problem to the electrical utility in-
              dustry.  From the perspective of fly ash utili-
              zation, one cubic yard of concrete can use 100
              pounds of fly ash, while one cubic yard of LFA
              can use 400 pounds of fly ash.  In pozzolanic
              mixtures containing sludge materials, one cubic
              yard of mix may contain up to 1,000 pounds of
              fly ash.

          7.   Once the material ages beyond the first winter,
              it continues to develop strength at a rate which
              exceeds the accumulated wheel loadings being apt-
              plied to the road.  Consequently, LFA pavements
              rarely fail from fatigue.  Moreover, it has been
              determined that, on low traffic volume facilities,
              LFA mixtures with well-graded aggregates possess
              sufficient mechanical stability to support wheel
              loadings through the first winter, even if no
              cementing of the base occurs.

          8.   LFA materials contain fly ash, which is a low
              energy-intensive material.  Therefore, use of
              LFA results in reduced energy input compared
              to that of alternative materials.  Substitu-
              tion of LFA base in lieu of bituminous base
              would not only result in lowered costs, but
              would conserve needed petroleum resources.

          On the other hand, there are certain disadvantages associated with
LFA materials  which must also be considered.  The main disadvantages of this
product are:

          1.   On state and Federally funded highway construction
              work, there are recommended construction cutoff
              dates  which are part of the material specifications.
              In northern states, where most of the LFA materials
              have been used, the material is not permitted to be
              installed on state projects beyond a specified  date,
              usually sometime between September 15th and October
              1st.  These dates may or may not be overly conserva-
              tive, but their net effect is to reduce the length
              of the construction season for LFA placement. On
              municipal projects, LFA has often been installed
              well beyond applicable state highway cutoff dates
              with no failure.
                                     1-100

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          2.  LFA base materials are not specified on many recon-
              struction projects where maintenance of existing
              traffic is necessary because, in the minds of many
              highway engineers, the material does not always hold
              up particularly well to heavy traffic (especially
              truck traffic).  This is more of a problem immedi-
              ately after the material has been placed and com-
              pacted.  It is normal practice to blacktop over LFA
              base as soon as possible (within one or two days)
              after it has been installed.

          3.  The production of LFA at the plant, as well as its
              placement at the job site, requires some reasonable
              quality control to assure a good performing product.
              This material is sensitive to variations in moisture
              which, if large enough, would adversely affect com-
              paction and eventual job performance.  The key to a
              successful LFA job is good compaction.   This cannot
              be achieved unless the product comes out of the plant
              at or close to its optimum moisture content and is
              properly compacted.

          4.  To many engineers, fly ash is a waste material and
              not a product.  When viewed as a waste material,
              fly ash is considered to be variable and of low
              quality.   While in some cases this may be true,
              there are many acceptable sources of fly ash avail-
              able for LFA use. Again, quality control of the ash
              and cooperation with the utility company is essen-
              tial.  The quality requirements for use of fly ash
              in LFA materials are far less stringent than for the
              use of fly ash in portland cement concrete.

          In objectively weighing the advantages vs.  the disadvantages of LFA
base materials, on balance, the good points of this material definitely out-
weigh its bad points.  It is a proven fact that, if this material is designed,
produced, and placed properly, it performs well.  It is a versatile product,
having been produced with almost every kind of aggregate and dozens of dif-
ferent sources of fly ash.  The obvious advantage of LFA base offers in dra-
matic costs savings is, in and of itself, a compelling enough reason for
justifying more widespread use of this material.

          All of the disadvantages cited above can in one way or another be
overcome by applying good, sound engineering coupled with a firm commitment
to product quality control.  Therefore, from a technical and economic stand-
point, use of LFA base is not only justifiable, but also very beneficial.
                                     1-101

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          The question therefore remains:  If LFA material is that good, why
isn't more of  it being used?  Although there may be no single answer to this
question, a number of possible explanations,  not necessarily related directly
to technical and/or economic considerations, are offered.

          Institutional Barriers and Related Factors.  To appreciate why a
seemingly acceptable construction material has had such difficulty gaining
acceptance since its development nearly 30 years ago, one must understand
the state highway engineering function and the relationship of the highway
construction industry to each respective state highway agency.

          In the first place, there are very few engineers as conservative as
the typical highway engineer.  They are conservative by necessity, being given
a budgeted amount of public funds and at the same time being charged with the
responsibility of keeping roads in as good a condition as possible.  Most
highway engineers are used to operating with sizable construction budgets and
relying on well-established construction materials.  Consequently, they are
somewhat skeptical and reluctant to endorse new or unfamiliar products, no
matter what advantages may be associated with the material.  They usually
resist change and prefer instead to continue utilizing materials with which
they are familiar.

          Secondly, LFA materials, because of early Poz-0-Pac patents, are
considered by many state highway engineers as a proprietary product, even
though all patents on the use of these materials have expired.  There is
still a certain aversion among some state highway engineers to using a pro-
duct of proprietary nature, such as LFA base.

          The specifying and use of highway construction products by engi-
neers and officials at the state  and local level is probably as attribu-
table to sales efforts and lobbying pressures as it is to the comparative
merits of the material itself.  Unfortunately, politics does play a role
in determining to what extent  various construction materials are included
in bids and specifications.

          There have been and still are intense lobbying pressures by con-
struction material producers associations on behalf of their products.  There
is nothing unethical or wrong about such efforts, as long as the sales in-
formation is factual and attempts are not made to discredit competitive
products.  Unfortunately, competitive material lobbyists have not always
portrayed LFA in a completely objective fashion to state highway engineers
and, consequently, certain misconceptions about the material have persisted.
An example of this is the notion that LFA materials are hard to handle and
place and require special installation equipment, when the truth is the ma-
terial is relatively easy to handle and place using conventional spreading
and rolling equipment.
                                      1-102

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          To combat ignorance of the product, a professional marketing approach
is absolutely necessary at all levels, but particularly at the state level.
Unfortunately, LFA materials have never had a real strong advocate or lob-
byist to counter the well-financed and well-organized representation from
other conventional highway product organizations.  Therefore, since the ma-
terial has not been well sold, it has failed to attract many supporters within
the highway establishment strictly on its own merits.

          Even though LFA materials are specified and used in some states,
other states which may have had less experience with the material sometimes
feel the need to "reinvent the wheel," in terms of years of laboratory in-
vestigation prior to using LFA on projects.  There are also instances where
engineers in a particular state gain familiarity with and confidence in a
material such as LFA.  However, once these engineers retire or pass away,
use of the material diminishes and other engineers who are not as familiar
with it must be re-educated concerning its use.  These are just some examples
of the institutional barriers to more widespread use of LFA materials.

Cement-Stabilized Fly Ash Bases and Sub-bases

          Another means of using fly ash as a road base or sub-base material
in highway construction is by stabilizing the fly ash with portland cement
(or, in some cases, hydrated lime).  Cement-stabilized fly ash base course
and sub-base materials are used in flexible pavement systems in the same man-
ner as lime-fly ash-aggregate and other pozzolanic base materials, except
that the cement-stabilized fly ash mixtures do not contain any conventional
aggregate.

          One of the most obvious advantages to the utilization of cement-
stabilized fly ash as a highway base course or sub-base is that between 80
to 90 percent by weight of the base course or sub-base material is fly ash,
instead of from 10 to 25 percent, as in the case with most lime-fly ash-
aggregate or other pozzolanic compositions.  Thus, use of  cement-stabilized
fly ash mixtures results in a substantially greater utilization of fly ash.

          History of Cement-Stabilized Fly Ash.  The use of cement-stabilized
fly ash is comparatively new in the United States. However, cement stabiliza-
tion of pulverized fuel  ash (PFA) and its subsequent use in road base con-
struction has been in practice in parts of Europe for nearly twenty years.
Both Great Britain and France have utilized this material to such an extent
that its ase is accepted routinely on public roads as well as private pro-
jects in both countries.  Specifications for fly ash-cement base courses
have been adopted by the British Department of the Environment (formerly
known as the Ministry of Transport) and commercial manufacturing plants
have been established for the production and sale of a ready-mix cement-
stabilized fly ash base course material.  In France, cement-stabilized fly
ash has been used as a sub-base on a number of major highway projects
(Reference 1-119).
                                     1-103

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          In the  United States, there has thus far been very little use made
of cement-stabilized fly ash base course and/or sub-base materials.  For the
most part, this is because American engineers have not had nearly as much ex-
perience as their European counterparts with the use of fly ash in general,
and in particular, with combinations of fly ash and portland cement containing
no aggregate.  Consequently, because of an ingrained reliance on conventional
materials of construction and an inherent aversion to the use of non-conven-
tional products, such as fly ash, American highway engineers have tended to
rely on proven technology and regard fly ash itself, and stabilized composi-
tions containing fly ash, with some mistrust.  Furthermore, until recently,
there has been a lack of technical documentation, reference materials, or
manuals describing the unique properties, design procedures, specification
guidelines, and construction techniques related to cement-stabilized fly ash.

          Pozzolanic Nature of Cement-Stabilized Fly Ash.  As discussed in the
preceding section on lime-fly ash-aggregate, fly ash is a pozzolanic material,
that is, it will react in the presence of calcium hydroxide and water at normal
temperatures to provide  cementitious compounds.  Therefore, the addition of
relatively small amounts of portland cement  (or hydrated lime) and water to
fly ash can result in significant and oftentimes rapid strength development.

          Fly ash itself contains varying amounts of calcium oxide, some of
which is present as free lime.  The quantity of free lime present in certain
fly ashes, particularly the so-called western fly ashes  (from the burning of
lignite or sub-bituminous coal) is sufficiently great that, when these ash
materials are moistened and compacted, they will harden and gradually develop
in strength of their own accord.  This strength, however, may not be of suffic-
ient magnitude for application in highway base course construction, either in
terms of load-bearing  capacity or durability in terms of resistance to freez-
ing and thawing.  Therefore, the addition of a stabilizing agent, such as port-
land cement or hydrated lime, in relatively  small amounts is required to pro-
mote additional and more rapid strength development and improve freeze-thaw
resistance.

          In general, portland cement is the most desirable stabilizing agent
to be added to fly ash, although lime can  be added instead of, or even to-
gether with, cement.  However, the strength  gain in fly ash-lime mixes is
significantly slower than  in fly ash-cement mixes, although comparable
strengths may be achieved after many months.  The use of lime instead of
cement may be considered in situations where longer curing periods or higher
curing temperatures can be anticipated or where the use of lime represents
an economic advantage over cement  (Reference  1-120).

          The hydration of portland cement in water proceeds rapidly so that
cement-stabilized fly ash mixtures normally  attain satisfactory early strengths,
while continuing to gain in strength over a  period of several years.  The amount
of cement needed to produce a given strength of mixture within a given period
of time under specified curing conditions is a function of the reactivity of
the fly ash.  This,  in turn, is related to  the physical as well as chemical
characteristics of the ash  (Reference 1-121).
                                      1-104

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          It is presently believed that silica, alumina, and calcium oxide
are the principal contributors to the pozzolanic reactivity of fly ash,
while the presence of carbon acts to inhibit the pozzolanic reactivity.
Generally, high surface area, which is a measure of the fineness of the
ash, also aids in the reactivity.

          Certain ash handling and storage techniques can directly affect
the pozzolanic reactivity of fly ash by altering the physical and chemical
characteristics of the material.  Sluicing of fly ash to ponds, for example,
often results in a non-uniform particle size distribution of the ash through-
out different areas of the pond, with coarser particles settling nearest the
outlet pipe and finer  particles settling farthest from the pipe.  Therefore,
the fineness of a. particular ash sample is a function of its particular loca-
tion within the sluicing pond.  Furthermore, the extent of fly ash exposure
to moisture over a period of time, either in ponds or stockpiles, can result
in the leaching of calcium oxide and the fly ash thus recovered could have
a somewhat reduced pozzolanic reactivity as a result of such leaching (Ref-
erence 1-122).

          Mixture Proportions.  Proportioning of cement-stabilized fly ash
mixtures is normally accomplished by means of laboratory tests to select a
design mix that, when mixed and compacted, is capable of attaining estab-
lished criteria for strength and durability.  The laboratory tests are es-
sentially the same as those recommended for soil-cement samples by the Port-
land Cement Association (Reference 1-123), with some modifications.  The
details of the recommended criteria for use in mix design, which have been
developed by the British Central Electricity Generating Board, will be dis-
cussed later in this report.

          Portland cement to be used in the construction mix should be Type
I cement and comply with the requirements of appropriate state or local
highway agencies for portland cement to be used in roadway construction.
The fly ash to be used should be tested in advance of trial mix designs in
order to determine the following properties:

          •   Moisture-density relationship (ASTM D698)
          •   Blaine fineness-specific surface (ASTM C618)
          •   Loss on ignition at 900°C, percent by weight
          •   CaO content, percent by weight.

          Because of the variability which often occurs in the character-
istics of fly ash from most power plants, due to changes in coal source,
firing conditions, or ash collection and handling procedures, the concept
of a construction mix has also been developed. The construction mix is es-
sentially a design mix in which the mix proportions selected from previous
tests may be adjusted in order to accommodate the least reactive fly ash
that may be expected to be obtained from a given ash source over the period
of construction.  Thus, variations in ash quality, disposal and/or storage
methods, and moisture conditions  can be factored into the mix design pro-
cedure.
                                     1-105

-------
          There is presently no method of  accurately determining  the  amount
of cement (or lime) necessary to produce the  required  amount  of strength and
durability for a given sample of fly ash,  although the percentage of  cement
is usually between 10 and 20 percent of the fly ash on a dry  weight basis.
However, the results of the chemical, physical, and laboratory compaction
tests provide   some indication of the potential  reactivity of a  sample  of
fly ash and can serve as a guide for selection of a trial mix.

          Based on laboratory test results of fly ash  samples, selection of
a cement content for trial mixes can be made  according to the following  guide-
lines :
          1.  Loss on Ignition  -
          2.   Calcium Oxide  -
           3.  Maximum Dry Density -
           4.   Elaine Fineness -
The carbon content of fly ash is
an important factor in strength
development of cement-fly ash mix-
tures. For a fly ash sample with a
loss on ignition greater than 5
percent, a trial mix with at least
20 percent cement by weight of fly
ash should be assumed.

The higher the CaO content of the
fly ash, the lower the cement re-
quired for stabilization.  For fly
ash samples with 10 percent or
greater CaO content, a cement con-
tent of 5 to 10 percent is recom-
mended.  For CaO contents below 10
percent, other factors will be of
greater influence in the selection
of a trial mix.

For fly ash samples with low loss
on ignition and CaO content, density
can be used as an indicator of re-
activity.  For fly ash samples with
maximum dry densities greater than
85 pounds per cubic foot, cement con-
tents of 10 to 15 percent are recom-
mended.  For fly ash samples with
maximum dry densities less than 85
pounds per cubic foot, 15 to 20 per-
cent cement is recommended.

The fineness of a fly ash sample with
low loss on  ignition and CaO content
is yet another indicator of reactivity.
For fly ash samples with a«Blaine fine-
ness in excess of 2,500 cm  per gram,
cement contents between 10 and 15 per-
cent are recommended, with increases in
the cement content as the Blaine fine-
ness decreases.
                                      1-106

-------
          Normally, in laboratory mix design testing, it is standard practice
to express the cement content of a mix in terms of a certain percent by weight
of dry fly ash.  However, this often does not give a clear indication of the
actual amount of cement being used in the mix because of variations in the
unit weight of fly ash from sample to sample.  Therefore, for cement-stabil-
ized fly ash mixes, it is more practical to express the cement content of the
design mix in terms of pounds of cement per cubic foot of compacted mix, based
on the maximum dry density and optimum moisture content of the mix as deter-
mined by ASTM D134-70.  This means of expressing the cement content permits
a direct comparison between design mixes on the basis of actual quantities of
cement required in each mix (Reference 1-124).

          Engineering Properties.  The most significant engineering properties
of cement-stabilized fly ash base course materials are compressive strength,
durability or freeze-thaw resistance, and moisture-density characteristics.
Unfortunately, due to the limited number of projects in which these materials
have been used in the United States, there is very little in the way of docu-
mentation of  these properties.  The following paragraphs summarize available
information on engineering properties of cement-stabilized fly ash compositions.

              Compressive Strength.  As noted earlier in this report, the
British have developed criteria for cement-stabilized fly ash base courses
which have been adopted and published by the National Ash Association (Ref-
erence 1-124).for mix design purposes.  The basis of these criteria are that
a specified compressive strength is an indication of the mix's ability to
resist damage due to cyclic freezing and thawing and frost action.  The fol-
lowing criteria have been developed for cement-stabilized fly ash mixes:

          •   The seven-day compressive strength of the mix, when
              cured under moist conditions at 70 + 3°F (21 + 2°C)
              must be at least 400 to 450 psi.

          •   The unconfined compressive strength of the mix must
              increase with  time.

          Since no data are available for laboratory freeze-thaw testing  of
cement-stabilized fly ash materials, the criteria listed above are assumed
to provide a design basis for development of sufficient compressive strength
to also satisfy durability requirements.

          Determination of mix formulations to meet those criteria must be
done by means of trial mixes.  Data from an access road project in Stone-
leigh, England provides an  indication of the possible strength development
of cement-stabilized fly ash.  Unconfined compressive strength data from
this project, using a mix with 10 parts fly ash to 1 part cement by weight,
are as follows:
                                     1-107

-------
                                             Un.confd.ned
              Age of Base                 •   Compressive
                 Course                        Strength
                 (days)                         (psi)

                     7                           400
                    28                           760
                    90                         1,250
                   270                         1,660

          Fly ash samples from different American power plants were tested
in the  laboratory to evaluate the engineering properties of trial mixes
using these materials.  The results of these tests, which include compres-
sive strength and moistuture-density data, are presented in Table 1-15.
These test results are useful in illustrating the range of engineering
properties that can be expected for design mixes using typical American
bituminous coal fly ashes.

          In addition, Figure 1-16 shows the variation in 7-day compressive
strength development with cement content for several of thse fly ashes.
From this figure, it is evident that the lagoon sample of fly ash from the
Willow Island plant requires a considerably higher cement content to achieve
strength comparable to the other silo ash samples  (Reference 1-124).

          Some minimal compressive strength data are also available from two
projects in West Virginia in which cement-stabilized fly ash has been used
as the base course for parking lot facilities.  These data, involving both
laboratory and field test specimens, are summarized as follows:

        Laboratory Test Specimens
          (Hoist Cured at 70°F)                 Field Core Specimens
Philip Sporn Plant - New Haven, W. Va.  Harrison Station - Haywood, W. Va

                          Unconfined                          Unconfined
Age of Base               Compressive   Age of Base           Compressive
   Course                   Strength       Course               Strength
    (days)                     (psi)          (days)                 (psi)

       7                      452              7                  566
      28                    1,362              90                  869

          It should be noted  that the base course material installed at the
Harrison  Station project was  placed rather late in the season and had under-
gone  several freeze-thaw cycles between 7 and  90 days.  Nevertheless, these
data, limited  though  they may be, demonstrate  that mix formulations have been
designed  and placed in service in this company that are capable of meeting the
six design criteria adopted by the National Ash Association.
                                      1-108

-------
                                                  Table 1-15

                             ENGINEERING CHARACTERISTICS OP CEMENT-STABILIZED
                               FLY ASH  MIXES USING DIFFERENT FLY ASH SOURCES
Utility Company Potomac Electric Potomac Electric Union Electric Allegheny Power
Power Station Chalk Point Morgantown Meramec Hatfleld's Ferry
Location Aquasco. Md. Newburg, Md. St. Louis. Mo. Masontown. Pa.
Ash Source S1lo Silo Silo Silo
Ash Content
(Ibs. per ft.1) 78 78 80 78
Cement Content
(Ibs. per ft.') 12 14 8 12
^ Cement Content
8 (percent) 15 18 10 IS
7- day Average
Compresslve
Strength (psl) 432 440 413 460
28- day Average
Compresslve
Strength (psl) 857 1341 1142 1020
Optimum Moisture
Content (t) 20.0 20.5 21.0 20.4
Maximum Dry Density
(Ibs. per ft.1) 90.5 92.6 87.7 89.4
Allegheny Power Allegheny Power
. Harrison Willow Island
Havwood. W. Va. Willow Is) and.W.Va.
Silo Lagoon
92
11
12 <30
421 696
580
19.0 31.0
102.5 79.8
NOTE:  Data Is from final  trial mix  formulations for each of the above fly ash  sources.

-------
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                      TRIAL  MIX tEMENT  CONTENT, pcf  (kg/ms)
   Figure  1-16.   Variation in 7-day compressive strength development with
                 cement content for cement-stabilized fly ash mixtures
                 using different sources  of fly ash.
                                         1-110

-------
              Moisture-Density.  Moisture-density characteristics of cement-
stabilized fly ash compositions  will, of course, be dependent on the mix
proportions used.  Data on the moisture-density characteristics of design
mixes using bituminous fly ash samples from several different American power
plants are shown in Table 1-15. Figure 1-17 shows the moisture-density curves
for several of these design mixes (Reference 1-124).

          The cement-stabilized fly ash base material placed at the Harrison
Station project in Haywood, West Virginia had a maximum dry density of 92.5
pounds per cubic foot at an optimum moisture content of 14 percent (Reference
1-124), according to the results of a moisture-density test  performed in ac-
cordance with ASTM D558.  A copy of this test method is included in the Ap-
pendix of this report.  In-place density tests performed at the site with a
nuclear density gauge confirm that the material was compacted to an average
of 98.5 percent of the maximum dry density value (Reference 1-124).  Similar
data are not readily available from other cement-stabilized fly ash instal-
lations .

              California Bearing Ratio.  The only published values for the
California bearing ratio (CBR) of cement-stabilized fly ash material used
in the United States are for the parking lot facility at the Philip Sporn
plant in New Haven, West Virginia.  It has been reported that seven day
soaked and unsoaked CBR values for the mix used on this project were 145
and 150 percent, respectively (Reference 1-125).

          Pavement Thickness Design Considerations.  As previously mentioned,
the thickness design procedure developed by the Portland Cement Association
(PCA) for soil-cement base courses has also been adopted for cement-stabilized
fly ash base courses.  This procedure has evolved over the years from previous
research, theory, test pavements, and actual construction projects involving
soil-cement pavement systems.. The design method is theoretically based on
the load-deflection and fatigue characteristics of soil-cement.  Thickness
design curves were previously developed by PCA for both granular and fine-
grained soils, but the curves for fine-grained soils are the ones used in
determining the thickness of fly ash-cement base courses.

        * The PCA design procedure consists of the determination of two
parameters, the subgrade strength and the fatigue factor, which are then
entered into a thickness design chart to yield the base course (Reference
1-126).  Once the initial thickness of the cement-stabilized fly ash base
course has been found, the thickness of the bituminous wearing surface can
then be determined.  The initial base course thickness can then be reduced
to account for the thickness of the bituminous wearing surface.
                                     1-111

-------
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-------
          The subgrade strength in. this procedure is measured by the modulus
of subgrade reaction  (k), which is determined by means of field plate-load
bearing tests.  However, CBR and Resistance  (R) value tests can also be used
to convert to equivalent k values, using appropriate charts (Reference 1-127).
Where light traffic conditions are expected, such as on rural roads or in
parking lots, subgrade strengths can be estimated based on soil classification
data.

          Four traffic parameters are necessary in order to determine the
fatigue factor.  These are the average daily traffic (ADT), the percentage
of trucks, the axle load  distribution of the trucks, and the annual traffic
growth rate.   The fatigue factor represents the total fatigue consumption of
the pavement over a specified design  period (usually 20 years) for given con-
ditions of traffic loading.  The fatigue factor is calculated using different
coefficients for different axle load groups and summing the individual totals.
For example, a two-lane road with an ADT of 3,000 vehicles and 3 percent trucks
had a calculated fatigue factor of 1,700,000.

          Figure 1-18 shows the base course thickness design chart used in this
thickness design procedure.  By entering this design chart with values for fa-
tigue factor and modulus of subgrade reaction  (k), a value for the initial
base course  thickness can be obtained.  The final base course thickness is
determined by selecting the thickness of the bituminous wearing surface and
using this value to adjust the thickness of the base course.   Graphs for de-
veloping these thickness values are shown in Figure 1-19.

          Late Season Construction.  As with lime-fly ash-aggregate and other
pozzolanic pavements, sufficient cured strength must be developed within the
base material in order to provide the amount of durability necessary to with-
stand the initial winter freeze-thaw cycles.  To assure that the material is
exposed to the required amount of degree-day curing conditions for adequate
strength development, a sensible construction cutoff date must be determined.

          A general guideline for establishing a construction cutoff date
for cement-stabilized fly ash base course is that the ambient air tempera-
ture should not fall below 50°F (10°C) for a period of seven days following
placement of the base course.  Since this material is similar in some re-
spects to lime-fly ash-aggregate, the pozzolanic reaction in cement-stabilized
fly ash base course practically ceases at temperatures below 40°F (40°C).
However, once the temperature increases, the pozzolanic reaction will again
resume.

          In the middle Atlantic states, a recommended construction period is
from April 15th through October 15th.  However, it is further suggested that
reference be made to the construction specifications of respective state high-
way departments for applicable cutoff dates for either lime-fly ash-aggregate
or soil-cement construction.  Such dates can be safely applied to the con-
struction  of cement-stabilized fly ash base course materials  (Reference 1-128).
                                     1-113

-------
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                      MODULUS  OF SUBGRAOE  REACTION, k, psi / in., (MPo/m)

            Figure  1-18.   Base course thickness design chart.
                                         1-114

-------
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                  INITIAL   BASE  COURSE THICKNESS,  inches  (mm)


                    ADJUSTED BASE  COURSE  THICKNESS
Figure  1-19.  Relationship between initial and adjusted base course thicknesses
             for cement-stabilized fly ash base materials.
                                   1-115

-------
          Assessment of Performance in Specific Projects.  In the United
States, several field trials and demonstration projects have been under-
taken in different locations to  evaluate the performance of cement-sta-
bilized fly ash base course materials.  To date, at least five cement-
stabilized fly ash projects have been constructed and the results of each
of these field trials have so far been favorable.  Several of these pro-
jects are discussed in this section of the report.

              Harrison Power Station - Haywood, West Virginia.  In September
1975, approximately 10,000 square yards of cement-stabilized fly ash was
placed as base course for an access road and parking area at the Harrison
Power Station.  Cement and fly ash from hoppers at the plant site were pre-
mixed in a pugmill with water at the rate of 83 pounds (37.5 kg) of fly ash
and 10 pounds  (4.5 kg) of cement per cubic yard of compacted mix.  This
base course material was spread and compacted to an 8-inch (203 mm) thick-
ness and sealed with a bituminous emulsion.  The material was tailgated
from dump trucks, spread to the required loose lift thickness, and com-
pacted by a vibratory roller having a dead weight of 8 tons.  A 3-inch
(76 mm) bituminous wearing surface was applied over  the base course.
Cores taken after 180 days indicated that the base course material had not
experienced any loss in strength over the winter months  (Reference 1-129).
As far as is known, this base course is still providing acceptable service.

              Philip Sporn Plant - New Haven, West Virginia.  During the
summer of 1978, a 70 x 300 foot (21 x 91 m) parking lot facility was con-
structed near American Electric Power Company's Philip Sporn plant along
the Ohio River about 35 miles north of Huntington, West Virginia.  The
experimental 'parking lot project was divided into five test strips, each
60 x 70 feet  (18 x 21 m).  Two of these five test strips involved the
placement of cement-stabilized fly ash base.  One section was 6 inches
(152 mm) thick, while the other was 15 inches (381 mm) thick.  Two other
test strips involved a cement-stabilized bottom ash  base,  while the
final section involved an emulsified asphalt bottom ash base.  All ash
utilized in the parking lot was obtained from the Philip Sporn plant.

          The experimental base course materials were blended in a continuous-
feed pugmill and then transported to the site.  Initial attempts to place
these base materials using an asphalt paving machine proved to be -cumbersome
and time-consuming, so the materials were simply spread by means of a motor
grader or small bulldozer and compacted using a steel-wheeled vibratory
roller.  All base materials were surfaced with 2 inches  (51 mm) of bituminous
wearing surface.

          The contractor's inexperience with ash materials and initial selec-
tion of inappropriate equipment to handle and place these materials was a
minor problem on this project.  A more serious problem involved the blending
of cement and fly ash in the pugmill.  Unfortunately, the cement-stabilized
fly ash material contained numerous small clumps of unmixed fly ash.  This
"balling" phenomenon was attributed to the use of damp fly ash, which had
been recovered from a disposal pond and mixed in its damp condition with
cement in the pugmill.  Previous European mixing experience has shown that
it is better  procedure to mix dry fly ash with cement, then introduce water
during additional blending.
                                      1-116

-------
          Monitoring of the performance of the cement-stabilized fly ash and
other base materials placed at this location is still underway.  No compres-
sive strength or other data have been made available for the cement-stabili-
zed fly ash base sections at this time.  However, it is believed that all of
the experimental base materials are still providing satisfactory performance
(Reference 1-130).

              Virginia County Road 665 - Carbo, Virginia.  During the summer
of 1978, a test section approximately 400 feet long was constructed of cement-
stabilized fly ash as part of the relocation of a portion of County Road 665
near the Clinch River  power plant at Carbo, Virginia.  The pavement section
consisted of a 5.5 inch (140 mm) thick cement-stabilized fly ash base course
overlaid by a 1.5 inch thick emulsified asphalt stabilized bottom ash wearing
course.  The base course material had a cement content of 14 percent of the
dry weight of the fly ash, with an optimum moisture content of 17 percent.
The compacted total unit weight of the mixture in the laboratory was approx-
imately 110 pounds per cubic foot.

          Because of logistical considerations, the base material was mixed
in-place on the site rather than mixed at a central mixing plant.   Some
minor construction problems resulted from the contractor's inexperience in
the handling and placement of stabilized base materials.  The base course
material was spread by a motor grader and compacted by means of a 10-ton
vibratory compactor and a bulldozer.  A tack coat was applied to the base
after placement.

          Thus far, the completed haul road has been in service for two years
with no obvious signs of pavement distress.  Examination of a core specimen
taken through the base course shows that the cement-stabilized fly ash ma-
terial is hard and coherent and the bond between the wearing surface and
the base appears to be satisfactory (Reference 1-130).

          Economic Evaluation of Cement-Stabilized Fly Ash Base.  In the
National Ash Association's "Guide for the Design and Construction of Cement-
Stabilized Fly Ash Pavements," a design example is given which compares the
costs of a cement-stabilized fly ash base with three alternative pavements.
These are full depth asphalt, bituminous wearing surface on a crushed ag-
gregate base course, and reinforced concrete on a crushed aggregate sub-base.

          The design methods used for the alternative pavements are those
developed by the Asphalt Institute and the Portland Cement Association.  The
design method developed by the Portland Cement Association for soil-cement
pavements has been adopted for cement-stabilized fly ash because of certain
apparent similarities between soil-cement and fly ash-cement. Until a design
method can be verified by test track operations, it is reasonable to assume
that other design methods, such as ultimate strength techniques, may be
equally applicable to cement-stabilized fly ash base course.
                                     1-117

-------
          A two-lane pavement carrying 300 vehicles per day was used in the
design example.  The modulus of subgrade reaction was 125 psi per  inch.
The Fatigue Factor, based on 3 percent trucks and an assumed axle  load dis-
tribution, was computed as 1,700,000.  For a bituminous wearing surface thick-
ness of 3 inches, the adjusted thickness for the cement-stabilized fly ash
base is 8 inches.

          Unit costs for this economic evaluation were based on data from
Building Construction Cost Data 1975, The Pennsylvania Department  of Trans-
portation 1974 edition of Construction Cost Catalog, and quotes received
from private contractors".  All unit costs are in-place, unless specified
otherwise.  It is assumed that the project site is 50 miles from the source
of the fly ash.

          Costs for each of these four alternatives, on the basis  of square
yard costs in-place, are computed as follows:

              Bituminous Wearing Surface on Cement-Stabilized Fly  Ash Base
Courses.  The base course thickness in the design example was determined as
8 inches and the bituminous wear surface thickness as 3 inches.  The base
course mix proportions are as follows:

          Fly Ash                    80 pcf of mix or 480 lb/yd2
          Cement                     8 pcf of mix of 48 Ib/yd2 _
          Water                      20 pcf of mix or 120 Ib yd    9
                                      C2-1/2 gal/cf)  (14-1/2 gal/yd^)

          a.  'Materials Costs:
              Fly ash, at a nominal cost of $0.50/ton;           -
               (480 lb/yd2 * 2,000 Ib/ton) x $0.50/ton  = $0.12/yd

              Trucking costs of fly ash for 50 miles at         _
              $0.30/100 Ib; 480 lb/yd2 x $0.30/100 Ib  = 1.44/yd

              Cement, in bulk; 48 lb/yd2 x $1.70/100             -
              Ib                                       =0.82 /yd

          b.  Mixing Costs:

              Central mixing in pugmill at $1.00/ton  (wet);     „
               (648 lb/yd2 * 2,000 Ib/ton) x $1.00 ton  = 0.32/yd

          c.  Placement, Compaction, Finishing and Curing:

              For  8-inch thickness, assume construction in       -
              one  layer; 1  layer x  $1.00/layer-yd2     = $1.00/yd

          d.  Bituminous Wearing Surface:
                                                       2
              Wearing course - 1^1/2  inches at $1.50/yd2            2
              Binder  course - 1-1/2  inches at $1.50/yd  =  $3.00/yd

              TOTAL  -  BITUMINOUS WEARING  SURFACE ON                _
               CEMENT-STABILIZED FLY ASH BASE  COURSE         $6.70/yd
                                      1-118

-------
              Full Depth Asphalt.  The required total thickness of pavement
for  the full depth asphalt alternative is 8-1/2 inches.  Assume the follow-
ing pavement configuration:
                                                  2
          Wearing Course - 1 inch       = $1.10/yd2
          Binder Course  - 1-1/2 inches =  1.50/yd2
          Base Course    - 6 inches     =  6.00/yd

          TOTAL - FULL DEPTH ASPHALT    - $8.60 yd2

              Bituminous Wearing Surface on Crushed Aggregate Base Course.
Based on a substitution ratio of 2.0 for high quality granular base and a
total required wearing surface thickness of 4-1/2 inches, the pavement con-
figuration  for this alternative is as follows:

          Wearing Course         - 1-1/2 inches = $1.50/yd2
          Binder Course          - 3 inches     =  3.00/yd2
          Crushed Aggregate Base - 8 inches     =  2.75/yd

          TOTAL - BITUMINOUS WEAR SURFACE ON              -
          CRUSHED AGGREGATE BASE COURSE         = $7.25/yd

              Reinforced Concrete Pavement on Crushed Aggregate Sub-base.
Based on a concrete modulus of rupture of 600  psi, the required thickness
of reinforced concrete pavement was determined as 7-1/2 inches, and the
thickness of crushed aggregate sub-base as 6 inches.  The pavement config-
uration is  as follows:

          Reinforced Concrete Pavement - 7-1/2 inches = $10.00/yd_
          Crushed Aggregate Sub-base   - 6 inches     =   2.00/yd

          TOTAL - REINFORCED CONCRETE ON CRUSHED                 2
          AGGREGATE SUB-BASE                          = $12.00/yd

          The four alternative pavement systems and their relative costs are
illustrated in Figure 1-20.  The unit costs for the alternative paving mater-
ials represent gross averages and definitely vary with project location and
availability of materials.(Reference 1-131).  Although the pavement costs
shown in this figure are based on 1975 cost data, it is assumed that the
costs of each of these pavement systems would not change significantly in
relation to the other alternatives, although all costs would definitely
have increased.

          The actual economy of the cement-stabilized fly ash pavement is
directly related, of course, to the availability of fly ash in reasonable
proximity to the project site.  However, in situations where fly ash is
more readily available than aggregate, it can be said that cement-stabilized
fly ash pavements obviously represent a more economical alternative than a
conventional pavement.
                                     1-119

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I.
2.
 3.
 4.
                                           * 6.70/YD2
             BITUMINOUS WEAR SURFACE ON
         CEMENT-STABILIZED FLY ASH BASE COURSE
                  FULL DEPTH ASPHALT
             Y/////7//////,
           BITUMINOUS WEAR SURFACE ON CRUSHED
                AGGREGATE BASE COURSE
             REINFORCED CONCRETE ON CRUSHED
                  AGGREGATE SUBBASE
   Figure I-2Q. Comparison of alternative pavements.
                                           *8.60/YD2
                                            *7.25/YD2
                           1-120

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          Overall Technical Assessment.  Cement-stabilized fly ash base
course material has been used on a very limited basis in the United States.
Although substantial use has been made of this material in some European
countries, and  the necessary design procedures and specifications for its
use in this country have been published in the form of a manual (Reference
1-131), the material itself has only been placed in a handful of projects.
Consequently, although cement-stabilized fly ash is similar to that of lime-
fly ash-aggregate or soil-cement base materials and the material appears to
have a proven record of performance, most engineers and, in particular, road-
building contractors are still not familiar with this material.  Therefore,
experience in the United States with cement-stabilized fly ash is simply not
sufficient to utilize the product on a routine basis at this time.

          Despite the performance record of cement-stabilized fly ash in
Great Britain, it is not appropriate to expect a rapid transfer of testing,
design, and construction procedures, as well as specifications, to be made
on the  part of American engineering practice with a comparatively untried
material.  In order to gain product acceptance and incorporate the use of
cement-stabilized fly ash base materials into American construction use, a
program involving several years of laboratory investigation and monitoring
of field performance must be undertaken by a number of Federal and state
agencies.  Only when confidence in this material has been gained through
experience can any consideration be given to possible development of guide-
lines for its use.

Mineral Filler in Bituminous Pavements

          The importance of mineral fillers in bituminous paving has been
recognized for many years.  Asphalt paving mixtures have been designed to
include mineral filler since 1980.  The term mineral filler generally ap-
plies to the fine fraction of a conventional aggregate that is predominantly
mineral dust, most or all of which is passing the 200 mesh sieve  (Reference
1-132).

          Mineral fillers in asphalt paving mixtures are particles suspended
in the asphalt binder which serve to improve the cohesion of the binder it-
self while contributing to the internal stability of the mixture by increas-
ing the contact points between aggregate particles.  When incorporated in
an asphalt mixture, mineral filler greatly increases the surface areas that
must be coated with asphalt.  If these surfaces are compatible with the
asphalt and are easily coated, use of the filler produces considerable
benefits.  If, on the other hand, the surfaces of the mineral filler are
highly susceptible to water, early pavement failure may result.

          An early investigation of mineral powders as fillers for bituminous
mixtures identified the following characteristics to be important:
                                     1-121

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          1.   Fundamental properties - particle size, size dis-
              tribution, and particle shape.

          2.   Mineral properties - texture, hardness, strength,
              specific gravity, and wettability.

          3.   Dependent properties - void content, void diameter,
              and surface area (Reference 1-133).

          Although the use of mineral fillers, either occurring naturally
in aggregates or added to mix, is common practice, existing knowledge of
the filler's effects on pavement performance is limited.  Selection of the
amount and type of filler is  based largely on experience.  However, speci-
fication requirements pertaining to particle size and plasticity character-
istics of candidate filler materials are often supplemented with additional
tests and requirements.

          Research on Use of Fly Ash as Mineral Filler.  Initial study of
the use of fly ash as a mineral filler dates back to 1931, when the Detroit
Edison Company recognized the opportunity to market fly ash for bituminous
road construction.  An initial laboratory investigation by the company com-
pared the physical and chemical properties of fly ash from the Trenton Chan-
nel Plant with those of natural filler found in Trinidad asphalt, which has
long been recognized as an excellent  material.  The results of this investi-
gation confirmed that the chemical composition of fly ash did not differ sub-
stantially from that of the natural Trinidad filler and that both materials
were composed, for the most part, of fine dust with a sprinkling of coarse,
gritty particles.  The fly ash was composed of spherical particles which
were somewhat coarser and of more  uniform size than the fine, angular par-
ticles in the Trinidad filler, although the coarsest particles in the fly
ash were small compared to the gritty particles of the Trinidad filler.
It was concluded from this early research that fly ash was sufficiently
similar to Trinidad asphalt filler to warrant consideration as a mineral
filler material.

          A followup program then compared the oil absorption of fly ash and
limestone dust fillers.  Laboratory tests were performed to compare the par-
ticle size distribution and specific gravity of these materials.  Trial mixes
were made using the same gradation of prepared aggregates in order to measure
aspahlt absorption, water-asphalt preference, and swelling of the resultant
mixes.   The results of this investigation indicated that fly ash is an ac-
ceptable filler, provided it  is proportioned on an equal volume basis,
since it has a lower specific gravity than limestone dust (Reference 1-133).

          A laboratory  test program was also performed to compare the suit-
ability of fly ash as a filler in sheet asphalt paving mixtures with lime-
stone and  silica dust  fillers.  The following studies were involved in the
program:
                                      1-122

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           1.  Void-reducing properties  of  fillers  used  in  dif-
              ferent proportions with sand.

           2.  Comparison of Hubbard-Field  stability values for
              different percentages of  these  fillers.

           3.  Exposure of mixtures to water for a  period of one
              month to determine the effect of such exposure to
              stability.

           4.  Effect of different percentages of carbon in the
              fly ash filler on the stability of the mixtures.

           In this program, filler contents were chosen to  correspond in
volume to  percentages by weight of limestone dust  of 0, 5,  10, 15, and 20
percent by weight of the aggregate.  Mixtures were designed to contain 8
percent by weight of asphalt and 92 percent aggregate.  The asphalt content
was not sufficient to fill the voids of any of the aggregate-filler combi-
nations.   Densities and voids in all mixes were computed from known pro-
portions and from the specific gravities  of the constituent  materials.
Stabilities of all mixes were determined by the Hubbard-Field method of
mix design (ASTM D1138), which is intended primarily for the laboratory
design of  sheet asphalt paving mixes and is included in the Appendix of
this report.

           A comparison of the data from this testing program led to the
following  conclusions:

           1.  Within the range of filler contents  generally used
              in sheet asphalt mixtures, fly ash has virtually
              the same void-reducing properties as limestone dust
              and is better than silica dust, when used on an
              equal weight basis.

           2.  Mixtures designed to have the same voids and con-
              taining equal weight percentages of  fly ash and
              limestone fillers have nearly identical stabilities
              by the Hubbard-Field test.  Of mixtures containing
              equal volume percentages of fly ash  and limestone
              fillers, those containing fly ash have lower sta-
              bility.

           3.  Exposure to water for a period of one month did
              not appear to affect the stability of fly ash
              mixtures.
                                     1-123

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          4.  The carbon content of fly ash does appear to affect
              the stability of sheet asphalt mixtures.  Maximum
              stability values seemed to be obtained with fly ash
              of about 9 percent carbon content in the normal sheet
              asphalt mixtures tested, although very little dif-
              ference  in stability values  were observed with
              carbon contents of the fly ash filler between 6.5
              and 12 percent.

          As a result of these studies, the Department of Public Works of
the City of Detroit in 1939 accepted fly ash as meeting their specification
requirements for mineral filler.  Since that time, additional research work
has been done to further evaluate fly ash as a filler material in asphalt
paving mixtures.

          A comprehensive study of various sources of mineral fillers was
performed in 1952 by the U.S. Bureau of Public Roads, now known as the Fed-
eral Highway Administration.  Twelve different sources of mineral fillers,
including four fly ashes, were investigated.  Filler sources also included
silica dust, limestone dust, mica dust, and traprock dust.  A total of 87
different laboratory mixtures were investigated using a variety of coarse
and fine aggregates with the fillers.  The proportions of the test mixtures
were 93 percent by weight coarse and fine aggregate and 7 percent by weight
filler.   All mixtures were tested with asphalt contents of 5.5 and 6.5 per-
cent by weight of aggregate, with the intention of confining the voids con-
tents of the compacted mixtures  to between 6 and 7 percent.  It was found,
however, that the type of filler affected the density and void content of
the mixes, so no further attempt was made to adjust mix designs to reduce
these differences, which were reflected in the test results.

          All test specimens were compacted in accordance with the procedures
of the Marshall mix design method, described in ASTM D1559, "Resistance to
Plastic  Flow of Bituminous Mixtures Using Marshall Apparatus."  A copy of
the Marshall mix design test  method is included in the Appendix of this
report.  The principal test characteristic upon which the ratings of the
different fillers were based was the resistance of the compacted asphaltic
concrete mix specimens to loss of strength after immersion in water.  The
specimens were tested by the Immersion-compression test  (ASTM D1075),
"Standard Method of Test for the Effect of Water on Cohesion of Compacted
Bituminous Mixtures."  In this test, a set of three compacted specimens for
each mixture is subjected to an unconfined compressive strength test to
determine   its "dry" strength.  A duplicate set of three specimens is immersed
in water for 4 days at 120°F, then also tested for unconfined compressive
strength to determine its "wet" strength.  The average "wet" and "dry" strengths
are then compared.  The ratio of the "wet" to the "dry" strength is referred
to as the retained strength.
                                      1-124

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          Of the 87 mixes tested, a total of 24 mixes contained fly ash as a
mineral filler.  The average retained strength of the mixes containing the fly
ash filler was 94 percent, which was with one exception the highest retained
strength of all the  filler sources  investigated.  One source of quartzite
dust was used as a filler and the mix containing this dust had a retained
strength of 97 percent.  All of the retained strengths of the mixes contain-
ing fly ash as filler had retained strengths in excess of 85 percent.

          By contrast, the average retained strength of 11 mixes containing
limestone dust fillers was 88 percent and the average retained strength of 19
mixes containing traprock dust fillers was 87 percent.  Normally, the minimum
recommended acceptable value of retained strength from the immersion-compres-
sion test is 75 percent.

          It was concluded from these laboratory studies that the fly ash
fillers tested can be expected to provide superior resistance to water in
bituminous concrete mixtures of the dense type (Reference 1-136).

          In 1956, the University of Michigan completed work sponsored by
Detroit Edison on a further comparison of limestone dust and fly ash fillers
to determine the effects of using various fly ashes as fillers in dense-graded
asphaltic concrete paving mixtures.  The characteristics of limestone dust
fillers were compared with those of low carbon and high carbon fly ashes from
four different sources.  The specification requirements of the Michigan Depart-
ment of Highways for dense-graded asphaltic concrete were used in the inves-
tigation.  At that time, the carbon content of fly ash as mineral filler had
to be between 7 and 12 percent by weight.

          Typical paving mixture compositions studied had the following  pro-
portions by weight:

          Component               Percent

          Asphalt                   5.5
          Filler                    6.0
          Fine aggregate           33.5
          Coarse aggregate         55.0

          All mixes tested used the Marshall mix design method (ASTM D1559).
The following mix design criteria were used:

          Marshall stability         1,500 pounds or more
          Marshall flow              0.20 inch maximum
          Voids                      3 to 5 percent
          Voids filled with asphalt  75 to 85 percent

          All test specimens were prepared  and tested in accordance with
the Marshall mix design method (ASTM D1559).  Mixtures were prepared with
three filler contents (4, 6, and 8 percent by weight) for each of six fil-
lers (two limestone dusts and  four fly ashes, ranging from 3 to 10 percent
carbon content) investigated.  Asphalt content was varied slightly to pro-
vide 4 percent voids for compacted specimens.
                                     1-125

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          The results of the Marshall stability tests showed that the sta-
bility values were somewhat affected by the source of the filler.  The
limestone dusts gave the highest stability values, followed by the high-
carbon fly ash and low-carbon fly ash fillers.  However, all mixes possessed
stabilities above the 1,500 pound design minimum.  The flow values of all
mixtures conformed to the design requirement, and only minor variations ac-
cording to filler type and carbon content of the fly ash were noted.

          The relative resistance of each of the test mixtures to water was
determined by means of the immersion-compression test (ASTM D1035).  The
specimens were tested in unconfined compression, three without exposure to
water, three after 4 days of immersion in water, and three after 14 days of
immersion in water.  Unconfined compressive strength tests were performed
in accordance with the procedures of ASTM D1074, "Compressive Strength of
Bituminous Mixtures," a copy of which is included in the Appendix of this
report.

          The results of these tests showed that the unconfined compressive
strengths of all mixtures, regardless of the source and nature of the min-
eral filler, were not significantly different.  Immersed strengths for all
mixes tested ranged from 89 to over 100 percent of dry strength values.

          The following conclusions were drawn from this study:

          1.  The source of a mineral filler can affect the
              Marshall stability of dense-graded asphaltic
              concrete mixes.  However, all of the fillers
              studied produced mixtures possessing stabilities
              above the minimum design limit of 1,500 pounds,
              as specified by the Michigan Department of
              Highways.

          2.  Marshall flow values show no significant differ-
              ence attributable to the source of the filler
              when other design criteria are satisfied.

          3.  The source of filler was not a significant factor
              in the unconfined compressive strength test.  Mix-
              tures containing high-carbon fly ash and low-carbon
              fly ash possessed equal strengths with those con-
              taining limestone dust.

          4.  All of the mixtures tested, regardless of the source
              of  the filler, were completely satisfactory with
              respect  to their resistance to the action of water,
              as determined by the immersion-compression test.
                                      1-126

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          5.  There are indications that mixtures containing fly
              ash from three of the sources were more critical
              with respect to design relationships between asphalt
              content, voids, stability, and flow than those con-
              taining the fourth fly ash or the limestone dusts.
              However, there appears to be some characteristic,
              other than carbon content, that seems to be respon-
              sible for the behavior of the fly ash fillers
              (Reference 1-137).

          The previously described studies all involved research into the
use of fly ash from the burning of bituminous coal as a mineral filler.
The use of fly ash from the burning of lignite coal as a mineral filler
was evaluated in a study conducted during 1968 at North Dakota State Uni-
versity.  This evaluation was made by comparing the properties of hot-mix
asphaltic concrete specimens that were compacted by means of the Marshall
mix design method (ASTM D1559), using either hydrated lime, crusher dust,
or lignite fly ash as the mineral filler.  Table 1-16 presents  a comparison
of the physical properties of each of these three fillers.

          The pH of a material being considered as a mineral filler is im-
portant because basic substances usually provide better adhesion than acidic
substances.  According to Tunnicliff, acidic substances have been known to
lead to emulsification (Reference 1-138).  As shown in Table 1-16, the pH
of the lignite fly ash is closer to that of the hydrated lime than the
crusher dust.

          The stability index was developed by Traxler (Reference 1-139) as
a parameter beyond that of bulk  density with which to evaluate the effect of
a mineral filler on a given asphalt cement.  Traxler pointed out in his re-
search that the viscosity of a liquid-solid mixture is inversely proportional
to the average void diameter of the filler present in the mixture, which he
used to develop  the relationship between viscosity and volume of filler upon
which the stability index is based.

          The stability index (SI) is computed as follows:
                      A
          SI = 100 (10  - 1), where A is constant for a given material.

          Stability index values have been found to range from 3 to 12.
Fillers with a higher stability index value are preferred for  use in as-
phalt concrete mixtures.  As shown in  Table 1-16, the stability index for
the lignite fly ash is approximately the same as the crusher dust, but
considerably less than hydrated lime.
                                     1-127

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                                 Table 1-16

               PHYSICAL PROPERTIES OF MINERAL  FILLERS
     Type of
     Filler
Surface area (cm^/g)

Liquid limit (percent)

Plastic limit (percent)

PH

Specific gravity
   (in water)

Specific gravity
  (in kerosene)

Stability  Index
Hydrated
  Lime
  3900
Crusher
 Dust
 5900
Lignite
Fly  Ash
.2660
     12.4

      2.303


      2.300


      8.30
     9.0

     2.760


     2.764


     4.05
   11.8

     2.906


     2.900


     3.87
             All mixes in the lignite fly ash study were compacted in accordance
   with Marshall mix design procedures (ASTM D1559).  Gradations of the test
   mixes were prepared to conform to  applicable North Dakota and Minnesota high-
   way specification requirements.  The results of Marshall tests on freshly
   molded and cured compacted samples were compared with mix design criteria
   recommended by the Asphalt Institute, as shown on Table 1-17.

             Because of the variation in specific gravity and density of the
   different filler materials investigated, the proportioning of the filler
   amounts in the test mixes was done on the basis of volume rather than weight
   of total aggregate in the mixture.

             Each of the three filler types (lime, crusher, dust, and lignite
   fly ash) were combined with either crushed stone or pit run gravel aggregates.
   A total of five different asphalt  contents were investigated for each binder
   and aggregate combination.
                                       1-128

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                              Table 1-17

                    MARSHALL  DESIGN CRITERIA
Traffic Category

No. of Compaction Blows
Each End of Specimen
  Heavy

   75
Medium

  50
      Light

        35
 Test- Property

Stability  (Ibs.)

Flow (.01 in.)

Percent Air Voids
  Surfacing or Leveling
  Sand or Stone Sheet
  Sand Asphalt
  Binder or Base

Percent Voids in
Mineral Aggregate*
  Surfacing or Leveling
  Sand or Stone Sheet
  Sand Asphalt
  Binder or Base
Min. Max.  Min. Max.  Min. Max.

750    -   500    -   500

  8   16     8   18     8    20
  3    5
  3    5
  5    8
  3    8
 15
 21
 18
 12
 3
 3
 5
 3
15
21
18
12
5
5
8
8
3    5
3    5
5    8
3    8
     15
     21
     18
     12
Note:
1. Laboratory compactive efforts should closely approach the
maximum density obtained in the pavement under traffic.
2. The flow value refers to the point where the load begins to
decrease.
3. The portion of the asphalt cement lost by absorption into the
aggregate particles must be allowed for when calculating percent
Air Voids.
4. Percent Voids in the Mineral Aggregate is to be calculated on
the basis of the ASTM bulk specific gravity for the aggregate.
5. All criteria, and not stability value alone/ must be considered
in designing an asphalt paving mix.
*Related to nominal maximum particle size of aggregate used in mix.
                                  1-129

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          Results of Marshall tests are shown in Table 1-18.  These results
indicate that the stability, flow, and voids in mineral aggregate values met
specifications for medium and heavy traffic, as recommended by the Asphalt
Institute.  Air voids values of 5.4 percent were barely in excess of the
recommended 5 percent limiting value.  However, results of immersion-com-
pression tests show that the retained strength of the fly ash test specimens
with either crushed stone or pit run gravel aggregates was in excess of 100
percent for both mixes at optimum asphalt content.  Even after seven days
Immersion, retained strength values for these mixes were 99.0 and 87.9 per-
cent, respectively.  Mixtures containing fly ash filler at optimum asphalt
content show less loss of compressive strength after immersion than mixtures
containing either lime or crusher  dust (Reference 1-140).

          Current studies of lignite fly ash as a mineral filler are being
conducted at the Texas Transportation Institute.  Early data from these studies
indicates that lignite fly ashes function well as fillers in asphaltic con-
crete and that the asphalt-fly ash binder may actually impart beneficial
changes in asphalt paving  mixtures.

          The high lime content of Texas lignite fly ashes appears to be
particularly beneficial when such ashes are used with asphalts from selected
sources.  For years, lime has been recognized as an effective anti-stripping
agent for polish-susceptible aggregates in asphalt concrete mixes.  Lime al-
so reduces the rate of service-associated increases in the viscosity of the
asphalt binder.  The results of the work at Texas Transportation Institute
also indicate that the use of Texas lignite fly ashes as mineral filler af-
fect the physiqal properties of the binder and serve to retard the rate of
age hardening of the asphalt cement  (Reference 1-141).

          Utilization of Fly Ash as Mineral Filler.  Since mineral filler
comprises only 5 to 7 percent by weight of the aggregate in a bituminous
paving mix, the use of fly  ash as a mineral filler does not presently
constitute a  high volume application for this material.  Since 1970, an
average of 140,000 tons per year of fly ash has been used as mineral filler
in the United States.  This use represents an average of only about  0.3
percent of all the fly ash generated each year in this country.  However,
in some areas, the use of fly ash as a mineral filler does involve signif-
icant quantities.  For  example, it has been reported that over the past
40 years, the Detroit Edison Company, which pioneered the use of fly ash
as a mineral filler, has sold nearly 1.5 million tons of fly ash to the
asphalt paving industry for that purpose  (Reference 1-142).  Since 1969,
the North Dakota Highway Department has utilized over 40,000 tons of lig-
nite fly ash as a mineral filler  (Reference 1-143).

          Fly ash was also used as a mineral filler in lieu of portland
cement in the placement of 35,000 tons of open-graded asphalt overlay sur-
face on the north-south runway at the Sioux City, Iowa Municipal Airport.
This open-graded overlay was selected because of its skid resistance qual-
ities.  Fly ash was used as the mineral filler to get the proper micron
coverage  of asphalt on the aggregates, while achieving considerable cost
savings to the city  according to Byron Brower of Brower Construction
Company,  contractor for the project  (Reference 1-144).
                                      1-130

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                                 Table 1-18

                     RESULTS  OF MARSHALL TESTS ON
      BITUMINOUS MIXTURES CONTAINING VARIOUS MINERAL FILLERS
Type of
Aggregate
          Percent
          Optimum
Type of  Asphalt
Filler   Content
      Marshall  Test Values

                                 Percent
                                 Voids  in
Stability  Flow     Percent   Mineral
(pounds)     (.01 in.)Air Voids Aggregate
Crushed
Stone
Pit  Run
Gravel
Fly  Ash     6.8
  1690
10.0
5.4
16.03
Lime
Crusher
Dust
5.67
6.5

2670
1750

13.5
11.6

4.9
7.6

15.9
19.1

Fly  Ash     5.5
  1500
10.2
5.4
16.85
Lime
Crusher
Dust
5.76
5.5

2150
1900

10.6
10.2

4.8
4.0

14.4
16.55

            The results, of a questionnarie on the use of recovered materials
   by state highway and  transportation agencies,  which was circulated by The
   American  Association of State Highway and Transportation Officials (AASHTO)
   during April 1980,  show that 22 states have at one time or another used fly
   ash as a mineral filler in bituminous paving.  Of these 22 states, a total
   of 14 presently  have a specification  for such use.  The states  which re-
   port the use of fly ash as a mineral filler are:
            Alabama
            Arkansas
            Colorado*
            Florida*
            Georgia
            Illinois*
            Iowa
            Kentucky*
            Louisiana
            Maryland
            Michigan*
            Montana*
            Nebraska*
            New York
            North Carolina*
            North Dakota*
            Ohio*
            Pennsylvania*
            South Carolina*
            Tennessee
            West Virginia*
            Wyoming*
   * Fly  ash use as mineral filler  is included in state specifications.
                                     1-131

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          In addition to the above states, Texas has reported that it is
actively investigating the use of fly ash as mineral filler in laboratory
studies.  Utah and Idaho are also involved in testing and planning activ-
ities for consideration of fly ash as a filler, according to the National
Ash Association  (Reference 1-145).

          Of the 22  states that have reported using fly ash as a mineral
filler, all consider its performance as either acceptable, good, or excel-
lent, except for Iowa, which has not used the material for a long enough
period of time to be able to properly evaluate its performance. In Colo-
rado, fly ash has only been used to a limited extent, but its performance
is considered excellent because of a "severe need for additional fines and
fly ash  solved  the  problem"  (Reference 1-146).  In Nebraska, where fly ash
fillers are used more routinely, the material provided "excellent pavement
performance, low prices, and a lower asphalt demand than other fillers"
(Reference 1-147).

          Review of  Specification Requirements.  In order to more fully
assess the technical ability of various sources of fly ash to function as
mineral fillers  on federally funded bituminous highway paving projects, it
is essential to  compare the characteristics fo fly ash with the mineral
filler requirements  of different specification agencies.  Table 1-19 pre-
sents a summary  of mineral filler requirements from a study of mineral fil-
ler specification requirements from six states and two Federal agencies,
all of which use fly ash as a mineral filler.  The overall physical prop-
erties of what is considered a. typical fly ash are also included in this
table.  In comparing the physical properties of fly ash with these mineral
filler specification requirements, it is apparent that fly ash is capable
of satisfying these  requirements.  Obviously, each source of fly ash must
be carefully and separately evaluated prior to use as mineral filler to
assure compliance with specifications.

          Although North Dakota  is the only one of the six states selected
for evaluation of specifications that places a. limit on loss on ignition
for mineral fillers, variation  in  ignition losses among different lignite
fly ash samples  do appear  to  seriously affect Marshall stability, flow,
and air voids values.  In  addition, certain of the more finely graded lig-
nite ashes did produce bituminous mixes that were gummy and difficult to
lay in the field.  The reason  for  this was that the fineness of the fly
ashes resulted in mixes with a  fairly high  percentage of uncoated parti-
cles  (Reference  1-148).  Therefore,  although a particular sample of fly
ash may meet applicable  gradation  specifications, an abundance of very
fine  (-#325 mesh) particles may be detrimental to its performance as a
mineral filler.

          Addition of mineral filler to an asphaltic concrete  paving mix
is a valuable component  in improving the  characteristics of the mix.  The
benefits of mineral  fillers  have been pointed out by many investigators.
The principal benefits are increased stability and better durability, both
of which are attributable  to  absorption.   Increased stability results from
a stiffened binder,  while  better  durability  is related to the character of
the absorbed  film.   Fly  ash has been proven effective in imparting these
properties.


                                      1-132

-------
to
CO
                                                       Table 1-19

                              COMPARISON OF FLY ASH  CHARACTERISTICS WITH APPLICABLE

                             SPECIFICATION  REQUIREMENTS FOR  MINERAL FILLER IN  ASPHALT


                                         ALLOWABLE PERCENT PASSING
Sieve
Size

#30
#50
#80
#100
#200
Plasticity
Index
Moisture
Content,
max. (%)
Loss on
Ignition,
max. (%)

Allowable
Materials








FHWA and
FAA Illinois
(AASHTO Ml 7)
100
95-100
N.A.
N.A.
70-100

4 Max.


N.A.


N.A.

Rock Dust,
Slag Dust,
Hydrated
Lime,
Hydraulic
Cement,
Other Suit-
able Mineral
Matter

Michigan
North
Dakota
Ohio
Pa.
West Physical Properties
Virginia of Typical Fly Ash*
(ASTM D242)
100
N.A.
N.A.
92+8
82+18

N.A.


N.A.


N.A.

Dry
Limestone
Dust or
Other
Approved
Material




100
N.A.
N.A.
N.A.
75-100

98-100
N.A.
N.A.
85-100
65-100

N.A. Non-plastic


N.A.


12.0 Max. 6

Limestone
Dust, Dol-
omite Dust,
Fly Ash,
Hydrated
Lime






1.25


.0 max.

Limestone
Dust,
Portland
Cement ,
Hydrated
Lime,
Crushed
Rock
Screenings
or Fly Ash
100
N.A.
95-100
N.A.
65-100

N.A.


N.A.


N.A.

Limestone
Dust,
Portland
Cement
or Other
inert
Mineral


.
TOO
95-100
N.A.
90-100
70-100

N.A.


N.A.


N.A.

Cement ,
Cement Dust,
Fly Ash, or
Fines From
Crushing of
Stone,
Gravel or
Slag


100
95-100
N.A.
N.A.
70-100

4 Max.


N.A.


N.A.

Rock Dust,
Slag Dust,
Hydrated
Lime, Hy-
draulic
Cement, or
Other Suit-
able Mineral
Matter

100
90-100
80-100
75-100
60-90

N.A.


N.A.
0.1-45
(Range)
2-8
(Normal)










      N.A. denotes  information not available or not given  in specification.
      *From Figure  4 - FHWA Implementation Package 76-16,  "Fly Ash - A Highway Construction Material.1

-------
          At the present time, utilization of fly ash as a mineral filler
in asphalt paving mixtures does not represent a significant use area for
the material.   Moreover, the actual quantities used for this purpose have
remained relatively constant over the past ten years.  Increasing quantities
of baghouse dusts from hot-mix asphalt plants and kiln dusts from cement
and lime plants, which are also being used as mineral fillers, are now com-
peting with fly ash as potential sources of filler material.  Therefore, it
is possible that the national market for fly ash filler may even be in de-
cline and that overall demand for mineral fillers may continue to diminish.
This is because many hot-mix asphalt producers prefer to recycle the bag-
house dusts from their plant as fillers rather than use outside filler
sources.

          Nevertheless, a review of previous research data, which has been
discussed herein, clearly indicates that fly ash is not only technically
suitable for use as a mineral filler,but is also a superior product for
this purpose.

          Most fly ashes are able to readily conform to existing specification
requirements for mineral fillers.  Several million tons of fly ash have been
used as mineral fillers in more than 22 states over the past 40 years with
more than satisfactory results.  Furthermore, the relatively high lime content
of Western  (lignite and sub-bituminous) fly ashes is an added feature which
appears to  impact anti-stripping properties to asphaltic concrete mixtures,
as well as  retarding the age hardening of the asphalt binder.

          In addition to technical considerations, use of fly ash as mineral
filler is dictated by economics.  In many areas where suitable fly ash is
available,  it  is considerably lower in cost than hydrated lime, which now
is selling  for  $50 or more per ton.  Fly ash is also available in many
densely populated areas, where demand for asphalt paving is presumably
greatest.

          Although fly ash has proven to be an excellent filler source, an
increase in the future demand for fly ash in this application appears un-
certain at  this time. Compared to other possible applications for fly ash,
mineral filler  use does not have the potential for consuming substantial
quantities  of the material.  The continued use of fly ash as a mineral fil-
ler  in asphalt  paving will be determined to a great extent by forces of sup-
ply  and economics within localized areas surrounding hot-mix asphalt plants.
For  these reasons, imposition of Federal procurement guidelines are not
recommended for stimulation of fly ash use as mineral filler.  Greater
marketing efforts and education of potential users are seen as more con-
structive ways  to further  such use.
                                      1-134

-------
BOTTOM ASH

Production and Handling

          The residual material which settles and collects at the base of
the boiler at coal-fired electric utility plants is termed bottom ash.
Approximately  25 to 30 percent  of all ash produced annually is bottom
ash.  Basically, two different types of bottom ash are produced:  dry bot-
tom ash and wet bottom boiler slag.  The term "power plant aggregate" is
often used to include both forms of bottom ash.

          Dry bottom ash is produced by injecting pulverized coal (at least
75 percent passing a 200 mesh sieve or 75 microns) into the furnace and
burning the coal.  This type of boiler is referred to as a "dry bottom"
boiler.  The ash that is not fine enough to go up the stack with the boiler
gases in the form of fly ash instead solidified and agglomerates into coarse
particles (from 5 cm down to 75 mm).  Some of the larger pieces may be porous
particles with varying degrees of friability.  These coarse particles then
fall into the ash hopper at the bottom of the furnace.

          The term "dry" bottom ash refers to the solid state of the ash when
it drops into the hopper.  A certain amount of molten slag, which forms on
the internal surface of the boiler during combustion, also drops into the ash
hopper.  In a typical dry bottom coal-fired furnace, from 20 to 30 percent of
the ash is bottom ash.  The ash hopper also generally contains some water.
When a sufficient amount of bottom  ash drops into the hopper, it is removed
by means of high pressure water jets and conveyed by sluiceways to a coarse
crusher and on to a storage area.

          The other basic boiler type is referred to as a "wet bottom" or
"slag tap" boiler.  In this type of boiler, the bottom ash is kept in a
molten state and tapped off as a liquid.  There are two varieties of "slag
tap" boilers:  those that burn pulverized coals and those than burn crushed
coals.  Boilers burning crushed coals are known as cyclone boilers.   Both
boiler types have a solid base with an orifice that can be opened to permit
the molten ash that has collected on the base to flow into the ash hopper
below.  As is the case in dry bottom furnaces, the ash hopper in wet bottom
furnaces also contains quenching water.  However, when the molten slag comes
in contact with the quenching water, it fractures instantly, crystallizes,
and forms a black angular, glassy material.

          The term "wet" bottom boiler slag describes the molten state of
the slag as it is drawn from the furnace.  In a typical wet bottom furnace,
50  to 70 percent of the ash produced will be boiler slag, with the remainder
being fly ash.  In cyclone furnaces, production of ash may be up to 80 per-
cent boiler slag and 20 percent fly ash.  Wet bottom boiler slag is some-
times also referred to as "black beauty" because of its black, glass-like
appearance.  At intervals, high pressure jets wash the slag from the hopper
pit into a sluiceway in which it is conveyed  to a collection basin for
dewatering, possible crushing, and disposal or reuse.
                                     1-135

-------
          In order to simplify terms, dry bottom ash will be referred to in
this report simply as "bottom ash" and wet bottom ash or wet bottom boiler
slag will  be referred to as "boiler slag."  As noted earlier, power plant
aggregate refers to both bottom  ash and boiler slag.

          A typical 1,000 megawatt coal-fired power  plant may burn 3 mil-
lion tons of  coal per year.  With an ash content of 13 percent, approxi-
mately 400,000 tons of ash will be produced, of which 120,000 tons will be
bottom ash and 280,000 tons will be fly ash.

          In 1979, the annual production of bottom ash was 12.5 million tons
and the annual  production of boiler slag was 5.2 million tons.  Therefore,
total production of power plant aggregates in 1979 was  17.7 million tons,
or 23.5 percent of the total 1979 ash production of 75.2 million tons.  Table
1-20 summarizes the annual production of bottom ash and boiler slag since
1970.  The National Ash Association has forecasted total ash production in
1985 at 90 million tons  (Reference 1-149).  Applying current percentages,
the combined production of bottom ash and boiler slag will be between 22.5
and 27.0  million tons.

Physical, Chemical, and Engineering Properties

          As a general rule, boiler slag tends to have more uniform properties
than bottom ash.  This is true for within plant variation and for plant to
plant variation.  However, the variation in properties of power plant aggre-
gates is minimized in so-called mine mouth plants that burn a single source
of coal  (Reference. 1-150).

          Power plant aggregates are composed principally of silica, alumina,
and  iron, with smaller percentages of calcium, magnesium, sulfate, and other
compounds.  The composition  of the ash particles is controlled primarily by
the  source of the  coal and not  by the type of furnace.  The chemical analysis
of selected samples of bottom ash and  boiler slag is given in Table 1-21.
As shown in this table,  chemical compositions for these materials are rela-
tively  similar and are generally of little practical importance when evalu-
ating power plant  aggregates for potential use in highway construction
 (Reference 1-151).

          However,  it must be noted that in some power plants coal pyrites
are  disposed  of with  bottom  ash.   In  such  cases, some pyrite or soluble sul-
fate winds up  in the  bottom  ash and must be separated from the ash prior to
use  (Reference 1-152).

          Bottom ashes have  angular particles with a very porous surface.
Some glassy particles can also  be  seen, particularly in the smaller sizes.
These glassy  particles represent the molten slag from the internal surfaces
of the  boiler.  Bottom ash particles  range in size from fine gravel to fine
sand.   Figure 1-21 shows the  particle  size  distribution of ash samples taken
from a  number of dry  bottom  boilers.  As  shown in the figure, bottom ash is
usually a well-graded material.   It  should be noted that some variation in
particle size distribution can be  expected from bottom ash samples taken from
the  same plant  source at different  times.  (Reference 1-153).
                                      1-136

-------
                              Table 1-20

          ANNUAL PRODUCTION  OP  POWER PLANT AGGREGATES
                IN THE UNITED STATES SINCE 1970

                        (Millions  of Tons)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
Total
Ash
39.2
42.9
46.3
49.3
59.5
60.0
61.9
67.8
68.1
75.2
Bottom
Ash
9.9
10.1
10.7
10.8
14.3
13.1
14.3
14.1
14.7
12.5
Boiler
Slag
2.8
5.0
3.8
3.9
4.8
4.6
4.8
5.2
5-1
5.2
Power
Plant
Aggregates
12.7
15.1
14.5
14.7
19.1
17.7
19.1
19.3
19.8
17.7
Percent
" of Total
Ash
32.4
35.2
31.3
29.8
32.1
*
29.5
30.9
28.5
29.1
23.5
SOURCE: National Ash Association
                                 1-137

-------
                  Table 1-21
CHEMICAL ANALYSIS  OF  SELECTED BOTTOM ASH
        AND BOILER SLAG SAMPLES
                (Percent)
Type of Ash:
Plant:
Location:
Si02
Al'203
Fe203
CaO
MgO
Na20
K2O
Bottom
Ash
Kanawha
River
Glasgow,
W. Va.
53.6
28.3
5.8
0.4
4.2
1.0
0.3
Bottom Boiler
Ash Slag
Boiler
Slag
Mitchell Rammer Muskingum
Moundsville,
W. Va.
45.9
25.1
14.3
1.4
5.2
0.7
0.3
Captina,
W. Va.
48.9
21.9
14.3
1.4
5.2
0.7
0.1
Beverly,
Ohio
47.1
28.3
10.7
0.4
5.2
0.8
0.4
Boiler
Slag
Willow
Island
St. Marys,
W. Va.
53.6
22.7
10.3
1.4
5.2
1.2
0.1
                      1-138

-------
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/IIC*CJ«tM\ /T*«^»l«\
                                            U,  S,  Standard Sieve Size
Figure 1-21.   Typical particle size distribution  for  selected  bottom ash samples.

-------
          In contrast to bottom ash, boiler slag is predominantly single-
sized in the range of 0.5 to 5.0 mm.  The particles themselves are hard,
usually black (sometimes dark brown) in color, and glass with a smooth
surface texture like crushed glass.  However, if gases are trapped in the
slag as it is tapped from the  furnace, the quenched material will be some-
what vesicular or porous.  Some vesicularility may be beneficial, in that
it improves the surface texture.  Lime injection, used to lower the fusion
temperature of  the coal during burning, markedly increases vesicularity.
Slag from the burning of lignite and sub-bituminous coals also tends to
be more vesicular than that of eastern bituminous coals (Reference 1-145).

          Figure 1-22 shows the  particle size distribution of slag samples
taken from several wet bottom boilers.  This figure shows the more uniform
size grading of boiler slag, compared to that of bottom ash, with most
boiler slag particles being in the minus #4, plus #30 sieve size range.

          Table 1-22 summarizes the results of tests to determine the key
engineering properties of selected bottom ash  and boiler slag samples,
such as void ratio, compaction characteristics, permeability, and angle
of internal friction.   The test results are also compared with the prop-
erties of a standard Ottawa sand.  In general, the properties of the ash
samples are similar to those that are obtained for many sands (Reference
1-155).  Maximum and minimum void ratios were  determined by means of the
relative density test  (ASTM D2049).  The angle of internal friction was
measured by means of the direct shear test   (ASTM D3080).  Copies of each
test method are included in the Appendix of  this report.

          Table 1-23 summarizes the results of standard aggregate tests such
as density  (unit weight), Los Angeles abrasion, and sodium sulfate soundness
on selected bottom  ash and boiler slag samples (Reference 1-155).  The
density test values represent dry rodded weights, taken in accordance with
procedures described in ASTM C29, "Standard  Test Method for Unit Weight and
Voids in Aggregate."  Soundness tests were conducted according to ASTM C-88,
"Standard Test Method for Soundness  of Aggregates by Use of Sodium Sulfate
or Magnesium Sulfate," and abrasion  resistance tests were performed in ac-
cordance with ASTM  C-131, "Standard  Test Method for Resistance to Abrasion
of Small Size  Coarse Aggregate by Use of the Los Angeles Machine."  Copies
of these test methods are also included in the Appendix of this report.

Utilization of Power Plant Aggregates

          TableI-24 summarizes the overall utilization of bottom ash and
boiler slag since 1970.  During this period, the average utilization of
bottom ash has been 25.1 percent, while the  average utilization of boiler
slag has been 49.8  percent.  Most  of the bottom ash and boiler slag that
has been used over  the years has been as a fill material for road and con-
struction sites.  Substantial amounts of each material are also utilized
as anti-skid material  on icy roadways during the winter.  This use consti-
tutes a large market for bottom ash  and boiler slag in some areas like West
Virginia and eastern Ohio.  There  are some power plants that use all or most
of the bottom ash or boiler slag produced at their plant on their own property,
with little or none being available  for use  outside the plant (Reference 1-156),
                                      1-140

-------
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Figure 1-22.  Typical particle  size  distribution for selected boiler slag samples.

-------
Ki
                                            v  Table 1-22

                              SUMMARY OF ENGINEERING  PROPERTIES OF
                          SELECTED BOTTOM ASH  AND BOILER SLAG SAMPLES
                                                           Compaction     Coefficient

Plant



Location


Type
of Ash


Void
Maximum


Ratio
Minimum




Characteristics*
Maximum
Dry
Density
Optimum
Moisture
(percent)
Of
Permeability
(cm.

per sec .

Angle of
Internal
) Friction
(degrees)
(Ibs. per

Port
Martin
Kanawha
River
Mitchell

Rammer

Muskingum

Willow
Island

Maidsville
W.Va.
Glasgow,
W.Va.
Moundsville,
W.Va.
Captina, ,
W.Va.
Beverly,
Ohio
St. Marys,
W.Va.

Bottom Ash

Bottom Ash

Bottom Ash

Boiler Slag

Boiler Slag

Boiler Slag


1.49

1.86

0.91

0.92

1.17

1.12


0.

1.

0.

0.

0.

0.


73

06

49

54

69

69

ft. 3)
85.0

72.6

116.6

102.0

91.1

92.4


24.8

26.2

14.6

13.8

22.0

21.2


2.8 x

5.0 x

9.4 x

6.7 x

4.0 x

2.5 x


10-2

10-3

10-2

10-2

10"2

10-2


40.0

38.0

42.5

41.0

40.0

42.0

     Ottawa  Sand
80    .50
               1.5 x 10"4
N.Ap.   N.Ap.  to 2 x 10-1
29-35
     *  Determined by Standard  Proctor  Compaction  Test  (ASTM D698-66T,  Method C) using only 3/4 inch
       material.
     N.Ap.  denotes  test results  not  applicable.

-------
                           Table 1-23

         STANDARD AGGREGATE TEST PROPERTIES OF SELECTED
               BOTTOM ASH AND BOILER SLAG SAMPLES
Plant
Location
Type of   Sodium
 Ash      Sulfate   Los Angeles  Dry Rodded
          Soundness  Abrasion      Weight
           Loss       Loss
          (percent) (percent)    (Ibs.per ft.3)
Big Sandy   Louisa,
              Ky.
              Bottom Ash
Philip Sporn New Haven,   Bottom Ash
              W.Va.

Ft. Martin  Maidsville,   Bottom Ash
              W.Va.
Kanawha     Glasgow,
River         W.Va.
              Bottom Ash
Mitchell    Moundsville,  Bottom Ash
              W.Va.
Muskingum   Beverly,
             Ohio
              Boiler Slag
Willow      St. Marys,    Boiler Slag
Island       W.Va.
             17


              6


             4-8


             16


             10


              4


             N.A.
  N.A.


  46


•  27-40


  N.A,


  37


  35


  33
 66


 62


71-83


 47


101


 90


 N.A.
ASTM Specification Limits
(Values dependent on use)
                            10
                        40
N.A. denotes value not available.
                                 1-143

-------
                                 Table 1-24

              UTILIZATION OF BOTTOM ASH AND BOILER SLAG
                          (Millions of Tons)
                              Percent                             Percent
Bottom Ash
Year Collected
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
9.9
10.1
10.7
10.8
14.3
13.1
14.3
14.1
14.7
12.5
Bottom Ash
Utilized
1.8
1.6
2.6
2.4
2.9
3.5
4.5
4.6
5.0
' N.A.
Bottom Ash
Utilized
18.6
16.0
24.3
21.9
20.3
26.7
31.5
32.6
34.0
N.A.
Boiler Slag Boiler Slag Boiler Slag
Collected Utilized Utilized
2.8
5.0
3.8
3.9
4.8
4.6
4.8
5.2
5.1
5.2
1.1
3.7
1.3
1.8
2.4
1.8
2.2
3.1
3.0
N.A.
39.1
75.2
35.3
44.3
50.0
40.0
45.8
60.0
58.8
N.A.
SOURCE: National Ash Association

N.A. denotes information not yet  available.
                                      1-144

-------
          There have, however, been numerous successful attempts over the
years to utilize power plant aggregates in some form of highway construc-
tion.  These highway construction uses can be divided into two general
categories:  base course and asphalt paving.  Each of these applications
will be considered separately.

          Power Plant Aggregates in Base Courses.  In discussing applications
of bottom ash and/or boiler slag in highway base courses, the versatility of
these materials will become apparent.  On many projects, they have been blended
together or combined with fly ash and/or other by-products, such as blast fur-
nace or steel mill slag, when used as base course materials.

          The experiences related herein reflect only selected applications
which have  been well documented in the technical literature.  There are pro-
bably numerous other successful projects wherein power plant aggregates have
been used on private property or in the construction of local roads that have
not been documented.

          Utilization of power plant aggregates as a road base material has
been accomplished with both unstabilized and stabilized road courses.  The
majority  of experience with both types of base courses has been, gained in
the state of West Virginia.  Each of these uses will be discussed separately.

               Unstabilized  Bases.  One of the first attempts to utilize
bottom ash in an unstabilized base course, while satisfying a standard high-
way specification, was in the construction of an access road to West Virginia
University's Evansville campus.  Bottom ash from Allegheny Power System's
Fort Martin Station was used without any screening.  This material was able
to meet the specified gradation, abrasion, and  sulfate soundness requirements
of the West Virginia Department of Highways for Class 2 crushed aggregate base
courses, which are in Table 1-25. As shown in this table, the bottom ash was
clearly able to meet the Class 2 base course specification requirements.

          The bottom ash  was placed with a conventional spreader box and
compacted with a 10-ton tandem steel-wheeled roller.  Field densities gen-
erally equalled or exceeded the required 95 percent of laboratory mayimmn
dry density, which was 85.0 pounds per cubic foot.  However, the bottom ash
lost stability when it dried out and it was necessary to keep the material
wet so that equipment could operate on its surface.  Placement of overlying
bituminous concrete binder and surface courses resolved the problem (Reference
1-157).

          Bottom ash was observed to behave in a  similar manner when  used as
the untreated base course for shoulders and lightly traveled access roads as
part of the relocation of West Virginia Route 2 south of Wheeling.  In this
application, bottom ash from the Ohio Power Company's Cardinal Plant in Bril-
liant, Ohio was placed at an average moisture content of 14 percent and com-
pacted with a 30-ton pneumatic roller, followed by a 10-ton steel-wheeled
roller.  This material also became unstable, even though it met gradation
and other quality requirements and had been compacted to densities in ex-
cess of 95 percent of the Standard Proctor value (Reference 1-157).
                                     1-145

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                       Table 1-25

   COMPARISON OF WEST VIRGINIA DEPARTMENT OF HIGHWAYS
    REQUIREMENTS FOR CLASS  2  CRUSHED AGGREGATE BASE
COURSE WITH TYPICAL PROPERTIES OF  FORT MARTIN BOTTOM ASH
                                Percent Finer
Sieve
Size
1 1/2"
3/4"
#4
#40
1200
Los Angeles
Abrasion
Sodium Sulfate
Class 2
Base Course
100
80-100
35-75
10-30
0-10
Less than
50
Less than
12
Fort Martin
Bottom Ash
100
97.0
70.3
23.0
4.5
27-40
4-8
                             1-146

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          In contrast to these two experiences, high compacted densities and
excellent dry stability were achieved on another base course application in
connection with the West  Virginia Route 2 project.  In this case, bottom
ash from American Electric Power Company's Mitchell plant was blended with
blast furnace slag in order to satisfy the gradation requirements of the
West Virginia Department of Highways for Class 1 crushed aggregate base
course.  In Table 1-26, a comparison is made between the Class 1 base course
specification requirements and the properties of an ash-slag blend contain-
ing 70 percent by weight bottom ash  and 30 percent by weight blast furnace
slag.  As shown in this table, the blend of bottom ash and blast furnace
slag was able to satisfy all the requirements for a Class 1 base course.

          The mixture was placed and  compacted in two lifts to a total thick-
ness of 9 inches.  Final compaction was obtained with four to six passes of
a 30-ton pneumatic roller.  The compacted dry density of the blended material
generally exceeded 95 percent of the laboratory maximum dry density value of
105 pounds per cubic foot.  This experience proved that it was possible to
construct a satisfactory base course using untreated bottom ash when using
the proper  gradation and combination of materials (Reference 1-157).

          In an effort to solve the problem of loss of stability upon drying,
a laboratory study was performed at West Virginia University using bottom
ash  and fly ash from the Fort  Martin station.  The findings of this study
showed that the addition of 30 percent fines in the form of fly ash provided
the required binder for achieving higher initial density and acceptable dry
stability.  These results were then verified in the field during the recon-
struction of access roads to the Fort Martin station.  Although these access
roads do not carry high traffic volumes, many heavily loaded vehicles use
these roads.

          Initially, the 70 percent bottom ash-30 percent fly ash combination
was used in the field, but some difficulty was encountered due to excessive
moisture and accompanying loss of stability during compaction.  A combina-
tion of 60 percent bottom ash-40 percent fly ash was then tried and this
proved to be a satisfactory blend for the conditions encountered at the
project site.  The materials were blended in volumetric proportions at the
site by a front-end loader.  Compaction was obtained by 6 to 10 passes using
a vibratory steel-wheeled roller with rubber-tired rear driving wheels.  Dry
density measurements made on the compacted 60-40 blended material showed den-
sities ranging from 96.0 to 105.7 percent of the laboratory standard Proctor
maximum density value of 97.5 pounds per cubic foot.  The average field mois-
ture content was 18.1 percent, which was considerably higher than the labora-
tory optimum moisture content of 10.0 percent.  These exceptionally high
densities for "wet of optimum" moisture conditions are surprising, but the
type and magnitude of field compactive effort are a partial explanation.  In
addition, the loss in strength of the bottom ash-fly ash mixture wet of opti-
mum was found to be very gradual when evaluated in the laboratory (Reference
1-157).
                                     1-147

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                             Table 1-26


       COMPARISON'OF WEST VIRGINIA DEPARTMENT OF HIGHWAYS
     REQUIREMENTS FOR CLASS 1 CRUSHED AGGREGATE BASE COURSE
                   WITH TYPICAL PROPERTIES  OF
        BLENDED MITCHELL BOTTOM ASH  - BLAST FURNACE SLAG
                                    Percent Finer
Sieve
Size
1 1/2"
3/4"
#4
#40
#200
Class 1
Base Course
100
50-90
20-50
5-20
0-7
Bottom Ash
Slag Mixture
100
78.6
40.6
13.1
2.5
Los Angeles
Abrasion
Less than
   50
37'
Sodium Sulfate
Soundness
Less than
   12
10*
*Values given are  for  Mitchell  bottom ash only.
                                  1-148

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          It has been reported that approximately 178,000 tons of bottom ash
from the Fort Martin station have been used to construct a 9 inch thick sub-
base along a 3.5 mile section of Interstate Route 79 near Route 50 in West
Virginia (Reference 1-158).

          It has also been reported that approximately 150,000 tons of boiler
slag from Central Illinois Public Service's Coffeen Station was used as ag-
gregate sub-base material to construct approach pavements for twin bridges
carrying Interstate Route 55 over the tracks of the Chicago, Burlington, and
Quincy railroad near Litchfield, Illinois.  The boiler slag was evaluated by
the Illinois Department of Transportation (IDOT) and approved as a substitute
base material after meeting the gradation requirements in the state specifi-
cations.  Engineers for the project determined that boiler slag was superior
to on-site material for sub-base use on this project (Reference 1-159).

          Current standard highway specifications for base course materials
attempt to control  the quality and performance of the materials by speci-
fying acceptable limits for gradation, soundness, abrasion, and percent fines
(-#200 mesh).  Many sources of bottom ash and boiler slag are able to satisfy
the requirements for soundness, abrasion, and percent fines, but may or may
not be able to meet the gradation requirements.  The applications in West
Virginia that have been discussed in this report, involving the use of bottom
ash as an unstabilized base material, clearly show that other materials can
be blended with bottom ash (or boiler slag) to overcome gradation deficiencies.

          Within the framework of existing specifications, mixtures containing
bottom ash and fly ash with percentages of fines greater than those specified
for base course use would be considered unacceptable.  However, in the case
of bottom ash-fly ash blends, the fines are not only non-plastic, but they
are actually cementitious.  Therefore, in the case of untreated base courses,
strict adherence to standard highway specifications in all instances is not
always reasonable, particularly when considering the unique engineering prop-
erties of power plant aggregates.

               Stabilized Bases.

          1.  Lime-Fly Ash-Aggregate Bases.  The use of fly ash in line-fly
ash-aggregate (LFA)  base course compositions was discussed in great detail
in an earlier portion of this report.  This section of the report discusses
the use of boiler slag as the aggregate portion in LFA base courses.

          Over the years, the leading market for use of LFA base materials
was the Chicago area.  In 1954, when the Chicago Fly Ash Company (now called
American Fly Ash Company) first became interested in lime-fly ash stabili-
zation, it did  so primarily as a means of handling the large tonnages of
boiler slag that had accumulated at  some Commonwealth Edison power plants
in the Chicago area.  The first LFA compositions were mixed in place and
used boiler slag as the aggregate.  In 1955, the first plant-mixed LFA
material also used boiler slag.  These early mixtures contained on the
average 5 percent by weight of hydrated lime, 35 percent fly ash, and 60
percent boiler slag.  Cores were taken from these mixtures at various ages
and ultimate compressove strengths as high as 500 psi were measured (Ref-
erence 1-160).
                                     1-149

-------
          The compressive strength development of a laboratory cured LFA
specimen containing 3.6 percent by weight hydrated lime, 36.4 percent fly
ash, and 60 percent boiler slag was documented by the University  of Il-
linois.  After 28 days at 70°F in the laboratory moist room, the test
specimen achieved a compressive strength of 300 psi.  This specimen con-
tinued to gain in strength, achieving 1,000 psi after 40 days of labora-
tory curing (Reference 1-161).

          One of the producers of LFA base course materials in the Chicago
area (Premix Base Company of Thornton, Illinois) still uses boiler slag as
the aggregate in the pozzolanic aggregate base produced at  their plant.
This company places nearly all of the LFA material from its plant and is
probably the only contractor to use an asphalt paving machine to place LFA
base material.  The contractor prefers the use of boiler slag because of
the black color it imparts to the LFA mix and uses an asphalt paver because
his crew formerly placed asphalt base  and is more familiar  with that type
of equipment (Reference 1-162).

          During 1979, an experimental LFA test section using boiler slag
was placed on Illinois Route 9 near the Coffeen power station in Montgomery
County, Illinois.  The test section was approximately  4 miles long and
used a mix containing 3 percent lime, 27.5 percent fly ash, and 69.5 per-
cent boiler slag.  The fly ash used was obtained from the Kincaid power
station, some 20 miles away, while bottom ash from the Coffeen station
was used in the project.

          Periodically, core samples have been obtained from the  site and
measurements taken of their compressive strength.  More recently available
core  sample data indicate that average compressive strengths of 1,400 psi
have been obtained after approximately one year in service (Reference 1-163)
This type of an installation is an excellent example of the use of power
plant ash by-products on the local level where strict adherence to material
specifications may be occasionally waived in favor of utilizing locally
available materials with a savings in cost.

          2.   Cement-Stabilized Bottom Ash Bases

          The use of cement-stabilized fly ash base course materials was
presented earlier in this report.  This section discusses cement stabili-
zation of bottom ash and/or boiler slag, with and without fly ash, for
use in highway base courses.

          The first known large-scale application of a portland cement
stabilized bottom ash base course in the United States was the relocation
and reconstruction of  West Virginia Route 2 south of Wheeling during the
1971 to 1972 construction seasons.  The cement-treated base course for
                                      1-150

-------
this 4-mile long project was constructed using 46 percent by dry weight 
-------
          a.    Particle  size distribution—The gradation of the
               bottom ash materials was found to be similar to
               that of the local crushed sandstone used in the
               West Virginia Department of Highways cement-treated
               base program from 1970 to 1972.

          b.    Maintenance of traffic—Additional cement must  be
               added as a safety factor to compensate for lack of
               curing time in order to maintain traffic where seven
               days of curing would normally be available.

          c.    Compressive or flexural strength—A sufficient per-
               centage of cement must be used to provide  the minimum
               strength required by West Virginia Department of High-
               ways specifications for cement-treated base to satis-
               factorily distribute anticipated wheel loads over the
               subgrade without failure.

          d.    Durability—Sufficient cement must be used to resist
               deterioration from freezing and thawing or wetting and
               drying.  Based on results of a 1974 field test, 10 per-
               cent by weight or 200 pounds of cement to 1,800 pounds
               of bottom ash was used at optimum moisture content.

          Core specimens were taken from three typical pavement sections after
less than two years in service.  Compressive strengths for these specimens
ranged from 1,270 to 1,425 psi, with an average compressive strength of 1,322
psi.  Not a single base failure was found  during visual inspection of 180
miles of roadway using cement-treated bottom ash in the spring of 1978.

          All of the  secondary  road projects using cement-treated bottom
ash base have been using  a  6-inch  thick base overlain by a 1-inch hot-mix
bituminous concrete surface.  Although  this thickness may not be adequate
from a frost design standpoint,  there have been no reported failures in
any of these pavements after  several winters  in service.

          Design of rigid pavement was  done in  accordance with practices
recommended by  the Portland Cement Association, based on Westergard analysis.
Design of the total flexible  pavement  system  is in accordance with the sta-
bilometer and cohesiometer  procedure practiced  by the California Division of
Highways.  Design  to  resist frost  action  is in  accordance with procedures
developed by the U.S.  Army  Corps of Engineers.

          In West  Virginia, the thickness of  flexible pavement sections is
based on  a gravel  equivalency rather  than on  structural coefficients.  The
cement-treated  bottom ash base has a  gravel equivalent of 1.497, which means
that 1.497 inches  of  gravel is equivalent to  1-inch  of cement-treated bottom
ash in the base course.
                                      1-152

-------
          A cost comparison was made using three equivalent base systems:
crushed aggregate, cement-treated aggregate, and cement-treated bottom
ash.  The costs of each of these systems were computed for a 1-mile length
of roadway 16-feet wide, using a 6-inch thickness of cement-treated bottom
ash and equivalent thicknesses for the other two base systems.

          By assuming construction in the Charleston area, certain cost ele-
ments associated with producing and transporting component materials for
each of the three comparative base systems were developed.  Table 1-27pre-
sents a tabulation of these cost elements for each base system.  The actual
cost comparison of the three base systems is presented in Table 1-28.

          The cost figures in Table 1-28 plainly show that the cost savings
of cement-treated bottom ash on a one mile basis for a 16-foot wide road
is approximately 2 to 1 over cement-treated base and 2.5 to 1 over the
crushed aggregate base.  These savings result from the cost of the aggre-
gate in the other two base systems and the additional quantities required
due to the lower density of the compacted bottom ash in comparison to the
aggregate.

          3.   Bituminous-stabilized Bottom Ash Base

          Some 45 to 50 miles  of light-duty, rural secondary roads  in West
Virginia were reconstructed during the summer of 1972 using bituminous-sta-
bilized power plant aggregates.  These base materials were placed directly
on existing gravel or badly deteriorated chip seal surfaces in single lifts
varying from 2 to 6 inches in thickness.

          The base materials did not receive a surface treatment until the
following construction season.  Bottom ash and boiler slag were used in the
project.  The bottom ash was obtained from the Fort Martin Station and the
boiler slag from the Kammer power plant.

          The dry bottom ash was used without blending with other aggregate.
The  design asphalt content was 7 percent.  Laydown characteristics of the
mix from a spreader box were excellent.   Optimum densities were achieved
with 3 to 4 passes from a pneumatic roller, followed by one or-two passes
from a steel-wheeled roller.

          On projects using boiler slag, it was necessary to blend the ma-
terial with locally available bank run gravel to meet the gradation for
Class 2 crushed aggregate base course (refer to Table 1-25).  A 5 percent
residual asphalt was added to these mixes.  The mixes were pugmilled while
cold at a central mixing plant, stockpiled for 10 days or more,  then cold
laid by paver or spreader box.  Adequate compaction was achieved from sev-
eral passes with a pneumatic roller, followed by a steel-wheeled roller.
                                     1-153

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 II
III
                             Table 1-27

                          COST ELEMENTS

                                OF

                    COMPARATIVE BASE SYSTEMS
       TYPE I OR II COMMERCIAL CRUSHED AGGREGATE

       Purchase Cost
       (Production, Shipping, Stocking)
       Hauling and Placing
         TOTAL

Ohio Limestone
       Sources:  Indiana, Kentucky
                 Ohio River Gravel
                 Weirton and Wheeling Slag
CEMENT-TREATED, LOCALLY-CRUSHED SANDSTONE

Quarrying,. Crushing and Stocking Cost

Cement Cost  (Per Ton of Mix)

Pugmill Mixing Cost

Hauling and Placing
CEMENT-TREATED ASH

Bottom Ash

Stocking Cost

Cement Cost (Per Ton of Mix)

Pugmill Mixing Cost

Hauling and Placing Cost
                                                $ 8.00/Ton


                                                  3.00/Ton
                                                $11.00/Ton
                                                      $ 5.00/Ton

                                                        1.80/Ton

                                                        1.00/Ton

                                                        3.00/Ton
         TOTAL   $10.80/Ton




                 $ 0.50/Ton

                   0.50/Ton

                   4.00/Ton

                   1.00/Ton

                   3.00/Ton
         TOTAL   $ 9.00/Ton
 NOTE:   The  above  figures are based on 1978 costs
                                   1-154

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                              Table 1-28


                          COST COMPARISON

                             FOR  SOME

                         *EQUIVALENT  BASE

                         SYSTEMS-16'  WIDE



    TYPE OF BASE     THICKNESS  TONS/MI.  COST/TON  TOT.  COST/MI.

Crushed Aggregate         8"       3736      $11.00     $41,096.00
(Type I or Type II)
(W. Va. Item 307)

Cement-Treated           6"       2802      $10.80     $30,261.60
Aggregate
(71 Cement)
(W. Va. Item 301)

Cement-Treated           6"       1877      $ 9.00     $16,893.00
Bottom-Ash
(10% Cement)
*Thickness equivalent for comparable wheel load distribution  over
 subgrade (does not include wearing surface).
 NOTE:   The  above figures are based on 1978 costs.
                                  1-155

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          During their first year of service, all mixes provided satisfactory
service with no appreciable rutting or shoving, despite receiving heavy wheel
loads from coal truck traffic in the area (Reference 1-166).  No further in-
formation is available on the performance of these bituminous-stabilized base
course materials.

Assessment of Power Plant Aggregate Use as Base Course Material

          From the foregoing discussion, it is  evident that the use of bottom
ash and boiler slag as a base course material has thus far been limited to only
a very few states.  The results of a questionnaire circulated in April 1980 by
the American Association of State Highway and Transportation Officials (AASHTO)
show that bottom ash and/or boiler slag in lime-fly ash-aggregate (LFA) base
have only been used in six states.  These six states are:

               Idaho                 Oregon
               Illinois              Washington
               Ohio                  West Virginia

          Two other states, North Carolina and Texas, report that they are
evaluating the use of bottom ash and/or boiler slag in LFA base in the labora-
tory.  Two states, Illinois and Ohio, consider utilization of bottom ash or
boiler slag in LFA base courses to be somewhere between limited and routine
field use in their respective states.  The others consider that the use of
bottom ash or boiler slag in LFA base courses in their states is being handled
on a limited field basis.

          All states considered the performance of bottom ash or boiler ash
either as acceptable or good, except for North Carolina, which considered
the performance of these materials in their laboratory tests as marginal.
Both North Carolina and Oregon are uncertain about the future use of bottom
ash or boiler slag in LFA pavements.  All other states plan some further
field use of these materials.

          No mention was made in the questionnaire about the use of bottom
ash or boiler slag in unstabilized, cement-stabilized, or bituminous-sta-
bilized base courses.  None of the respondents to the questionnaire indicated
any such use, although space was provided for describing applications for re-
covered materials other than those specifically noted in the questionnaire.

          In summary, there appears to have been widely scattered examples
of the use of bottom ash and/or boiler slag in highway base course applica-
tions.   Aside from the use of boiler slag in LFA compositions in the Chicago
area, there have been no continuing examples of using these materials in base
course construction.  Several projects in West Virginia, most notably the
Route 2 project, have consumed substantial quantities of power plant aggre-
gates, but utilization has been on a project by project basis, not part of an
ongoing program. Such is also the case with the use of boiler slag as an ag-
gregate base on an interstate project in central Illinois.
                                      1-156

-------
          At present, West Virginia is the only state to specify the use of
bottom ash or boiler slag as an aggregate in cement-treated and cold-mix
bituminous base mixes.  The use of bottom ash or boiler slag in hot mix
bituminous base courses is specified in five states:  Maryland, Nebraska,
Ohio, Texas, and West Virginia.

          As has been noted previously, use of power plant aggregates in
certain types of road base applications may or may not be in accordance
with some state specifications.  Non-conformity with existing material
specification requirements, lack of familiarity with ash materials them-
selves and their unique properties, absence  of a proven performance record,
and the relative unavailability and/or unpredictability of sizable quantities
of bottom ash or boiler slag for a particular use are factors which may ef-
fectively prevent widespread utilization of bottom ash or boiler slag in
highway base courses.

POWER PLANT AGGREGATES IN BITUMINOUS PAVING MIXTURES

          Over the past 25 years, there has been an increase in the use of
power plant aggregates (bottom ash and boiler  slag) in bituminous paving
mixtures.  This section of the report discusses findings from the research
and utilization of these materials.

Research Investigations

          West Virginia University.  A number of bottom ash and boiler slag
materials were evaluated as potential aggregate sources in bituminous paving
mixtures by the Civil Engineering Laboratories of West Virginia University.
These studies  were performed over several years during the early to mid-1970s,
and involved  standard aggregate tests, mix design studies, and evaluation of
field performance in test sections.

          One of the early discoveries in this work was that there are sig-
nificant variations in the engineering properties of power plant aggregates,
and in particular the bottom ashes.  Over a period of several years, Los
Angeles abrasion loss values for one source of West Virginia bottom ash
varied between 27 and 59.  While part of the variation is attributable to
the ash itself, selection of representative samples of any material prior
to testing also plays an important role.

          It was noted during the aggregate testing phase of the program
that friable particles, sometimes referred to as "popcorn," were present in
some bottom ash samples.  These particles are porous, absorb asphalt, and
have poor  crushing resistance.  Specific gravity was recommended as a de-
pendable parameter for identifying the presence of friable particles in
bottom ash, with higher specific gravities indicating a better quality ash
(Reference 1-151).

          Boiler slags, in general, were found to have higher specific
gravity and  lower water absorption values than bottom ashes, probably
because of the smoother texture and glassy nature of the slag particles.
                                     1-157

-------
          In the mixture design studies at West Virginia University, partic-
ular attention was focused on the gradation requirements, asphalt contents,
air voids and durability, and skid resistance characteristics of bituminous
paving mixtures containing bottom ash or boiler slag.

          Because of their well-graded particle size distribution and rough,
gritty surface  texture bottom ash mixes generally had high stabilities.
However, bottom ashes containing appreciable quantities of popcorn-like
friable particles were found to be highly absorptive to asphalt and have
high air voids contents.  In general, bottom ash tends to have a higher
asphalt demand than  natural aggregate.  The rough texture of the bottom
ash contributes to high air voids, particularly when the Marshall drop ham-
mer method of compaction is used.

          The kneading compactor more closely approximates field compaction
because of its shearing or kneading action and, therefore, was considered to
provide more realistic asphalt content and air voids values.   In fact, mix-
tures considered unacceptable when evaluated by normal Marsahll compaction
were found to be adequate when compacted with the kneading compactor.

          A description of the kneading compactor and procedures employed for
preparation of samples using this apparatus are given in ASTM D1561, "Pre-
paration of Test Specimens of Bituminous Mixtures by Means of the California
Kneading Compactor."  This test method may be found in the Appendix of this
report.

          The uniform particle sizing and smooth surface texture commonly as-
sociated with most boiler slags necessitates that these materials be blended
with other aggregates for use in asphaltic mixtures. The type of aggregate
used for blending and the relative proportions of the aggregate and the
boiler slag were found to significantly influence mixture properties.  For
a given compactive effort,  Marshall stability and flow values generally in-
crease with decreasing percentages of boiler slag.  Higher quality mixes
resulted from the blending of crushed limestone having angular particles
with a rough surface texture than from blending with rounded siliceous
aggregates.

          The effect of the compaction method on mixture properties was also
quite pronounced with the blended mixtures containing boiler slag.  Again,
kneading compaction was found to improve stability and flow characteristics
compared to Marshall drop hammer compaction.

          Comparative Marshall test data on bituminous mixes containing
bottom ash and boiler slag, prepared using either the Marshall drop hammer
or  the kneading compactor, are given in Table 1-29.  From the data in this
table, it is evident that greatly improved Marshall stability values result
from sample preparation using the kneading compactor.  These data also show
that the best boiler slag asphalt mixtures are obtained when blending the
boiler slag with a rough textured aggregate in which the percentage of the
boiler slag is limited  to 50 percent or less.
                                      1-158

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                                             Table 1-29
                                 t

                          MARSHALL TEST DATA FOR POWER PLANT AGGREGATE
                         PREPARED BY DROP HAMMER OR KNEADING COMPACTOR
                                                                             Marshall Test Values*
K
Ash Type of
Source Ash
Fort Martin Bottom Ash

Kammer Boiler Slag


Kammer Boiler Slag

Willow Island Boiler Slag

Aggregate
Blend
100%
100%
60%
40%
50%
50%
40%
60%
65%
35%
48%
52%
50%
50%
50%
Fort Martin
Fort Martin
Kammer
Limestone
Kammer
Limestone
Kanuner
Limestone
Kammer
Limestone
Kanuner
Limestone
Willow Island
Limestone
Willow Island
Compaction
Method
Drop Hammer
Kneading
Drop Hammer
Drop Hammer
Drop Hammer
Kneading
Kneading
Drop Hammer
4
Drop Hammer
Stability
(Ibs.)
925
1320
275
335
380
1075
1452
420
105
Flow
(.01 in.)
7
6.5
7.5
7
7
15
13.5
6.5
6
                                     50% River Sand
     Willow Island   Boiler Slag


     *Marshall test values given only at optimum asphalt content.
50% Willow Island   Kneading
50% Limestone
773
10

-------
          Based on Che results of these laboratory tests, it was concluded
that:

          1.   Bottom ashes are exceedingly stable and can
               tolerate large variations in gradation and
               asphalt content without great loss of sta-
               bility.  However, their use in bituminous
               mixes is more suited toward base  courses
               where gradation requirements are not as
               severe as for wearing surfaces.  Prior to
               use, pyrite particles must be separated
               from the ash.

          2.   There is no technical reason why boiler slag
               cannot be used in asphaltic mixtures.  As a
               rule of thumb, mixture stability will suffer
               if the percentage of boiler slag is in excess
               of 50 percent.  Optimum skid resistance is
               best achieved in open graded sand mixes where
               boiler slag is the top aggregate.  Boiler slag
               does not improve skid resistance in coarse
               graded mixtures if the coarse aggregate is
               polish susceptible (Reference 1-157).

          Ohio State University.  In 1976,  the Federal Highway Administra-
tion sponsored a laboratory research study to investigate the characteris-
tics of power plant aggregates and to evaluate their performance in bitum-
inous paving mixtures. The work was performed over a two year period at the
Ohio State University Department of Civil Engineering.

          A total of 10,000 pounds of ash were collected in the form of 32
different bottom ash and boiler slag samples from 21 power companies in 14
states.  Consideration was given to plant type, ash type,source of coal, and
tonnage of ash produced in the selection of these samples.  Twenty of the
samples were bottom ash.  Samples were obtained from plants burning bituminous,
sub-bituminous, and lignite coals.

               Material Characterization

               Gradation.  The physical and engineering properties of these
samples were determined in the laboratory by means of standard testing pro-
cedures used to evaluate conventional aggregate materials.  Comparing the
gradation of these samples to state specifications for aggregate in base,
sub-base, and wearing surface mixtures, it was found that most ashes tested
could meet specification requirements, although some samples had to be blended,
either with coarser bottom ashes or conventional aggregates in order to meet
specification limits.
                                      1-160

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          Los Angeles Abrasion and Sodium Sulfate Soundness.  Only two of
the samples tested were unable to meet Los Angeles abrasion test require-
ments  (ASTM C131).  The applicability of this test procedure to evaluation
of bottom ash samples is questionable because, due to the gradation of bot-
tom ash and its relatively high percentage of fines (passing #8 sieve),
only a small portion of most bottom  ash samples would fall within one of
the four specified gradations for the test.  Consequently, less  than 20
percent of each sample was being tested and the test results are not really
representative of the abrasion potential of the total sample.

          All but one of the ash samples tested met ASTM and state trans-
portation department specifications for sodium sulfate soundness (ASTM CSS).
However, the applicability of this test is also subject to question.  For
bottom ash samples, the porosity of these materials may prevent the buildup
of internal stresses, as expected in the testing procedure.  The opposite
may be true  for boiler slag samples, in which stresses developed during
the quenching process can result in formation of internal fracture planes.
Thermal shock and energy release during soundness testing of boiler slags
could be misinterpreted as high soundness loss due to the expansive forces
of sodium sulfate.

          Although these two widely-accepted quality control tests are nor-
mally required by transportation agencies for material acceptance, their
applicability to the testing of bottom ash and boiler slag is uncertain
because they do not take into account the rather distinctive properties
of these materials.

          Specific Gravity and Absorption.  Standard ASTM test methods were
used for  determining the  specific gravity and absorption of coarse aggre-
gates  (ASTM C127) and fine aggregates (ASTM C128).   Copies of each test
method are included in the Appendix.  The apparent specific gravity of the
bottom ash samples ranged from 2.08 to 2.49 with an average  of 2.35.   Vari-
ations in specific gravity values are related to differences in ferric oxide
contents.  Bottom ash absorption values varied from 0.4 to 8.0 percent by
weight, with greater absorption values for the coarse fraction than the fine
fraction.

          The apparent specific gravity of the boiler slag samples ranged
from 2.60 to 2.86 with an average of 2.75.  This is considerably higher
than the specific gravity of the bottom ash samples.  The absorption values
for the boiler slag samples varied from 0.2 to 2.18 percent by weight, sig-
nificantly lower than the bottom ash samples because of the glassy texture
of the boiler slag.

          In the sense that most bottom ash and boiler slag samples can meet
conventional material specifications, they can be said to compare favorably
with conventional aggregates.  However,  one of  the main questions regarding
testing of power plant aggregates is whether tests designed for conventional
aggregates are truly applicable for evaluation of non-conventional materials
(Reference 1-2).
                                     1-161

-------
               Bottom Ash—Bituminous Mixtures.  Based on results of the
material characterization tests, certain bottom ashes showed greater po-
tential than others for use as aggregate in bituminous paving mixtures.
The boiler slags evaluated in the program were considered less versatile
and best suited to limited use, such as in granular bases.  Therefore,
only selected bottom ash samples were further tested as bituminous aggre-
gate in this program.

          Five bottom ash samples were tested using the Marshall mix design
method (ASTM D1559).  Three of the bottom ash samples were also prepared by
kneading compaction.  For comparative purposes, a mixture containing a blend
of limestone and sand aggregate was also tested.  Results of these tests are
summarized in Table 1-30.  These results do show that samples prepared by
kneading compaction have higher stabilities and lower optimum asphalt con-
tents than drop hammer prepared specimens  (Reference 1-3).

          But the data also point out that optimum asphalt contents for bottom
ash  mixes are much higher than for mixes with conventional aggregates, as are
the air voids values.  These high asphalt demands, caused by the porous nature
of the bottom ash, are an economic concern.  It was, therefore, decided to in-
vestigate mixtures in which bottom ash was blended with conventional aggregates,

               Bottom Ash-Aggregate-Bituminous  Mixtures.  In this phase of
the program, two of the bottom ash samples (Mitchell and Rockdale) were tested
by the Marshall method in varying combinations with crushed gravel and sand
in mixes designed to meet state specifications for base course and wearing
surface mixtures.  The Mitchell bottom ash sample was used in both base and
surface mixtures at ash contents of 0, 30, 50, 70, and 100 percent, in com-
bination with the sand and gravel aggregate.  The Rockdale bottom ash sample
was used only in a surface coarse mix at ash contents of 40, 60, and 100 per-
cent, also with sand and gravel aggregate.

          Table 1-31 summarizes the mixture designations, asphalt contents,
and bottom ash contents of these mixtures.

          Figure 1-23 shows the Marshall curves for the Mitchell surface course
mixes.  The relationship between ash content and Marshall properties for these
mixes is shown in Figure 1-24. As shown in  this figure, stability increased
with initial introduction of the bottom ash into the mixture up to an ash
content of about 50 percent, then a reduction in stabilities with further ad-
ditions of ash.

          Figure 1-25 shows the Marshall curves for the Rockdale surface course
mixes.  The relationship between the ash content and Marshall properties for
these mixes is shown in Figure 1-26. In this figure, a decrease in stability
was noted up to 60 percent ash, then a slight increase in stability was ob-
served to 100 percent ash.
                                      1-162

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                TABLE   1-30

   COMPARISON OF MARSHALL  TEST RESULTS
FOR SELECTED BOTTOM ASH SAMPLES PREPARED
  BY DROP HAMMER OR KNEADING COMPACTOR
Drop Hammer Compaction Test Results Kneading Compaction Test Results
Optimum Optimum
Asphalt Marshall Marshall Percent Asphalt
Sample Content Stability Flow Air Content
Description Source (percent) (Ibs.) (.01 in) Voids (percent)
Conventional Sand and
Aggregate Gravel 7.5 1320 8 2
Bottom Ash Mitchell
Moundsville, 14 1540 98 10
M W. Va.
L
^^
S Bottom Ash Stanton
Stanton, Md. 19 1800 16 6 18
Bottom Ash Choi la
Joseph City, 17 1600 12.5 8
Arizona
Bottom Ash Mohave
Laughlin, Nev. 29 1340 16 6 23
Bottom Ash Alcoa
Rockdale, Tex. 12 850 13 6
Marshall Marshall Percent
Stability Flow Air
(Ibs.) (.01 in) Voids

_

1960 10 10



2250 10 8

_ _ _


1700 11 5

- _

-------
                           TABLE  1-31


 DIFFERENT TYPES OF MIXES AND THE OPTIMUM ASPHALT CONTENT OF
                          EACH MDC
Mix
Type
5-1
s-n
s-m
5- IV
5-V
5-A
5-B
5-C
5-D
5-IA
25-1
25-H
25-m
Composition
100% B. Ash (Mitchell Plant)
70% B.Ash + 30% N.Sandfc Gravel
50% B. Ash + 50% N. Sand&Gravel
30% B. Ash + 70% N. Sand&Gravel
100% N. Sand&Gravel
100% B.Ash (Mitchell Plant)
70% B.Ash + 30% N. Sand&Gravel
50% B.Ash + 50% N. Sand&Gravel
30% B. Ash + 70% N. Sand&Gravel
100%B.Ash (Mitchell Plant)
100% B.Ash (Rockdale, Texas)
60% B. Ash •*• 40% N. Gravel f8
40% B. Ash -i- 60% N. Gravel #8
Gradation
ODOT
404*
404
404
404
404
301**
301
301
301
404
As is
404
404
Asphalt
85/100
85/100
85/100
85/100
85/100
85/100
85/100
85/100
85/100
60/70
85/100
85/100
85/100
Opt.
AC-%
14
12
10
8.5
6.5
11
9
7
6
14
12
10
10
 * ODOT Item Designation for Surface Course Mixtures
** ODOT Item Designation for Base Course Mixtures
                                 1-164

-------
8    10     12     14
  PERCENT  ASPHALT
                                      >
                                                 8    10    12     14
                                                 PERCENT ASPHALT
         8     10     12    14
           PERCENT ASPHALT
                                       8     10     12    14
                                       PERCENT ASPHALT
        B    10    na    14
         PERCENT ASPHALT
Figure 1-23.   Marshall Curves for Mitchell Plant Surface Course Mixtures
              ( O 5-1, & 5-n, O 5-m, 0 S-IV and A 5-V)
                                 1-165

-------
                                           o  no
           PERCENT
                            so
              100
OF BOTTOM ASH
  40    60    80
PERCENT OF BOTTOM ASH
           20     40   60     80    100
            PERCENT OF BOTTOM ASH
                                40    60    80    100
                             PERCENT OF BOTTOM ASH
     o
     o
     1
     fc.
                        so
                      «G

                      >ao


                        70
          SO    1O    BO   SO   TOO
            PERCENT OF BOTTOM ASH
                                4O    BO   BO    TOO
                              PERCENT OF BOTTOM ASH
Figure 1-24. Relationship between Ash Content and Marshall Properties, Mitchell Plant
                  Surface Course Mixtures
                                       1-166

-------
  — ICO
  8.

  H
  £ 130
  H
  2
  D ISO
              !
             ,o
             6      8     10    12
              PERCENT ASPHALT
                                                     6     8      10    12
                                                      PERCENT ASPHALT
5 S4OO
  EOOO —
«
E-
  1000
             6     8     10    12
             PERCENT ASPHALT
                                            SB
                                         1"
                                            SO
                                                   •6,

                                                          8    10    12
                                                    PERCENT ASPHALT
             B     a    ia    is
             PERCENT ASPHALT
                                                   s    a    10    is
                                                   PERCENT ASPHALT
    Figure 1-25.     Marshall Curves for Rockdale Ash Surface Course Mixtures
                   ( O 25-1, O 25-H, & 25-m and 0 5-V)
                                     1-167

-------
                                            no
          20    40     60
           PERCENT ASH'
80
20    4Q    6TT
 PERCENT  ASH
          20    40     60
           PERCENT ASH
20    40
PERCENT
                                          SO
o
o
                                           9O
            I
            {=,
                                           SO
         SO    4O   BO
           PERCENT ASH
so
                      SO    4O    BO
                        PERCENT  ASH-
  Figure 1-26.  Relationship.between Ash Content and Marshall Properties,
                Rockdale Ash Surface Course Mixtures
                                      1-168

-------
          For both the Mitchell and Rockdale surface course mixes, increas-
ing ash contents resulted in sharp decreases in mix densities and an in-
crease  in optimum asphalt content and VMA (voids in mineral aggregate)
values.

          Figure 1-27 shows the Marshall curves for the Mitchell base  course
mix.  The relationship between ash content and Marshall properties for these
mixes is shown in Figure 1-28.

          The same general trends observed in the surface course mixes were
also noted in the Mitchell base course samples.  The use of bottom ash in
base course mixes yielded optimum asphalt contents two to three percent less
than for comparable ash contents in Mitchell surface course mixtures.

          The results of immersion-compression tests (ASTM D1075) indicate
that bituminous mixtures using bottom ash are not particularly susceptible
to water damage.  In fact, mixture stabilities actually increased after Im-
mersion, contrary to what would ordinarily be expected in conventional pav-
ing mixtures.  If the tendency to develop higher stability after saturation
is a material property peculiar to bottom ashes, which was not identified in
standard quality control testing, this characteristic could be of benefit in
designing pavements for areas subjected to high rainfall or multiple cycles
of freezing and thawing.

          The principal conclusions of this study were:

          1.   Bottom ash is basically suitable for use in
               bituminous base course and wearing surface
               applications.  Because of widely varying ash
               properties, materials from different sources
               must be carefully tested on an individual
               basis prior to their acceptance for such use.

          2.   The properties and performance of bituminous
               mixtures containing bottom ash depend on the
               ash content.  Increasing ash content results
               in a higher optimum asphalt content, increased
               voids, and lower mix density.   Marshall sta-
               bility tends  to decrease with initial intro-
               duction of bottom ash, up to 30 percent  ash
               content.  Beyond that level, depending on the
               individual bottom ash, stability and other
               properties are relatively insensitive to ash
               content.

          3.   When used in bituminous mixtures, bottom ash
               materials apparently exhibit unusual behavior
               in the presence of water.  Unlike conventional
               paving mixtures, which suffer loss of strength
               and durability as a result of saturation, bot-
               tom ash paving mixtures appear to increase in
               strength following sample saturation (Reference
               1-3).
                                     1-169

-------
5-A -O  , 5-B
                        ,  5-c -D   , 5-0 - O
o
o.
  14O
  13O
z
D
  ISO
           PERCENT ASPHALT
                                     IB
                                        W
                                     10
                                            6      8    . 10    12

                                              PERCENT ASPHALT
           68      10    12

             PERCENT ASPHALT
                                          3O



                                        S
                                        >as
                                                          s/-
                                            68     10    12

                                             PERCENT ASPHALT
          6     8    1O   12

          PERCENT ASPHALT
                                            B     B     1O    IS

                                             PERCENT ASPHALT
    Figure 1-27.
               Marshall Curves for Mitchell Plant Base Course Mixtures
                                 1-170

-------
            20    40    60    80
         PERCENT OF BOTTOM ASH
                                              20    40    60     80
                                            PERCENT OF BOTTOM ASH
Saaoo —
            20    40    60    80
         PERCENT OF BOTTOM ASH
                                              20    40
                                           PERCENT OF BO
>TTOM!?SH
   JIB

   o
   o
           2Q   40   6O   30

         PERCENT OF BOTTOM ASH
                                              SO   4Q   6O   BO
                                           PERCENT OF BOTTOM ASH
Figure 1-28.
                 Relationship Between Ash Content and Marshall Properties,
                 Mitchell Plant Base Course Mix
                                     1-171

-------
Use of Power Plant Aggregates in Bituminous Paving

          There are numerous examples of the use of power plant aggregates in
bituminous paving projects.  Most of these, however, involve the use of boiler
slag.  Despite the favorable test results on bottom ash mixtures at Ohio State
University, there has been no known use of bottom ash in hot-mix asphalt pave-
ment  applications.  The most extensive use of bottom ash in bituminous
paving has been in West Virginia where, since 1972, bottom ash has been cold
mixed with 6 to  7 percent by weight of emulsified asphalt and used in the pav-
ing of secondary "Farm to Market" roads.  In some cases, the bottom ash is also
blended  with boiler slag.  Both cationic and anionic asphalt has been used in
the preparation of these cold mixes, but asphalt suppliers are of the firm opin-
ion that better coverage and performance can be obtained by using a cationic
blend.

          More than 200 miles of low-volume traffic roads in the northern part
of the state have been improved with these cold mix compositions,  which are
referred to as  "Asphalt."  A specification for "Asphalt" is included in the
Appendix of this report.  Similar applications have also been made in eastern
Ohio.

          Besides being a relatively inexpensive material, one of the biggest
advantages of "Asphalt" is its simplicity.  First, the bottom ash is loaded
into the hopper of a portable continuous pugmill, frequently located on the
power plant site.  It is then mixed with a metered amount of asphalt and
either loaded directly into haul trucks or stockpiled for future use.  There
is no need for hot bins or dryers.  "Asphalt" can be stockpiled for several
weeks and still be suitable for placing on the road.

          Because the mix can be stockpiled, crews from the Highway Depart-
ment are  afforded a great deal of flexibility.  Those who perform the lay-
down work are not dependent on plant production for an uninterrupted flow of
material to the job.  Furthermore, "Asphalt" can be installed on the roadway
without resorting to fancy techniques or sophisticated machinery.  In West
Virginia, "Asphalt" is usually placed by state maintenance crews using state
equipment.

          The ™i'x is hauled to the jobsite and placed with conventional
spreading equipment.  The best compaction results have been achieved with
a single 10-ton tandem steel-wheeled roller following closely behind the
spreader.  Once on the road, the mix requires about 10 days to fully cure.
This curing period depends on the season and length of time the mix was in
a stockpile  (Reference 1-160).

          State road crews have been placing "Asphalt" at about half the
cost of conventional asphalt concrete.  And in most applications, the ash
will go about one-third farther than comparable materials due to its fav-
orable  weight-volume ratio.  This material, because it is not a. hot-mix
                                     1-172

-------
composition, can  be placed in cold or inclement weather.  The bottom ash
can also be blended with sand, gravel, limestone, or blast furnace slag to
meet any desired gradation.  Aside from occasional problems due to base
failures, "Ashphalt" has provided excellent service over the years.  It
can even be used as a patching  material, and frequently is, on some of
the more heavily-traveled primary roads (Reference  1-161).

          Boiler slag has been used to a much greater extent in bituminous
paving than bottom ash.  Boiler slag has been used frequently in wearing
surface mixtures because of the hardness of its particles  (average of 7 on
the Mohs hardness scale), its affinity for asphalt, and its dust-free sur-
face, which aids in asphalt adhesion and resists stripping.  Use of boiler
slag helps eliminate fat spots in paving mixes, and subsequent asphalt bleed-
ing that causes slippery pavements.  The material is relatively abrasion
resistant, enabling it to provide desirable skid resistant characteristics
(Reference 1-162).

          Another of the properties of boiler slag which enhances its value
as an aggregate in bituminous paving is its permanent black color, which is
not affected by sun or weather.  This enables the surface of a. blacktop road-
way to retain much of its original dark appearance, which is helpful for
contrasting with pavement markings and is particularly advantageous for
night driving.  It also helps roads and streets surfaced with boiler slag
dry faster after rain and snow because the black color attracts the sun's
heat (Reference 1-163).

          Boiler slag was first used in asphalt paving on an experimental
basis many years ago in Hammond, Indiana, where it was blended with con-
ventional aggregate to help solve the problem of aggregate polishing.  The
early success of that and several other wearing surface demonstration pro-
jects in Indiana led to its acceptance and use in that state and several
others, including Ohio, Michigan, Missouri, and West Virginia.  In addition,
boiler slag has been used in a number  of cities, such as Cincinnati and
Columbus, Ohio and Tampa, Florida (Reference 1-163).

          In West Virginia, boiler slag has been blended with graded river
sand for resurfacing and deslicking applications, especially where thin
overlays are used.  A considerable amount of this resurfacing has been done
in the northern panhandle using a West Virginia Department of Highways
Wearing Course III mixture composed of 50 percent by weight boiler slag,
39 percent river sand, 3 percent fly ash, and 8 percent asphalt cement.
The mixture is hot mixed and laid as a conventional sand mix in depths
from 1/2 to  2 inches.  Some sections have been in service for over 10
years with little change in  surface texture under heavy truck traffic
and only minor tendency to rut or shove, if at all.
                                    1-173

-------
          A typical example of the use of boiler slag in a deslicking appli-
cation was a short section of U.S. Route 119 near Morgantown, which was over-
laid in 1969.  Accidents on this portion of the road were reduced by about
50 percent in the year following completion of the project.  Table I-31A com-
pares the gradation and asphalt contents of the northern panhandle and Route
119 overlays with the  requirements of the  Department of Highways Wearing
Course III mixtures.  A comparison of these mixture properties with the
Class III specification limits shows that these mixes meet applicable wear-
ing surface requirements.  It should be noted that in these applications,
boiler slag is considered an economical replacement for locally scarce
natural aggregates and is not being promoted as a skid-resistant aggregate
(Reference 1-164).

          Some 10,000 tons of boiler slag were used to construct the wearing
surface and shoulders of a portion of Interstate Route 94 near the Detroit
Airport.   This section of roadway is reportedly still in good condition af-
ter more than six years in service (Reference  1-165).

          Boiler slag from the burning of lignite coal has been used on
streets in several parts of Texas for resurfacing work.  The mixes have
used a blend of 75 percent by weight lignite boiler slag and 25 percent
limestone screenings, with an asphalt content of 6 to 7 percent by weight
of aggregate.  Retained strengths of 90 percent were observed after immer-
sion-compression testing.  These pavements have held up well with no signs
of shoving or raveling, despite heavy truck traffic, while maintaining their
brilliant, black texture, non-skid properties, and smooth, quiet riding
qualities (Reference 1-166).

          Boiler slag has also been used successfully as a seal coat aggre-
gate for bituminous surface treatments in a number of states.  The Minne-
sota Department of Transportation reports that boiler slag seal coat sec-
tions have performed in a highly acceptable manner, although these sections
set up more slowly than sections using normal aggregate.  Once the sealed
sections were  swept, this problem was solved.  The only problems thus far
with boiler slag  seal coats have been some wearing at intersections where
high volumes of turning vehicles are involved (Reference 1-167).

          Boiler slag is also used as a seal coat aggregate in local road
construction. Cost savings of over $2,000 per mile using boiler slag as a
chip seal material have been documented by the Montgomery County Highway
Department in central Illinois.  In addition, county road crews are able
to place 5 miles of seal coat per 8-hour day, compared to 4 miles per day
using conventional limestone chips (Reference 1-168).

          Table I- 32 presents a per mile cost comparison between regular
crushed limestone chips and boiler slag for a 22-foot wide pavement.   Ac-
cording to these  figures, the cost per mile for using limestone chips is
practically twice as high as the cost per mile for using boiler slag (Ref-
erence 1-168).
                                     1-174

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                             Table I-31A


              COMPARISON  OF BOILER SLAG-AGGREGATE
           WEARING  SURFACE  MIXTURES TO WEST VIRGINIA
     DEPARTMENT OF  HIGHWAYS WEARING COURSE III REQUIREMENTS
Sieve
Size
3/8"
#4
#8
#16
#50
#200

Specification
Limits
100
90-100
60-90
40-65
10-30
3-15
Percent Passing
Northern
Panhandle
Overlays
100
95
80
52
14
6

Route 119
Overlay
100
95
85
48
16
6
Asphalt
Content
(percent)
5-11
                                 1-175

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                                     Table 1-32                           Page 1 of  2
                                  COST COMPARISON
                        WET  BOTTOM BOILER SLAG SEAL COATS
                                       V. S.
                         5/8" CRUSHED LIME STONE SEAL COATS

(A)   5/8 " Crushed Lime  Stone Chips, single Seal Coat    (C.L.S.C.)

     (1)  Surface Width   -   22'  0"
          MC-800 or  3000 Asphalt at 0.25 gallons per square yard
          5/8" chips at  25 pounds per square yard
          8-2 1/2  tons dump trucks & drivers
          1 - 955 "Cat"  track type end loader & operator
          1 - Etnyre Chip Spreader & two operators
          1 - Gallion Rubber tired Roller & operator
          2 - Pick-up trucks & 2 drivers

          Average production of  A miles per 8 hr. day.

     (2)  Material Quantities and Cost;

          MC-800 or  3000    3227 gals, per mile at 0.82 per gal. spread on roads
             0.25 x  22 x 5280 x  A - 12,907 x 0.82             -     $10,583.7A
                          9

         C.L.S.C.            161 tons per mile at 7.00 per ton FOB Stockpile
               25 x  22 x 5280 x  1	x A   -  645 tons @ 7.00  -     A,515.00
                         9      2000

     (3)  Equipment  Costs;

          8 dump trucks  x $13.30 x 8          -  851.20
          1 "Cat"        x 30.60 x 8          -  2AA.80
          1 Etnyre       x 30.00 x 8          -  240.00
          1 Roller       x 13.18 x 8          -  105.AA
          2 Pick-upa    x   3.1A x 8          -   50.2A
                                                                     1,491.68

     (A)  Labor Coats;   S6.AO per hour

          1A x 8 x 6.A0           -                             -       716.80
                                             Total Cost        -    17,307.22
         Cost per mile     -   17,307.22                       -     A,326.81
                                   A
                                            1-176

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                                           1-32 (continued)
                                  COST COMPARISON                      page  2  of 2
                        WET  BOTTOM BOILER SLAG SEAL COATS
                                     v.s.
                        5/8" CRUSHED LIME STONE SEAL COATS

(B)    VET' BOTTOM BOILER SLAG SINGLE SEAL COAT     (W.B.B.S.)

      (1)  Surface Width  - 22' 0"
          RC-800 or 3000 Asphalt At 0.15 gallon per square yard
          Wet  Botton Boiler Slag at 15 pounda per square yard
          8-2 1/2 ton* dump trucks & drivers
          1 - 955 "Cat" tracktype end loader & operator
          1 - Etnyre Chip Spreader & two operators
          1 - Gallion Rubber tired Roller & operator
          2 - Pick-up trucks & 2 drivers

          Average production of 5 miles per 8 hr.  day

      (2)  Material Quantities and Cost;

          RC-800 or 3000   1936 gals,  per mile at  0.83 per Gal. spread on roads
             0.15 x 22 x 5280 x 5 - 9680 x 0.83           •     $8-,034.40
                           9
          W.B.B.S.           97 tons per nile at  2.00 per ton  FOB Stockpile
               15 x 22 x 5280 x _1	x 5 - 484 Tons at 2.00 -     968.00
                          9     2000
      (3)  Equipment Costs;

          8 duap trucks x $13.30 x 8         -  851.20
          1 "Cat"       x  30.60 x 8         -  244.80
          1 Etnyre      x  30.00 x 8         -  240.00
          1 Roller      x  13.18 x 8         - 105.44
          2 Pick-ups    x   3.14 x 8         -  50.24
                                                            -   1,491.68

      (4)  Labor Coats:   $6.40 per hour

          14 x 8 x 6.40                                     -     716.80

                                         Total  Coat          •  11.210.88


          Cost per Bile -   11.210.88                        -   2.242.18
                              5
                                            1-177

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          Not only does the boiler slag provide better coverage per mile
than the limestone chips (97 tons vs. 161 tons), but the boiler slag seal
coat retains its black color, while the surface of the stone chip seal
gradually acquires a faded, gray appearance.  Even after an up-close vis-
ual inspection of a boiler slag seal coat pavement, it is difficult to tell
that it was not originally placed as a conventional hot-mix asphaltic con-
crete pavement.

          Skid tests on a boiler slag seal coat section north of Hillsboro,
Illinois were performed in 1976 by the Illinois Department of Transportation,
using a. locked-wheel skid trailer run at 40 miles per hour.  Friction numbers
for the north-bound lane ranged from 46 to 64, with an average value of 56.
Friction numbers for the south-bound lane ranged from 43 to 57, with an av-
erage value of 50 (Reference 1-12).   Generally, friction numbers in excess
of 40 are desired in terms of skid resistance, although in the state of Il-
linois a value of 53 is considered acceptable.

          Assessment of Power Plant Aggregate Use in Bituminous Paving.  Ac-
cording to the results of an  AASHTO questionnaire, a total of 23 states have
reported some sort of field use of power plant aggregate in asphalt paving.
These states are:

          Alabama          Indiana*          New Jersey
          Arizona          Iowa              New York
          Arkansas         Kansas            Ohio*
          Connecticut      Kentucky          Oklahoma
          Florida          Michigan          Pennsylvania
          Georgia          Minnesota         Texas*
          Idaho            Missouri*         West Virginia*
          Illinois         Nebraska*

* States currently including power plant aggregates in bituminous material
  specifications.

          Interestingly, two of these states  (Connecticut and Idaho) do not
have any coal-fired power plants.  It is possible that the term "bottom ash"
or  "boiler slag" may be mistakenly used in referring to another material,
such as phosphate furnace slag in one or more of these states.  Of the 23
states using power plant ash, five  (Alabama, Georgia, Illinois, Kentucky,
and Missouri) report routine use.  The others report limited field use or
field experimentation.

          Only one state  (New Jersey) considers the performance of power plant
aggregate in asphalt paving to have been poor.  The reason given for this as-
sessment was poor skid resistance  (Reference 1-169).  Four other states (Ari-
zona, Connecticut, Ohio, and Oklahoma) reported marginal performance.  Ken-
tucky considers  the performance of bottom ash and/or boiler  slag as aggre-
gate in bituminous wearing surfaces  to have been excellent because the crushed
material had "sharp edges and provided good skid resistance" (Reverence 1-170),
The remaining  states all reported  either acceptable or good performance.
                                     1-178

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          New Jersey is the only state which does not intend to make any
further use of power plant aggregates in the future.  Arizona and Oklahoma
are uncertain about further use of these materials.  The other 20 states
all plan to make additional use of either bottom ash or boiler slag in
asphalt paving.

          Of the 23 states indicating some level of field use, only six
have incorporated bottom ash and/or boiler slag into the specifications
as an aggregate for use  in bituminous paving mixtures.  These six states
are Indiana, Missouri, Nebraska, Ohio, Texas, and West Virginia.

          In summary, there have been 23 states which have at one time or
another made use of power plant aggregates in asphalt paving.  Only one of
these states does not plan to make further use of  these materials in this
manner.  Over the years, boiler slag has been widely used as  a  partial
aggregate replacement in wearing surface mixtures and thin overlays, as
well as in seal coat applications, in many sections  of the country.  Dur-
ing this time, it has acquired a good performance record as a. durable,
wear-resistant material with a number of unique properties.  Except for
seal coat applications, boiler slag must be blended with other aggregates
to meet gradation specifications and attain sufficient mix stability.

          Bottom ash, on the other hand, does not appear to have been uti-
lized to any great extent, if at all, in hot-mix asphalt paving.  However,
it does have a good performance record as an aggregate in cold-mix, cold-
laid emulsified asphalt paving mixes on secondary roads in West Virginia
and eastern Ohio.

          Based on available laboratory data and documented field performance,
it is evident that power plant aggregates can be successfully used in bitumi-
nous mixtures.  Before this can be done on a. routine basis, however, additional
effort is needed to develop test methods and specifications that are more ap-
propriate for use in evaluating power plant aggregates, particularly bottom
ashes.

          In some cases, current test methods and specifications are too
restrictive and exclude acceptable materials.  In other instances, the
standards may not be sufficiently discriminating and allow materials that
could be unacceptable from a field performance standpoint.   Again, this
problem is somewhat more pertinent to the evaluation of bottom ash than
boiler slag.

          A good example of a standard aggregate test method which is not
entirely suitable  for evaluating bottom ash is the Los Angeles abrasion
test (ASTM C131).  This test does not sufficiently identify the highly
friable "popcorn" particles in bottom ash,  nor is the test  indicative of
the amount of degradation that may occur under field compaction.   The
unique properties of bottom ash also obscure test results on asphalt pav-
ing mixtures incorporating  these materials.   Existing methods of assess-
ing moisture damage on bituminous mixtures  are not sufficient to properly
                                     1-179

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identify the potential problems that may be associated with bottom ash, let
alone explain the apparent cementing and strength gain of the bottom ash
particles in the paving mix following saturation (Reference 1-171).

          There are  yet other questions which can be raised concerning evalu-
ation of the use of power plant aggregates in bituminous paving mixtures, such
as:

          •    Are high air voids values associated with the use
               of some bottom ashes acceptable?

          •    How  significant is the sodium sulfate soundness
               test for boiler slags and what are the acceptable
               test limits?

          •    Is  the specific gravity test an adequate indicator
               of the presence of "popcorn" particles in bottom
               ashes and, if so, what should be the acceptable
               lower limit for specific gravity?

          For power plant aggregates to  be used successfully, they must also
be used properly.  These materials should not generally be viewed simply as
other conventional aggregates and evaluated with the stock-in-trade question,
"Do they meet specifications?" (Reference 1-16).

          After reviewing available literature and assessing the current status
of utilizing bottom ash and boiler slag in bituminous paving, the following
technical recommendations are made:

          1.   Bottom ash is best used in cold-mix emulsified
               asphalt mixtures on low volume roads, in hot-
               mix base mixtures, or in shoulder construction
               where specification requirements for gradation
               and toughness are not as critical.  Many bottom
               ashes are probably not acceptable for use in
               hot-mix wearing courses, unless blended with
               conventional aggregates in relatively low per-
               centages .

          2.   Boiler slag can be used without any special con-
               sideration in conventional hot-mix asphalt pav-
               ing applications, provided the percentage of
               boiler slag is limited to less than approximately
               50 percent of the total aggregate in the mixture.
               Boiler slag is also highly recommended in seal
               coats on comparatively low volume roads.  The
               aost favorable use of boiler slag in hot-mix
               paving is in surfacing mixtures when blended with
               other aggregates.  Mixtures with acceptable skid
               resistance using boiler slag are possible, pro-
               vided careful attention is given to mixture de-
               sign (Reference 1-172).
                                      1-180

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          Because of the very limited use of bottom ash in asphalt paving,
as well as the variable quality of some sources  of bottom ash, it would be
inappropriate to consider adoption of guidelines for the use of this material
in asphalt paving.  Furthermore, bottom ash simply has not gained the level
of acceptance necessary for it to be used on anything like a routine basis,
except where it is used as "Ashphalt" in West Virginia.

          Although boiler slag is better suited for bituminous paving appli-
cations from the technical sense, there are also definite reservations about
considering guideline development for boiler slag  use in asphalt paving.
One reason for such reservations is the fact that nearly 50 percent of all
boiler slag in the United States is used for ice control during the winter.
This use could consume a large percentage of the  stockpiled boiler slag at
a particular power plant during  the winter season, leaving relatively small
amounts available for aggregate use.  Another substantial market for boiler
slag in some sections of the country is roofing granules for the manufacture
of shingles.   Boiler slag also finds application in sandblasting and as a
construction fill material.  In addition, some power plants are able to uti-
lize the majority of the bottom ash (or boiler slag) generated at the plant
in construction activities on the plant premises.  In such cases, little or
no ash is even made available to prospective users.
                                     1-181

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                                  Part I

                                REFERENCES



1-1       National Ash Association, Washington, D.C.

1-2       Lin, King, Dotter, Jerry, and Holmes, Connie, "Steam Electric
          Plant Factors - 1978," National Coal Association, Washington,
          D.C., 1978.

1-3       Covey, James  N., "An Overview of Ash Utilization in the United
          States," presented at Ash Management Conference, College Station,
          Texas, May 1980.

1-4       Hecht, N. L., and Duvall, D. S., "Characterization and Utili-
          zation of Municipal and Utility Sludges and Ashes:  Volume III -
          Utility Coal Ash," National Environmental Research Center, U.S.
          Environmental Protection Agency, May 1975.

1-5       Meyers, James F., Pichumani, Raman, and Kapples, Bernadette S.,
          "Fly Ash as a Construction Material for Highways," U.S. Depart-
          ment of Transportation, Federal Highway Administration, Report
          No. FHWA-IP-76-16, Washington, B.C., May 1976.

1-6       DiGioia, Anthony M., Jr., and Nuzzo, William L., "Fly Ash as
          Structural Fill," Proceedings of the American Society of Civil
          Engineers, Journal of the Power Division, pp. 77-92, June 1972.

1-7       Hecht, N. L., and Duvall, D. S., Op. Cit.

1-8       DiGioia, A. M., Jr., McLaren, R. J., and Taylor, L. R., "Fly Ash
          Structural Fill Handbook," Electric Power Research Institute
          Report No. EA-1281, Palo Alto, California, December 1979.

1-9       Meyers, James F., Pichumani, Raman, and  Kapples, Bernadette S.,
          Op. Cit.

1-10      Ibid.

1-11      Manz, Oscar E., "Utilization of Lignite and Subbituminous Ash,"
          presented at the 1973 Lignite Symposium, Grand  Forks, North
          Dakota, 1973.

1-12      Gray, Donald H., and Lin, Yen-Kuang, "Engineering Properties of
          Compacted Fly  Ash," Proceedings of the American Society of Civil
          Engineers, National Water Resources Engineering Meeting, Phoenix,
          Arizona, January 1971.

1-13      Croney, D., and Jacobs, J. D., "The Frost Susceptibility of Soils
          and Road Materials," British Ministry of Transport, Road Research
          Laboratory, RRL Report No. 90, 1967.
                                      1-183

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1-14      Organization for Economic Cooperation and Development, "Use of
          Waste Materials and By-Products in Road Construction," Paris,
          France, 1977.

1-15      Myers, James F., Pichutnani, Raman, and Kapples, Bemadette S.,
          Op. Cit.

1-16      DiGioia, Anthony M., Jr., and Nuzzo, William L., Op. Cit.

1-17      Gray, Donald H., and Lin, Yen-Kuang, Op. Cit.

1-18      DiGioia, Anthony M., Jr., and Nuzzo, William L., Op. Cit.

1-19      Lamb, D. William, "Ash Disposal in Dams, Mounds, Structural Fills,
          and Retaining Walls," Proceedings of Third International Ash Sym-
          posium, Pittsburgh, Pennsylvania,  March 1973.

1-20      DiGioia, Anthony M., Jr., and Nuzzo, William L., Op. Cit.

1-21      Central Electricity Generating Board, Pulverized Fuel Ash Utilization.

1-22      Sutherland, H. B., et al, "Engineering and Related Properties of
          Pulverized Fuel Ash," Journal of Institution of Highway Engineers,
          Volume 15, No. 6, 1968.

1-23      DiGioia, Anthony M., Jr., and Nuzzo, William L., Op. Cit.

1-24      Lin, Yen-Kuang, "Compressibility, Strength and Frost Susceptibility
          of Compacted Fly Ash," Ph.D. Thesis, University of >achigan, 1971.

1-25      Hough, B. K., "Basic Soils Engineering," Ronald Press, New York,
          New York, 1960.

1-26      U.S. Environmental Protection Agency, Office of Technology Transfer,
          "Methods of Chemical Anlaysis for Water and Wastes," Report No.
          EPA-625-6-74-003, Washington, D.C., 1974.

1-27      Webster, W. C., and Gulledge, W. P., "Final Report - Phase II Col-
          laborative Test Program Analysis of Selected Trace Metals in Leachate
          from Selected Fossil Energy Materials," U.S. Department of Energy,
          Laramie, Wyoming, January 1980.

1-28      Central Electricity Generating Board, Op. Cit.

1-29      DiGioia, Anthony M., Jr., and Nuzzo, William L., Op. Cit.

1-30      Lewis, Thomas S., "Construction of Fly Ash Roadway Embankment in
          Illinois," Transportation Research Board Record No. 593, Wash-
          ington, D.C.
                                     1-184

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1-31      Meyers, James F., Pichumani, Raman, and Kapples, Bernadette S.,
          Op. Cit.

1-32      Faber, John, and DiGioia, Anthony M., Jr., "Use of Ash in Embank-
          ment Construction," Transportation Research Board Record No. 593,
          Washington, D.C., 1979.

1-33      Lewis, Thomas, E., Op. Cit.

1-34      National Ash Association, Ash at Work. Volume XII, No. 2, 1980.

1-35      American Society for Testing and Materials, Standard Specification
          C593, "Fly Ash and Other Pozzolans for Use with Lime."

1-36      Ahlberg, Harold L., and Barenberg, Ernest J,., "Pozzolanic Pavements,"
          University of Illinois, Engineering Experiment Station, Bulletin 473,
          Urbana, Illinois, February  1965.

1-37      Minnick, L. John, "The New  Fly Ash," Proceedings of Second Ash Utili-
          zation Symposium, Pittsburgh, Pennsylvania, U.S. Bureau of Mines,
          Information Circular No. 8488, 1970.

1-38      Minnick, L. John and Williams, Ralph N.,  "Field Evaluation of Lime-
          Fly Ash-Soil Compositions for Roads," Highway Research Board, Bul-
          letin No. 129, 1956.

1-39      Pound, Joseph H., Vice President,  American Fly Ash Company, DesPlaines,
          Illinois, private communication.

1-40      Monroney, Harold S., Director of Highways, Illinois Department of
          Transportation,  Springfield, Illinois, private communication.

1-41      Barenberg E., and Thompson, M., "Lime-Fly Ash-Stabilized Bases and
          Subbases," National Cooperative Highway Research Program, Synthesis
          of Highway Practice No.  37, Washington, D.C., 1976.

1-42      Meyers, James F., Pichuman, Raman,  and Kapples, Bernadette S., "Fly
          Ash as a Construction Material for Highways," U.S. Department of
          Transportation,  Federal  Highway Administration, Report No. FHWA-IP-
          76-16, Washington, D.C., May 1976.

1-43      Barenberg, E.,  and Thompson, M., Op. Cit.

1-44      Meyers, James F., Pichumani, Raman,  and Kapples, Bernadette S.,
          Op. Cit.

1-45      Barenberg, E.,  and Thompson, M., Op. Cit.

1-46      Ahlberg, Harold L.,  and  Barenberg, Ernest J., Op. Cit.

1-47      Meyers, James F., Pichumani, Raman,  and Kapples, Bernadette S.,
          Op. Cit.
                                      1-185

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1-48      Barenberg, E., and Thompson, M., Op. Cit.

1-49      Ahlberg, Harold L., and Barenberg, Ernest J., Op. Cit.

1-50      Meyers, James F., Pichumani, Raman, and Kapples, Bemadette S.,
          Op. Cit.

1-51      Ahlberg, H. L., and McVinnie, W. W., "Fatigue Behavior of a Lime-
          Fly Ash-Aggregate Mixture," Highway Research Board, Bulleton No.
          335, Washington, D.C., 1962.

1-52      Ahlberg, Harold L., and Barenberg, Ernest J., Op. Cit.

1-53      Miller, R. H«, and Conturier, R. R., "Measuring Thermal Expansion
          of Lime-Fly Ash-Aggregate Compositions Using SR-4 Strain Gages,"
          Highway Research Board, Record No. 29, Washington, D.C., 1963.

1-54      Barenberg, E., and Thompson, M., Op. Cit.

1-55      Dempsey, B. J., and Thompson, M. R., "Interim Report - Durability
          Testing of Stabilized Materials," Illinois Cooperative Highway
          Research Program, Series No. 132, University of Illinois, Urbana,
          Illinois, 1972.

1-56      Dempsey, B. J., and Thompson, M. R., "Vacuum Saturation Method for
          Predicting the Freeze-Thaw Durability of Stabilized Materials,"
          Highway Research Board, Record No. 442, Washington, D.C., 1973,

1-57      Webster, W. C., and Smith, C. H., "New Poz-0-Pac Compositions,"
          Report for G. and W. H. Corson, Inc., Plymouth Meeting, Pennsyl-
          vania, June 1971.

1-58      Vantil, C. J., McCullough, B. F., Vallerga, B. A., and Hicks,  R. J.,
          "Evaluation of AASGTO Interim Guides for Design of Pavement Struc-
          tures,"  National Cooperative Highway Research Program, Report No.
          128, Washington, D.C., 1972.

1-59      AASHTO Road Test Report No. 7,, "Summary Report," Highway Research
          Board, Special Report No. 616, Washington, D.C., 1962.

1-60      AASHO Roadt Test Report No. 5, "Pavement Research," Highway Research
          Board, Special Report No. 61E, Washington, D.C., 1962.

1-61      "AASHTO Interim Guide for Pavement Structures," American  Association
          of State Highway and Transportation Officials, Report No. GDPS-1,
          Washington, D.C., 1972.

1-62      Ahlberg, H. L., and Barenberg, E., Op. Cit.

1-63      Dunn, Howard C., Jr., "A Study of Four Stabilized Base Courses,"
          Ph.D. Thesis, Pennsylvania State University, State College, Penn-
          sylvania, 1976.
                                     1-186

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1-64      Asphalt  Institute,  "Asphalt Handbook," Manual  Series No. 4,
          College  Park, Maryland, July  1962.

1-65      Gehler,  James,  Illinois Department of Transportation, Bureau of
          Construction, Springfield, Illinois, private communication.

1-66      Windisch,  Richard,  Assistant  District Engineer, Pennsylvania De-
          partment of Transportation, District 6-0,  St.  Davids, Pennsylvania,
          private  communication.

'1-67      Thompson,  M. R.,  and  Dempsey, B.  J., "Final Report  - Durability
          Testing  of Stabilized Materials," Illinois Cooperative Highway
          Research Program, Series  No.  152, University of Illinois, Urbana,
          Illinois,  1974.

1-68      Colony,  D. C.,  "Summary of a  Study of Axle Load Accumulations on a
          Residential  Subdivision Street,"  Toledo, Ohio, August 1975.

1-69      Fang,  H. Y., and  Chen, W. F., "New Methods for Determination of
          Tensile  Strength  of Soils," Highway Research Board  Record No. 345,
          Washington,  B.C., 1971.

1-70      Hoffman, Gary L., Cumberledge, Gaylord, and Bhajandas, Amar C.,
          "Establishing a Construction  Cutoff Date for Placement of Aggre-
          gate-Lime-Pozzolan,"  Pennsylvania Department of Transportation,
          Research Report,  1975.

1-71      Colony,  D. C.,  Op.  Git.

1-72      Merkel,  Richard,  Vice President,  Nicholson Concrete and  Supply
          Company, Toledo,  Ohio, private communication.

1-73      Young, David, City of Toledo, Streets Department, Toledo, Ohio,
          private  communication.

1-74      Lawrence,  Kenneth, City Engineer, City of  Lancaster, Pennsylvania,
          private  communication.

1-75       Savage,  Frank,  M., "Establishing  a Market  for  Lime-Fly Ash Base,"
          Proceedings  of  the Second Ash Utilization  Symposium, Pittsburgh,
          Pennsylvania,  U.S. Bureau of  Mines Information Circular  No. 8488,
           1970.

1-76      Pound, Joseph H., Vice President, American Fly Ash  Company, Des
          Plaines, Illinois, private communication.

 1-77       Savage,  Frank M.,  Op.  Cit.

 1-78       Pound, Joseph H., Vice President, American Fly Ash  Company, Des
          Plaines, Illinois, private communication.
                                      1-187

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1-79      Monroney, Harold, Director of Highways, Illinois Department of
          Transportation, Springfield, Illinois, private communication.

1-80      Ebers, Jack, "Specifications for PAM Base and Subbase," Presented
          at Illinois Pozzolanic Concrete Seminar, Chicago, Illinois, April
          1980.

1-81      Nicholson, J. Patrick, Chief Executive Officer, N-Viro Energy
          Systems, Ltd., Toledo, Ohio, private communication.

1-82      Turner, Richard P., "Status Report on Aggregate-Lime-Fly Ash Base,"
          Ohio Department of Transportation Report, August 1976.

1-83      Talbert, Leon, Ohio Department of Transportation, Bureau of Research,
          Columbus, Ohio, private communication.

1-84      McDonald, Robert, Chief Construction Engineer, City of Toledo, Ohio,
          private communication.

1-85      Minnick, L. John, and Williams, Nalph N., Op. Cit.

1-86      Williams, Ralph N., Third Quarterly Report, Poz-0-Pac Company of
          America, Plymouth Meeting, Pennsylvania, 1964.

1-87      Williams, Ralph N., Fourth Quarterly Report, Poz-0-Pac Company of
          America, Plymouth Meeting, Pennsylvania, 1965.

1-88      Koehler, William, Pennsylvania Department of Transportation,  Bureau
          of Materials and Testing, Harrisburg, Pennsylvania, private com-
          munication.

1-89      Lawrence, Kenneth, City Engineer, City of Lancaster, Pennsylvania,
          private communication.

1-90      Williams, Ralph N., Third Quarterly Report, Poz-0-Pac Company of
          America, Plymouth Meeting, Pennsylvania, 1964.

1-91      Buehler, Russ, President, City Wide Asphalt Company, Kansas City,
          Missouri, private communication.

1-92      Tang, Nai C., Schmerl, Harry, and Waller, Myron,  "Newark Airport
          Expansion Pilots Cost-Saving Runway Paving Concept," Civil Engi-
          neering , June 1978.

1-93      Port Authority of New York and New Jersey, "Newark Airport Rede-
          velopment:  The Pavement Story,"  New York, New York.
                                     1-188

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1-94      Yang, Nai C., Schmerl, Harry, and Waller, Myron, Op. Cit.

1-95      Grimaldi, Alfred, Chief Engineer, Port Authority of New York and
          New Jersey, New York, New York, Correspondence with Joseph Pound,
          American Fly Ash Company, Des Flaines, Illinois, dated October 22,
          1980.

1-96      Huey, Dale E., Airport Engineer, Federal Aviation Administration,
          Detroit, Michigan, Correspondence with Ralph Hannon, Director of
          Planning and Engineering, Toledo-Lucas County Fort  Authority,
          Toledo, Ohio, dated February 26, 1980.

1-97      Opatray, James M., State Program Officer, Federal Aviation Admin-
          istration, Detroit, Michigan, Correspondence with Ralph Hannon,
          dated May 15, 1980.

1-98      Goeb, Eugene 0., Chief Engineer, N-Viro Energy Systems, Ltd.,
          Toledo, Ohio, Correspondence with Ralph Hannon, dated May 20, 1980.

1-99      Barenberg, Ernest, Civil Engineering Department, University of
          Illinois, Champaign,  Illinois, Correspondence with Ralph Hannon,
          dated May 19, 1980.

1-100     Colony, David C., Civil Engineering Department, University of
          Toledo, Toledo, Ohio, Correspondence with Ralph Hannon, dated
          May  20, 1980.

1-101     Toledo .Testing Laboratory report to Charles L. Barber and Asso-
          ciates, Toledo, Ohio, August 22, 1980.

1-102     Toledo Testing Laboratory report to Nicholson Concrete and Supply
          Company, Toledo, Ohio, July 29, 1980.

1-103     Barenberg, Ernest, Civil Engineering Department, University of
          Illinois, Champaign,  Illinois, Correspondence with Richard Merkel,
          Nicholson Concrete and Supply Company, Toledo, Ohio dated October
          16,  1971.

1-104     Toledo Testing Laboratory report to Charles L. Barber and Asso-
          ciates, Toledo,  Ohio, August 22, 1980.

1-105     Huey, Dale E., Airport Engineer, Federal Aviation Administration,
          Detroit, Michigan, Correspondence with Ralph Hannon dated July 21,
          1980.

1-106     Nicholson, J. Patrick, Chief Executive Officer, N-Viro Energy
          Systems, Ltd., Toledo, Ohio, private communication.

1-107     Rulison, Robert,  Illinois Department of Transportation, private
          communicat ion.
                                      1-189

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1-108     Gallagher, John J., President, Premix Base Company, Thornton,
          Illinois, Presented at Illinois Pozzolanic Concrete Seminar,
          Chicago, Illinois, April  1980.

1-109     Miller, K. M., Pavement and Soils Engineer, Ohio Department of
          Transportation, Columbus, Ohio, private communication.

1-110     Koehler, William, Pennsylvania Department of Transportation, Bureau
          of Materials and Testing, Harrisburg, Pennsylvania, private communi-
          cation.

1-111     Falkenstine, Barry, Pennsylvania Department of Transportation,
          Bureau of Design, Harrisburg, Pennsylvania, private communication.

1-112     Lawrence, Kenneth, City Engineer, City of Lancaster, Pennsylvania,
          private communication.

1-113     Arnold, Mark, Vice President, D. M. Stoltzfus, Inc., Talmadge,
          Pennsylvania, private communication.

1-114     DiRenzo, John, Vice President, Highway Materials, Inc., Bridgeport,
          Pennsylvania, private communication.

1-115     Long, Donald C., Chief Geologist,  West Virginia Departcent of High-
          ways, Charleston, West Virginia, private communication.

1-116     Berrier, L. H., Jr., Construction and Testing Engineer, North Caro-
          lina  Department of Highways, Raleigh, North Carolina, private
          communication.

1-117     Allemeier, K. E., Engineer of Testing and Research, Michigan De-
          partment  of Transportation, Lansing, Michigan, private communi-
          cation.

1-118     Savage, Frank M., Op. Git.

1-119     National Ash Association, "Guide for the Design and Construction of
          Cement Stabilized Fly Ash Pavements," Washington, D.C., 1976.

1-120     Ibid.

1-121     Meyers, James F., Rapples, Bernadette Steele, and DiGiola,  Anthony M.,
          Jr., "Guide for the Design and Construction of Cement-Stabilized Fly
          Ash Pavements," Proceedings of the Fourth International Ash Utiliza-
          tion Symposium, St. Louis, Missouri, U.S. Energy Research and  De-
          velopment Administration, Report No. MERC/SP-76/4, 1976.

1-122     National Ash Association, Op. Cit.
                                     1-190

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1-123     Portland Cement Association, "Soil-Cement Laboratory Handbook,"
          Skokie, Illinois, 1971.

1-124     National Ash Association, Op. Cit.

1-125     Head, W. J., and Seals, R. K., "Design and Construction of Experi-
          mental Haul Road and Parking Lot Facilities Utilizing Power Plant
          Ash," Proceedings of the Fifth International Ash Utilization Sym-
          posium, Atlanta, Georgia, U.S. Department of Energy, Report No.
          MERC/SP-79/10, 1979.

1-126     Packard, R. G., "Thickness Design for Soil-Cement Pavements,"
          Portland Cement Association, Skokie, Illinois, 1971.

1-127     Packard, R. G., "Design of Concrete Airport Pavement," Portland
          Cement Association Engineering Bulletin, Skokie, Illinois, 1973.

1-128     National Ash Association, Op.  Cit.

1-129     Meyers, James  F., Pichumani, Roman, and Kapples, Bernadette S.,
          "Fly Ash - A Highway Construction Material," U.S. Department of
          Transportation, Federal Highway Administration, Implementation
          Package No. 76-16, Washington, D.C., 1976.

1-130     Head, W. J., and Seals, R. K., Op. Cit.

1-131     National Ash Association, Op. Cit.

1-132     Asphalt Institute, "Mix Design Methods for Asphalt Concrete and
          Other Hot-Mix  Types," Manual Series No. 2, College Park, Maryland,
          1963.

1-133     Traxler, R. N., and Miller, J. S., "Mineral Powders, Their Physical
          Properties and Stabilizing Effects," Proceedings of the Association
          of Asphalt Paving Technologists, Volume 7, 1936.

1-134     Zinnaer, F. V., "Fly Ash as a Bituminous Filler," U.S. Department of
          Interior, Bureau of Mines, Information Circular No. 8488, Proceed-
          ings of Second Ash Utilization Symposium, Pittsburgh, Pennsylvania,
          1970.

1-135     Foid.

1-136     Carpenter, Carl A., "Fillers in Asphaltic Concrete," Public Roads,
          7oluae 27, So. 5, December 1952.

1-137     Zisaer, F. V., Op. Cit.
                                      1-191

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1-138     Tunnicliff, D.G., "A Review of Mineral Filler," Proceedings of the
          Association of Asphalt Paving Technologists, Volume 31, 1962.

1-139     Traxler, R. N., "The Evaluation of Mineral Powders as Fillers for
          Asphalts," Proceedings of the Association of Asphalt Paving Tech-
          nologists, Volume 8, 1937.

1-140     Brahma, S. P., "Use of Lignite Fly Ash as a Mineral Filler In
          Bituminous Concrete," North Dakota State University, Engineering
          Experiment Station Series No. 3, 1968.

1-141     Galloway, B. M., "A Review of the Use of Mineral Filler in Asphalt-
          Aggregate Mixtures," Proceedings of Fly Ash Applications in 1980
          Conference, College Station, Texas, May 1980.

1-142     Zimmer, F. V. Op. Git.

1-143     Manz, Oscar E., "Utilization of Lignite and Subbituminous Ash,"
          Presented at 1973  Lignite Symposium, Grand Forks, North Dakota,
          1973.

1-144     Ash at Work, Volume VII, No. 1, 1975.

1-145     Faber, John H., "U.S. Overview of Ash Production and Utilization,"
          Proceedings of Fourth International Ash Utilization Symposium, St.
          Louis, Missouri, 1976.

1-146     Tapp, Stuart C., Staff Materials Engineer, Colorado Department of
          Transportation, Denver, Colorado, private communication.

1-147     Swing, Donald, Materials and Tests Engineer, Nebraska Department of
          Transportation, Omaha, Nebraska, private communication.

1-148     Manz, Oscar E., Op. Cit.

1-149     Covey, James N., "An Overview of Ash Utilization in the United
          States," Proceedings of the Fly Ash Applications  in 1980 Con-
          ference, College Station, Texas, May 1980.

1-150     Anderson, David A., "Utilization of Bottom Ash in Highway Construc-
          tion," Proceedings of the International Conference on Use of By-
          Products and Waste in Civil Engineering, Paris, France, November
          1978.

1-151     Anderson, David A., Usmen, Mumtaz, and Moulton, Lyle K., "Use of
          Power Plant Aggregate in Bituminous Construction," Presented at
          the 55th Annual Meeting of the Transportation Research Board,
          Washington, D.C., January 1976.
                                     1-192

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1-152     Moulton, Lyle K., Seals, Roger K., and Anderson, David A.,
          "Utilization of Ash from Coal Burning Power Plants in Highway
          Construction," Highway Research  Record No. 430, Washington,
          D.C., 1973.

1-153     Moulton, Lyle K., "Bottom Ash and Boiler Slag," Proceedings of
          the Third International Ash Utilization Symposium, Pittsburgh,
          Pennsylvania, U.S. Bureau of Mines Information Circular No. 1C
          8640, 1973.

1-154     Anderson, David A., Op. Cit.

1-155     Moulton, Lyle K., Op. Cit.

1-156     Faber, John H., President Faber Associates, Shepherdstown, West
          Virginia, private communication.

1-157     Moulton, Lyle K., Seals, Roger K., and Anderson, David A., Op. Cit.

1-158     Seals, Roger K., Moulton, Lyle K., and Ruth, Byron E., "Bottom Ash:
          An Engineering Material," American Society of Civil Engineers,
          Journal of The Soils and Foundation Division, April 1972.

1-159     Ash at Work, National Ash Association, Volume IV, No. 3, Washington,
          D.C., 1972.

1-160     Pound, Joseph, Vice President, American Fly Ash Company, Chicago,
          Illinois, private communication.

1-161     Hollon, George W., and Marks, Byron A., "A Correlation of Published
          Data on Lime-Fly Ash-Aggregate Mixtures for Highway Base Construc-
          tion," University of Illinois, Highway Engineering Series No.  2,
          Urbana, Illinois, July 1960.

1-162     Gallagher, John, President, Premix Base Company, Thornton, Il-
          linois, private communication.

1-163     Georgeff, Anthony T., Montgomery  County Superintendent of Highways,
          Hillsboro, Illinois, private communication.

1-164     Moulton, Lyle K., Op. Cit.

1-165     Kinder, Dennis, "Cement-Stabilized Bottom Ash Base and Subbase
          Courses," Presented at the Short Course on Power Plant Ash Uti-
          lization, Arizona State University. Tempe, Arizona, 1978.

1-166     Moulton, Lyle K., Seals, Roger K.,  and Anderson, David A., Op.  Cit.

1-167     Usmen, Mumtaz, and Anderson, David A., "Use of Power Plant Aggregate
          in Asphaltic  Concrete," Proceedings of Fourth International Ash
          Utilization Symposium, St. Louis, Missouri, U.S. Energy Research
          and Development Administration, Report No. MERC/SP-76/4, 1976.
                                     1-193

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1-168     Majidzadeh, K., Borkowski, G., and El-Mitiny, R., "Material
          Characteristics of Power Plant Bottom Ashes and Their Per-
          formance in Bituminous Mixtures:  A Laboratory Investigation,"
          Proceedings of Fifth International Ash Utilization Symposium,
          Atlanta, Georgia, U.S. Department of Energy, Report No.  MERC/
          SP-79/10, 1979.

1-169     Majidzadeh, K., El-Mitiny, R., and Borkowski, G., "Power Plant
          Bottom Ash in Black Base and Bituminous Surfacing," U.S. De-
          partment of Transportation, Federal Highway Administration,
          Report No. FHWA-RD-78-148, Washington, D.C., 1977.

1-170     Root, Richard, E., and Williams, Ellis G., "ASHPHALT - West
          Virginia Turns Waste Material into Useful Aggregate," Asphalt,
          Volume 29, No. 2, The Asphalt Institute, College Park, Maryland,
          April 1976.

1-171     Clayton, Gary K., "Low Cost Pavements Utilizing Power Plant Ash,"
          Presented at the National Conference on Local Transportation,
          Des Moines, Iowa, 1975.

1-172     Kerkhoff, G. 0.,  "Bottom Ash and Wet Bottom Slag," Presented at
          the Annual Soils  Engineers Meeting, Lansing, Michigan, November,
          1968.

1-172     Morrison, Ronald, "Applications of Boiler Slag," Presented at the
          Regional Seminar  on Ash Utilization, St. Louis, Missouri, November
          1974.

1-173     Moulton, Lyle K., Seals, Roger K., and Anderson, David A., "Uti-
          lization of Ash  from Coal Burning Power Plants in Highway Con-
          struction," Highway Research Record No. 430, Washington, D.C.,
          1973.

1-174     Zimmer, Frank V., Supervisor, Salvage Sales Division, Detroit
          Edison Company,  Detroit, Michigan, private communication.

1-175     Jimenez, R. A.,  and Galloway, B. M., "Lignite Slag Paves the Way,"
          Industrial and Engineering Chemistry, Volume 51, No. 7, July 1959.

1-176     Conner, R. M., Research Planning Engineer, Minnesota Department of
          Transportation,  St. Paul, Minnesota, private communication.

1-177     Georgeff, Anthony T., Montgomery County Superintendent of Highways,
          Hillsboro, Illinois, private communication.

1-178     Hellriegel, Edgar J., Principal Engineer, Transportation Research,
          New Jersey Department of Transportation, Trenton, New Jersey,
          private communication.
                                      1-194

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1-179     Drake, W. B., Assistant State Highway Engineer, Kentucky Department
          of Transportation, Frankfort, Kentucky, private communication.

1-180     Usmen, Mumtaz,  Anderson, David A., and Moulton, Lyle K., "Appli-
          cability of Conventional Test Methods and Material Specifications
          to Coal-Associated Waste Aggregates," Presented at the 57th Annual
          Meeting of the Transportation Research Board, Washington, D.C.,
          January 1978.

1-181     Anderson, David A., Usmen, Mumtaz, and Moulton, Lyle K., "Use of
          Power Plant Aggregate in Bituminous Construction," Presented at
          the 55th Annual Meeting of the Transportation Research Board,
          Washington, D.C.,  January 1976.
                                     1-195

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                                  Part II

                 USE OF CEMENT KILN DUST AND LIME KILN DUST
                          IN HIGHWAY CONSTRUCTION
INTRODUCTION

Cement Kiln Dust  (CKD)

          Cement kiln dust is the dust collected from the exhaust gases of
cement kilns.  The dust is "a mixture of raw kiln feed, partly calcined ma-
terial, finely divided cement  linker and alkali sulfates (Reference II-l).


          Its chemical composition is variable but usually falls within the
ranges shown in Table II-l.

          CKD is a fine granular material similar in appearance to cement.
The  gradation of a  typical sample  is shown in Table II-2.


Lime Kiln Dust (LKD)

          Lime kiln dust or lime stack dust is a solid waste generated by the
manufacture of lime.  "The dust contains a mixture of raw kiln feed, partly
calcined material, and finely divided material (Reference II-3).

          The chemical compositions  of both high calcium and dolomitic lime
dusts are shown in Table II-3.

          The gradation of a typical sample of LKD is shown in Table II-4.

          A good description of .the  process by which cement kiln dust is
produced is contained in a paper UTILIZATION OF WASTE KILN DUST FROM THE
CEMENT INDUSTRY (Reference 11-14) and is reproduced here.

MANUFACTURING PROCESS

          Manufacture of portland cement involves five basic steps:  quarry-
ing, raw grinding, blending, burning, and finish grinding.  The raw materials
for portland cement consist of materials containing four particular compounds:
liae, silica, alumina, and iron oxide.  The more commonly used materials are
various combinations of limestone, shale, clay, sand, oyster shell, cement
                                     II-l

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                             Table II-l
          Chemical Composition of  Cement Kiln  Dust
Ingredient

Si02
Al 0
2 3
Pe O
2 3
CaO
MgO
S03
Na20
K20
Loss on Ignition
Range
Low %
6.0
3.2

0.8

16.0
0.8
0.7
0.08
1.08
2.50
High %
28.5
9.6

5.9

65.0
4.83
26.3
3.13
26.23
32.0
Average %
16.5
4.35

2.66

47.6
2.34
7.07
0.78
5.52
16.0
Source:  Reference II-l.
                                 II-2

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                           Table II-2


   Particle Size Analysis  of a Typical Cement Kiln Dust


                 Particle  Size          Weight
                 Range-Microns *         Percent

                     48-68                  0.3
                     34-48                  0.4
                     24-34                  0.7
                     17-24                  1.8
                     12-17                  5.1
                      6-12                 27.3
                      <  6                  64.4
   *The opening of  a  $200  sieve is 74 microns,
Source:  Reference 11-10.
                               II-3

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                            Table II-3
         Chemical  Composition  of Lime Kiln Dust
Ingredient

CaO
MgO
co2
Available
Lime
si°2
Fe2°3
A1203
S
P,0C
Range
High Calcium
Lime Dust
Low %
13.1
0.1
2.2

10.0
0.3
0.01
0.01
0.03
0.001
High. .%.
80.1
4.2
46.5

64.3
28.7
4.1
9.2
3.0
0.06
Average %
51.3
1.3
22.3

35.5
6.7
0.9
1.8
0.8
0.04
Dolomitic Lime
Dust
Low i
17.2
10.0
19.0

5.0
0.1
0.05
0.05
0.004
0.1
High %
50.0,
40.5
40.9

17.5
10.0
6.0
3.6
3.0
0.04
Average %
37.0
23.9
25.4

10.2
2.4
1.5
1.1
1.2
0.02
Source:  Reference II-4.
                                 II-4

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                            Table II-4




      Particle Size Analysis  of a Typical Lime Kiln Dust
Sieve
No.
8
20
60
100
200
Sieve
Opening- mm.
2.36
0.85
0.25
0.15
0.075
Percent Finer
by Weight
100
97
78
64
42
Source:  Reference 11-14.
                                 II-5

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rock, marl, iron ore, and various by-product materials including ash, slag,
and tailings from several mineral processing industries.  These materials
are proportioned as necessary to form a suitable raw mix and ground together
either as a dry mixture or as a water slurry.  At this stage, most of the
material is 200 mesh or finer and after blending is ready for introduction
to the kiln.

          Kilns for  producing portland cement are large, rotating, inclined
metal tubes, usually 8 to 15 feet in diameter and 200 to 500 feet in length.
At the lower end of the kiln is a burner, fired by gas, oil, or coal, that
produces a 3,000°F flame.  Raw materials enter the upper end of the kiln and
move down  the kiln toward the burner as the kiln rotates.  As the mix tra-
verses the kiln, its temperature increases and three things happen.  Moisture
is driven off, calcium carbonate decomposes to calcium oxide (lime), and the
mass reaches a temperature of incipient fusion, about 2,700°F,  at which hard,
marble-size balls called clinker are formed.  The  clinker is discharged from
the kiln, cooled, and ground into portland cement, with a fineness of about
325 mesh.  During this  process about 3,400 pounds of raw materials have
been transformed into one ton of portland cement and 3 to 5 million Btu of
energy have been consumed.

          Kiln dust originates when finely ground raw materials become air-
borne in the stream of combustion gases traveling up the kiln.  Carbon di-
oxide, liberated by the decomposition of calcium carbonate, adds to the
agitation of the materials and thus to the amount of airborne dust.

          Mechanical collectors (cyclones), glass-bag filters (baghouses)
and electrostatic precipitators are commonly used to collect kiln dust.
Because they are relatively inexpensive and maintenance free, cyclones are
often used ahead of baghouses or precipitators to collect the larger dust
particles, but the cyclones cannot be used alone because their efficiency
for collecting particles less than 10 microns is low.  High collection ef-
ficiencies, approaching 100 percent, can be achieved with baghouses and
precipitators.

QUANTITIES AVAILABLE

Cement Kiln Dust

          Twenty million tons of CKD are generated annually.  Eight to 10
million tons are recycled into the kilns, while 10 to 12 million tons are
wasted (References II-5 and II-6).  In addition, it is estimated there are
100 million tons of the material that are reusable piled throughout  the
country (Reference II-7).  Table II-5 summarizes the number of ceaent plants
located in the contiguous 48 states, according to a listing of cement plants
in North. America  (Reference II-8).
                                     II-6

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                             Table II-5

           Cement Producing Plants in the United States*
                  (48 contiguous states only)
  Alabama     7
  Arizona     2
  Arkansas    2
  California 12
  Colorado    3
  Florida     5
  Georgia     3
  Idaho       1
  Illinois    4
  Indiana     5
  Iowa        5
  Kansas      5
  Kentucky    1
  Louisiana   2
Maine       1
Maryland    3
Michigan    5
Mississippi 2
Missouri    8**
Montana     2
Nebraska    2
Nevada      1
New Mexico  1
New York    7
North Carolina 1
Ohio        5
Oklahoma    3
Oregon      2
PennsyIvania
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Washington
West Virginia
Wisconsin
Wyoming
         TOTAL
15
 3
 1
 6
33***
 2
 1
 4
 1
 1
 1
168 plants
  *Does not include plants that grind only
 **Includes one plant under construction
***Includes two plants under construction
                                 II-7

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Lime Kiln Dust

          The annual accumulation of LKD is considerably less than that of
CKD.  In a 1977 survey conducted by the National Lime Association (Refer-
ence II-4), in which 60 out of 75 commercial lime plants responded, a re-
ported 4,275 tons per day of dust were collected.  It was estimated that
this was two-thirds dust and one-third sludge.  Of this amount, approxi-
mately 75 percent was wasted and 25 percent either sold or given away.
If these data are factored up for 330 working days per year, for a 50 per-
cent addition to adjust for captive lime plants,* and for the non-reporting
plants in the survey, the following available annual output can be computed:

  4,275 x 2/3 x .75 x 330 x 1.5 x -^ - 1.3 million tons per year.
                                  ou
This amount was partially confirmed from another source (Reference II-9) which
stated that 1.6 million tons of lime kiln wastes were produced in the U.S.
A rough estimate can be obtained by using  a 15 percent loss factor on the
total annual lime production from rotary kilns.  This would amount to 1.8
million tons of the 12 million tons of lime production.

          In summary, approximately 1.3 to 1.5 million tons of dry LKD is
now wasted annually.  The locations, by states of the commercial liae plants
in the U.S., are shown in Table II-6.

USZ OF WASTE KILN DUSTS IN HIGHWAY CONSTRUCTION

          The primary application of both kiln dusts would be in Trii-n dust-
pozzolan-aggregate road base compositions.  This type of road base would be
used in place of black base as a quality base.  It would also provide a base
superior in quality to an unstabilized crushed stone or gravel base.  CKD
can also be used in combination with fly ash alone to produce a stabilized
composition for use as a road base or structural fill.

          One other application in highway construction is the use of LKD as
an anti-stripplng agent and/or filler in bituminous compositions.

          These kiln dusts have additional potential in any highway applica-
tion for which hydrated lime is used.  This would include soil stabilization,
combination with sulfate wastes to form stabilized base material, and treat-
ment of wet, plastic subgrades.  The use of kiln dusts in these applications
has  been largely unproven; however, it is anticipated that it will provide
a similar product to that where the usual hydrated lime is used.
  Plants where the lime producer uses the lime (steel plant),
                                     II-8

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                                   Table II-6

                Commercial Lime Plants in the United States
States
Alabama
Arizona
Arkansas
California
Connecticut
Florida
Illinois
Indiana
Iowa
Kentucky
Louisiana
Maryland
Massachusetts
Michigan
Missouri

No. of plants
having rotary
kilns*
5
2
0
2
1
0
3
1
1
2
2
0
1
2
2

Total No.
of
plants**
5
2
1
3
1
2
3
1
1
2
2
1
2
3
3

States
Nevada
New Jersey
New Mexico
Chio
Oklahona
Oregon
Pennsylvania
South Dakota
Tennessee
Texas
Utah
Virginia
Washington
West Virginia
Wisconsin
Totals
No. of plants
having rotary
kilns*
3
1
1
8
1
0
6
1
0
6
1
4
1
1
3
61
Total No.
of
Plants**
3
1
1
12
1
1
7
1
1
7
1
5
1
2
5
81
 *Includes lime plants that  have rotary kilns only and both vertical and
  rotary kilns
"Includes lime plants that  have
      - rotary kilns only
      - vertical and rotary
      - vertical or other  kilns  (no rotary)
      Does not include hydrating plants only
         Source: Reference 11-11.
                                        II-9

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COMMERCIAL AVAILABILITY OF PRODUCTS CONTAINING KILN DUST

          The commercial availability of products containing cement and lime
kiln dust is considered in three parts:

          1.  Available amounts and locations of kiln dusts.
          2.  Locations of current producers of kiln dust,
              fly ash, aggregate compositions including all
              plants where the  product has been produced
              in the recent past.
          3.  Locations of potential producers.

Amounts and Locations of Cement Kiln Dust

          As shown in Table II-5, the latest available information on the
location of cement plants shows 168 plants distributed throughout 39 states.
Over half of these plants are located in eight states.  In addition, the
geographical distribution of the plants within these states indicates that
CKD would be available within reasonable transportation distance at most lo-
cations.  These states are:  Alabama, California, Indiana, Michigan, Ohio,
Pennsylvania, Tennessee, and  Texas.  Three other states have a significant
number of cement plants but they are more or less concentrated in one sec-
tion of the state.  These states are as follows:

          Kansas—plants are in the eastern portion of state
          Missouri—plants are in the eastern portion of state
          New York—plants are in the southeastern portion of state

          Other states that have four or more cement plants that would po-
tentially  have CKD available are:  Florida, Illinois, Iowa, and Washington.
It can be seen that most of the heavily industrialized states would have CKD
available.  These states are also among the heavy users of road base materials.

Amounts and Locations of Lime Kiln Dust

          Table II-6 shows that there are 61 commercial lime plants in 30
states that have rotary kilns.  There are 20 plants that have vertical or
other kilns but no rotary kilns.  It has been reported that there is minimum
dust accumulation from vertical kilns.  Based on the location of the rotary
kiln plants, the following states would appear to have the most available
supply of LKD:  Alabama, Ohio, Pennsylvania, Texas, and Virginia.  These
five states have almost half of the plants.  It was reported in 1977 (Ref-
erence 11-12) that six states, Ohio, Pennsylvania, Missouri, Texas, Michigan,
and Alabama, accounted for 57 percent of the total output of lime.   In ad-
dition, it is known that LKD is available in the Chicago area which would
add Illinois to the list.  Combining these into one tabulation would produce
a list of eight states:  Alabama, Illinois, Michigan,  Missouri,  Ohio,  Penn-
sylvania, Texas, and Virginia.  It is believed that this is a fair  represen-
tation of the most plentiful sources of LKD in the United States.
                                     11-10

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          No precise data on the amounts of LKD and CKD that are available
at various locations has been given.  It is believed that the information
presented is sufficient for the purpose particularly in view of the very
limited usage that these materials have had in road base construction and
the difficulties of obtaining "hard" data.

Locations of Past and Present Producers of Kiln Dust-Fly Ash-Aggregate
Compositions

          Three companies have been engaged in the past in providing kiln
dust,  fly ash, aggregate compositions  for field installations.  These
companies are:

          •  Nicholson Industries, Toledo, Ohio
          •  Gallagher Asphalt Co., Chicago, Illinois
          •  City Wide Asphalt Co., Sugar Creek, Missouri

          These organizations would be capable of supplying the material now
to  local clients.

Locations of Potential Producers of Kiln DustjrFly*Ash-Aggregate Compositions"

          While there are only a few plants that have had experience with kiln
dust road base compositions, there are many that could supply the material in
a. relatively short period of time.  These potential suppliers would fall into
two categories.  The first category are those who have in the past or are cur-
rently engaged in supplying lime, pozzolan, aggregate base course materials.
It would be necessary only to replace the hydrated lime in  one of the storage
bins with kiln dust and possibly recalibrate the feed system for the new mix-
ture.  The second category are those mixing plants that normally supply bitum-
inous mixtures and/or portland cement concrete.  With some addition of bins
and conveyors, it is conceivable that these plants could be readily (within
a matter of months) fitted to produce "pozzolanic concrete."  In  some plants,
additional bins are not necessary.  They could be fitted within three months
at a cost of approximately $30,000.

          In addition  to these possibilities, it has been estimated that a
aev plant could be put into operation within approximately 9 months—assuming
there would be no excessive delay in obtaining the required equipment.  The
plants are not very sophisticated to assemble or to operate.

          The availability of producers is not considered to be a deterrent
to the expanded use of kiln dust.


TECHNICAL ASSESSMENT*

          Field experience with kiln dust compositions is limited.  Details
on experimental road bases that have been in service for as much as five years
* JSjch of  the  data  on  which this assessment  is  based  was  supplied by Nicholson
  Industries.
                                      11-11

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are presented later in this report.  Laboratory studies, however, are of much
more significance than they ordinarily would be because of the close similarity
to lime, fly ash, aggregate compositions which have a long history of solid
performance.  In addition, it is important to note that the compositions can
be improved by small additions of Portland cement.

          Much of the technical assessment is based on the extensive labora-
tory work that has been done.  The performance of the field installations is
used as confirmation of the results of the laboratory evaluations.

Laboratory Investigation - Cement Kiln Dust

          Evidence of laboratory data that was generated by a number of labora-
tories and/or consultants was obtained.  A list of laboratories and consultants
that were involved in the laboratory work is shown in Table II-7.  The list  is
not necessarily a complete one.  It contains only those organizations and in-
dividuals who provided data and/or laboratory reports that were reviewed by
the writer.  Laboratory testing included the use of cement kiln dust from the
sources shown in Table II-8.

          Compressive Strength.  The laboratory investigations of compressive
strength were made in accordance with generally accepted standards for the
evaluation of compositions of this nature.  Much of the testing was done in
accordance with ASTM C593, Fly Ash and Other Pozzolans for Use with Lime.
The procedure specified in this ASTM test consists of the following steps:

          1.  Mixing of the dry materials until a uniform mixture
              is obtained.
          2.  Mixing in a specified amount of water that would
              closely correspond to the water required to produce
              a material that would be most efficiently compacted
              in the field (the moisture content obtained by the
              addition of this amount of water is known as the
              "optimum moisture content").
          3.  Molding cylindrical specimens (4 inch diameter by
              4.6 inches high) in accordance with a specified
              compactive effort.  The specimens are molded in a
              steel mold.  The material is placed into the mold
              in three equal layers and is packed in by the use
              of a steel drop hammer of specified weight and
              height of drop.
          4.  Curing (allowing the samples to gain strength) of
              the molded specimens for a specified period of time
              at controlled temperature and humidity conditions.
              The usual time periods are 7, 14, 28, and 90 days.
          5.  Breaking the specimens in compression at the end
              of the curing period.  Specimens are usually soaked
              in water for at least 4 hours prior to breaking.
                                     11-12

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                      Table II-7


Laboratories and/or Consultants That Contributed

   Laboratory Data on Kiln Dust Compositions
            Bowser-Morner Testing Laboratories, Inc.
            Toledo District
            5247 Secor Road, P.O. Box 5847
            Toledo, Ohio  43613

            Flood Testing Laboratories, Inc.
            1945 E. 87th Street
            Chicago, Illinois 60617

            Toledo Testing Laboratory, Inc.
            Toledo, Ohio  43624

            Department of Civil Engineering
            Construction Materials Research Group
            The University of Toledo

            Ernest J. Barenberg, PhD.
            Engineering Consultant
            617 W. Church Street
            Champaign, Illinois 61820

            David C. Colony
            Civil Engineer and Surveyor
            3648 Maxwell Road
            Toledo, Ohio 43613
                          11-13

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                         Table II-8






Sources of Cement Kiln Dust Used in Laboratory Testing







    General Portland Cement Co. - Tampa, Florida



    Ideal Cement Co.            - Galena Park, Texas



    General Portland Cement Co. - Paulding, Ohio



    Medusa Portland Cement Co.  - York, Pennsylvania



    Medusa Portland Cement Co.  - Cleveland, Ohio
                             II-1A

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          The following observations were made after reviewing the compres-
sive strength data:

          1.  Figure II-l shows the results of a number of com-
              pressive strength determinations.  It can be seen
              that the majority of the strengths at seven days
              are greater than 600 psi and went as high as 1,200
              psi.  Figure II-2 shows compressive strengths at
              7 days ranging from 420 psi to 1,150 psi (excluding
              the 4-6-90 mix which is not recommended).  It also
              shows • 28-day strengths ranging from 700  psi to
              1,400 psi.  These strengths are quite comparable
              to a typical lime-fly ash-aggregate composition.
              Recent work has shown that kiln-dust compositions
              can be designed for strength levels as required.
          2.  The 28-day compressive strengths showed an increase
              over the  7-day strength that was typical of cemen-
              titious products.  Although there was a significant
              variation, the average 7-day strength was about 75
              percent of the 28-day strength (see Figure II-2).
              It must be reported (but not verified) that some
              of the 28-day specimens were cured at lower temp-
              eratures during the period from 8 to 28 days.  If
              so, the percentage (75 percent) would be high.
          3.  In most cases, the 90-day strength was significantly
              greater than the 28-day strength.  On the basis of
              the limited data, the 90-day strength was approxi-
              mately 130 percent of the 28-day strength.
          4.  There were some instances in which 90-day compres-
              sive strength samples disintegrated when they were
              soaked in water in preparation for strength testing.
              This did not occur in the 7 and 28-day specimens and
              there was no apparent explanation for the phenomenon.
              It is quite likely that this was related to testing
              technique rather than a material characteristic.
              Additional data are required.
          5.  Strength gain was a function  of curing temperature.
              The compressive strengths increased significantly
              as the curing temperatures increased  from 558F to
              85°F.  A curing temperature of 100°F did not produce
              any greater strength than that produced by 85°F.
              This observation was based on limited data (see
              Table II-9).  Compressive strengths were obtained
              for one mix, using CKD from one source; and for 4
              different temperatures  (55°, 70°, 85°, 100°F).
              Additional, data are required to verify this performance.
                                      11-15

-------
                             y
                   ;   j         -
11-16

-------
                     Figure II-2
        COMPXESS/VE  STRENGTH
                 .or
        POZZOLANIC
        CEMENT K/LM DUST, f°L Y-
I

1
1
     tft
     /9 I
     /o
     ff
        X/U. L'»v £
if: O
   c
   UST)
                              , r
048
                                     32
                              L   'I    t   I
                   AT T£ST:
                     H-17

-------
                       Table II-9
 Compressive Strengths of  CKD-Fly Ash-Aggregate
Compositions Showing Curing Temperature  Effects
       (Strengths are in  Ibs. per sq.  in.)
Age
Days
7
14
28
Curing Temperature °P
55 70 85 100
0
370
706
502
675
912
813
987
1074
763
1029
1059
Note:  Mix composition  (by weight) was as  follows:
            - Cement Kiln Dust     8%
            - Fly Ash             12%
            - Aggregate           80%
       Specimens were compacted in accordance with ASTM  C593
                           11-18

-------
          6.  Twenty-nine sets of data out of 33 showed compres-
              sive strengths In excess of 400 psi which is the
              minimum requirement in ASTM C593; Fly Ash and Other
              Pozzolans for Use with Lime.  Most strengths were
              considerably in excess of the minimum requirements.
              ASTM C593 is generally regarded as a standard for
              lime-fly ash-aggregate road base compositions.  It
              is quite probable that the mix design of low strength
              specimens could be adjusted to provide suitable
              strengths.
          7.  The addition of small amounts (1 to 2 percent by weight)
              of portland cement produced a significantly higher
              compressive strength in laboratory specimens.  Additions
              of these small amounts may not be practical in field use.
          8.  There are indications that the reactivity of CKD varies
              depending on the source.  In one instance, where a com-
              parison was possible between four CKD sources, the
              strengths using one source were lowest in four out of
              five comparisons.   Except for an apparent anamoly in
              the data, it probably would have been low in all five
              cases.
          9.  The type of fly ash that was used in the compositions
              also appeared to affect the compressive strength.  Evi-
              dence of this was not conclusive because of limited
              comparable data.
         10.  The surface material 0 to 6 feet in one instance) of
              stockpiled kiln dust agglomerates and, even though it
              is pulverized, is virtually inert in producing any
              cementitious reaction.  In addition, it retains con-
              siderable moisture (in excess of optimum) which is
              difficult to reduce.
         11.  Moisture-density relationships that were determined
              for the kiln dust-fly ash-aggregate compositions show
              the usual result with a well-defined maximum dry density
              and optimum moisture content. A typical moisture-density
              curve is shown in Figure II-3.
         12.  The range of dry densities that were obtained on num-
              erous laboratory compacted test cylinders ranged be-
              tween 124 pcf and 135 pcf with an average of about
              130 pcf.  The corresponding molding moisture range
              was approximately 8 percent to 12 percent. In cases
              where the moisture contents were higher than 12 per-
              cent, the compacted densities were quite low indi-
              cating that the moisture content was too high.

          The preceding observations show that the compressive strength and
density characteristics of cement kiln dust, fly ash, aggregate compositions
are typical for stabilized materials.  In particular, they resemble closely
results that would be obtained with lime, pozzolan, aggregate compositions.
                                     11-19

-------
                          Figure II-3
                    REPORT OF PROCTOR CURVE
                                                                2/20/76

DoriiFrr- Pozz-0-Pac Time- Temp era tore- Strength Tests
LAB NO.
1522

niTPoiAt • Type 301 Crushed Limestone
SOURCE OF MATE
127
126
H- 125
u
a
_>
£
UJ
*
z 124
3





-
177
RIAL:





France Stone Company - Silica Quarry
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MOISTURE CONTENT. X
Tyr-pr~t«, Modified A.S.T.M. D-1557







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Maximum Dry Density	II	UM./CU. fu Optimum Moiuure Content    ' _
..S
                               11-20

-------
          Pur ability.  The resistance to freezing and thawing of compositions
containing CKD has been measured by the methods of ASTM C593.  This method
specifies that the compressive strength of vacuum saturated specimens should
be used as a measure of freeze-thaw durability.   A compressive strength of
400 psi is required on specimens that are vacuum saturated after being cured
for 7 days.  The results of a number of these tests are shown in Table 11-10.
The data represents compositions made from cement kiln dusts from five dif-
ferent sources.  In each case, the minimum strength required for acceptance
was obtained.

          Autogenous Healing.  There is significant evidence that  compositions
containing CKD possess the property of autogenous healing. Autogenous healing
is the property that enables compositions that gain strength slowly over a
long period of time to regain strength after their original strength has been
exceeded.  It is typically evaluated by testing specimens in compression that
have been previously tested to failure.  Table 11-11 shows a set of test data
from such an evaluation.  The property of autogenous healing is of obvious
benefit for a road base composition.  It insures that continual rejuvenation
of the structural capability of the base will take place over a long period
of time.  Damage to the pavement that is caused by temperature changes and
load applications is neutralized by the continuous healing.

Laboratory Test*"^ - Lime Kiln Dust

          Compressive Strength.  Compressive strength evaluations of potential
base compositions utilising lime kiln dust are preformed in a manner identical
to those where cement kiln dust is used.  The laboratory data that were avail-
able for  review on LKD were substantially less than for CKD.  The following
observations can be made about the compressive strengths of the mixtures con-
taining LKU.

          1.  Figure II-4  shows a plot of compressive strength
              data.  The range of 7-day  strengths is from 380
              ?si to 700 psi.  The 28-day strengths range from
              380 psi to 1,400 psi.  These strengths are on the
              order of one to tvo hundred pounds per square inch
              lower than a typical lime-fly ash-aggregate compo-
              sition..  As with CKD compositions, various strength
              levels can be obtained by proper mix design.

          2.  The 28-day compressive strengths showed an increase
              over the 7-day  strengths except for two relatively
              low strength coapositiotis (see Table 11-12).  Except
              fcr those two coapositions, the 7-day strength av-
              eraged 46 percent of the 28-day strength.  There was
              insufficient data available to draw any conclusions
              vith respect to the 90-day strengths.
                                      11-21

-------
                            Table 11-10

           FREEZE-THAW RESISTANCE  OP CKD COMPOSITIONS
           AS MEASURED BY THE COMPRESSIVE STRENGTH OF
                   VACUUM SATURATED SPECIMENS
Mix Formula (% by
Source of
CKD
General
Portland
Cement Co.
Medusa
Sylvania
Medusa-
Dixon
Marquette
Kansas City
Fly
CKD Ash
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
Portland
Cement
0
1
0
1
1
1
0
0
weight)
Aggregate
84
83
84
83
83
83
84
84
Vacuum Saturated
Compressive Strength*
psi
887
1433
1113
1683
666
825
960**
1110 (28 days)
 *Average of 3 strengths
**Average of 6 strengths
                                11-22

-------
 §

 5
 5;
                       Figure II-4
                            vs
             COM/=Vf£SS/V£
              AGE  AT TES
                          MIXTURES
                                   DUST
                /O  /S  20   25*
                         -  Days
f/y Ash
                     3?
7.L
                      86
                      3.0
                          3.0
//.O
            3.O
a/
7/.'o
                8.0
S_o
~/i.o
                         79
//.o
             /O.D
63_
//.o
    20.0
                         11-23

-------
  Mix**
                           Table 11-11
           Autogenous Healing of Laboratory Specimens
                         Containing  CKD*
  Original   Healing   Compressive   Strength After
Compressive    Time      Strength    Healing as a  %
  Strength    Weeks   After Healing   of Original
     psi                    psi
6-6-88
6-6-88
6-6-88
8-8-84
8-8-84
8-8-84
8-8-84
10-10-80
10-10-80
10-10-80
850
658
281
1147
989
934
558
1200
1167
581
7.3
10.9
6.3
7.3
3.9
10.9
9.9
7.3
10.9
5.3
952
836
448
1150
1506
1117
745
1213
1406
728
112
127
160
100
152
120
134
101
120
125
 *Data was obtained from Reference n-13.

**Mix gives composition by weight in the following order:

    CKD-Fly Ash-Aggregate
                                11-24

-------
                             Table. 11-12
   Compressive  Strengths of LKD-Fly Ash-Aggregate Compositions
                                  Compressive Strengths
LKD
8
10
8
9
10
20
6.4
8
Mixture
Formula
% by Weight

Fly
Ash Aggregate
12
12
11
11
11
11
7.6
6
80
80
81
80
79
69
86
86
7 Days
852
847
420
475
400
375
420
700
psi
28 Days
1580
1954
755
518
1050
375
1270
1370
90 Days
1626
1866
NA
NA
NA
NA
NA
NA
% of 2 8- Day
Strength
7 Days
54
43
56
92
38
100
33
51
90 Days
103
96
-
-
-
-
-
—
NA - not available
                                 11-25

-------
          3.  Moisture-density relationships that were determined
              for the kiln dust-fly ash-aggregate compositions
              show the usual result with a well-defined maximum
              dry density and optimum moisture content.  Dry
              densities that were obtained in a number of labora-
              tory compacted cylindrical specimens ranged from
              122 to 133 pcf at an average moisture content of
              10.9 percent.

          Durability Tests.  Limited data on freeze-thaw testing are avail-
able.  Table 11-13 shows data excerpted from a table shown in the patent
application (Reference II-3).  Figure II-5 shows a phenomenon that is typ-
ical of hydrated lime-fly ash-aggregate compositions.  That phenomenon is
the continued strength gain after 12 cycles of alternate freezing and
thawing.

          Those compositions that show a weight loss during freeze-thaw
cycles of 14 percent or less are considered to have satisfactory durability.
The data in Table 11-12 shows that this requirement can be obtained by  proper
mixture design.  The ability  of the material to gain strength after a long
period of adverse temperature variations indicates that any deterioration
caused during cold weather will tend to correct itself when the temperature
rises (probably at 55°F or higher).

Field Installation

          Cement Kiln Dust.  A number of field installations of road base
consisting of CKD-fly ash-aggregate compositions have been made and are
periodically being  evaluated.  Table 11-14 shows the locations and extent
of these installations together with other pertinent data.

          Specimens have been removed from some installations and tested in
compression.  The data obtained are shown in Table 11-15.

          The most complete documentation of the performance of a field in-
stallation has been made on a road base in a concrete plant drive in Silica,
Ohio (Reference 11-13).  Test strips of six different mixes, each 100 feet
long, were placed at this  location.  It is reported that "A total of 25,820
equivalent 8,165 kg (18,000 pounds) single axles were recorded in six months
with no cracking or surface damage visible except for a localized area."
In addition, deflection measurements and periodic compression tests of field
samples were performed.  The six compositions are given in Table 11-14, along
with other data relevant to the project.

          Deflection measurements, made with a Benkelman Beam, generally
decreased with time, an indication that the pavement structure was becoming
stiffer with time.  The compressive strengths of field samples were obtained
after the base was in use for six months and for almost one year.  These
strengths are shown in Table 11-16.
                                     11-26

-------
       Mixture
Formula  (% by Weight)
      Fly
 LKD  Ash  Aggregate
       Table 11-13

 Freeze-Thaw Test Data

    LKD Compositions

                   Compressive
% Weight Loss        Strength
after 12 cycles  after  12  cycles
of freeze-thaw   of freeze-thaw
                        psi
  Compressive
Strength after
 re curing-ps i
8
8
8
8
8
8
8
8
8
8
8
8
10
10
10
10
10
10
12
12
12
12
12
12
82
82
82
82
82
82
80
80
80
80
80
80
5
4 806
3 1180
3 1075
3 396
5
18
17
21
10
30
8

    Source:  Sefereace II-3.
                                    H-27

-------
    12 -
    11
                    12 Freeze-Thaw Cycles
                  10     15    20    25    30

                                Time:  Days
35
•45
50
55
Figure II-5.  History of cylinders with 10 percent fly ash  and  8 percent
              "lime" (precipitator dust).
                                     11-28

-------
               Table 11-14
DATA ON FIELD  INSTALLATIONS  -  CKD ROAD BASE COMPOSITIONS
NAME
&
l nrATTftN


SILICA, OHIO
PLANT ROAD


MEADOWBROOK
ESTATES
STREETS &
MOBILE HOME
PARK
TOLEDO EXPRESS
AIRPORT
PARKING LOT

SHERWIN
WILLIAMS CO.
PLANT DRIVES,
CHICAGO, ILL.
JOHN OUSKY
PARK -
PARKING LOT
OREGON, OHIO
DATE
"s
TA


11/5/77



Oct
1976


Nov
1978

10/19/77

10/21/77

LENGTH
&

WIDTH

Six strip
each 100'
long


LF 2670'
W 24 '-36'
LF 220'
W 24'


5000 ay

LF 500'
W 30'

6000 ay

ROAD BASE DESIGN
THICKNESS
_


10



5
5


a

6-10"

5"-6"

MIX FORMULA (2 by weight)

CKD
-
8
10
12
8
8

8
8


10

9

8


FLY
ASH
6
8
10
12
8
8

8
a


10

10

8

PORTLAND
CEMENT
o
0
0
0
0.5
1

0
1


0

0

1

AGGREGATE
ft a
84
80
76
83.5
83

84
83


80

81

83

AGGREGATE
TYPE



Ohio spec.
301
crushed
aggregate

*
Ohio 304
Ohio 304


Ohio 304

Illinois
CA-6

Ohio 304

SOURCE
OF
CKD


Medusa
Cement Co.
Silica,
Ohio

General P C
Paulding
General P C
Paulding

General
Portland
Cement Co.
Paulding OH
Universal
Atlas
Buff ington
Indiana

General
Paulding

DESCRIPTIO
OF
SURFACE


Double
"tar 6
chip"
Seal Coat


2"
2"


2" BT

3-1/2" -
4"

2" BT


-------
                            Table 11-15

    Compressive Strength of Specimens  from Field  Installations
                                                Compressive Strength
             Construction    Type of     Date         psi
  Project        Date        Specimen   Sampled  Ave.    Range


Meadowbrook                  3" cubes   5/26/77   780l  660-950
  Estates      Oct. 1976

Centennial     Nov. 1977     Various    9/30/78  13853 1056-1826
   Plant                     sizes of
                           re ct an gul ar
                             solids2

Sherwin Williams             4" dia.   10/20/78  1511" 1352-1639
Chicago, 111.  Oct. 1977     cores

	n_	6/20/80  1083s	


15 test specimens

2Vary from 3-1/2" x 4-5/8" x 6-3/8" high to 6" x 6-3/8" x 4-1/2"
 high

39 test specimens

"4 test specimens, vacuum saturated.

56 test specimens
                                 11-30

-------
                              Table 11-16*

               Compressive Strengths of Field Samples

                  (from test  strips, Silica,  Ohio)
Mix Formulation  (% by weight)

          Portland   Crushed
CKD  Ash   Cement   Limestone
Compressive Strength (on dates shown)
                psi
            Dates Tested
5/10/78  5/17/78  10/16/78  10/17/78
6
8
10
8
8
6
8
10
8
8
0
0
0
1/2
1
88 1177
84 612 1540
80 611
83-1/2 251 1231
83 811


1438

355
*Data were obtained from Reference H-13.

NOTES:

 - Road base was constructed November 5,  1977.

 - All strengths are the average of  3 samples.
                                 11-31

-------
          Dr. Ernest Barenberg of the University of Illinois, a recognized
expert in the performance of stabilized road bases, inspected the Sherwin-
Williams Co. plant drives in June of 1980, approximately three years after
they were constructed.  He reported that the installations were in excellent
condition.  There was only a slight amount of cracking which is typical of
stabilized bases of a similar type.  The  bituminous wearing surface was
adhering properly to the base material.  The pavement was cored at the time
of the inspection.  The mix formulation and other information relevant to
this project are shown in Table 11-14.  The compressive strengths of the
cores  are included in Table 11-15.  Split tensile tests were also run on
some of the cores.   An average of  204 psi tensile strength was obtained
on 9 specimens.  In this case, the tensile strength was approximately 20
percent of the compressive strength.  This is somewhat higher than the 10
to 12 percent normally anticipated.

          Lime Kiln Dust.  The Chicago area has been using a "polyhydrate"
lime in lime-fly ash-aggregate compositions for several years. "Polyhydrate"
lime can contain as much as 80 percent lime kiln dust and 20 percent quick-
lime.  This experience has been successful and illustrates an application
of LKD but one that has previously not been identified as such.

          The first field application of lime kiln dust using the formula-
tions discussed in this report is scheduled for early November 1980 in the
Toledo, Ohio area.  Developers of the material feel that it will perform
in a manner similar to the cement  kiln dust compositions.  This is based
on the fact that the major constituent of Portland cement is limestone and
the sole constituent of lime is also limestone; therefore, the dust result-
ing in the processes should be similar.  An examination of the chemical
compositions of each that are shown in Tables II-l and I1-3 indicates that
there is a close similarity between  cement kiln dust and high calcium lime
kiln dust.

SUMMARY ASSESSMENT

          The documentation that is available shows that kiln dust, fly ash,
aggregate compositions have considerable potential in a road base applica-
tion.  We would generally  agree with a statement contained in a report
"N-Viro-Crete, A Current Evaluation, 1978" by D. C. Colony, PhD., Professor
and Chairman of Civil  Engineering, University of Toledo, as follows:
"Substitutions of CKD in place of lime to obtain a pozzolanic mixture pro-
vides at least three advantages.

          a.  Lower cost of material.
          b.  Enhancement of the environment by consumption of
              waste products which would otherwise require the
              use of  land and other resources to store in a
              proper manner.
          c.  Lower energy consumption per mile of pavement,
              since both fly ash and CKD are by-products re-
              quiring virtually no energy for their own pro-
              duction."
                                     11-32

-------
          The laboratory data, which is mostly compressive strength testing
of various compositions, shows a striking similarity to that obtained with
proven hydrated lime, fly ash, aggregate road base compositions.  This helps
to substantiate the viability of using kiln dust in these applications.

          The acquisition of additional data is an ongoing process.  Repre-
sentatives of N-Viro Energy Systems, Ltd., Toledo, Ohio, one of the principal
protagonists of the system, state that various strength levels of the compo-
sitions can be achieved by proper mix design.  This will insure that the
compositions will be able to meet strength and durability requirements.  It
has also been stated by them that this will increase the flexibility of the
system beyond that which is possible with lime, fly ash, aggregate materials.

          There is also evidence to show that the  variability of kiln dust,
which is one of the chief disadvantages claimed by some,  is not as great or
as significant as has been stated (Reference 1-15).  Sampling procedures for
the kiln dust in the past appear to have largely  ignored good sampling tech-
niques and the process by which the material is produced and stored.

          Studies are now underway to verify the consistency of the signif-
icant properties of cement kiln dust when the material comes from a given
location in the collection process.  There appears to be no reason why the
kiln dust should vary significantly if the raw materials and operating pro-
cedures of the plant remain constant.  It is obvious that control of these
two factors is also of vital importance to the quality of the primary pro-
duct—cement or lime.

          Five field installations of road base containing kiln dust prove
that the material can be successfully used.

          It is obvious, however, that there are significant gaps in the
information that is available.  This  is particularly true with regard to
durability.  There is also a need for larger; fully documented experimental
field installations that will provide the type of information that will be
convincing to potential users of road base materials.  The Federal Highway
Administration (supported by the U.S. Department of Energy) requested and
received proposals for the evaluation of Kiln Dust-Fly Ash Systems for Pave-
ment Bases and Sub-bases (RFP #DTFH61-80-R-00056) in January 1980 and was
awarded to Valley Forge Laboratories in February 1980.  This project is a
laboratory evaluation with a followup proj ect involving experimental instal-
lations in three states is planned.  Projects of this type will go a long
way toward providing some  of the additional documentation that is required.

          Kiln dust is a promising material whose use should be developed
by support of experimental work, including field demonstrations, that will
prove its value.  It is essential  that the combined FHWA-DOE project,
described briefly in the previous paragraph, be implemented without delay.
                                     11-33

-------
EPA should monitor this project so that as soon as sufficient information
becomes available it may influence guideline decisions.  There are strong
reasons for utilizing kiln dusts, beyond their applicability in highway
construction.  Of great importance among these reasons is the energy sav-
ing involved in the use of a material that requires virtually no additional
energy in its production and a much reduced energy consumption during con-
struction when compared to  materials it would replace.  There are also en-
vironmental and economic benefits derived from reduced disposal requirements.
                                     II-34

-------
                                  Part II

                                REFERENCES
II-l      U.S. Patent #4,018,617, Mixture for Pavement Bases and the Like,
          and #4,101,332 Stabilized Mixture.

II-2      What is CKD?. June 1979 issue of Rock Products.

II-3      U.S. Patent #4,038,095, Mixture for Pavement Bases and the Like.

II-4      Report of Second NLA Dust Disposal Survey prepared by Kenneth A.
          Gutschick, National Lime Association, June 1977-

II-5      July 21, 1977 issue of The Blade, Toledo, Ohio newspaper quotes
          J. E. Poole, President and Chairman of the Board, Marquette Co.,
          a major cement producer.

II-6      Pit and Quarry. March 1979.

II-7      July 21, 1977 issue of The Blade, Toledo, Ohio newspaper quotes
          J. Patrick Nicholson, President and Chief Executive Officer of
          Nicholson Industries Co., Inc., Toledo.

II-8      Portland Cement Plants, U.S., Canada, and Mexico  (a map) published
          by Pit & Quarry, 105 West Adams Street, Chicago,  Illinois 60603,
          1980.

II-9      Rough draft of Section IV.6 report by Research Group No. 12 of the
          Organization for Economic Cooperation and Development.

11-10     Elimination of Water Pollution by Recycling Cement Plant Dust -
          N. R. Greening, Richard J. Hinchey, and Hikaru Nagao, Skokie,
          Illinois:  Portland Cement Association,  1973.

11-11     Commercial Lime Plants in U.S. and Canada (map) published by National
          Lime Association, Washington, D.C., 1978.

11-12     Lime in 1977 (Annual Advance Summary) Mineral Industry Surveys, U.S.
          Department of the Interior, Bureau of Mines, Division of NonMetallic
          Minerals, September  1978.

11-13     Draft, Pozzolanic Concrete Base Courses Using Cement Kiln Dust and
          Fly Ash; Miller, Bensch, and Colony, prepared for presentation at
          the 59th Annual Meeting, Transportation Research  Board, 1980.
                                      11-35

-------
11-14     Utilization of Waste Kiln Dust from the Cement Industry; Thomas A.
          Davis and Don B. Hooks, Proceedings of The Fourth Mineral Waste
          Utilization Symposium, 1974.

11-15     Interviews with J. Patrick Nicholson, Chief Executive Officer,
          N-Viro Energy Systems, Ltd.,  Toledo, Ohio, and Steven A. Hayden,
          Vice President-Operations, Keystone Portland Cement Company,
          Bath, Pennsylvania.
                                     11-36

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                                  Part  III

               USE OF ASPHALT-RUBBER IN HIGHWAY CONSTRUCTION
INTRODUCTION
          Asphalt-rubber is a mixture of a  blend of various types of rubber
with asphalt.  The mixture may be modified with an extender oil or by the ad-
dition of kerosene.  The rubber blend is  mixed with asphalt after the asphalt
has been heated to 350° to 425°F.  Heating of the mixture is continued for a
period of between 30 and 90 minutes.  It is applied while hot.  In those high-
way applications where the material  is applied in a layer which will be sub-
jected to traffic, a layer of stone  (chips) is immediately spread and rolled
into the still hot asphalt-rubber.

          The recovered material in  asphalt-rubber  is the rubber.  The rubber
consisting of vulcanized and devulcanized, natural and synthetic is obtained
from scrap automobile and truck tires.  Special purpose processing plants re-
duce the rubber to a granulated or ground form in accordance with a given
specification.  The rubber usually is reduced to a size such that 100 percent
is finer than a #10 sieve (2.00 mm opening).

          Asphalt-rubber is a relatively new material, being a man-made mixture
that does not occur in nature.  It was originally developed sometime in the
early 1960s, and was first used in a limited field test in 1964.  A summary
of its development since that time is presented in Table III-l.

APPLICATIONS

          There are seven present and potential applications for asphalt-rubber:
1) chip seals;*  2) SAMI-stress absorbing membrane interlayer;  3) encapsulating
membrane;  4) crack and joint sealant;  5) bridge deck waterproofing;  6) hot-
mix  binder; and 7) roofing material.

          The present study is concerned primarily with uses (1) and (2) above,
although reference will be made to uses (3) and (4) which appear to have pro-
gressed beyond the experimental stage.  Uses C5) to (7) inclusive are still very
auch in  the experimental period and will not be considered.
* When chip seals are  used over a distressed  (severely cracked) pavement it
  is scmetises referred to as SAM-stress absorbing membrane.  If it is cov-
  ered vith an overlay it becomes a SAMI.
                                     III-l

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                                Table III-l
Early 1960s
1964-65

1967


1968



1968
1968-71

1971-73
1973


1974-75


1975
1976


1976 on
1980
HISTORY OF THE DEVELOPMENT OF ASPHALT-RUBBER

     Early experimentation by Charles H. McDonald who is
     credited for originating the concept of using a rela-
     tively large amount (25 percent) of granular rubber in
     the asphalt-rubber mixture.  Mr. McDonald was an engi-
     neer with the City of Phoenix, Arizona.

     Field trials were initiated in Phoenix.
                         *
     First full-scale field trial—taxiway at Phoenix Sky
     Harbor Airport.

     Sahuaro Petroleum and Asphalt Co., Phoenix, Arizona
     began to develop the formulations, construction tech-
     niques, and special equipment.

     Arizona Department of Transportation became interested
     in the concept for preventing reflection cracking.
     Placed 2-1/2 miles of asphalt-rubber seal on freeway
     frontage and access roads.

     ADOT and other public agencies placed several projects.

     Three special projects known as the Aguila, Flagstaff,
     and Minnetonka Projects were carried out by ADOT.  The
     Minnetonka Project was part of the NEEP program on Pre-
     vention of Reflective Cracking in Overlays.

     Publication of Implementation Package 73-1, Rubber-Asphalt
     Binder for Seal Coat Construction, by FHWA.

     A second commercial producer, Arizona Refining Co., Phoenix,
     Arizona enters the field.

     Arizona DOT implements the use of stress-absorbing membrane
     interlayer (SAMI) as standard procedure for all overlays
     less than 4-inches in thickness that are placed over cracked
     pavements.

     FHWA implemented Demonstration Project No. 37, Discarded
     Tires in Highway Construction.

     Continued application of the asphalt-rubber concept by
     Arizona DOT, City of Phoenix, Corps of Engineers, Pro-
     vince of Saskatchewan, and many other agencies.  Somewhere
     between 35 and 42 states, several Canadian provinces and
     organizations in Australia, England, and the Scandanavian
     countries have been involved in use of the materials.

     Genstar Conservation Systems, Inc. begins production of
     crumb rubber in a new and innovative tire recycling plant
     in Phoenix, Arizona.
References:  III-4, III-6, 111-27, and 111-28.

                                     III-2

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Crack Control

          The consensus is that asphalt-rubber is a unique product having
distinct properties that enhance its use as a paving material in rather well
defined situations.  It has been particularly effective as a technique for
restoring and increasing the life of distressed  (cracked) bituminous pave-
ments.  Highway pavements, portland cement concrete as well as bituminous,
are subjected to destructive forces such as traffic and climate immediately
after they are put into service.  Eventually these forces cause deterioration
of the pavement to the extent that corrective measures are required.  In many
cases the pavement is severely cracked and may be marked with a substantial
number of pot holes.  In the past, bituminous overlays of one inch or more in
thickness have been used over the cracked pavement in order to restore its
serviceability-  One of the disadvantages of this type of remedy has been that
in a relatively short period of time cracking of the overlay occurs at the
same places that the original distressed pavement was cracked.  These cracks
in the overlay  are commonly referred to as "reflection" cracks.  The elimi-
nation or control of reflection cracks is possible by the proper use of as-
phalt-rubber.

          An understanding of the various types of cracks that occur in high-
way pavements is necessary in order to understand why asphalt-rubber is ef-
fective in their control.  There are  three types of cracks:

          •  fatigue cracking—due to repeated deflection of the
             pavement caused by traffic loads.

          •  cracks caused by direct tensile  strength—usually
             caused by temperature change or shrinkage of the
             pavement material.

          •  cracks caused by differential vertical movement
             (Reference III-l).

          The formation of these cracks is resisted by  a material that has
sufficient elasticity that will enable it to deform under stress without
rupturing.

          The use of rubber in asphalt has a direct effect on two important
properties:  (1) it improves the elasticity of the asphalt; (2) it reduces
the susceptibility of the asphalt to changes in temperature.  It therefore
makes the asphalt-rubber more elastic and keeps it in this condition at temp-
eratures 20 to 30°F lower than conventional  asphalt (Reference III-2).

          When the layer of asphalt-rubber and chips is placed as a surface
layer (SAM) on top of a cracked pavement it has been shown to be effective
in controlling fatigue cracks.  The underlying cracks do not come through
the SAM for a much longer period of time than if a conventional  seal coat
is used.  As an interlayer   (SAMI), where a 2-inch to 4-inch bituminous
overlay is added on top, it appears to control all types of cracking.  In
this case the underlying cracks will not be reflected through the overlay.
In both these instances little or no maintenance is required for extended
periods.
                                      III-3

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          One of  the most comprehensive analyses made on the effectiveness
of asphalt-rubber for crack control is presented in Reference 111-10.  This
case study was conducted in conjunction with Federal NEEP Project, Number 10 -
Reducing Reflective Cracking in Bituminous Overlays.  Eighteen selected road-
way test sections were evaluated in this study which was carried out on a 9-
mile section of  Interstate 40 near Winslow, Arizona.  Among five treatments
"found to have significantly reduced cracking" were listed:  "Asphalt-rubber
membrane seal coat under ACFC*" and "Asphalt-rubber membrane flushed  into
asphaltic concrete overlay".  The report also recommended that one of the
five treatments "be used in conjunction with a thin overlay (less than 4
inches of AC)".  In 1978, 6-1/2 years after construction, the asphalt-rubber
membrane seal coat under ACFC showed the least amount of reflective cracking
of the 18 test sections.  By that time the highway had been subjected to over
1,000,000 18 kip equivalent loads.  The following statement is also included
in the above report:  "As a result of this project and other evidence, ADOT
implemented in 1975 the use of the stress absorbing interlayer (SAKE) as
standard procedure for all overlays under four inches in thickness that are
placed over pavements where cracking is a  problem."

          A recent analytical study (Reference III-3) has also determined that
"the effect of including a low modulus interlayer (rubber asphalt) can be sig-
nificant in the inhibition of reflection cracking resulting from both load
and temperature changes,..."

Waterproofing

          When  asphalt-rubber is used as a waterproofing layer it is referred
to as an encapsulating membrane.  It has been used successfully in a number of
cases to prevent water from entering expansive soils that make up the subgrade
(foundation) of highway and airfield pavements.  Moisture increases in expan-
sive soils causes them to increase in volume with a subsequent buildup of high
pressures under the pavement.  These  high pressures will raise the pavement
(cause heave).  Since this phenomenon  rarely occurs in a uniform manner,
differential heave or vertical movement will occur.  This will create an un-
even riding surface and, more seriously, unusual stress conditions that will
significantly reduce the life of the pavement.

          If, in this application, the asphalt-rubber layer is in an area that
will be subjected to traffic, it will be covered with stone.  If it is in an
area not subjected to traffic, such as on the side  slope, no stone cover is
necessary.

Crack or Joint Sealant

          Asphalt-rubber is poured while hot into cracks or joints in pavements
for the purpose of sealing them against intrusion of dirt and water.  This ap-
plication is similar in nature to that of other asphalt products.  No stone
chips are added.  The high elasticity enables the material to adjust to defor-
mations caused by load or temperature stresses.
* ACFC stands for Asphaltic Concrete Friction Course.


                                     III-4

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COMMERCIAL AVAILABILITY OF PRODUCTS CONTAINING RECOVERED MATERIALS

          The current situation can be summarized by pointing out that volume
use of the asphalt-rubber product has occurred in only one state—Arizona.
The asphalt-rubber product is readily available from two suppliers.  The re-
cycled rubber that goes into the asphalt-rubber is obtained from out of state
sources in California and Mississippi.  This, too, is readily available and
of satisfactory quality.  A new modern facility for processing recycled rubber
is under construction in Phoenix and is scheduled to go into production in
early 1980.  As for future availability, facilities will be forthcoming as the
market develops.  There is an ample supply of scrap tires. Plants for recycling
the rubber are scattered throughout the country and a new plant can be put into
service within 12 to 15 months of a decision to proceed.  Special distributor
trucks have been manufactured by Bear Cat Manufacturing Company of Wickenberg,
Arizona.  In addition one of the processes uses conventional distributor trucks
that are available from several sources.  The lack of availability of personnel
experienced in the use of asphalt-rubber could be a temporary bottlenect to de-
velopment.  With the probability that use  of the product will develop slowly
over a long period of time there does not appear to be any constraint due to
availability of the recovered material.

          There are two companies that provide  asphalt-rubber in Arizona.
Both are located in Phoenix.  They are Sahuaro Petroleum and Asphalt Company
and Arizona Refining Company.  The asphalt-rubber products that are produced
by these companies are not identical.  A comparison of the two materials is
show in Table III-2.  Projects supplied by one supplier date back to 1962
while the other supplier has more recently entered the field (1975).  The re-
sults obtained by each supplier appear to be comparable.  It is difficult,
however, to fully  document this conclusion because of the disparity in the
length of history of each.

          In assessing the ability of asphalt-rubber suppliers to meet the
demand, the following aspects have been studied.

          1.  Availability of recycled rubber.
          2.  Availability of the asphalt-rubber mixture
              (including availability of equipment).
          3.  Availability of experienced personnel to
              insure proper construction.
          4.  Industry demand for asphalt-rubber.

Availability of Recycled Rubber

          The raw material from which recycled rubber is obtained consists of
scrap tires from both automobiles and trucks.  It has been determined that there
are 200 million automobile tires  (Reference III-4) and 40  million truck  tires
scrapped each year.  In addition, an estimated 1-1/2 to 2 million tires are re-
coverable in stockpiles or landfills.  Approximately 20 pounds (Reference III-5)
of recycled rubber can be obtained from each passenger car tire.  If it is as-
sessed that this applies to truck tires as well as automobile tires, a total of
2,400,000 tons of recycled rubber could be produced annually.
                                      III-5

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                                                    Table  III-2

                                        COMPARISON  OF  ASPHALT-RUBBER PRODUCTS
H
0>
        Supplier

        Sahuaro Petroleum
        & Asphalt Company
        Arizona Refining
        Company
   Asphalt-Rubber Composition —
 Rubber       Asphalt       Other
Ambient
ground 25%
by weight of
asphalt-rub-
ber mix
AR-1,000
or 120-150
pen.
40% pow-
dered devul-
canized rub-
ber, 60% pow-
dered vulcan-
nized rubber
with a 30%
minimum nat-
ural rubber
contant. 20%
+2% by weight
of asphalt-
rubber mix.
AR-4,000
or 8,000.
                          Distributor
                             Trucks
7% kerosene Special-con-
is added to tains pugraill
control     mixer, heater,
viscosity   heat controls,
            load cells, and
            automatic vis-
                 Mixing
                 Process

                 Performed in
                 special dis-
                 tributor
                 truck. Rubber
                 added manu-
                 ally. Process
               Remarks

               Mixing temp. 350-
               400°F. Application
               temperature 375-
               425°F.
                                                                        coslty measure-  is  closely
                                                                        ment              monitored
2-6% aro-
matic ex-
tended oil
(luboex-
tract) is
added if
asphalt is
deficient
in aromatic
oil.
Conventional
Bath process   Mixing temp. 350-
in any tank    400°F. Application
that provides  temperature 375-
for mixing by  425°F.
recirculation,
stirring, air
agitation, or
other appropri-
ate means &
heat exchanger
& temperature
controls. 2/
        If  ARCO ARH-R-SHIELD process is detailed in U.S.  Patent  4,068,023.
        2J  Claimed that mixing can be done in conventional pressure distributor truck.

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          At an application rate of 4-1/2 pounds or 0.6 gallon per square yard
for the asphalt-rubber, 8,000 pounds  (4 tons) of rubber would be required per
lane mile.  There is, therefore,  a potential for supplying sufficient rubber
to place the asphalt-rubber chip seal on 600,000 lane miles of highway per
year.  It is difficult to obtain the number of lane miles that have already
been placed.  Approximately 200 lane miles have been placed in the City of
Phoenix with an additional equivalent of 51 lane miles on the south runway
of Sky Harbor Airport (Phoenix) (Reference III-6).  Reference III-l is based
on the "Results from approximately 2,000 lane miles of construction...".  The
report was prepared in 1975.  Since that time asphalt-rubber was placed on an
estimated 200 kilometers of 2-lane low traffic roads (250 lane miles) (Ref-
erence III-7) in the Canadian province of Saskatchewan as of spring 1980.
The anticipated production for 1980 was 186 kilometers or 230 lane miles.
The results have been so encouraging that the use of asphalt-rubber on low
cost roads in Saskatchewan is almost routine.  There are approximately 6,000
miles of these roads, with ADT no greater than 800 vehicles per day, in the
Province.  In an article on Asphalt Rubber in the April 1979 issue of Construc-
tion West Magazine, Gary Heiman of the Saskatchewan Highway and Transportation
Department is quoted as follows:  "Just from rough calculations we are looking
at using all the rubber we can get our hands on in Saskatchewan.  Even on the
pessimistic side we're looking  at requiring 7,000 tons* a year."  In the same
publication he is also reported to have said that the future of rubberized
asphalt in Saskatchewan will depend on the supply of rubber and its cost.
Additional mileage of experimental sections has been placed throughout the
United States in connection with the FHWA Demonstration Projects.  It is be-
lieved that the total usage would be less than 10,000 lane miles.  Sahuaro
Petroleum and Asphalt Co. says in promotional literature "Proven on over 8,000
lane miles."  Even with these rough figures, it can be seen that the potential
supply of recycled rubber would far exceed the demand for its use in highways.

          A crude forecast of total usage of asphalt-rubber could be based on
the experience, to date, in Arizona.  If the 2,000 lane miles constructed in
Arizona was assumed to occur between the first full scale trial (1967) and
1975, a period of 8 years, the production rate would be 250 lane miles per
year.  This would use 1,000 tons of rubber annually.  Assuming that this would
be the average consumption  in each state, a total of 50,000 tons would be in-
volved.  This would represent about 2 percent of the potentially available rub-
ber in scrap tires.  It has been reported that Sahuaro Petroleum and Asphalt
Co., probably the largest producer of asphalt-rubber, produced 15,000 tons  in
1979 (Reference III-4).  This quantity of asphalt-rubber would utilize 3,750
totis cf  rubber or about 0.15 percent of the potential.
* 7,000 tens vculd. surface approximately 875 miles of  2-lane road.
                                      III-7

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CHARACTERISTICS OF THE RUBBER USED IN ASPHALT-RUBBER MIXTURES

          For the most part, the rubber used in the asphalt-rubber mixture
is an ambient ground  product with approximately 100 percent finer than 2
milimeters.  The introduction of rubber into the asphalt is intended to im-
prove the resulting binder in three ways:

          1.  Improve its response to temperature change by
              reducing the temperature at which it becomes
              "glassy" and increasing the temperature at
              which it softens.

          2.  Improve its long-term durability.

          3.  Improve its ability to adhere to aggregate.

          There are essentially three types of rubber than can be included
in the rubber component of the asphalt-rubber mixture: natural, synthetic,
and devulcanized (also called "reclaim").  The natural rubber contributes a
high degree of elasticity and tackiness to the rubber product; the synthetic
rubber provides toughness and resilience; and the devulcanized rubber is more
easily dispersed into the asphalt.  The  particle size of the ground rubber
is important.  The finer rubber has greater surface area and thus probably
speeds up the asphalt-rubber reaction.

          Manufacturing of ground rubber consists essentially of six steps:
tire shredding; metal removal; fabric removal; grinding; sizing; and pack-
aging.  A brief description and flow chart of the new plant in Phoenix,
Arizona of Genstar Conservation Systems, Inc. is contained in the Appendix.
With plants such as this, a carefully controlled rubber product can be fur-
nished to the asphalt-rubber producers.

AVAILABILITY OF THE ASPHALT-RUBBER MIXTURE (INCLUDING AVAILABILITY OF EQUIPMENT)

          There are two suppliers of the asphalt-rubber mixture in Phoenix,
Arizona.  These companies operate not only  in Arizona, but throughout the
United States.  One company is capable of supplying, with their present
capacity, 100 tons of asphalt-rubber per day.  Approximately 15.8 tons of
asphalt-rubber is used per lane mile.  At these rates, it would be possible
to supply 6.3 lane miles per day.  Since their system involves the use of
conventional distributor trucks, they could provide additional capacity
quickly.  The heating of the asphalt and the mixing of the rubber with the
hot asphalt takes place in the distributor truck.  After allowing the proper
time for the asphalt-rubber to take place, the material is sprayed on the
roadway.  It is necessary for the distributor truck to be in good operating
condition.
                                     III-8

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          It was not possible to obtain accurate information on the capacity
of the other supplier.  This company uses special distributor trucks.  In
early 1978 it was reported that they owned 16 of these trucks.  They send
their trucks all over the United States and into Canada.  A route is estab-
lished in the early part of the construction season that enables them to
start work in the warmer locations and to proceed  to the colder areas.  The
company maintains that they have no problem in handling the present demand.
Only a few months would be required from the time an order is placed for a
special distributor truck until delivery of the truck is made.  This might
create a temporary inability to satisfy the demand should there be a sudden
and dramatic increase in this demand.  The possibility of such a shortage
developing does not appear to be realistic.

AVAILABILITY OF EXPERIENCED PERSONNEL TO INSURE PROPER CONSTRUCTION

          Assuming that adequate specifications relating to design, materials
quality control, and construction have been developed, there are two opera-
tions that require the availability of experienced personnel.  They are:
(1) acceptance testing of materials and  the design of satisfactory mixtures
in cases where materials are to be combined; and  (2) the actual construction
work in which the material(s) is utilized.  The most often used statement by
people who work with asphalt-rubber was "good results are obtained if it is
used properly by people who know what they're doing."  At least one person
should have intimate knowledge of the laboratory procedures and one should
have detailed knowledge of the construction practices in each jurisdiction
in which the material is to be used.   The jurisdictions would include the
city, county, and state agencies that are normally responsible for conducting
these activities..  These individuals would then be available to train addit-
ional personnel in the techniques that are peculiar to the materials.

          In addition to the requirements for trained personnel on the part
of the users, it will be necessary to have their  counterparts in the employ
of the producers.

          The Federal Highway Administration through its Demonstration Pro-
jects Program FHWA-DP-37, has initiated a technology transfer activity that
will support the training of new personnel.  As of September 1979, asphalt-
rubber projects were constructed or planned in 23 states. It is estimated
that a total of 70 individuals either experienced laboratory or construction
people were introduced to  the techniques of using asphalt-rubber.

INDUSTRY  DEMAND FOR ASPHALT-RUBBER

          It is extremely difficult to quantify the demand for asphalt-
rubber in its two major uses as a chip seal and as a stress-absorging
membrane interlayer.  The  amount of potential demand would be related to
the amount of serious deterioration in the condition of existing pavements.
The evidence suggests that both of the above applications should be used
                                      III-9

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  only on pavements that show excessive cracking.  It is apparent that many
  existing roadways are approaching this condition.  It can at least, then,
  be assumed that there will be substantial potential demand for a product
  such as asphalt-rubber that is effective in controlling the reflection*
  of these cracks.

  COST OF ASPHALT-RUBBER  AND COMPARISON WITH COMPETING SYSTEMS

            Proponents of the SAM and SAMI approach to restoring deteriorated
  pavements claim that the asphalt-rubber chip seal performs a unique function,
  that of preventing reflection cracking.  There is no other established method
  of doing this effectively that would enable a one to one cost comparison to
  be made.  This limitation is further complicated by a lack of well documented
  data that would provide a base for life-cycle cost comparison between com-
  peting systems.  It is clear that many potential users consider asphalt-rub-
  ber to  be "expensive" as far as initial cost is concerned. Some of these
  potential users have not been convinced by the available data and evidence
  of precisely what the long-term economic benefit is.  In the present atmosphere
  of belt tightening that exists in most state highway departments, first cost
  considerations are becoming more and more important.  In summary, (1) com-
  paring the cost of asphalt-rubber with competing systems is hazardous, (2)
  first cost of asphalt-rubber is high and this could serve as a deterrent to
  the further development of its use, (3) a reliable data base documenting long
  term improvement in pavement serviceability is necessary, and (4) a life cycle
  cost analysis is needed in order to address the question of economic benefit.

            The following cost information has been developed.  The cost of an
  asphalt-rubber chip seal where the asphalt-rubber is applied at 0.6 gallon
  per square yard with 40 pounds per square yard of chips is $1.25 per square
  yard.** The source of this information contains the following introductory
  statement:  "A research study has shown  that an Arm-R-Shield*** surface
  treatment, followed by a 3/4-inch thick conventional overlay, is as effec-
  tive, and sometimes more effective, as four inches of regular asphalt con-
  crete overlay when it comes to resisting reflective cracking.  So, the thinner
  resultant structure reduces construction costs, even though Arm-R-Shield is
  more expensive than regular aspahlt.  A subsequent cost comparison shows
  that the Arm-R-Shield plus the 3/4-inch overlay would cost $2.59 per square
  yard which is $3.16 per square yard less than the $5.75 per square yard for
  the 4-inch overlay.
  * Reflection cracks are cracks that are propogated through a  layer  of material
    that is placed on top of existing cracks.
 ** From a cost analysis prepared by Arizona Refining Co.  entitled ARM-R-SHIELD,
    Cuts Resurfacing Cost in Half, Saves Energy,  Consumes  Old Tires.   (See Ap-
    pendix for the entire analysis.)
*** Arm-R-Shield is Arizona Refining Company's trade name  for the asphalt-rubber
    mixture.
                                       111-10

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          Other cost estimates obtained were:   (1) the asphalt-rubber chip
seal is equivalent to 1-inch of asphaltic concrete which would mean between
$1.00 and $1.25 per square yard (Reference III-5) and (2) the asphalt-rubber
is equivalent to a 1-1/4-inch asphalt overlay or $1.50 per square yard  (Ref-
erence III-8).

          The City of Phoenix reported the following costs (Reference III-9):

                    	Standard Chip Seal	
                     Major            Residential        Asphalt-Rubber
Year                Streets*           Streets**            Chip Seal

1970-71        $0.27 per sq. yd.      0.24 per  sq. yd.  0.96 per sq. yd.
1979            0.47 per sq. yd.            —          1.05 per sq. yd.
1980            0.67 per sq. yd.            —          Not Available

 * 3/8 inch chips + AR8000 asphalt.
** 1/4 inch chips + AR4000 asphalt.

          This cost history shows the narrowing relationship between the cost
of a conventional chip seal and the asphalt-rubber chip seal between 1970 and
1979.

          On the basis of eight projects bid in 1978 for the Arizona Depart-
ment of Transportation, the average cost of asphalt-rubber was $1.121 per
square yard (Reference 111-10).   The costs ranged from a low of $0.83 per
square yard to a high of $1.452 per square yard.

          An experimental project  carried out  at Wrightsville, Pennsylvania
consisted of a hot-mix application.  This is a  more recent development in the
use of asphalt-rubber.  Two-thousand and sixteen tons of an open graded hot mix
were placed in a single layer 1-1/2 inches thick.  The mix contained 6.2 per-
cent by weight of a blend of ground rubber and  AC 20 asphalt cement.  The
blend was 20 percent rubber and 80 percent AC 20 by weight.  Equipment from
Arizona Refining was dispatched to Pennsylvania on a rental basis for the
project.  The cost was $52.24 per ton in-place.  Because of the experimental
nature of the project, the cost was higher than might normally be expected.
Under ordinary circumstances the cost of the asphalt-rubber open graded mix
in-place would be between $38 and $40 per ton.  The conventional open graded
mix would be $29 to $30 per ton.  These costs per ton convert to the following
cost per square yard based on a unit weight of  153 pcf and a layer 1-1/2
inches thick:

          $52.24 per ton             $4.50 per  square yard
          $38.00 per ton             $3.27 per  square yard*
          $29.00 per ton             $2.50 per  square yard
* This  cost  is very  close  to  that used  by  the  Arizona Refining Company cost
  analysis  (see Appendix).

                                      III-ll

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          The cost of rubber for this project was 23.25$ per pound plus
shipping charges of $3.50 per hundred weight for a total of 26.750 per
pound.  The rubber was supplied by the U.S. Rubber Reclaiming Company in
Vicksburg, Mississippi (Reference III-ll).  The mileage from Vicksburg to
the asphalt mixing plant in Bridgeport, Pennsylvania is approximately
1,150 miles.  Estimates of the cost of rubber that were developed during
the interviews varied  from lOc per pound at the plant to 30c per pound
delivered.  The cost would vary depending on the composition of the rubber.

SPECIFICATIONS

          Specifications have been developed by both producers and users of
asphalt-rubber products.  These include both material and construction speci-
fications for chip seal (SAM), stress absorbing membrane interlayer (SAMI),
bridge deck waterproofing membrane, joint and crack filler and open graded
asphalt-rubber friction.

          The materials that are covered In the specifications are:

             asphalt cement
             rubber extender oil
             ground rubber
             asphalt-rubber blend
             diluent
             cover aggregate
             blotter material

          The following examples of specifications  are included in the
Appendix:

          1.  SPECIFICATION FOR ARM-R-SHIELD^, Arizona Refining
              Company Specification M 101-80, dated 2/80.

          2.  CONSTRUCTION SPECIFICATION FOR ARM-R-SHIELD^ STRESS
              ABSORBING MEMBRANE INTERLAYER, Arizona Refining Company
              Specification C 202-80, dated 2/80.

          3.  CONSTRUCTION SPECIFICATION FOR ARM-R-SEIELD^ SURFACE
              TREATMENT, Arizona Refining Company Sepcification C 201-
              80, dated 2/80.

          4.  GUIDE SPECIFICATIONS FOR ASPHALT RUBBER FOR STRESS
              ABSORBING TREATMENTS (SAM or SAMI), Sahuaro Petrol-
              eum and Asphalt Co., Sated November 1979.

          5.  STRESS-ABSORBING MEMBRANE (INTERLAYER) and STRESS-
              ABSORBING MEMBRANE (SEAL), Arizona Department of
              Transportation, dated 8/22/79 and 8/23/79.
                                     111-12

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          6.  SPECIFICATION FOR ARM-R-SHIELD-CF, Arizona Refining
              Company Specifications, dated 1/80.

          7.  OPEN GRADED RUBBERIZED ASPHALT FRICTION COURSE, SRL-H
              (Reclaimed), Pennsylvania Department of Transportation,
              for experimental project in 1979.

          These specifications are, for the most part, typically definite in
their requirements.  Many of them, however, contain statements that reflect
the lack of precise methods for controlling the properties of the asphalt-
rubber blend.  The following examples are provided to illustrate these
uncertainties:

          •   Under a section of ASPHALT-RUBBER MATERIAL MIXING
              one specification says:  "The materials* shall be
              carefully combined and mixed and reacted for a
              period of time as required by the engineer which
              shall be based on laboratory testing by the asphalt-
              rubber supplier or contracting agency."**

          •   The same specification also allows for adding a
              diluent not to exceed 7-1/2 percent by volume of
              the hot asphalt-rubber  mixture in order to adjust
              the viscosity for "spraying and/or better "wetting"
              of the cover material."

          •   One specification calls for mixing the asphalt and
              rubber "as rapidly as possible for such a time and
              at such a temperature that the consistency of the
              mix approaches a  semi-fluid material."

          •   Another specification says with regard to the asphalt
              cement:  "It shall be fully compatible with the ground
              rubber  to be used...".  There is no further explana-
              tion of what "fully compatible" means.

          There are various other statements that indicate that the determi-
nation of a suitable asphalt-rubber mix is still an art that must be prac-
tised by an experienced expert rather than an science that can be applied
by a qualified practitioner.
 * Writer's note—refers to the asphalt and the rubber.
** Three experts in laboratory evaluations of this material indicate that
   the time-temperature relationship for the reaction between asphalt and
   rubber and its correlation with field performance of the material are
   still in need of additional study.
                                     111-13

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RESEARCH NEEDS - ASPHALT-RUBBER

          It is clear that there are serious gaps in the information that is
available in evaluating asphalt-rubber mixtures for construction conditions
(sprayability) and service conditions (durability).  As a result, there is a
lack of standard tests that are available to measure appropriate properties
and specifications are vague on requirements of the asphalt-rubber mixture.

          Dr. Gerald D. Love, of FHWA, in a talk presented at the Asphalt-
Rubber Users-Producers Conference, Scottsdale, Arizona, May 1980, gave the
following estimate of research needs.

                                     Estimated Required    Time Estimated
     Research Topic                   Funding-Dollars     Required - Years

Energy requirements for asphalt
  rubber and alternatives                 100,000
Develop end product specifications      1,000,000              2 to 3
Develop design procedures for crack
  control                               1,000,000              2 to 3


          The following additional information was suggested by  Dr. John Epps
of Texas A&M University at the Scottsdale Conference.

                                     Estimated Required
     Topic                             Funding-Dollars

Optimum Use Conditions                     200,000
Summary of Existing Performance            150,000
Standard Performance Information
  and Data Base                            400,000


          An expanded list of research topics would include the following:

          1.  The nature of the physical-chemical reaction between
              rubber and asphalt.

          2.  Development of appropriate tests and laboratory equip-
              ment for evaluating application and service related
              properties.

          3.  Determination of the temperature susceptibility of
              various asphalt-rubber mixtures.

          4.  Determination of the interaction of A-R with aggre-
              gate.
                                     111-14

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          5.  Evaluate durability and other field performance
              parameters.

          6.  Develop design procedures for crack control.

          7.  Develop better specifications—probably of the
              performance type.

          8.  Establish energy requirements and costs—par-
              ticularly life cycle costs.

          The working group on construction and maintenance at the Scottsdale
Conference emphasized the following "problems:"

          •   Lack of knowledge on the part of the designers,
              supervisory engineers, and construction person-
              nel (control people).  There is a need for ad-
              ditional training probably through a coordinated
              technology transfer program.

          •   Lack of coordination of control on the ADOT projects.
              There must be an established quality control procedure
              about which the necessary people are informed.

          •   There is a need to consolidate the available information.

          Most of these "problems" seem to be in the technology transfer
category.

CORPS OF ENGINEERS EXPERIENCE WITH A-R

          The Corps of Engineers is evaluating asphalt-rubber installations
at several locations.  The data shown in Table III-3 presents preliminary
Information on the extent of reflection cracks in test sections designed to
evaluate the crack control provided by various systems.  The asphalt-rubber
sections are those shown as Sections 1 to 4 inclusive at Fort Stewart, Georgia,
and Sections 1, 6, 7, 11, 15, 16, 18, and 19 at Fort Devens, Maine.  The fol-
lowing test sections are at the Fort Stewart location:

          Asphalt-rubber - tack coat,* SAMI, 1-1/2 inch overlay.
          Fabric - emulsion (CRS2), fabric, 1-1/2 inch overlay.
          Control - .35 gallon/square yard asphalt cement, 50 to
            60 pounds/square yard of stone chips, 1-1/2 inch overlay.
 * On Sahuaro  sections only—at  the rate  of  0.05 gallon per  square yard.


                                      111-15

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              TABLE III-3

Summary of Performance of Field Tes
                                              Sections - Corps  of Engineers
                                                      Waterways Experimental
                                                                  Station
Section
No.
Material
Lineal Feet of
Reflected Cracks , %
Ft. Stewart, GA - Sections Placed in October 1977
Airfield
. 1
2
3
U
5
6
7
8
9
10

Airfield
1
2
3
U
5
6
7
8
9
10
11
12
13
1U
15
16
17
Roadvay
18
19
20
21
22

Sahuaro
Sahuaro
U. S. Rubber
U. S. Rubber
Mons ant o-Bi dim
Mons ant o-Bi dim
Celanese-Mirafi
Celanes e-Miraf i
Control (Keystone)
Control (Keystone)
Ft. Devens , MA - Sections

U. S. Rubber
Control
Monsanto-Bidim
Celane s e-Miraf i
Control
Sahuaro
Sahuaro
Control
Monsanto-Bidia
Celanese-Mirafi
U. S. Rubber
Control
Monsantc-Bi dim
Celanese-Mirafi
Sahuaro
U. S. Rubber
Control

Sahuaro
U. S. Rubber
Celanes e-Miraf i
Monsant o-3i dim
Control
May 1978
0
0
0
0
0
0
29.7
8.3
0
0
Aug 1979
0
0
0
16. U
5.0
26.5
37.0
19-9
0
0
Aor 1980
0
0
13-6
17-9
31.3
35.8
US. 6
33.6
0
0
Placed in October 1977
Jun 1978
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

0
0
0
0
0
Aug 1979
3k.k
U9.9
5^.5
33.8
70.7
?T. 5
25-5
66.7
29-5
65.6
58.3
26.3
61. U
32.8
37.3
20.2
37.0

0
9.8
12.2
16.3
0
Jun 1980

-





















Source:  Reference 111-12.
                                 111-16

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          The fabrics used were the following:

          •   Bidim, a. polyester fabric manufactured' by Monsanto
              Textiles Company—$0.75 per square yard.*
          •   Mirafi, polypropylene and nylon manufactured by
              Celanese Fibers Marketing Company—$0.75 per square
              yard.**

          These materials were placed on an airfield parking apron that had
a 10-inch soil cement base and 1-1/2-inch bituminous concrete surface.
Another competing fabric is Petromat, a polypropylene fabric manufactured
by Phillips Fibers Company ($0.55 per square yard).*

          At Fort Devons, the sections are the following:

          Asphalt-rubber—same as Fort Stewart but with a 2-inch
            overlay
          Fabric—AGIO, fabric, 2-inch overlay
          Control—2-inch overlay only.

          The experimental sections at Fort Devens were  placed on top of
three different types of paving:  an airfield runway; an airfield parking
apron; and a roadway.  The bases for each were as follows:

          Airfield runway—6-inch soil cement base, 2-inch
            bituminous concrete surface
          Airfield parking apron—6-inch soil cement base,
            two bituminous concrete surfaces each 1-1/2-inch
            thick
          Roadway—5 to 7-inch aggregate bituminous base,
            1-1/2-inch bituminous concrete surface.

          The results of these sections are inconclusive and it is felt that
there has been an insufficient lapse of time for reflective cracking to occur.

          Additional roadway test sections have been constructed at three
other Army installations:  Ft. Lewis, Washington; Ft. Carson, Colorado; and
Ft. Polk, Louisiana.  In these tests, a SAKE has been placed under a thin
(1-1/2-inch)  overlay.  At Ft. Polk, Louisiana the existing pavement is a  •
6-inch portland cement concrete slab with a 2-inch bituminous concrete over-
lay.  At the other two locations, the existing base is crushed stone or gravel
with a 1-1/2-inch bituminous surface.  Evaluation of these sections is con-
tinuing; the results, as yet, are not conclusive, and a final report will be
issued when sufficient time has elapsed.
* Cost of fabric only.


                                     111-17

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          The Corps of Engineers seems to have the present position that the
use of asphalt-rubber is still in the experimental stage and its long-term
benefit has not as yet been proven.  They have a funding at the Waterways
Experiment Station for a laboratory program to develop test methods and
specifications.  This seems to indicate a feeling that the concept shows
promise.  They have  a real need for a material that will control cracking.
Maintenance of roads and streets at Army installations is a big problem
since most of them have far exceeded their economic life.  The Air Force
is also investigating the use of asphalt-rubber.

SUMMARY ASSESSMENT

          1.  Proponents of the use of asphalt-rubber, and these include
users as well as producers, are convinced that the material is unique in
controlling cracking when used on top of a cracked pavement and then cov-
ered with a thin overlay.  The State of Arizona requires its use in this
situation when the overlay is less than four inches in thickness.  The
material should be thought of  as a unique product having desirable prop-
erties rather than as a disposal mode for scrap tires.

          2.  Opponents object to the first coat of the material and -maintain
that it is difficult to achieve consistently successful applications.  Ad-
vocates contend that the first coat is amply offset by a reduction of main-
tenance requirements and that the material can  be placed properly when done
by experienced people.

          3.  There are enough miles of asphalt-rubber membranes in service
for enough years  to prove that the material has been successfully used.

          4.  An analysis of life cycle costing is necessary in order to de-
termine whether or not an economic benefit results.

          5.  The use of an  asphalt-rubber chip seal has  been used with ap-
parent success as a surface treatment on severely cracked pavements where the
only other  available option seemed to be reconstruction.  It should not, how-
ever, be used on high speed roads or under other circumstances where loose
chips would create a hazard.

          6.  There is need for additional research into the nature of the
asphalt-rubber reaction and the manner in which it is affected by asphalt
type, composition of the rubber, and reaction time and temperature.

          7.  One of the goals of asphalt-rubber research should be to
develop laboratory and field tests that will insure consistent success
in construction and that will correlate with field performance of the
installations.

          8.  There are ample supplies of scrap rubber and facilities for
producing  the asphalt-rubber mixture in order to cope with the present de-
mand for the product.
                                     111-18

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          9.  It is apparent that demand for the material will increase
slowly and that the industry will be capable of responding to the demand
and will respond as the market develops.

          10.  The availability of experienced technical and construction
people is essential to successful application.  Disastrous results have
occurred where the material has been used by people who were not aware of
the difficulties.  These unhappy results have caused some highway people
to "sour" on the material, an attitude that may continue for years.

          11.  There are competent organizations and people involved in all
phases of asphalt-rubber development.  They are unanimous in their feeling
that use of the material should be developed carefully with full knowledge
of its capabilities and its pitfalls.  They are fearful that extravagant
claims of success and a "snake oil" approach will lead to failures that can
retard development indefinitely.

          12.  Considerable interest is developing in pavement recycling.
The material and energy savings inherent in this process make it attractive.
This system will compete in those situations where asphalt-rubber would be
feasible.

          13.  The current lack of highway funds acts against the use of
asphalt-rubber because of its high first coat and the pressure that is
brought to bear on highway administrators to "do something about our roads."

          14.  Exact estimates of the potential use of asphalt-rubber are
difficult but it is believed that if used for all situations where it is
applicable there would be a significant reduction in the number of scrap
tires that would need to be disposed of.

ASPHALT-RUBBER AS A CRACK AND JOINT FILLER

          Asphalt-rubber may be applied as  a filler for longitudinal joints
between the  concrete riding surface and asphalt shoulder, for longitudinal
and transverse joints on concrete surfaces, for reflection, alligator and
other cracks, and for potholes and spoiling.

          Some state highway departments use rubber-asphalt as the sole
crack and joint filler material and are very satisfied with the results
(Reference 111-17).  Other highway officials prefer to use asphalt-rubber
for joints and cracks in portland cement concrete while applying bituminous
filler for asphalt surfaces.  There are also highway maintenance operations
which do not use any asphalt-rubber crack filler.  Asphalt-rubber has been
used to varying extents in 49 states, including Canada and Puerto Rico
(Reference 111-18).
                                     111-19

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Filler Materials

          There are many products on the market today which are used as crack
and joint fillers.  These products  vary in cost and effectiveness.  Some of
the notable products include:  hot and cold asphalt cement compounds, neoprene
strips, cold sand emulsions, asphalt with limestone dust, powder or latex,
polyvinyl chloride, polysulfite, urethane, low modulus silicon, epoxy, pow-
dered devulcanized rubber-asphalt mix, vulcanized asphalt-rubber mixes,
roofing tar and felt and other rubberized products.  This section will focus
on the asphalt-rubber fillers.

          Source.  There are several manufacturers and distributors of prepared
rubber and asphalt-rubber crack sealing products throughout the U.S.  Not repre-
senting a complete listing, there are known sources in Arizona, Pennsylvania,
and Mississippi which illustrates a wide geographical distribution (Reference
111-19).

          Preparation.  One of the more common rubber-asphalt filler materials
is similar to the rubberized stress absorbing membrane in composition.  Accord-
ing to specifications, the granulated crumb rubber (100 percent vulcanized)
should meet the following requirements:

          Passing Sieve              Percent
              No. 8                    100
              No. 10                  98-100
              No, 40                   0-10

          The specific gravity of the rubber should be 1.15 + 0.02 and should
be free of fabric, wire or other contaminating materials, except that up to
4 percent calcium carbonate may be included to prevent particles from sticking
together.  The proportions by weight of the asphalt-rubber mixture shall be
75 percent + 2 percent asphalt and 25 percent + 2 percent rubber (Reference
111-20).

          The secret to a successful seal is proper crack or joint preparation.
This holds for rubberized and non-rubberized fillers.  Smaller cracks must be
routed to a minimum width and depth to allow the asphalt-rubber to  flow into
the crack.  For larger carcks or joints, routing is not necessary to remove
all dirt or dust and non-compressible particles.  With warmer weather and
surface expansion, non-compressible particles will cause spalling and cracking
of the edges.

          The asphalt-rubber is applied hot and may require special equipment
for heating and placement.  A typical procedure is to heat the material to
375 to 400°F for 25 to 30 minutes before placement (Reference  111-21).  Pumps
may be necessary to place the thick filler material.   The asphalt-rubber may
require more care than traditional crack sealers.  If the mix is overheated,
it may not go into dissolution and if underheated it won't properly form or
pour (Reference 111-21).  The additional cost and labor must be compared
with the benefits of asphalt-rubber fillers.
                                     111-20

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          Properties.  The asphalt-rubber filler material combines the sealing
quality of asphalt with the expansion and contraction properties of rubber.
Asphalt-rubber has shown higher bonding strength than traditional asphalt
fillers.  It is also functional over a wider temperature range and does not
embrittle as easily.  Asphalt-rubber has demonstrated a notably longer life
although exact figures are difficult to obtain at present due to insufficient
and uncompleted  studies.  One manufacturer states that given proper applica-
tion, the asphalt-rubber should last from seven to ten years (Reference 111-18).

          Asphalt-rubber may be more suitable for portland cement concrete
joints where bituminous products often flow out of the joints in warmer weather.
It is sometimes difficult for the asphalt-rubber to flow into smaller carcks in
bituminous surfaces if not properly prepared.

          The ductile, adhesive and durable properties of asphalt-rubber filler
have been very successful on many projects.

Potential Quantity Consumption

          Asphalt-rubber has been used to varying extents in 49 states in-
cluding Canada and Puerto Rico  (Reference 111-18).  In some states, it is
used as the sole  crack filler material (Reference 111-17).  A conservative
estimate of potential consumption based on present consumption of several
states  (Reference 111-22) and one asphalt-rubber supplier's projections
(Reference 111-23) would be a consumption of rougly one million pounds per
state per year.   If the asphalt-rubber composition included 25 percent
rubber, this would represent a  rubber consumption of 250,000 pounds of
rubber per state per year.  This would imply a national consumption of rub-
ber in crack and joint fillers of 12.5  million pounds per year, as compared
to 6,018 million pounds of waste rubber tires discarded during the year 1968.

          Although asphalt-rubber as a crack filler has been proven cost ef-
fective for many applications, there are still many competing products on the
market.  It is unlikely that the rubber consumption of 12.5 million pounds
per year will be realized in the near future.

Economic Evaluation

          Asphalt-rubber crack and joint filler has been found to be cost ef-
fective in many applications.  The initial cost is usually higher for the
asphalt-rubber as compared to common bituminous fillers.  This is due to the
cost of rubber preparation, crack preparation, and special equipment required
to place the thicker material.  The additional cost is offset by greater ser-
viceability and life of seal.

          Life expectnacy information is sketchy and incomplete.  Observa-
tions up to the present have shown asphalt-rubber to be serviceable for up
to 10 years and sore.  Few suppliers give guarantees with asphalt-rubber
crack filler products.  The life expectancy of asphalt-rubber crack filler
                                      111-21

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given proper application is seven to ten years (Reference 111-18).  With
improper preparation or placement, the material may only last two to three
years (Reference 111-19).  In almost all cases, the rubber-asphalt has out-
performed conventional bituminous fillers.  There are other exotic crack fil-
ler products which may out-perform asphalt-rubber but these would incur ad-
ditional cost.

          The cost of purchasing asphalt-rubber crack and joint filler ma-
terial is approximately $0.30 per pound or $2.50 per gallon (Reference III-
23).  The total ill-place cost including materials, labor, equipment, traffic
control, etc., will depend on many factors including road surface, type of
crack or joint, degree of deterioration, weather and climate.  A rough esti-
mate for total in-place costs would be about $0.45 per linear foot (Reference
111-24).  The amount of coverage in terms of linear feet of crack would ob-
viously vary depending primarily on the size of crack.  Estimates that were
obtained varied from 16 (Reference 111-23) to 50 (Reference 111-19) linear
feet of crack per gallon of asphalt-rubber.  This factor alone would cause
a variation of approximately $0.10 per linear foot in the in-place cost.

          There are alternative non-rubberized products which perform various
functions with various costs.  These range from non-sealing filler materials
such as asphalt cement products to sophisticated epoxy, polysulfite, poly-
vinyl chloride and silicate sealers.  The following estimated costs are pro-
vided for a cost comparison of the various materials.

                                      Approximate In-Place Cost (Reference 111-24)
               Material                  ($ per Linear Foot)

          Liquid Asphalt                         0.15
          Asphalt-Rubber                         0.45
          Silicon                                1.00
          Neoprene                               1.30
          PVC                                    3.00

Advantages and Disadvantages

          In order to evaluate the potential or feasibility of using asphalt-
rubber as a crack and joint filler, it is often helpful to review the  advan-
tages and disadvantages as related to an individual project or area.  Follow-
ing is a general list of these advantages and disadvantages:

(Note:  Some of the advantages and disadvantages are in comparison to
        standard asphalt cement crack filler mixtures.)
Advantages
          •  Functions as crack sealant rather than just as a
             filler  (Reference 111-27).
          •  Cost effective (Reference 111-17).
          •  Longer life.
          •  High bond strength.
          •  More ductile (stretches further)  (Reference 111-23).
                                     111-22

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             Expands and contracts within wide temperature range.
             Outperforms bituminous sealers (especially on con-
             crete pavement).
             Stays in joints better.
             No tracking problem (with overfilling joint) (Ref-
             erence 111-20).
             Costs less than more exotic sealants.
             Does not embrittle (Reference 111-26).
             Maintains integrity of crack.
Disadvantages
             Costs more than asphalt cement fillers.
             More difficult to place.
             Have to apply hot.
             Thicker material (flows slower).
             Requires pump for placement.
             Doesn't penetrate as well.
             Longer to heat.
             Requires special equipment.
             Not as suitable for all surfaces and types of cracks.
             (More effective on concrete than on bituminous surfaces.)
CONCLUSIONS
          There are various asphalt-rubber crack and joint filler products.
These different products are suited to different surfaces, climates, etc.
There are also many non-rubberized products.  In many cases, the non-rubber-
ized crack filler materials can be replaced by asphalt-rubber products with
cost-effective results.

          The largest potential of asphalt-rubber sealants for joints in con-
crete pavements,  longitudinal joints  between concrete pavements and asphalt
shoulders, and fatigue cracks in asphalt pavements  (Reference III-29).  As-
phalt mixtures may better seal small bituminous cracks because they flow more
easily, but they are very poor as concrete joint fillers because they often
flow out or are squeezed out with expansion of slabs.

          The main problems with asphalt-rubber crack filler are the diffi-
culty in placing and additional costs.  The main benefits are the longer life
and performance ability over ordinary bituminous fillers.

          A rough estimate is that asphalt-rubber as a crack and joint filler
may consume up to 12.5 million pounds of rubber per year.  This figure is un-
likely to be realized because of competing products.

          In terms of solving the rubber tire solid waste problem of over 2
million tons per year, crack fillers will likely not result in use of 2,000
tons of tires per year, or less than one-tenth of one percent.
                                      111-23

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                                 Part III

                                REFERENCES*
III-l     Asphalt-Rubber Stress Absorbing Membranes, Field Performance and
          State-of-the-Art, Gener R. Morris, Director, Transportation Re-
          search Center, Arizona Department of Transportation, and Charles H.
          McDonald, Consulting Engineer, Phoenix, Arizona, Transportation
          Research Record No. 595, Transportation Research Board, Washington,
          D.C., 1976.

III-2     Interview with B. J. Huff, Technical Director, Arizona Refining
          Company, Phoenix, Arizona.

III-3     An Analytical Study of The Applicability of a Rubber Asphalt Mem-
          brane to Minimize Reflection Cracking in Asphalt Concrete Overlay
          Pavements, N. F. Goetzee and C. L. Monismith, Department of Civil
          Engineering, University of California, Berkeley, June 1978.

III-4     2,000,000,000 Tires Per Year: Options for Resource Recovery and
          Disposal, Volume 1, P. L. Deese, J. F. Hudson, R. C. Innes, and
          D. Funkhouser, Urban Systems Research and Engineering, Inc.,
          Cambridge, Massachusetts, November 1979.

III-5     Interview with R. D. Pavlovich, PhD, Manager-Research and Develop-
          ment, Engineers Testing Laboratory, Inc., Phoenix, Arizona.

III-6     Eleven-Year Pavement Condition History of Asphalt-Rubber Seals in
          Phoenix, Arizona, Russell H. Schnormeier, Engineering Supervisor
          (Materials), City of Phoenix, 1979.

Ill-7     Conversation with G. Heiman, Surfacing Engineer, Saskatchewan
          Highway and Transportation Department.

III-8     Interview with J. Huffman, Director, Technical Services, Sahuaro
          Petroleum and Asphalt Company, Phoenix, Arizona.

III-9     Interview with R. Schnormeier, Engineering Supervisor (Materials),
          City of Phoenix, Arizona.
* This list includes only the direct references in the report.  Many more
  references were analyzed than are listed here.
                                     111-24

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111-10    Prevention of Reflective Cracking Minnetonka-East (1979 Addendum
          Report), Report Number 1979-GW1, George B. Way, Senior Research
          Engineer, Arizona Department of Transportation, August 1979.

III-ll    Interview with J. DiRenzo, Highway Materials, Inc., Bridgeport,
          Pennsylvania.

111-12    Presentation by P- J. Vedros, U.S. Waterways Experiment Station,
          Vicksburg, Mississippi, at the Asphalt-Rubber, Users-Producers
          Workshop, Scottsdale, Arizona, May 1980.

111-13    An evaluation of Asphalt-Rubber Mixtures for Use in Pavement
          Systems, Pages 50 to 55 only of Final Report April 1977 -
          February 1979 by Eric H. Wang, Civil Engineering Research
          Facility, University of New Mexico for Civil and Environmental
          Engineering Development  Office, Tyndall Air Force Base, Florida.

111-14    Rubber Asphalt Binder for Seal Coat Construction, Implementation
          Package 73-1, Robert B. Olsen, Implementation Division, FHWA U.S.
          Department of Transportation, February 1973.

111-15    Design of Asphalt-Rubber  Single Surface Treatments with Multi-
          Layered Aggregate Structure, B. A. Vallerga and J. R. Bagley,
          presented at ASTM Symposium, San Diego, California, December
          1979.

111-16    Characteristics and Performance of Asphalt-Rubber Material Con-
          taining a Blend of Reclaim and Crumb Rubber, B. J. Huff, Tech-
          nical Representative, Arizona Refining Co., and B. A. Vallerga,
          Consulting Civil Engineer, Oakland, California, presented at
          58th Annual Meeting, Transportation Research Board, Washington,
          D.C., January 1979.

111-17    Dan Swing, Nebraska DOT, telephone conversation.

111-18    Sealing and Resealing Cracks the Crafco Way, Crafco, Inc., Phoenix,
          Arizona.

111-19    O'Connor, John, Crackdown on Pavement Cracks, American City and
          County, May 1980.

111-20    Demonstration Project No. 37 Discarded Tires in Highway Construc-
          tion, Jamestown, North Dakato, U.S. Department of Transportation,
          Federal Highway Administration, Arlington, Virginia.

111-21    Frank Witkoski, private company marketing asphalt-devlucanized
          rubber product, Harrisburg, Pennsylvania, telephone conversation.

111-22    Georgia DOT, PennDOT, Nebraska DOT, telephone conversations.
                                     111-25

-------
111-23    Mark Manning, CRAFCO, Phoenix, Arizona, telephone conversation.

111-24    Estimate based on ragne of cost figures.

111-25    Carl Lubold, Asphalt Institute, telephone conversation.

111-26    Bobby Huff, Arizona Refining Company, telephone conversation.

111-27    Asphalts, Aggregates,  Mixes and Stress-Absorbing Membranes,
          Morris and McDonald, Transportation Research Record, 595, 1976.

111-28    Remarks of Dr. John Epps, Texas A&M University at Asphalt-Rubber
          Workshop, Scottsdale, Arizona, May 1980.
                                     111-26

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                                  Part IV

                        USE OF INCINERATOR RESIDUE
                          IN HIGHWAY CONSTRUCTION
INTRODUCTION

          The term "incinerate" is defined as, to burn or reduce to ashes
(Reference IV-1).  The incineration process, however, is commonly viewed
as a tool merely to reduce the volume and weight of heavy, wet, bulky
refuse.

          In this country, most refuse is disposed of directly into land-
fill sites.  This direct disposal accounts for over 90 percent of the net
municipal solid wastes generated annually (Reference IV-2).

          In some parts of the country, a shortage of available landfill
sites exists.  Present incineration methods can reduce the volume of in-
coming refuse by as much as 85 percent to 95 percent (Reference IV-3).
This is advantageous because massive hauling and landfilling efforts can
be substantially reduced.  In addition, limited landfill areas can be
preserved.

          With the recent concern for the conservation of materials and
energy, residue disposal from incineration plants has attracted attention.
Application of this residue material in some form of highway construction
is currently being investigated.  The following addresses the present
status of incinerator residue as a highway construction material.

BACKGROUND

          Construction of incinerators in this country began around the late
nineteenth century (Reference IV-4).  Following World War II, there was a
significant increase in the number of incinerators constructed.  Most of the
incinerators built at that time were of a small capacity (i.e., 100 to 200
tons per day units).

          Over the last two decades, many incinerators have been closed due
to operation and maintenance costs  (including  large investments required
for air pollution controls).  This has come about by more stringent govern-
ment control of  the effects of the incineration process  (i.e., air quality
and disposal methods).  The escalating costs of the required pollution con-
trol equipment in most cases, do not warrant the upgrading of smaller capac-
ity plants.

          Incinerators being constructed today can handle volumes of refuse
in the 1,000 to  1,500 tons per day range. Economy of scale is predicted for
the larger plants.  In the newer, larger volume plants, energy recovery and
selective materials  recovery are of significant consideration.
                                      IV-1

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QUANTITIES OF MATERIALS

          It is  estimated that the net municipal solid waste disposed of
annually in the United States, approximates 150 million tons (Reference
IV-2).  This appears to be a small percentage of the 3.5 billion tons of
total solid waste generated each year  (Reference IV-4).  Total solid wastes
generated include agricultural, animal, mineral, industrial, commercial,
and household wastes.  Of the net municipal solid waste disposed of annu-
ally, less than 10 million tons are processed by incineration.  From the
less than 10 million tons incinerated annually, there is a production of
approximately 2 million tons  of incinerator residue.

          On the following page is a map (Figure IV-1) of the United States
which shows the location of the currently operating municipal incinerator
plants.

          Table IV-1 is a listing of the currently operating municipal
incinerators in the United States.  The list does not include existing
operational resource recovery facilities.

          The list was compiled using various sources of information.
Among these sources were:  a list published in Federal Highway Administra-
tion Report RD79-B8, prepared by the Jaca Corporation of Fort Washington,
Pennsylvania; a June 1980 computer printout from the United States En-
vironmental Protection Agency's Compliance Data System (CDS); and written
and verbal communication with numerous state and municipality solid waste
mangement agencies and divisions.

          It should be mentioned at this time that in addition to municipally
operated incinerators, residues are also produced by privately owned incin-
eration facilities.  The determination of the quantities of  residue produced
by these private facilities is impractical due to the sheer total number of
facilities.  Preparing a list of privately owned incineration facilities which
produce residue that could be used in construction applications, would involve
individual screening of the thousands of incinerator emission sources com-
piled by the Environmental Protection Agency.  In addition to the sheer
number of facilities, the residue output from each facility would have to
be categorized, as each private incinerator burns a  widely variable refuse
which results in an individual characteristic residue.

          A program such as this, which would include the listing of private
incineration facilities, is beyond the scope of this report.

          In Table IV-1, a predicted yearly residue output volume for the
municipally operated plants is listed.  This volume is approximated using
a procedure developed by Messrs. Pindzola and Collins published in a Fed-
eral Highway Administration Report FHWA-RD-75-81.
                                     IV-2

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Figure IV-1.
Location of Currently Operating Municipal  Incinerator Plants.
        (Encircled is the number of operating plants)

-------
                    Table IV-1
List of Currently Operating Municipal  Incinerator Plants -  1980
Plant
No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Plant Location
ARKANSAS
No. Little Rock
CONNECTICUT
Ansonla
East Hartford
Hartford
New Canaan
New Haven
Waterbury
FLORIDA
Miami (NE)
Orlando
Pahokee
HAWAII
Honolulu
(Uaipahu)
Year
Built
1966
1968
1956
1954
1956
1963
1952
1975


1969
Refuse
Capacity
(Tons Per
24-Hr. Day)
100
200
350
600
125
720
300
300
100
50
600
Residue
Output
(Tons Per
Year)
8,800
17,500
35,000
60,000
12,500
31 ,500
30,000
26,300
10,000
5,000
52,500
Furnace
Type & Grate
Batch/Traveling
Cont. /Traveling
Batch/Rocking
Bat eh/Me ch.
Batch/Mech.
Cont. /Travel Ing
Batch
Cont.
N.A.
N.A,
Cont.
Predicted
Residue
Quality
3
3
4
4
4
3
4
3
4
4
3

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                                                       Table IV-1



                           List of Currently Operating Municipal Incinerator Plants (Continued)
Ol

Plant
No.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.

Plant Location
ILLINOIS
Chicago (Calumet)
Chicago (NW)
Chicago (SW)
INDIANA
East Chicago
KENTUCKY
Louisville
LOUISIANA
Shreveport
MARYLAND
Baltimore #4
Baltimore - Pyrolysis
MASSACHUSETTS
Braintree
East Bridgewater

Year
Built
1959
1970
1963
1970
1957
1960
1956
1963
1971
1973
Refuse
Capacity
(Tons Per
24-Hr. Day)
1200
1600
700
200
1000
200
800
1000
240
800
Residue
Output
(Tons Per
Year)
105,000
120,000
52,300
17,500
75,000
15,000
80,000
36,000
18,000
60,000

Type & Grate
Cont. /Rocking
Cont./Recip.
Cont. /Rot. Kiln
Cont.
Cont. /Rot. Kiln
Cont. /Rocking
Batch/Rocking
Cont. /Rot. Kiln
Cont./Recip.
Cont./Recip.

Predicted
Residue
Quality
3
2
1
3
1
2
4
1
2
2

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                            Table IV-1
List of Currently Operating Municipal  Incinerator Plants  (Continued)
Plant
No.
22.
23.
24.*
25.
26.
27.
28.
29.
30.
31.
32.
Plant Location
MASSACHUSETTS (Cont.)
Fall River
Framingham
Saugus (Resco)1
MICHIGAN
Central Wayne County
Clinton-Grosse Pointe
S.W. Oakland Co.
MISSOURI
St. Louis (North)
St. Louis (South)
NEW HAMPSHIRE
Dunham
NEW YORK
Canajoharie
Hemps tead
(Oceanslde)
Year
Built
1973
1973
1975
1964
1972
1953
1956
1951
1970
1964
1965
Refuse
Capacity
(Tons Per
24-Hr. Day)
600
500
1500
800
600
600
400
400
50
50
750
Res i due
Output
(Tons Per
Year)
45,000
37,500
112,500
60,000
45,000
60 ,000
40,000
40,000
5,000
'5.000
56,300
Type 4 Grate
Cont./Recip.
Cont./Recip.
Cont./Recip.
Cont./Recip.
Cont. Rot. Kiln
Batch/Mech.
Batch/Rocking
Batch/Rocking
Batch
Batch/Mech.
Cont. /Rocking
Predicted
Residue
Quality
2
2
2
2
1
4
4
4
4
4
2

-------
                           Table IV-1
List of Currently Operating Municipal  Incinerator Plants  (Continued)
Plant
No.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.

44.
45.
46.
Plant Location
NEW YORK (Continued)
Hempstead (Merrick)
Huntington
Lackawanna
NYC (Betts Ave.)
NYC (Greenpoint)
NYC (Hamilton)
NYC (South Shore)
N. Hempstead
Old Bethpaqe
Old Bethpage
Tonawanda
OHIO
Dayton (N. Mont-
gomery County)
Dayton (S. Mont-
gomery County)
Franklin2
Year
Built
1952
1966
1949
1959
1959
1961
1954
1966
1967
1962
1933

1940
1970
1969
Refuse
Capacity
(Tons Per
24-Hr. Day)
600
300
150
1000
1000
1000
1000
600
400
500
300

600
600
150
Residue
Output
(Tons Per
Year)
60 ,000
22,500
15,000
87,500
87,500
87,500
87,500
45,000
30,000
37,500
22,500

52,500
52,500
13,100
Type & Grate
Batch/Mech.
Cont. /Rock ing
Batch/Manual
Cont./Trav.
Cont./Trav.
Cont./Trav.
Cont./Trav.
Cont. /Rocking
Cont./Recip.
Cont./Recip.
Cont./Recip.


Cont. /Travel ing
Fluidized Bed
Predicted
Residue
Quality
4
2
4
3
3
3
3
2
2
2
2

3
3
3

-------
                                                Table IV-1



                    List of Currently Operatlnq Municipal Incinerator Plants (Continued)


I





Refuse
Capacity
Plant Year (Tons Per
No. Plant Location Built 24-Hr. Day)
OHIO (Continued)
47. Miami County 1968 150
OKLAHOMA
48. Tahlequah 50
PENNSYLVANIA
49. Harrisburg3 1973 720
50. Philadelphia
(E. Central) 1966 750
51. Philadelphia (NW) 1960 750
RHODE ISLAND
52. Pawtucket 1964 200
TENNESSEE
53. Nashville" 1974 720
UTAH
54. Oqden 1966 450
VIRGINIA
Residue
Output
(Tons Per
Year) Type & Grate
13,100 Cont. /Pusher
5,000 Batch
54,000 Cont. /Red p.
65,600 Cont./Trav.
65,600 Cont./Trav.
17,500 Cont./Trav.
63,000 Cont. /Travel ing

39,400 Cont. /Travel ing
4

Predicted
Res 1 due
Quality
3
4
2
3
3
3
3

3

55.     Newport News
1968
400
35,000    Cont./Travel ing

-------
                                          Table  IV-1

               List of Currently Operating Municipal Incinerator Plants (Continued)


Plant
No.
56.
56.
57.

58.


59.
60.



Plant Location
VIRGINIA (Continued)
Portsmouth
Salem
WASHINGTON, O.C.
Solid Waste Reduc-
tion Center #1
WISCONSIN
Sheboygan
Waukesha
Refuse
Capacity
Year (Tons Per
Built 24-Hr. Day)

1963 350
1977 90


1500

1965 240
200
Residue
Output
(Tons Per
Year)

35 ,000
7,900


112,500

18,000
15,000



Type & Grate

Batch/Rocking
Cont. /Pusher


Cont. /Rocking

Cont. /Rocking
Cont. /Rocking

Predicted
Res 1 due
Quality

4
3


2

2
2
                                                  2,621,400

'Steam generation facility combined with resource recovery operation.
'Operated as a resource recovery facility.
30esiqned and operating as a steam producing facility.
''Operated as an energy recovery plant.

    NOTE:  1 short ton  =  .9072 tonne.

    N.A.  denotes Information not available.

-------
          The predicted residue output of each plant may be calculated by
multiplying plant design capacity times the number of operating days per
year* times the weight fraction of the refuse remaining after incineration.

          From these computations, it is predicted that approximately 2.6
million tons of residue are produced annually from the currently operating
municipal incinerators as listed in Table IV-1.

          It is noted, however, that in publication FHWA-RD-79-83 prepared
by the Jaca Corporation of Fort Washington, Pennsylvania, it is stated that,
"the use of the prediction procedure on a national basis is likely to over-
state the amount of residue available for use as highway material."**

          Using the 2.5 million tons of municipal incinerator residue which
may be produced annually as an upper limit, and applying a factor of .55;
this yields an amount of approximately 1.4 million tons of municipal incin-
erator residue which may be produced annually.  This 1.4 million ton number
is a reasonable estimate of the lower limit of annual municipal incinerator
residue production.

          Assuming a number somewhere in the middle of this range (2.5 to
1.4) would be the most accurate approximation to the actual, annual pro-
duction.  It is, therefore, reasonable to state that the current annual
production of municipal incinerator residue in the United States is ap-
proximately 2 million tons.

          As a basis for judging the quantities of materials involved, the
United States total annual production of aggregate for the year 1979, which
was used for highway construction, was 1,074 million tons (Reference IV-5).
The amount of municipal incinerator residue which may be produced annually
represents only approximately 0.2 percent of this total annual production
of aggregate.  The United States total animal production of hot mix asphalt
paving for the year 1978, was 376 million tons (Reference IV-6).  The amount
of municipal incinerator residue which may be produced annually represents
only approximately 0.5 percent of this total annual production of hot mix
asphalt. As indicated by the annual quantities of aggregate used in the United
States, if all the municipal  incinerator residue which may be produced was
used in construction applications, only a minute portion of  the national
aggregate market would be affected.
 * Operating schedule of 120 hours per week was used unless reported other-
   wise.  A 50-week operating period per year  was used for all plants.
** This statement was based on an in-depth investigation of 10 municipal
   incinerators operating during 1979.  A ratio of residue quantity actually
   produced to residue quantity predicted for the ten incinerators (employ-
   ing the  Pindzola and Collins technique) was reported as approximately .55.
                                     IV-10

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DESCRIPTION  OF  MATERIAL

          All incinerators do not handle and process refuse in the same
manner.  The basic differences in refuse processing within the incinerator
plants occur with the feeding and supply of refuse to the furnace, and the
type of furnace itself.

          The four types of furnaces used for municipal solid waste refuse
are:  the vertical circular furnace; the rectangular furnace; the multi-
celled rectangular furnace; and the rotary kiln furnace (Reference IV-3).
These furnaces may be considered as either being batch fed or continuous
fed.

          A grating system transports the refuse and residue through the
furnace.  The types of grates currently used in refuse processing may be
described as traveling, reciprocating, rocking, rotary kiln, circular,
vibrating, oscillating, and reverse reciprocating  (Reference IV-7).

          In combustion, the important variables which affect the quality of
the residue produced (well burned as opposed to poorly burned) are time of
combustion, temperature of combustion, and the turbulence during combustion.
It is noted that the different types of grates are somewhat correlated to
the quality of the residue produced.  As an example, with the use of a
rocking grate as opposed to a traveling grate, better burnout may be achieved
due to the better agitation action of the refuse on the rocking grate.

          A special type cf incineration process, known as pyrolysis, should
be mentioned along with the aforementioned incinerator types.  Pyrolysis in-
volves the combustion of refuse in an oxygen controlled chamber.  This re-
sults in the oxidation and thermal decomposition of combustibles (Reference
IV-3).

          Variations in the composition of incoming refuse for incineration
occur often.  This is due to variations in seasonal quantities such as food
wastes and yard wastes.  Even with the variation of the incoming refuse,
residue compositions tend to be reasonably uniform.  Below is the estimated
national  average composition of municipal refuse  (Reference IV-8):

               Component
          Paper
          Food Wastes
          Metals
          Glass
          Wood
          Textiles
          Leather and rubber
          Plastics
                                                 100.0

SQTE:  These composition figures have been developed on a "yard waste" free
       ?T»H "siscellaneous" free basis.  "Yard waste" includes leaves, grass,
       branches, etc.  "Miscellaneous" includes bricks, rocks, and dirt.
       Toese tw fractions are highly  variable and can constitute up to one-
       chlrd of the refuse at certain times.
                                      17-11
Percent by Weight

-------
          It is noted, however, that the principal objective of municipal
incineration is the reduction of the volume of the refuse.  Normally, no
attempt is made to control the quality of the residue.  Thus, some fluc-
tuations in the composition of the residue will occur even under well main-
tained incinerator operating conditions.

          The quality of incinerator residue may best be described in terms
of the burn-out achieved.  The burnable fraction of the incoming refuse rep-
resents 75 percent of the refuse weight.

          A classification system for  the residue was developed identifying
six basic categories of residue according to degree of burnout (Reference
IV-3).  These classes are:  ultra-well burned out residue; well-burned out
residues, intermediately burned out residues; poorly burned out residues;
residues with especially low metal content, and pyrolysis residues.  In
general, these six categories may be related to basic plant design.  Well
burned residues are usually produced from refuse that is transported by
agitating type grates (i.e., rocking, reciprocating).  Intermediately burned
residues are usually produced on well operated traveling grates.  Poorly
operated traveling grates and batch fed furnaces will usually produce a
poorly burned residue.

          It is noted that lower percentages of combustible material are
found in well burned residues, and that very low percentages of combustible
materials are found in pyrolysis residues.  High percentages of glass are
also found in pyrolysis residues.

          Table IV-2 is a breakdown of the quantities of  incinerator residue
produced according to type and state.   The number of operating plants in each
state is also listed.  Table IV-3 is strictly a tabulation of quantities of
types of residue produced, and number of plants producing the residue.

          Generally, incinerator residue is primarily composed of glass,
metals, minerals, ash, and unbumed combustibles.  The percentages of its
components are not subject to huge variations.  A representative average
approximation of percentage by weight of the residue components is as
follows (Reference IV-3):

          Glass                      48 percent
          Metals                     18 percent
          Minerals and ash           21 percent
          Combustibles               13 percent
                                    100 percent
                                     IV-12

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                                  Table IV-2
       LIST BY STATE OF QUANTITIES AND TYPE OF RESIDUE, OPERATING PLANTS
Number of
Operating Plants
1
6

3

1
3


1
1
1
2

5
3


2
1
13


4
1
3

1
1
1
3

1
2


Arkansas
Connecticut

Florida

Hawaii
Illinois


Indiana
Kentucky
Louisiana
Maryland

Massachusetts
Michigan


Missouri
New Hampshire
New York


Ohio
Oklahoma
Pennsylvania

Rhode Island
Tennessee
Utah
Virginia

Washington, D.C.
Wisconsin
Type of
Residue*
3
3
4
3
4
3
1
2
3
3
1
2
1
4
2
1
2
4
4
4
2
3
4
3
4
2
3
3
3
3
3
4
2
2
Quantity Produced
(Tons per year)
8,800
49,000
137,500
26,300
15,000
52,500
52,300
120,000
105,000
17,500
75,000
15,000
36,000
80,000
273,000
45,000
60,000
60,000
80,000
5,000
213,800
350,000
80,000
131,200
5,000
54,000
131,200
17,500
63,000
39,400
42,900
35 ,000
112,500
33,000
                                                            2,621,400
* See text for explanation.

-------
                                Table IV-3-
         TABULATION OF QUANTITIES OF TYPES OF RESIDUES PRODUCED
Ultra Well Burned       Type 1
Well Burned             Type 2
 Intermediately Burned   Type 3
.Poorly Burned
Type 4
                                 Number of Plants
                                  Producing This
                                     Residue
                18
                22
16
Quantity of
  Res i due
 Produced

  208,300


  881,300.


1,034,300


  497.500


2,621,400
                                  IV-14

-------
          Incinerator residue is also fairly uniform with respect to particle
size distribution, if all the gross oversized materials  (such as appliances)
have been initially removed.  Nearly all residue is able to pass through a 3-
inch screen.  Approximately 70 to 90 percent of the residue by weight can pass
through a 1-1/2-inch screen (38  milimeters).  The material passing this screen
can usually conform to existing gradation specifications for bituminous base
course aggregate  (Reference IV-3).  The Pennsylvania Department of Transporta-
tion Gradation Requirement for Bituminous Concrete Base Course is (Reference
IV-9):

                                Base Course

          Sieve Size                 Percent Passing

          2" (50.8 mo)                     100
          1-1/2"  (38.1 mm)                95-100
          3/4" (19.1 mm)                  52-100
          3/8" (9.52 mm)                  36-70
          #8 (2.38 mm)                    16-38
          #30 (0.590 mm)                   8-24
          #50 (0.297 mm)                   6-18
          #100 (0.149 mm)                  4-10

          An additional property of significance with respect to incinerator
residue (other than physical composition and material grain size) is moisture
content.  The moisture content of residue varies greatly.  Residues that have
been freshly quenched (due to heat of incineration) obtain a high moisture
content. As a. range value, the water content of as received residues (reported
in a Federal Highway  Administration Report No. FHWA RD78) varied between 28
percent and 47 percent.  It has been observed that residues that have been
stockpiled for a period of time contain a much lower moisture content than
non-stockpiled residues.

          It has been recommended in a report prepared by Valley Forge Labora-
tories for the Federal Highway Administration in 1976, that only well burned
or intermediately burned incinerator residues should be considered for use in
highway construction.  This same report recommended that residues for con-
struction be stockpiled for several months prior to use; and that a loss on
ignition test value of greater than 10 percent of the residue, would deem the
residue undesirable for highway construction.

          With respect to the residues produced by resource recovery and
reclamation plants, only some of the residues may be used for roadway con-
struction materials.  The determination of what residues from which plants
can be used, should be made on individual and specific application criteria.
This is so, as some of the resource recovery facilities produce a synthetic
type fuel which is similar in consistency to peat moss.  With all the pre-
separation and screening involved to produce this fuel, the residue charac-
teristics are appreciably altered.  Residues produced, often do not contain
                                     IV-15

-------
acceptable amounts of desirable components (for construction applications)
such as glass, and often contain appreciable amounts of undesirable com-
ponents which may be considered as hazardous.  The residues from these
recovery facilities would be unacceptable as an aggregate replacement in
highway construction applications.

          In a report written by Valley Forge Laboratories in 1977 (FHWA RD77
151), the moisture content of six different types of incinerator residue were
listed as follows:
Residue
  Type

   1
   2
   3
   4
   5
   6
  Point of
  Sampling

Discharge Chute
Stockpile
Stockpile
Discharge Chute
Stockpile
Stockpile
     Average
     Moisture
     Content
    (Percent)

       42.9
       17.8
       23.8
       45.9
       21.6
        0.8
               Type of Grate

             Rotary  Kiln
             Reciprocating
             Traveling
             Traveling
             Traveling (Metal Recovery)
             Pyrolysis
NOTE:  The average of all moisture content values (except for Type 6 residue)
       was 31.6 percent.  However, the average moisture content of the stock-
       piled residues (except for Type 6 residue) was 21.1 percent.

          Below is the average particle size distribution of these six dif-
ferent types of incinerator residue (expressed as percent passing):
Sieve Size

3" (76.2 mm)
1" (25.4 mm)
1/2" (12.7 mm)
1/4" (6.35 mm)
#10 (2.00 mm)
#40 (0.420 mm)
#200 (0.074 mm)
       Type 1  Type 2  Type 3  Type 4  Type 5  Type 6
       100
       100
        96
        87
        41
        15.5
         4.5
100
 86
 66
 45
 24
 11
100
 65
 60
 49
 29
 15
100
 79
 65
 48
 29
 12
100
 79
 67
 53
 32
 13
100
100
100
 83.5
 46.4
  9.6
  3.3
NOTE:  Size control of "as received" samples involved omly the removal of
       oversize material prior to sieve analysis.  The mavimim particle
       size in this analysis was limited to 3 inches (76.2 mm).  Sieve
       analyses were performed in accordance with ASTM Designation C136
       using samples of 1,000 gram size.

          On the following page is Figure IV-2, a gradation chart of the six
types of incinerator residue as compared to the specification limits of Penn-
DOT for base course aggregate.
                                     IV-16

-------
                   0.149
0.420
2.00
4.76   9.52     19.1     38.1 nn\
              TOO100   60   40
                               1/4 3/8 1/2 3/4 1  1-1/2
                                  U.S,  STANDARD SIEVE SIZE
                                    • •
Figure IV-2.   Particle  size distribution of "as received" incinerator residues.

            (Shaded  area  is PennDOT base course aggregate specification limits.)

-------
          A laboratory  test program on these six types   of residues was con-
ducted by Valley Forge  Laboratories, Inc. during 1976.   Below  is the average
particle size distribution of the six types of graded incinerator residue,
expressed as percent passing,  which were used in the program  (1-1/2" maxi-
mum top size).

Sieve Size          Type_l  Type 2  Type 3  Type 4  Type 5  Type 6

1-1/2" \38.1 mm)    100    100     100     100     100     100
1" (25.4 mm)        100     95      94      96      97     100
1/2" (12.7 am)       96     69      64      80      82     "100
1/4" (6.35 mm)       87     43      33      55      57      83.5
#10 (2.00 mm)        41     25      17      33      34      46.4
#40 (0.420 mm)       15.5    12       8      18      17        9.6
#200 (0.074 mm)       4.5     6       3      10       4        3.3

NOTE:  Size control of  graded incinerator residue samples involved passing
       all materials (except types 1 and 6) through a 1-1/2 inch (38.1 mm)
       portable screen.  Sieve analyses were performed in accordance with
       ASTM Designation C136 using samples of 1,000 gram size.

          On the following page is Figure IV-3, a gradation chart of the six
types of graded incinerator residue as compared to the aggregate specification
limits of PennDOT for wearing surfaces.

          Incinerator residue is able to satisfy many of the quality control
standards used for conventional aggregate materials.  Some tests presently
being used, however, require modification of their present form for testing
incinerator  residue.   An example of such a test is specific gravity.  The
difficulty of accurately determining the apparent specific gravity of incin-
erator residue is due to its property of high absorption.

PRINCIPAL USES

          Incinerator residues have been used in a variety of highway appli-
cations.  These include bituminous base courses, wearing surfaces, stabilized
bases and sub-bases, and fused aggregate material uses.

          In fused aggregate applications, prepared municipal incinerator
residues are burned out to completion and then channeled through a second
furnace (Reference IV-10).  The second furnace melts or  fuses this burnt
out material together at temperatures near 2,000°F.  The melted product is
allowed to cool, and is subsequently crushed and broken  to a desired size
(i.e.,  with all particles smaller than 1-1/2 inches).
                                     IV-18

-------
                      0.149
                   0.420
2.00
4.76   9.52
38.1 m
                                                              4 1/4 3/8 1/E 3/4 1  1-1/2
                                    U,S,  STANDARD SIEVE SIZE
Figure IV-3.
 Average particle  size  distribution of graded incinerator residues.
(Shaded area is  PennDOT ID-2A wearing surface specification limits.)

-------
Bitvtnlnous Base Courses

          In Houston, Texas, construction of a test section of roadway using
incinerator residue in a bituminous base was undertaken in 1974  (Reference
IV-11).  This test section consisted of construction of approximately 200
feet  of roadway at the intersection of Bingle Road and Hempstead Highway.
The incinerator residue bituminous base used in the construction has been
termed "littercrete" in numerous publications (References IV-12, IV-13).

          Roadway construction consisted of a 1-1/2-inch thick conventional
wearing  surface, placed on a 6-inch thickness of littercrete.   The litter-
crete was placed on top of a 6-inch thick lime stabilized soil having a sandy
soil subgrade.

          The incinerator residue used  in the littercrete had passed a 1-inch
(25 mm) screen.  The gradation of the material had passed the Texas AA Type C
specification.  The percentage of glass in the residue was approximately 45.

          The approximate composition of the placed littercrete was as follows:

Composition  Incinerator Residue  RC 20 Asphalt  Hydrated Lime

 % Volume            80.9              17.4           1.7
 % Weight            89.0               9.0           2.0

          A control  section of conventional materials was placed alongside
the test section for comparison purposes.  The control section base had a 6
percent asphalt composition by weight.

          The particle size distribution of the graded incinerator residue
used in the Houston, Texas Test Section, in percent by weight was as follows
(Reference IV-11):

             Sieve Size              Percent Passing

          Unwashed
          1" (25.0 mm)                     100
          3/4" (19.0 mm)                    95
          1/2" (12.7 mm)                    80
          3/8" (9.52 mm)                    63
          #4 (4.76 mm)                      46
          #8  (2.38 mm)                     25
          #16 (1.19 mm)                     17
          #30 (0.590 mm)                    11
          #50 (0,297 mm)                     7
          #100 (0.149 mm)                    4
          #200 (0.074 mm)                    2
          Washed
          #4 (4.76 mm)                      48
          #80 (0.180 mm)                    11
          #200 (0.074 mm)                    7
                                     IV-20

-------
          On the following page is Figure IV-4, a gradation chart of the
littercrete base used in the Houston test section, as compared to the
Texas Class AA Type C, aggregate gradation specification for base courses.

          Both sections of pavements, have been evaluated for performance
employing testing methods for stability, thermal expansion, direct tension,
splitting tensile strength, resiliency and flexural fatigue.  The pavements
have also been evaluated visually.  Three-year tests and evaluations of the
two pavements indicated that the littercrete and the control section are
performing equally.

          A summary  of laboratory test results of optimum mix design (as-
phalt 9 percent by weight of total mix) for the bituminous base test  sec-
tion placed in Houston, Texas was as follows (References IV-12, IV-13):

                                        6 Months Field        3 Year Field
                                     Test Mix  Control Mix   Test   Control

Stability  (pounds)                     1,150       920       1,340   1,940
Flow (0.01 inch)                         .17        .15         .18     .12
Air Voids  (percent)                    4.2       8.5         4.7     6.9
Recovered Asphalt Content  (percent)   10.8       5.3
Maximum Specific Gravity               2.06      2.43        2.13    2.43
Density (pounds per cubic  foot)          129


           In Anacostia, Washington, D.C., construction  of a test section of
roadway with an incinerator residue base was completed in June of 1977 (Ref-
erence IV-14).  This test  section consisted of construction of approximately
400 feet of roadway on 14th Street, S.E., near Cedar Street.

           The roadway wearing surface consisted of a 1-1/2-inch thick con-
ventional  hot mixed  asphalt.  This was placed on  top of a 4-1/2-inch bit-
uminous incinerator base with 6 inches of gravel sub-base.  For this test
section, 30 percent aggregate was blended with the residue in the base mix.

           The particle size distribution of incinerator residue plus aggregate
used in the Washington, D.C. test section was as follows:
                                      IV-21

-------
ro
              100
                                    0.149      0.420
                             0.074       0.250       0.840
2.00     4.76   9.52     19.1     38.1  mn
     2.38    6.35   12.7   25.4
                 Q
                                                                           4 1/4 3/8 1/2 3/4 1  1-1/2
                                                  U.S,  STANDARD SIEVE SIZE

          Figure IV-4.  Particle  size distribution  of littercrete base  used  In  the Houston  test section.

                                 (Shaded  area  is  Texas  Class  AA Type  C  grading  specification).

-------
                              PERCENT PASSING
Sieve Size

1" (25 mm)
3/4" (19 mm)
1/2" (12.5 mm)
3/8" (9.5 mm)
#4 (4.75 mm)
#8 (2.36 mm)
#16 (1.18 mm)
#30 (0.60 mm)
#50 (0.30 mm)
#100 (0.15 mm)
#200 (0.075 mm)
      DC
    Residue
                                                              DC
Sand   Stone   Lime   Mix*
100
98
91
80
53
39
30
24
19
15
11.7



100
98
90
79
53
12
5
0
100
91
50
26
3
2
0




                              100
100
97
86
75
53
42
34
26
16
12
9.5
100
90-100
71-91
60-85
45-65
33-52
22-40
14-30
6-21
3-15
2-8
* Mix contains 68.5 percent residue, 15 percent sand, 15 percent stone,
  and 1.5 percent lime.
          On the following page is Figure IV-5, a gradation chart of the
particle size distribution of the material used in the Washington, D.C.
test section as compared to the District of Columbia DOT aggregate grading
specification for base courses.

          A summary of laboratory test results of the Mix Design for bit-
uminous based used in the Washington, D.C. test section is as follows
(Reference IV-14).
Stability (pounds)
Flow (0.01 inch)
Air Voids (percent)
VMA (percent)
Asphalt Content (percent)
Bulk Specific Gravity
Density (pounds per cubic foot)
                     Test Mix

                       2,600
                          16
                           1.8
                          13.4
                           9,
                           2,
                         137
               0
               20
                         Criterion

                         Minimum, 5,100
                         8 to 18
                         3-8
                         Minimum, 14
          This
performance.
test section is presently being completely evaluated for
          In Baltimore, Maryland, a test section  of incinerator bituminous
base was installed along Barford Road in July of 1972   (Reference IV-15).
The incinerator residue used in this base test  section, comprised 50 per-
cent by weight of the total mix.  The residue was combined with 17.5 percent
#4 stone, 10 percent #10 stone, 20 percent sand, 2.5 percent lime and 6.5
percent asphalt by weight.
                                     IV-23

-------
                                     0.149
0.420
2.00
4.76   9.52    19.1    38.1 m
?
              lOO
                                                                            6.35    12.7  I  25.4
                                                                            4 1/4 3/8 1/2 3/4  1  1-1/2
                                                  U,S,  STANDARD SIEVE SIZE
        Figure IV-5.   Particle size distribution of mix design used in the Washington, D.C. test section*
                                   "•Contains 68.5% residue, 15% sand, 15% stone, 1.5% lime.
                     (Shaded area is the District of Columbia Dept. of Transportation grading specification)

-------
          Below is a listing of the sieve sizes of the raw materials used
in the Baltimore test section.
Sieve Number
    (1)
Hydrated
  Lime
   (2)
Number
  4
Stone
 (4)
Number
  10
Stone
 (5)
1-1/2 inch
3/4 inch
3/8 inch
4
8
16
50 100
200 95
Specific Gravity 2.20
Loss on Ignition
as a Percentage


100
98
91
81
26
1
2.63

-

100
57
17
6
3
2
1
2.82

-


100
94
81
65
37
11
2.82

-
   Baltimore
Treated Residue
      (6)

      100
      100
       64
       31
       21
       15
        8
        3
        2.50

        6.0
          On the following page is Figure IV-6, the gradation chart of the
particle size distribution of the material used in the Baltimore test sec-
tion as compared to the Maryland State Roads Commission grading specifica-
tion for base course aggregate.

          A summary of test results for the bituminous base test section
placed in Baltimore is as follows:
     Parameters

Asphalt Concrete, as a percentage
Stability, in pounds
Flow, in hundredths of an inch
Weight per cubic foot, in pounds
Air Voids, as a percentage
                             Plug
                             No. 2

                               6.5
                             974
                              10
                             143.1
                               3.0
                     Baltimore
                   Specification
                      >500
                       8-18

                       3-8
The most recent field report for this section indicated that there was
acceptable performance of the residue material.

Wearing Surfaces

          In Philadelphia, Pennsylvania construction of a test section of
roadway using incinerator residue as a wearing surface was performed in
December of 1975  (Reference IV-7).  This test section consisted of approxi-
mately 108 feet of roadway at the intersection of States Drive and Belmont
Avenue (Reference IV-3).
                                      IV-25

-------
                                       0.149
0.420
2.00
4.76   9.52    19.1     38.1  m
9
to
                                                                              4  1/4  3/8 1/2 3/4  1  1-1/2
                                                     U.S, STANDARD StEVE SIZE
         Figure IV-6.  Particle  size  distribution  of mix  design used  in  the  Baltimore, Maryland  test  section*.
                           *Contains  50%  residue,  20% sand,  17.5%  M  stone,  10%  //10  stone,  and 2.5%  lime.
                             (Shaded  area is  the Maryland State Roads  Commission grading specification).

-------
          The wearing surface placed was approximately 1-1/4-inches to 1-1/2-
inches in thickness.

          The residue materials used in the wearing surface had been passed
through a 5/8-inch screen and stockpiled for approximately two weeks prior
to use.  Incinerator residue comprised approximately 50 percent by weight of
the aggregate in the mix.  Asphalt content comprised approximately 7 percent
by weight of the total mix.

          On the following page is  Table IV-4, the design gradation for the
Philadelphia test section (in percent passing by weight).

          On the following page is Figure IV-7, the gradation chart of the
particle size  distribution of the material used in the Philadelphia test
section as compared to the PennDOT ID-2A wearing surface specification limits.

          Below is a comparison of the design and field gradations for  the
Philadelphia test section (as percent passing by weight).

                               Design         Field          ID-2A
Sieve Size                    Gradation     Gradation*       Limits

1/2 inch (12.7 mm)               100           100             100
3/8 inch (9.52 mm)                91.0          92            80-100
#4 (4.76 mm)                      59.3          60            45-80
#8 (2.38 mm)                      39.3          40            30-60
#16 (1.19 mm)                     27.4          26            20-45
#30 (0.590 mm)                    19.1          16.5          10-35
#50 (0.297 mm)                    13.0          10             5-25
#100  (0.149 mm)                    9.2           7             4-14
#200  (0.074 mm)                    6.4           5             3-10

* Derived from asphalt extraction and sieve analysis.
          A summary of Laboratory Test Results for the Incinerator Residue
and ID-2A Wearing Surface Mixes Used in Philadelphia Test Section is as
follows  (Reference IV-17).
                                     IV-27

-------
          1/2" (12.7 mm)

          3/8" (9.52 mm)

          #4 (4.76 nm)

          #8 (2.38 mm)

          #16 (1.19 mm)

          #30 (0.590 mm)

^         #50 (0.297 mm)
IsJ
00         #100 (0.149 mm)

          #200 (0.074 mm)
                                DESIGN GRADATION FOR PHILADELPHIA TEST SECTION PAVING MIX

                                                IN PERCENT PASSING BY WEIGHT


                               Type 3 Residue          Natural Sand          Type IB Stone
Gradation
100
86
50
34
26
19
14
10
8
50% Blend
50.0
43.0
25.0
17.0
13.0
9.5
, 7.0
9.0
4.0
Gradation
100
100
99
73
48
32
20
14
8
30% Blend
30.0
30.0
29.7
21.9
14.4
9.6
6.0
4.2
2.4
Gradation 20% Blend
100 20.0
90 18.0
23 4.6
2 0.4





uca iyn
Gradation
100
91.0
59.3
39.3
27.4
19.1
13.0
9.2
6.4
Limits
100
80-100
45-80
30-60
20-45
10-35
5-25
4-14
3-10

-------
N>
                                0.074
                                       0.149
0.420
2.00
4.76   9.52    19.1     38.1  run
                                                                              4  1/4  3/8 1/2  3/4  1  1-1/2
                                                    U.S, STANDARD SIEVE SIZE
        Figure IV-7'.   Particle size distribution of wearing surface  mix used In Philadelphia test section.
                               (Shaded area is PennDOT 1D-2A wearing surface specification limits.)

-------
                                     Design
                                       Mix

Stability (pounds)                    1,472       1,562       1,508
Flow (0.1 inch)                          12.3        19.5        11.5
Air Voids (percent)                       5.7         0.7         3.17
VMA (percent)                            24.9        14.9        11.1
Retained Strength*                       72.8        83.3
Asphalt Content**                         8.0         7.0         4.9
Bulk Specific Gravity                     2.13        2.39        2.44
Density (Ib/ft3)                        132.9       149.1       152.3

 * Retained strength expressed as percent of molded strength as determined
   by immersion-compression test.
** Asphalt content expressed as percent by weight of total mix.

          1 pound = 0.4536 kilogram
          1 inch = 25.4 mm
          1 lb/ft3 = 16.02 kilograms/cubic meter
          Testing and inspection after one year, indicated that the wearing
surface had performed adequately.

          A visual inspection, during the summer of 1980, revealed it to be
in good condition.  The Philadelphia test section appears to be performing
as well as the control section.

          In Harrisburg, Pennsylvania, construction of a test section of road-
way using incinerator residue as a wearing surface was also performed in
December of 1975  (Reference IV-3).  This test section consisted of approxi-
mately 250 feet of roadway at Wayne Street between 14th and 15th Streets,

          The wearing surface placed was approximately 1-1/2-inches in
thickness.

          The residue materials used in the wearing surface had been passed
through a 1/2-inch screen and stockpiled for approximately two weeks prior
to use.  Incinerator residue comprised approximately 50 percent by weight of
the aggregate in the mix.  Asphalt content comprised approximately 7 percent
by weight of the total mix.

          On the following page is Table IV-5, the design gradation for the
Harrisburg test section (in percent passing by weight).

          On the following page is Figure IV-8, the gradation chart of the
particle size distribution of the material used in the Harrisburg lest Sec-
tion as compared to the PennDOT ID-2A wearing surface specificaticn limits.
                                     IV-30

-------
                                                  Table  IV-5
                          DESIGN GRADATION FOR HARRISOURG TEST SECTION PAVING MIX
                                      IN PERCENT PASSING BY WEIGHT
  Sieve Size
1/2" (12.7 mm)
3/8" (9.52 mm)
#4 (4.76 mm)
#8 (2.38 mm)
#16 (1.19 mm)
#30 (0.590 mm)
#50 (0.297 mm)
#100 (0.149 mm)
#200 (0.074 mm)
Type 2
Gradation
100
86
53
34
23
17
12
9
6
Residue
50% Blend
50
43
26.5
17.0
11.5
8.5
6.0
4.5
3.0
1/4" Limestone
Gradation
100
100
51
7
4
3
2
1
0.7
30% Blend
25
25
12.75
1.75
1.00
0.75
0.50
0.25
0.18
Screenings
Gradation 20% Blend
100
100
100
75
46
28
17
10
6
25
25
25
18.75
11.50
7.00.
4.25
2.50
1.50
Design
Gradation
100
93.0
64.3
37.5
24.0
16.3
10.8
7.3
4.7
ID-2A
Limits
100
80-100
45-80
30-60
20-45
10-35
5-25
4-14
3-10

-------
t
ro
                                  0.074
                                         0.149
                         0.420
2.00
4.76   9.52
38.1 irni
          Figure IV-8.
                                                                               4  1/4  3/8  1/2 3/4 1  1-1/2
                            U.S. STANDARD SIEVE SUE
Particle size distribution of wearing surface mix used In Harrisburg test section.
      (Shaded area ia PennUOT ID 2A wearing surface specification limits.)

-------
          Below is a comparison of.the design and  field  gradations  for the
Harrisburg test section  (as percent passing by weight).

                                     Design        Field        ID-2A
Sieve Size                         Gradation     Gradation*     Limits

1/2" (12.7 mm)                        100           100            100
3/8" (9.52 mm)                         93.0           93          80-100
#4 (4.76 mm)                           64.3           61          45-80
#8 (2.38 mm)                           37.5           37          30-60
#16 (1.19 mm)                          24.0           24          20-45
#30 (0.590 mm)                         16.3           17          10-35
#50 (0.297 mm)                         10.8           13            5-25
#100 (0.149 mm)                         7.3            9            4-14
#200 (0.074 mm)                         4.7            5            3-10

* Derived from asphalt extraction and  sieve analysis.
          A summary of Laboratory Test Results for the Incinerator Residue
and ID-2A Wearing Surface Mix Used in Harrisburg Test Section  is as follows
(Reference IV-17):

                                     Design
                                      Mix

Stability (pounds)                   1,401         1,558       1,221
Flow  (0.01 inch)                        10.0          14.0        10.5
Air Voids (percent)                      8.2           2.6         7.5
VMA. (percent)                           25.2          19.4        17.6
Retained Strength*                      86.4          96.8
Asphalt Content**                        7.6           7.6         5.7
Bulk  Specific Gravity                   2.14          2.31        2.36
Density (Ibs/ft3)                      133.5         144.1       147.3

 * Retained strength expressed as percent of molded  strength as  determined
   by immersion-compression test.
** Asphalt content expressed as percent by weight of total mix.

          1 pound » 0.4536 kilogram
          1 inch » 25.4 mm
          1 lb/ft3 » 16.02 kilograms/cubic meter


          Testing and inspection after one year, indicated that the wearing
surface was in a poor condition.  Some of the glass  particles  on the surface
had lost their asphalt coating.
                                      IV-33

-------
          A visual inspection during October of 1980 was performed.  Although
the thickness of the wearing surface placed had been reported as 1-1/2-inches,
the majority of the test section wearing surface actually placed appeared to
be much thinner than reported.   Areas of the pavement examined established
that the wearing surface placed was approximately 1/2-inch in thickness.*
It appeared that no tack coat had been placed on the contact surface to
the underside of the wearing surface.  It is noted also that this experi-
mental section was placed during a period of cold weather.

          Despite the unfavorable conditions in which the test section was
paced (re.  minimal pavement thickness, minimal tack coat preparation of base,
and seasonal weather)  the October 1980 inspection confirmed that  other than
asphalt stripping from the glass particles of the test section, there was no
discern able difference between the performance of the test section and the
control section.

          In Lima (Delaware County), Pennsylvania, construction of a test
section of roadway using incinerator residue as a wearing surface was per-
formed in October  of 1975 (Reference IV-3).  This test section consisted
of approximately 60-feet of roadway at the main entrance to Fair Acres Farm
off of Middletown Road.

          The wearing surface placed was approximately 1-1/2-inches in
thickness.

          The residue materials used in the wearing surface had been passed
through a 1/2-inch screen.  The materials had been obtained from a stockpile
at the Northwest Philadelphia incinerator.   The age of the stockpile was un-
known, but  it was estimated to have been approximately two to three months
old.  Incinerator residue comprised approximately 50 percent by weight of the
aggregate in the mix.  Asphalt content comprised approximately 7 percent by
weight of the total mix.

          On the following page is Table IV-6, the design gradation for the
Lima test section (in percent passing by weight).

          On the following page is Figure IV-9, the gradation chart of the
particle size distribution  of the material used in the Lima test section
as compared to the PennDOT ID-2A wearing surface specification limits.
* Pennsylvania Department of Transportation guidelines for resurfacing of
  roadways recommends that wearing surface overlays be placed in thicknesses
 / no less than 1-1/2-inches.

                                     IV-34

-------
CO
Ul
                                                             Table IV-6


                               DESIGN GRADATION FOR DELAWARE COUNTY TEST SECTION  PAVING MIX
Sieve Size
1/2" (12.7 mm)
3/8" (9.52 mm)
#4 (4.76 mm)
#8 (2.38 mm)
#16 (1.19 mm)
#30 (0.590 mn)
#50 (0.297 mm)
#100 (0.149 mm)
#200 (0.074 mm)
Type 3
Gradation
100
91.5
68.7
55.0
44.0
33.0
24.0
15.0
11.1
Residue
50% Blend
50.0
45.75
34.35
27.5
22.0
16.5
12.0
7.5
5.55
Pa. IB
Gradation
100
84.5
21.5
10.0
4.8
4.0
3.0
2.0
0.8
Stone
25% Blend
25.0
21.13
5.38
2.5
1.2
1.0
0.75
0.5
0.2
Anti-Skid
Gradation
100
100
90.6
40.0
19.0
9.0
4.0
3.0
2.3
Material
25% Blend
25.0
25.0
22.65
10.0
4.75
2.25
1.0
0.75
0.58
Design
Gradation
100.0
91.9
62.4
40.0
28.0
19.8
13.8
8.8
6.3
IO-2A
Limits
100
80-100
45-80
30-60
20-45
10-35
5-25
4-14
3-10

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                                       0.149
                           0.420
2.00
4.76   9.52    19.1     38.1  urn
OJ
o>
                100
                                                                              6.35    12.7    25.4
       Figure IV-9.
                                                                              4 1/4 3/8 1/2  3/4  1  1-1/2
                              U.S,  STANDARD SIEVE SIZE

Particle size distribution of wearing surface mix used in Delaware 'County test section.

        (Shaded area ia PennDOT ID-2A wearing surface specification limits.)

-------
          Below is a comparison of the design and field gradations  for the
Lima test section (as percent passing by weight).

                                      Design         Field        ID-2A
Sieve Size                           Gradation     Gradation*     Limits

1/2" (12.7 mm)                          100           100            100
3/8" C9.52 mm)                           91.9          94.0         80-100
#4 (4.76 mm)                             62.4          68.2         45-80
#8 (2.38 mm)                             40.0          '36.5         30-60
#16 (1.19 mm)                            28.0          24.5         20-45
#30 (0.590 mm)                           19.8          17.5         10-35
#50 (0.297 mm)                           13.8          12.4          5-25
#100 (0.149 mm)                           8.8           8.0          4-14
#200 (0.074 mm)                           6.3           6.1          3-10

* Derived from asphalt extraction and sieve analysis.
          A Summary of Laboratory Test Results  for  the Incinerator Residue
Wearing Surface Mix Used  in Delaware  County Test  Section  is  as  follows
(Reference IV-17):

                                      Design Mix       Field Mix

Stability  (pounds)                       1,195             1,165
Flow  (0.01 inch)                           11.7             16.8
Air Voids  (percent)                         2.4             5.5
VMA (percent)                              26.0             18.9
Retained Strength*                         35.2             49.5
Asphalt Content**                           7.0             7.1
Bulk  Specific Gravity                       2.05             2.25
Density (Ibs/ft3)                          127.9           140.4

 * Retained strength expressed  as percent  of molded strength as determined
   by immersion-compression test.
** Asphalt content expressed  as percent  by weight of total mix.

          1 pound = 0.4536 kilogram
          1 inch - 25.4 mm
          1 lb/ft3 = 16.02 kilograms/cubic meter


          Testing and inspection after one year,  indicated that the wearing
surface was in a fair condition.  There  were some signs of asphalt stripping
from  the glass particles.

          This test section had been  paved over in  1977.  The resurfacing of
this  section was not connected  with poor performance of the  test pavement,
but was a result of an extensive resurfacing project which randomly included
the test section.
                                      IV-37

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Stabilized Bases and Sub-bases

          "Chempac" is a trade name for a mixture of incinerator residue and
lime used in stabilized base applications.  This mixture has certain quali-
fications (Reference IV-17).  "Chempac" is defined as "a mixture of processed
ash produced by  rotary kiln type incinerators operating at temperatures in
the vicinity of 1,800°F, and hydrated  lime, in the approximate proportions
of 95 percent processed incinerator ash and 5 percent lime."  These percent-
ages are subject to slight variations.

          Qualifications regarding the gradation specifications of the incin-
erator residue used in the "Chempac" mix are as follows:

          Passing 1" sieve           100%
          Passing 1/2" sieve         85-100%
          Passing #4 sieve           60-90%
          Passing #10 sieve          40-70%
          Passing #40 sieve          15-40%
          Passing #80 sieve          5-20%
          Passing #200 sieve         4-15%

          Suggested limits with respect to carbon content, organic content,
and water content for "Chempac" mixtures have also been established.

          To date, "Chempac" base course mixtures have been used primarily
in parking lot type applications.  Perhaps the largest area application of
a "Chempac" base material has been in north and south parking lots of Lawn-
dale High School, Chicago, Illinois (Reference IV-19).  In June of 1976,
approximately 1,700 tons (dry weight) of "Chempac" was placed at this site.
"The average percentage flue dust lime based on a dry weight of the delivered
Chempac of approximately 1,700 tons was 15 percent + (Reference IV-19).   Res-
idues from the Chicago Southwest  Incinerator and the Stickney, Illinois in-
cinerator were used for this project.  These residues have been characterized
in a U.S. Department of Transportation Report as follows (Reference IV-20):

Sieve Size	1"    3/4"    3/8"    #4     #10     #40     #100    #200

Sample Collection
  #       Date
1
2
3
4
5
6
7
8
9
10
11
12
13
09/02/73
09/11/73
09/25/73
10/05/73
10/15/73
10/24/73
11/02/73
11/09/73
11/13/73
11/23/73
11/29/73
12/06/73
12/14/73
100
100
100
100
100
100
100
97.6
100
100
100
100
100
99.5
94.9
90.6
95.5
100.0
97.3
96.6
97.6
98.3
98.9
95.0
98.1
97.0
91.2
93.2
61.6
87.5
81.0
90.6
89.1
88.7
93.3
90.3
86.8
87.4
88.6
74.8
82.5
38.1
74.5
65.0
76.3
78.4
71.4
80.7
74.2
68.7
71.2
76.0
53.7
57.6
17.6
51.6
43.4
53.1
53.8
48.3
49.5
46.7
46.1
48.9
49.0
38.4
29.6
7.5
26.3
19.4
27.4
22.0
23.9
18.6
22.3
23.4
25.1
16.2
30.9
20.8
4.3
16.0
10.3
14.6
12.5
13.0
10.7
12.6
14.3
15.1
7.9

16.1
3.1
12.0
8.6
9.3
8.4
8.6
8.1
9.5
11.1
11.3
5.5
                                     IV-38

-------
Sieve Size	1"     3/4"    3/8"    H     #10     #40     #100
Sample Collection
  #       Date
14
15
16
01/08/74
01/18/74
01/24/74
100
100
100
9.1
97.2
98.0
74.6
89.2
88.8
58.6
77.1
76.0
37.4
49.8
52.3
14.3
19.6
19.7
8.3
11.6
10.9
5.T
8.8
7.9
       Average           99.9  96.6    86.4    71.5   47.4    22.1    13.4     9.9
       High             100   100      93.3    82.5   57.6    38.4    30.9    25.0
       Low               97.6  90.6    61.6    38.1   17.6     7.5     4.3     3.1

* Percent Passing Sieve - ASTM Method D-422


          On the following page is Figure IV-10, the gradation chart for the
39th and Iron Street 16 weekly samples.  This chart includes a gradation of
the incinerator residue from a stockpile created by the Associated Contractors,
Chicago, Illinois.

          Twenty-nine field tests for water content, and in-place dry density
were taken at the time of the Lawndale installation.  All tests reported com-
paction of greater than 95 percent of maximum lab dry density, with 19 of the
29 results of the tests exceeding 100 percent maximum density.

          Maximum lab dry density was 75 pounds per cubic foot, with an optimum
water content of 14 percent by dry weight of residue.

          The Lawndale "Chempac" base is reportedly in a good condition at
present.  No additional testing has been performed at the site since the time
of the initial installation.

          In St. Charles, Illinois, construction of a section of a parking
lot using incinerator residue as a stabilized base was performed in October
of  1974 (Reference IV-20).  This test section was  placed in the southwest
corner of Illinois Bell Telephone parking lot.  The "Chempac" material used
at this site was from the Stickney, Illinois incinerator.  This material had
been aged for at least one month in the yard stockpile of Associated Con-
tractors, Chicago, Illinois.

          The Stickney residue material had been laboratory tested with a
lime concentration of 8 percent by weight.

          Field compaction data for the subgrade and "Chempac" at the Bell
Telephone site test area is shown on the following page in Table IV-7.

          Field tests and visual examinations of the test area were conducted
over the next 2-1/2 year period.  The following data were reported for dry
density and CBR testing;
                                     IV-39

-------
                                       0.149
     0.420
2.00
4.76   9.52    19.1     38.1  m
z
o
                                0.074
                              Associated Contractors
                                                                                          Range  of
                                                                                          Gradation
                                                                                   Average   —
                                                                                   Gradation
                                                                              4  1/4 3/8 1/2  3/4  1  1-1/2
      Figure  IV-10.
        U,S,  STANDARD SIEVE SIZE

  Gradation Range of Weekly Samples  From
39th & Iron St.  Incinerator, Chicago,  111.

-------
                                                          Table  IV-7
                                        Held Oenslty  Ttst MJiltL*_-_J>F»»n»ir.ill5JlJLI*
                                                                            _ruin              .__,	
                                Depth Below                   Use        GFy      HolTlur*  Haxlmuin    "Optimum   Haxlmmt      I  of
Test    Paved Areas  for Parking  final Sutgrade Description     of         Density  Content   Dry Density  Moisture  Dry Density  Specification
Ho,             and  Drive	  Elevation      of Material     Material   Jpcfjl   |	d'cfp       Content!  Obtained     Requirements
        30'  South t  10* Nett of
        Southwest corner of         -8.0"
        building

        60*  South of Center of      -8.0"
        South side of building

        «'  West I 21* South of
        Southeast corner of         -8.0"
        building
                                       Brown sllty
                                       Clay with sand    Fill
                                       and gravel

                                                         Fill
                                                         Fill
          IZ5.6     10.7
          123.0     12.1
          129.0
                                                                            0.3
132.0
132.0
132.0
9.1
9.1
9.1
95.2
93.2
97.8
                                   90.0
                                   90.0
                                                                                                                          90.0
10
39* East 1 21*  South of
Southwest corner  of         -8.0"         CIIEHPAC
building

95' West t 25'  South of
Southeast corner  of         -6.0"
building

751 East I 42'  South of
Southwest corner  of         -0.0"         ClltHTAC
building
                                                                Fill       70.7    16.3        81.6        25.0      86.6         95.0
                                                 CIICHPAC         Fill      69.8     21.2        81.6        25.0      85.5         95.0
Fill      77.2     IS.6        81.6        2S.O      94.6         95.0
        •Source Testing Service Corporation
         I pcf • 16.01  kg/ml

-------
                             Dry Density, pcf*
                                C% Proctor)**
                                                              C.B.R.
Location            3/13/75    11/14/75      6/28/76          10/22/76
                                                            Deflection
                                                        0.1  inc.     0.2 in.

B-l                 Sample       67.9        68.1         34           27
                    Damaged      (84%)       (84%)
B-2                  69.7        70.5        75.1         61           54
                     (86%)       (87%)       (92%)
B-3                  75.5        74.0        76.1         74           75
                     (93%)       (91%)       (94%)

 * 1 pcf - 16.01 kg/m3
** Percent of optimum density
   1 inch =2.54 cm.
          At the end of the 2-1/2 year monitoring period, it was observed
that there was sone distress of the test section.  The observed cracking
of the pavement of the test section ("Chempac base") however, did not ap-
pear to be as extensive as the cracking of the adjacent control (crushed
stone base) pavements.  At present, the "Chempac" base appears to be per-
forming as well as the crushed stone  base control.

          A "Chempac" test section of  roadway placed in Stickney, Illinois
in 1963 has since been removed due to pulling and shrinkage of the base ma-
terials over time (Reference IV-21).  Another residential street applica-
tion of "Chempac" material in Illinois had to be removed because a wearing
surface was  not placed on top of it.  It is noted, however, that  one of the
first applications of "Chempac" type materials was in the parking lot of Soil
Testing Services, Inc. of Northbrook, Illinois in 1962; this section is still
in good condition.

          The total number of "Chempac" material field tests that have been
performed to date is approximately 12 (Reference IV-21).

Fused Aggregate

          As to date, the only test section of fused  aggregate placed, has
been in 1976 in the area of Harrisburg, Pennsylvania (Reference IV-22).  This
test section consisted of approximately 180 feet of roadway placed on the
southbound lane of Traffic Route 22, Dauphin County, between 181 and the
Rockville railroad bridge.

          The wearing surface placed was approximately 1-1/2-inches in
thickness.
                                     IV-42

-------
          The fused residue used had been passed through a scalper which
had removed the particles larger than 3/4 of an inch.  The materials had
been obtained from a stockpile of fused incinerator residue produced at
Catasauqua, Pennsylvania, and broken at Broomall, Pennsylvania.

          Fused aggregate comprised all of the aggregate in the mix, as
the gradation of the material was such that it did not require the addi-
tion of a fine aggregate.

          The asphalt content comprised approximately 6.5 percent by weight
of the total mix.

          Testing and inspection after one year, indicated that the wearing
surface was in an excellent condition.

          Below is  the particle size distribution of the graded incinerator
residue used in the Harrisburg Fused Incinerator Test Section, in percent
by weight.*
          Sieve Size

          5/8" (15.9 mm)
          1/2" (12.7 mm)
          3/8" (9.52 mm)
          #4  (4.76 mm)
          #8  (2.38 mm)
          #16  (1.19 mm)
          #30  (0.590 mm)
          #50  (0.297 mm)
          #100 (0.149 mm)
          #200 (0.074 mm)
Percent Passing
      100
       99.0
       88.
       63.
       44,
       28.
       18.9
       12.0
        7.6
        4.4
,7
,2
.4
.1
* From truck mix, draft report  (Reference  IV-22).

          On the following page  is Figure  IV-11, a gradation chart  of the
particle  size distribution of the wearing  surface mix used  in- the Harris-
burg  fused aggregate  test section as  compared  to the PennDOT ID-2A  wearing
surface specification limits.

          A summary of Laboratory Test  Results for the  Fused Aggregate
Incinerator Residue used in  the  Harrisburg test section is  as  follows:
Stability  (pounds)
Flow  (0.01 inch)
Air Voids  (percent)
VMA.  (percent)
Asphalt  Content
Laboratory Specific  Gravity
density  (lbs/ft3)
  % weight  of  total mix
Job Mix
PA DOT
 1,784
    10
     4.0
    19.6
     6.8
     2.354
   147.1
   Control
     Mix
     2,250
PA DOT
Spec.
1,200 min.
10.6
3.9
17.7
5.9
2.418
150.9
6-16
3-5
—
4.5-8.0
—
—
                                      IV-43

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                                    0.149
0.420
2.00
4.76   9.52    19,1     38.1  m
              100
                                                                           4  1/4  3/8  1/2 3/4 1  1-1/2
                                                  U,S, STANDARD SIEVE SIZE
Figure IV-11.  Particle size distribution  of wearing surface mix used  in Harrisburg fused aggregate test section.
                            (Shaded  area  is PennDOT ID-2A wearing surface specification limits.)

-------
follows:
          Additional field  core data for the Harrisburg test section is as
              FIELD CORE DATA FOR SEPTEMBER, 1976 EXTRACTIONS
                           TEST PAVEMENT  SECTION
Theo. Sp. Gr. @ 77 F
Sp. Gr. @ 77 F
Voids % by Volume
VMA % by Volume
VFA % by Volume
Compaction % of Theo.
Avg. Thickness, Inches
                                   Station 300+26
Core 1
2.454
2.214
9.8
24.4
59.9
90.2
Core 2
2.454
2.210
10.0
24.6
59.4
90.0
Core 3
2.454
2.217
7.5
22.4
66.7
92.5
                                       Station 3014-31
Core 4
2.454
2.300
6.3
21.4
70.8
93.7
Core 5
2.454
2.281
7.0
22.1
68.1
93.0
Core 6
2.454
2.311
5.8
21.1
72.3
94.2
                  1-3/4
                             1-1/2
Core T-6A
Core T-8A
Core T-9A
Core C-8A
Core C-9A
              FIELD CORE DATA FOR NOVEMBER, 1979 EXTRACTIONS

                     Recovered Asphalt


e
Absolute
Viscosity
140 F, poises

Penetration
@ 77 F
Specific
Gravity
@ 77 F

%
by

Voids
Volume
% Voids
in the Mineral
Aggregate (VMA)


*
17,555
25,899
10,877
 6,014
 4,848
24.5
22.0
31.0
41.0
49.0
2.288
2.322
2.297
2.424
2.447
6.8
5.4
6.4
3.7
3.7
21.4
20.3
20.7
17.5
17.7
* Calculated from total asphalt content, not effective asphalt content.
          A visual inspection during October of 1980 confirmed that this
test section was performing as well as the control section of pavement.
The only noticeable difference between the test section and the adjacent
pavesents, was that the test section had retained a darker natural color
(black),  and had not faded to grey.

TECSTTCAL ASSESSMENT OF USES

          Overall performance (durability, life expectancy, visual appearance,
etc.), of paveaents and subgrades which contain incincerator residue have
varied frcn good to poor.

          An initial problem encountered with using incinerator residue in
paveaent applications, is that a great amount of material quality control
is -eeced.  This is so, as only certain quality residues may be used in
         applications.  The problem is having to monitor all the residue
                                     IV-45

-------
(which is to* be used in pavement applications) arises from the incineration
process itself.  As previously mentioned, the factors affecting the quality
of the residue are time of combustion,  temperature of combustion, and tur-
bulence during combustion.  These three factors are normally of little sig-
nificance during municipal incineration operations.

          An example of this type of uncontrolled combustion is evidenced
by the procedure which may occur at an incineration facility having more
than one furnace.   If the facility operates two  furnaces at a certain in-
coming volume of refuse and is subsequently only able to operate one furnace,
due to  breakdown of, or maintenance on, the other furnace; the constant
volume of refuse would be cycled through the single operating furnace.  The
channeling of the refuse through  the single unit  would produce a residue
of poorer quality than that produced by dual furnace combustion. Also, in
municipal refuse processing, variations in seasonal quantities and incoming
moisture contents of refuse are not adjusted  for during combustion opera-
tions for the production of a uniform residue.

          A disadvantage in processing of residue material to be used in
construction applications (other than quality control), is that stockpiling
is necessary.  In conjunction with stockpiling, additional screening, shred-
ding or trommeling of residue (to that of conventional materials) may have
to be done as a means of preparing the residue to a desired gradation.

          Incinerator residue, however, can be used in pavement applications
if properly prepared.  An advantage  of using incinerator residue in base,
sub-base, and wearing surfaces is that it may be placed with conventional
equipment.  Placement of materials on various jobs has been performed with
conventional paving equipment, dump trucks, hand raking, and standard com-
paction rollers.  Another advantage is that the residue material is also
easily mixed and handled in the field.  Mixing techniques of lime in the
residue on different base and  sub-base projects varied from handraklng to
pugmill mixing.  The addition of lime to the residue in asphalt mixes may
be performed in a dry  or slurry form.  Slurry addition is done in advance
of pugmill mixing, but requires added time and effort as compared to the dry
mixing technique.  Dry addition of lime of the pugmill is an effective mix-
ing method, though dust control measures must be implemented for this oper-
ation, as appreciable amounts of dust can be generated.

          It is noted that blending of a  natural aggregate with the residue
in mixes is necessary to economize on the use of asphalt while at the same
time increasing coatability of the mix.  Control of the quantities of the
components to be blended in the mixtures is of importance.  The feeder con-
trol for blending of residue in residue/aggregate mixes is sometimes not
easily controlled, due to the clogging and clotting capacity of the resi-
due.  This was evidenced in the Washington, D.C, section, as the designed
residue to aggregate ratio in the mixture was not achieved for the first
truckload batches.  This situation was corrected at the beginning of place-
ment operations, but  not until after some of the mis-proportioned material
had been placed in the field.
                                     17-46

-------
Stabilized Base and Sub-base

          A disadvantage of using incinerator residue in a Chempac type base
application is that the material requires a time period of approximately 3
days before placement of the wearing surface may be performed.  This is re-
quired to dissipate potentially damaging (to the wearing surface) hydrogen
gas pressures.

          Residue material compacts well in the field, but a determination
of optimum moisture for compaction is difficult due to the high absorption
of the material.

          Incinerator residue/lime material does not appear to perform well
under laboratory freeze-thaw testing, though high 180-day compressive strengths
of +700 pounds per square inch and good California Bearing Ratio values have
been attained for certain products (i.e., Northbrook, Illinois).

          Below is the CBR data for the St. Charles, Illinois site (Reference
IV-20):

                              CBR - 10/22/76

Boring Location     0.1 inch Deflection     0.2 inch Deflection

      Bl                     34                      27
      B2                     61                      54
      B3                     74                      75
           It  is  noted  that  variations  of  the  type  and  quality  of  the  lime
 in residue mixtures  slightly affect  the strength of  the mixtures.  Types
 of lime  used  in  base applications  are  calcitic  lime, dolomitic lime,  flue
 dust  lime, and carbon  sludge.    Calcitic  lime and  dolomitic lime are the
 two most commercially  desirable limes.  Below is a comparison  of  these two
 limes (Reference TV-3):

               Results  of Compressive Strength Evaluation  of
                     Stabilized Base Course Mixtures
                         with Variable Binder  Types

 1. LIME STABILIZED  BASE COURSE

    1 "as received"  residues
    2 average of 3 specimens  cured  for 7 days  @ 1008F.

                                                          Average
                                                       Compressive
 Residue                Crushed             Type of     Strength**
  Type*     Residue      Stone     Lime       Lime        (lbs/in^)

   2           45         45         10    Dolomitic        197
                                           Calcitic        149

   2           48         48          4    Dolomitic        197
                                           Calcitic        164
                                      IV-47

-------
Wearing Surfaces

          Wearing surface mixtures which  contain incinerator residue may
be batched directly at the asphalt plant as conventional mixes are, al-
though more dust at the mixing plant may be created during the mixing
operations than occurs from the mixing of conventional materials.

          The residue/aggregate mixtures can perform as well as conven-
tional aggregate mixtures.  Marshall design criteria for medium to heavy
traffic road surfaces have been met by the test sections placed to date.

          There appears to be an advantage for using residue/aggregate
mixtures instead of conventional aggregate mixtures with respect to skid
resistance.  To measure the safety performance of incinerator residue in
wearing surfaces, skid resistance tests were made on the control  and ex-
perimental pavement sections.  Two different types of skid resistance tests
were used in evaluating the pavements (Reference 1-23).  The two skid tests
used were the BPN and SN 40.*

          To evaluate  the Harrisburg fused aggregate section of pavement,
the SN40 test was used.  This test  is standard ASTM test E274.  The test
procedure involves using a specially equipped vehicle which can measure
the tractive force of a test tire (horizontally applied force) as compared
to a vertical load on the test wheel.  On  the following page are the re-
sults of the Harrisburg fused aggregate section (Reference IV-22).

                          SKID TEST DATA (SN40)

                                     Incinerator       Control Section*
                                       Residue    Passing Lane  Traffic Lane

October 1976                              52            40           44
April 1977                                53            41           39
June 1977                                 50            —
October 1977                              51            33           33
October 1978                              46            36           33
September 1979                            49            38           35

* Adjacent section (Station 302+50 is an experimental blend of gravel and
  limestone aggregates.

  Skid number is average of three separate  passes.
* A BPN (British Pendulum Number) of 55 correlates with a skid number (SN)
  of 40, as obtained from skid trailer measurements.  A skid number of 40
  is generally considered a tiymiTmnn acceptable value for skid resistance
  of bituminous pavements in Pennsylvania (Reference 1-23).
                                     IV-48

-------
          Traffic counts for the Harrisburg fused aggregate section of
pavement are as follows  (Reference IV-3):
                            TRAFFIC COUNTS FOR
                             TEST AND CONTROL
                            PAVEMENT SECTIONS
                                      Test      Control
                                    Pavement    Pavement
                                     Section     Section     Total

March 15, 1978                        9,710       4,917     14,627
July 18, 1978                         9,769       3,693     13,462
September 18, 1978                    1,482         640      2,122
November 16, 1978                     3,713         782      4,495
September 6, 1979                     3,742       1,173      4,915


          To evaluate the Philadelphia section of pavement, the BPN test
was used.  The British Pendulum Number (BPN) test is standard ASTM test
E303.  This test procedure involves measurement of forces on a dynamic
pendulum impact device.  This test was used  due to the inaccessibility
of the pavement to the SN40 test vehicle with respect to safety.  On the
following page is Table IV-8, the results of the BPN testing of the
Philadelphia section (Reference IV-17).

          As a means of comparison to the traffic count data for the Harris-
burg section, the Philadelphia section had a total count of 1,777 vehicles
between 8:00 a.m. and 7:00 p.m. as observed  on January 7, 1976 (Reference
IV-17).

          The test results from these two experimental sections indicate
that the wearing surfaces with incinerator residue show slightly better
skid resistance characteristics than their adjacent control pavement sec-
tions.  This may be due to differential wearing of the particles of residue
and aggregate.  The BPN test results of the Harrisburg (Wayne Street) sec-
tion also showed better skid resistance of the incinerator residue pavement
as compared to the control pavement section.

Bituminous Base Mixes

          A disadvantage of using incinerator residue in bituminous mixes
is that additional asphalt is required in the mix, beyond that required
in conventional aggregate mixes.

          Incineration facilities often recycle the stack ashes from their
burning operations back through the furnace.  This results in the production
of a more powdery or finely sized residue.  If placed in a bituminous mix,
this finely sized residue would require a greater amount of asphalt than a
coarser sized residue.
                                     IV-49

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                               Table IV-8

                  SUMMARY OF SKID RESISTANCE VALUES

                      PHILADELPHIA TEST SECTION
 March/  1976
 September,  1976
September, 1976
November, 1976
November, 1976
Sample No,

  1-1
  1-2
  1-3

  1-7
  1-8
  1-9
  1-10
  1-11
  1-12

  2-1
  2-2
  2-3
  2-4
  2-5
  2-6

  2-7
  2-8
  2-9

  3-1
  3-2
  3-3
  3-4
  3-5
  3-6

  3-7
  3-8
  3-9
Mix Type

Control



Residue
Residue
Control
Residue
Control
British
Pendulum
Number
 (BPN)

   88
   80
   93

   92
   92
   87
   86
 .  86
   87

   92
   90
   82
   92
   87
   83

   89
   80
   85

 105
 111
   85
   87
   80
   87

   38
   77
   93
                                                             Average
                                                               BPN
                                                              Value

                                                              87.0
88.3
87.7
84.7
92.5
86.0
* A total of six control mix specimens were  taken.   However,  no
  test could be performed on three of the core  specimens due  to
  the uneven surface of these specimens.
                                    17-50

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           An advantage of using incinerator residue in bituminous mixes as
 opposed to lime  stabilized mixes is that the asphalt tends to bind or en-
 capsulate the residue particles, thus diminishing detrimental leachate
 characteristics.

 ENVIRONMENTAL FACTORS


           It is considered that incinerator residue base materials are more
 economically attractive than fused materials at present.  The primary en-
 vironmental considerations related to incinerator materials in construction
 applications (base/lime base) are leachate characteristics.  Leachate pro-
 duction and composition are related to solubility, permeability, and chemical
 composition of the residue.


           Generally, water penetration through incinerator residue is rela-
 tively low, as the permeability of residue may be considered equivalent to
 that of a silty sand or fine sand.  The toxic substances contained in residue
 materials are trace metals including arsenic,  cadmium, copper, and lead.
 With respect to these toxic substances, the Environmental Protection Agency
 has established a guideline for Safe Drinking Water Standards.  A waste ma-
 material is considered hazardous if the extract from the material (obtained
 by the EPA extraction procedure) has a concentration of any constituent
 greater than one. hundred times the established drinking water standard.

          Permissible concentrations of chemicals are listed in the drinking
water standard established by the U.S. Public Health Service include (Ref-
erence IV-24; also see Summary on Page 1-24).

          It was reported in leachate testing performed  during 1980 by the
Pennsylvania Department of Transportation, as well as by the Port Authority
of New York and New Jersey, that concentrations of chemicals in  excess of
one hundred tines the drinking water standard were measured on tested samples
of incinerator residue.  The samples tested by the Pennsylvania  Department of
Transportation came from an incinerator located in Central Pennsylvania  (Ref-
erence IV-25).  The samples tested by the Port Authority of New  York and New
Jersey came from two resource recovery plants  located in  the northeastern
region of the United States (Reference IV-26).  It was noted  that a reported
concentration of lead in the Port Authority report was greater than three
hundred times the drinking water standard.
                                     IV-51

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           The material from which these samples were taken would be classi-
 fied as hazardous by the Environmental Protection Agency.  The use of this
 material, "as is," in a construction fill application would be highly
 restricted.

           There is the possibility, however, that this material may be used
 in a bituminous base application.  In the bituminous base application, the
 leachate from the residue may not be deemed as hazardous due to the encapsu-
 lating effect of the asphalt on the residue (i.e., restricting permeability,
 etc.).

           In addition to the leachate problem, the potential of having path-
 ological wastes make their way into the refuse stream (and residue) is an
 additional complication with respect to use of the residue as a highway
 construction material.    Many existing incineration facilities such as
 Harrisburg,  Pennsylvania are authorized to burn hazardous materials includ-
 ing chemical wastes and hospital wastes.   If the temperatures during the
 incineration process are not maintained high enough to destroy the pathogens
 (in hospital wastes) and control chemicals, serious health problems of these
 in contact with the materials would result.

           Appreciable amounts of these specialized wastes can be burned at
 incinerators licensed to do so.   In addition to the refuse burned in con-
 junction with the hazardous materials, residual effects of the burning of
 these hazardous materials on subsequently burned refuse are also sources of
 potential problems.   Especially tight quality control would be a necessity
 in any attempt to use the residue from these specially licensed incinerators
 in construction applications.

           Air pollution control poses an additional environmental problem
 with respect to using incinerator residue in highway applications.   In ad-
 dition  to the air quality problems at the incineration site,   dust genera-
 tion at the asphalt plants (for bituminous base applications) occurs.   It
 is noted that air pollution problems at incineration sites have also been
 experienced at the newer resource recovery facilities,  as evidenced at the
 Hempstead, New York plant.

           Aside  from environmental drawbacks, the political system should
be  recognized as a major factor which influences the use of incinerator
residue in construction applications.  General problems and restrictions
which are  inherent in the political processes regarding the use of residue
deal with  budgeting,  length of personnel employment, coordination with
various departments, and existence of priority programs.

           The Resource Conservation and Recovery Act of 1976 requires existing
landfill sites to be upgraded to acceptable governmental specifications or
be  closed.  JIf__strict adherence to this Act is maintained, the economics of
this procedure (of upgrading) will most likely be the most important factor
with respect to  municipal solid waste management programs.  Any amendments
to this act or followup legislation will be of significance to the direction
of current waste disposal operations.
                                     IV-52

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ECONOMICS

          At this time, a detailed analysis of the economics of incinerator
residue in construction applications  (residue vs. virgin aggregate) does
not provide the means to realistically judge the most economic alternative.
The reason for this is that incinerator residue is not being presently widely
used in the aggregate market.  Supported by the fact that residue is not be-
ing used in the current market, and that there has been a considerably limited
number of field applications to date; exact cost comparison figures for in-
place materials using incinerator residue cannot be ascertained.  Hidden and
undetermined costs involved with the use of incinerator residue on a large
scale basis include dollar costs in the following areas:  provisions for
control of degree of burnout; provisions for monitoring of residue to be
used including leachate testing, equipment and maintenance costs, transpor-
tation costs, and mixing and preparation costs.  For example, long range ef-
fects on machinery that handles and processes residue for construction ap-
plications has not been observed, as the machinery used  in the past has not
been operated for sustained periods of time. Detrimental long range effects
may relate to unanticipated costs in the following areas:  additional cleaning;
part replacement from excessive wear; or even modification of equipment.

          Although research into the economics of using incinerator residue
as a construction material has begun  (Reference IV-2), it should be realized
that research analysis can provide only projected cost figures.  Until a de-
tailed breakdown analysis on a minimal number of specific projects is per-
formed, actual representative costs of using incinerator residue as a con-
struction material cannot be accurately ascertained.  However, Reference IV-2
does provide a basis for developing cost categories and in determining ap-
proximate costs.

OTHER APPLICATIONS

          Incinerator residue has been tested for applications other than
direct roadway usage.  This testing includes incinerator residue as a struc-
tural fill, as a soil cover substitute in a lined sanitary landfill, as a
soil stabilizer, and in portland cement concrete.  Incinerator residue has
also been used as a wearing surface on "off highway" trails  (i.e., bicycle
and foot paths).

          In portland cement concrete mixes, a volume expansion of the ma-
terial is caused by the reaction of the aluminum in the residue and the
cement in the mixture.  Accompanying this volume expansion is a loss of
strength.  In these mixes, high strengths are not attainable  (even where
the same proportions of aggregate and residue are used) as the inherent
strength  of the residue is a limiting factor.

          Lime slurry ing of the residue can eliminate some of the aluminum
cement reaction, but compressive strengths comparable to those of conven-
tional mixes are still not achieved.  It is noted that pyrolysis residues
in portland cement concrete have better strength gains than the other types
of incinerator residues in these mixtures.

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          In use as a fill material, the leachate from incinerator residue is
considered as a negative factor.  Incinerator residue does compact well though,
and can serve as an adequate fill material.

MISCELLANEOUS

          Solid waste is now considered  as a raw material and source of
energy.  Energy recovery systems appear to be an area upon which emphasis
will be placed.  Working energy recovery systems  are already a reality.

          In Europe, resource recovery and incineration systems are largely
based on optimum design principles, as opposed to minimum cost principles.
A justifying factor in this type of analysis relates to population density.
In the United States, cost principles are a major factor in design analysis.

          In this country, good burnout, energy recovery, and excellent air
pollution control have been reported by such facilities as Chicago's 1,600
tons per day steam generating incinerator.  "Resource recovery plants in
northwest Chicago, Ames, Iowa, and Nashville are already considered finan-
cially successful, but the first structured to show a profit that has ac-
tually done so is the mass-burn waterwall boiler system in Saugus, Massa-
chusetts.  Operated by a joint  venture including Wheelabrator-Frye, Inc.,
Hampton, New Hampshire, the plant  showed a profit in 1979, but revenues
included a Federal subsidy from DOE's entitlement program.  The Saugus
plant is the first to have received these funds" (Reference IV-27).

          Current problems with regard to growth and expansion in the area
of resource recovery in this country vary.  In New York City, for example,
a New York State law which prohibits cities from contracting with one en-
tity and giving that entity full responsibility for a job, is the current
resource recovery project stopper.  A bill is being considered by the state
legislature which may give the city relief.  In some cities such as Detroit,
financing troubles are the biggest project stoppers.  The solution  to these
financing problems are as yet undetermined.

          In addition to financing and political problems, some existing
resource recovery facilities have had technological difficulties. For ex-
ample, the Hempstead, Long Island plant has "been plagued by odor problems,
labor strife, contractual disagreements...and  even by the discovery of
traces of dioxin  in stack emissions.  ...Repairs have included doubling
the size of the ventilation system, rebuilding the odor control system,
replacing a pneumatic fuel feed system and installing a new ash handling
system" (Reference IV-27).
                                     IV-54

-------
          Despite current drawbacks, resource recovery systems appear to be
along the most desirable path of future projected Incineration processes.
Cities with current waste disposal problems such as Harrisburg, have de-
veloped their own remedies for potential solutions.  Harrisburg's solution
involves construction of a separate metals recovery and screening separation
facility to function in conjunction with their existing steam generation in-
cinerator (Reference IV-28).  Harrisburg's solution also involves the use of
the residue, produced from the combined incineration process system, in limited
situations such as roadway patching and pothole filling.  Harrisburg has no
current plans to use the residue from their new program on a large scale basis.
In any event, an evaluation of the new program residue will be necessary prior
to any type of re-use application.

          Environmental factors not withstanding, the present annual amount
of incinerator residue produced as compared to the national annual production
of aggregate used for highway construction, is approximately 0.2 percent and
is not large enough to present a serious business conflict within the highway
industry.  Some factors which may affect the price and supply of virgin ag-
gregates may be surface mine reclamation laws, air pollution controls, and
blasting and safety regulations.  These may make the use of substitute ag-
gregates  such as incinerator residue more attractive than at present.
Disinterment, or the unearthing of incinerator residue, may also become
increasingly attractive at some future time.

          United States Government patents on certain mixtures which contain
incinerator residue and other "waste materials" have been issued.   The use
of  patented products, such as "Chempac," have dated back as far as 1962.

          In an attempt to achieve an environmentally balanced condition,
research and investigation projects are  currently being sponsored by num-
erous governmental agencies.  With the passing of the Resource Conservation
and Recovery Act, further investigation and research especially in the area
of the individual incineration/recovery plant residue characteristics, should
be continued.

SUMMARY

          Annual production of municipal incinerator residue in the United
States is approximately 2 million tons.  This represents only approximately
0.5 percent of the annual production of hot mix asphalt paving in the United
States.

          Non-uniformity of incinerator residue has precluded it from being
used on a large scale in construction applications to date.  Quality control,
including environmental testing, should be exercised on all samples scheduled
for construction applications.  Extremely tight controls should be exercised
over samples from municipal incinerators which are licensed to burn chemical
and  hazardous wastes.
                                     IV-55

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          Strict adherence to the Resource Conservation and Recovery Act of
1976 will have a substantial impact on existing refuse disposal programs.

          The current focus in the waste management field is on resource re-
covery plants.  The residue from these plants is not well suited for construc-
tion applications.  It appears that the number of municipally operated incin-
erator plants, which produce residues acceptable for construction applications,
will most likely not substantially increase.

          Properly processed incinerator residue can be used in construction
applications.

          Monitoring of residue sources from municipal incinerators, as well
as from privately owned incinerators and resource recovery plants, should be
continued.
                                     IV-56

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                                  Part IV

                                REFERENCES
IV-1      Webster's New World Dictionary of the American Language, 1972, the
          World Publishing Company.

IV-2      Evaluation of the Economic and Environmental Feasibility of Using
          Fused and Unfused Incinerator Residue in  Highway Construction,
          United States Department of Transportation - Federal Highway Admin-
          istration Report FHWA-RD-79-83, April 1979, Patankar, Uday M.,
          Palermo, Emilio, Glndlesperger, Gary D., and Taylor, Michael R.

IV-3      Technology for Use of Incinerator Residue as Highway Material,
          United States Department of Transportation - Federal Highway Ad-
          ministration Report No. FHWA-RD-77-151, October 1976, R. J. Collins,
          R. H. Miller, S. K. Ciesielski, E. M. Wallo, M. J. Boyle, D. M.
          Pindzola, J. Tropea.

IV-4      Municipal Refuse Disposal, prepared by the Institute for Solid
          Wastes of American Public Works Association - Copyright 1970 by
          Public Administration Service.

IV-5      Mineral Industry Surveys - current, United States Department of
          the Interior, Bureau of Mines, Washington, D.C., 20241.

IV-6      Future Demand for Asphalt for Paving, Roofing, and Other Products,
          Special Report July 1980 - National Asphalt Pavement Association,
          Riverdale, Maryland 20840.

IV-7      Municipal-Scale Incinerator Design and Operation Reprinted by United
          States Environmental Protection Agency, 1973 - Public Health Service
          Publication No. 2012, De Marco, Jack, Keller, Daniel J., Leckman,
          Jerold, and Newton, James L.

IV-8      The Nature of Refuse, In Proceedings of 1970 National Incinerator
          Conference,  American Society of Mechanical Engineers, New York,
          1970 Niessen and Chansky.

IV-9      Form 408 Specifications, Pennsylvania Department of Transportation,
          Commonwealth of Pennsylvania, Harrisburg, Pennsylvania, 1973 Edition.

TV-1Q     Synthetic Aggregate from Incinerator Residue by a Continuous Fusion
          Process, United States Department of Transportation, Federal Highway
          Administration Report No. FHWA-RD-74-23, April 1974, D. Pindzola and
          R. C. Chou.
                                     IV-5 7

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IV-11     Incinerator Residue in Bituminous Base Construction, United States
          Department of Transportation, Federal Highway Administration Report
          No. FHWA-RD-76-12, December 1975, Interim Report, J. Haynes and W. B.
          Ledbetter.

TV-12     Performance of Incinerator Residue in a Bituminous Base, Transporta-
          tion Research Board, Transportation Research Board 734, 1979,
          David J. league and W. B. Ledbetter.

IV-13     Incinerator Residue as Aggregate for Hot Mix Asphalt Base Course,
          Transportation Research Board, Transportation Research Record 734
          1979, R. D. Pavlovich, H. J. Lentz, and W. C. Ormsby.

IV-14     Installation of Incinerator Residue as Base-Course Paving Material
          in Washington, D.C., United States Department of Transportation,
          Federal Highway Administration, Report No. FHWA-RD-78-114, December
          1977, Interim Report, R. D. Pavlovich, H. J. Lentz, and W. C. Ormsby.

IV-15     Three Years Results  on the Performance of Incinerator Residue in a
          Bituminous Base, United States Department of Transportation, Federal
          Highway Administration Report No. FHWA-RD-78-144, August,1978,
          Interim Report, D. J. league and W. B. Ledbetter.

IV-16     Practical Refuse Recycling, Journal of the Environmental Engineering
          Division, February 1976 - Proceedings of the American Society of
          Civil Engineers, Vol. 102, No. EE1, Waller, C. Edward.

IV-17     Results of Performance Monitoring of Experimental Paving Sections
          Using Municipal Incinerator Residues, United States Department of
          Transportation - Federal Highway Administration Report No. FEWA-RD-
          77, September 1977, Draft, Collins, Robert J.

IV-18     Detailed Specifications for Pavements Using Chempac Base Course -
          Patent 3293999, Gnaedinger, John P.

IV-19     Report on Utilization of Chempac Base Course Material in Parking
          Lots, Roadway and Walkways, Lawndale High School, Chicago,
          Illinois, September 1978, Gnaedinger, John P.


IV-20     Lime Treatment of Incinerator Residue for Road Base Construction,
          United States Department of Transportation - Federal Highway Ad-
          ministration Report No. FHWA-RD-78, September 1978, Gnaedinger,
          John P.
                                     IV-58

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                                Appendix A

                  SUPPORT DOCUMENTATION - POWER PLANT ASH
          This Appendix contains copies of specifications, patents, and
other related documents cited in Chapter 5 of Volume 1 of this report.
At the end of this Appendix there is also a list of relevant ASTM speci-
fications.  The reader is referred to the appropriate standard ASTM docu-
ments for the complete specification.
                                     A-l

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                                                          JU'iU.1. HIChAAY AO.. '.(•"'IS'IAT.OM
     aiiiorancium        •                         Washington, D.C. 20590

                                                          DAU,  JUN. 221977

           . „   , ,                                        ,"i,'/" HHO-33
     Use  of ^ly Ash
,,0u .  Associate Administrator  for
        Engineering and  Traffic Operations
TO    ' Regional Federal  Highway Administrators
      Regions 1-10
      The need  to  effect  measures  to  conserve our resources •whenever possible.
      in all facets  of  our  private and  public endeavors has been well publicized.
      The Federal  Highway Administration and the State highway agencies  can. be
      very proud of  our joint responsiveness to the national goals and objectives
      as articulated by both the executive and legislative branches of our
      Government.  However,  we can anticipate being called upon further  to
      account for  positive  conservation actions in highway construction  and
      maintenance  activities.

      Considerable research and. experimentation has been conducted on conserva-
      tion strategies in  highway construction and maintenance.  The use  of
      waste materials in  areas where  they are'readily available ranks high in
      conservation payoff.   In addition to the potential for energy conserva-
      tion, the use  of'such materials would have the benefits of preserving
      land use, ridding the environment of a waste product, conserving the
      materials for which they are substituted,, and possibly providing a more
      economical end product with  no  loss in performance.

      One waste material,  fly  ash,  is presently in abundant supply-in cany
      areas of  the country.   Fly ash  is a waste product which is collected
      from the  stack gases  from coal burning power plants.  In 1975,  some
      42.3 million. tons . of  fly ash were produced while only 4.5 million  tons ••
      were utilized.  The costs of disposing of the remainder of this fly ash
      in stockpiles  and ponds  is passed on to the consumers of electrical
      power. Considering the  present condition of the petroleum industry, it
      is likely that.coal will be  the primary source for power generation and
      the production of fly ash will  increase.

      The use of fly ash,  either alone  or in combination with lime or cement,
      has been  demonstrated to be  a viable construction material, soil
      •modifier, and  stabilizer for all  elements of the pavement structure up
      to and including  base courses for bituminous pavements.  Much has been
                                           A-2

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vrittcn about: the use of fly ash in highway work.  The  tuo-aost
pertinent documents are Transportation Research Board's  (TR3)
National Cooperative Highway Research rro£r.-iin  (NCHRP) Synthesis .37,
"Lioc-Fly Ash-Stabilized Bases and Subbar.es" and FlIWA Implementation
Package 76-16, "Fly Ash A Highway Construction Material."  Both of
these publications contain comprehensive references.

In recent contacts with industry representatives (particularly the
fly ash industry), we were advised that there are usany areas where
fly ash is readily available but that its use is not being realized
by highway a£encics.  Their expressed concern was particularly that"  '
cement-stabilized fly ash and lime-stabilized fly ash mixes were not
being considered for base courses and subbaces in flexible pavement
systeras.  This is in contrast to other areas where such  consideration
is given.

Therefore, we request that you bring this matter to the  attention of
State highway agencies and ask that this material be given full
consideration in the pavement selection process in those.States
where fly ash is available.  "We further request the appropriate States
which are not experienced in the use of cement-fly ash  or linie-fly ash
in bases and subbases be strongly encouraged to incorporate experi-
mental sections of this material on flexible pavement projects.

VJe believe this matter is of sufficient importance as to warrant it
being discussed with the highest levels of  the State highway agencies.
The Washington Headquarters staff is nvailnble to assist the field
offices if deemed desirable.
                                  H. A. Lindberg
                                  A-3

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        ..
!    /.   'I   -;
i    £  / V '."'
 Fi'S.liECT
U. .'-. L3EF Af'TiuSWT Of- TRANSPORT ATUIJ

     £*;iGi-:\.VA'V   ADr.dl;^iSYliAViOL\
           Use  of Fly Ash in Portrland Cement
           Concrete and St;;bilized Base
           Construction
                                   FH'/.'A NOTICE
                                   N 5080.4
                                January  17,.197-
1.  PlrRPOSE.  Tc  direct the attention of Federal Highway Adrduistration
    (HIWA) field  offices and highv^ay agencies  to asthods vhich Uave
    bi;cn approved by i'HWA for substitution of  pozsolanic rir.terio.ls,
    .inch so fly ashj  for a "portion of the cement for concrete pavements
    cud structures,  and ±n lieu of ceraent for  GtaLilisation of soils  ;mc'
    bases by cozbinataon with line.
    z.  In tha r.urrent  year,  spot shortages of  part laud con-ent have
        occtirrcci in variour-  parts of the countx^  on highway uorl;.
        The cpiiiion of  tho^c kDOwledyccbic in the ceneat industry is
        that these shortages' are likely to increase in number Jn the
        n^sr future, and rosy  become a general condition for some year
        to ~ooui.  Tnc. problen is ngrravn ted by  L'nc lack of ip.c.'Mtive
        to ircr^rsc ]>roductxon because of lark  of capital unvcr
        rr^mln;, i:.a;:!;v.t conditicuu a:;a the I to
        tha a'llev ';.r.ion  of unviyonviont."..t Tjrob.l--.--3  c:i':yid  by  f;Lfvi-.:^e
        cJid ficci-o.-.Icition o£  the nn.eeri«':i.
    c..   Fly cch J-.?c been ur-jd  extensively for years ia r,asr? concrete
        for sue.!; structui\-.^ as doi^s.   In Hurrj.-s lar-jc acour.ts are
        x-ju:-.i;;cly used ic hi r;l:-:ay  construction.  Er.cc'nt  for n]/ecial
        cor/cr^fco, w.ch as for grout.!:™  or px::.ipw r,~> f.ly  ash lits not
        ba:j.n :-.-"r.cl v-^ry r^ucl: in hi^.!i'.;ay construct; -n in this country.
        0,in jioi-s'jja exception bcs  been ubc; State of Alribsr:?..  O.^i's .1
        Lul-r t-n'iil supply of  fly  ,i.-=h  h':?. urde it fc-rsible  to rf-qvi;:-i
                                     A-4

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     the use of fly ash as a substitute for part of the cer.cnt is
     pavement concrete, as well us  its  optional use in other classes
     of  concrete.

do   The minimal use in this country  possibly results from several
     factors,  such as:  handling and  mix control details, especially
     when air cntrainment additives arc used; lever initial concrete
     strengths whan fly ash is substituted in the field for part of
     the ceaent; variations in the  quality of fly ash, depending on
     sources and coal types; and possible pollution effects x-;lien
     incorporating fly ash in portland  cement concrete mixtures.
     7.1}ece factors,  which apply primarily when fly ash is usad
     directly  as an admixture to concrete, can be' adequately con-
     trolled by ths use of proper denijjn,  handling, and control
     procedures with fly ash conforming to ASTM C618,  Type ?
     specification.   When fly ash is  added to concrete as an
     ingredient of the cement, as in  Type IP  cement under AA5I10
     Specification H240, the factors  mentioned above should not
     rose  any  greater problems than when normal portland ccmrint
     iy  used without fly ar.h.

c.  Tli ere has  also  been a reluctance to use  fly ash in paving •
     concrete becruise of uncertainty  concerning the scaling resistance
    of.  such concrete when subjected  to  deicing salts.   Av.iilr.bla
    1; '--oratory d;:ta indicates that replacing part of  the co-fiut
    tvltli i:ly  L'Sh  tends to lever the  resistance of concrete to
    scaling,  although there is no  evidence that fly ash concrete
    it,  inherently susceptible to scaling  under f:l._.ld' com' it ion:;.
    In  this connection,  it '..wild be  desirable  10  av-.- id late sosr.on
    nnvinr*  with fly ash concrete wli^rc  sa.lt  ir  til  -I/  to be ;.-, --\-Lzd
    wo-fore  a?';-vcciable agii,~  of the ccucrcti l-.-.s  tr:!.-n place,  nr-.r.cpt
    on an e:-:pe;:i!7:antal hnsis.   Tliis precaution in  
-------
    {*.  Attachment "A" contains  a  short bibliography of the very
        extensive nuabcr of  reports  and publications on the use of
        fly ash in portland  cement concretes  and as a stabilizer in
        lime-fly ash-soil combinations.  It indicates that the
        technology is well rasc-arched  and developed and is ready to
        be put to iinscdiate  use.

3.  ACTION
    •^HM^KW^KWM*   0

    a.  In view of an anticipated  general cement shortage and the
        potential value of fly ash in  lowering concrete costs, the
        States should be encouraged  to allow  substitution of fly
        csh for cement on a partial  basis as  an alteruntc whenever
        feasible.  Tests have shown  that replacement of cement with
        fly asb. of up to 30 percent  by weight has been  satisfactory
        and no quality losses were noted.   It has also  been shown
        thst replacement of cement with fly ash of  the  order of
        10 percent to 15 percent can be rjacie  without loss of concrete
        strength at 28 days of age.  These figures  apply to situations
        vbcre the fly ash is substituted in the fieltl for part ojc the
        cement.  The appropriate specification to refer to is
        "ASTl-i CG.18, Type F - Specifications for Fly Aab and Raw or
        Calcined Natural Pozzolans for Use in Portland  Cement Concrete."
                                                                       •%
    b.  In soae areas of the country,  cement  plants produce Type IP
        cement v:harcin fly ach or  ether pcizxolauic  r.^tfij:ial is :L.-iLar-
        ground or otherwise blended  directly  with portland cementc
        'Hie generally finer grind  of this cement  produces a blended
        product having about the same  strength characteristics as a
        Type I cenf-nt.  The appropriate specification is "AASHO 1-I.VtO  -
        Specifications for Blended Hydraulic  Cements."   If available
        h;Lg!,vcy agencies will probably  fiaid the use of  this cccient  to
        be a more i-.atir-fac.tory n?.-ns of  using fly ash iu concrete tlian
        as an admixture from the standpoint of handling and product
        ccntrol.

    c.  In the case of stabilization of  so.i.ls  and nubbares,  there is
        X.-ferbaps an even greater potential  for oaviugs in ccmant by
        *:he cubstit-ution of lina-fly ash  as the stabilising agent*
        I5JbJ.u.rc3  of this type have been use::  in years i>;ist  by  a  nu=Tier
        of fgencies in construction  of' highways and  is based  upon the
        centuries  old o.xperier.cc of  the additional  str.'-.ngths  obtained
        by the cdclitic;-; of li-.e end "volcanic:  cinders  to  soils.   Una of
        thcs£ lisc-fly ash mixturc-s has not been  very czrtennive  due. to
                                      -isorc-
                                     A-6

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    the ready availability in the past  of relatively inexpensive
    talents.  The St.ites should be  encouraged to allow the use of
    l.li:e-fly ash ccsbinations as either the specified stabilizing
    cgent, or as a perraissable alternate to cement din situations
    where this type of stabilization would ordinarily be ur.cd and
    appropriate design parameters of strength and durability can
    be satisfied.

d,  Approaches by industry representatives to minimize impending
    shortages which we support are:

   (1)  Promote closer coordination between suppliers and contractors.
        Ihe approach of placing firm orders for  cement needs well
        in advance of actual deli-very will be particularly helpful
        to the industry in reducing or even eliminating the spot
        or temporary shortages which occxir.   There are often areas
        where surplus cement exists at the same  tiiae as a shortags
        elseivhere.

   (2)  Allow the use of different brands  of  cement on a project.
        Except for architectural  consideration.*: where different
        braaus may  produce different colored  concretes,  FiiKA has
        nc  objections to the use  of different brands  ncctiag project
        rc:nuii£i::entK.  Generally,  such cements should be usc-.d in
        difiexent parts of the concrete construction  and should
        not. ba in!:cxTii::cd.                                  _.

   (3) "Ailov the use of foreign  cements..  This practice is
        acceptable  to FIIPA since  such cements must be subject to
        the sace  requiren-sits for acceptance as specified  for
        United States counts, such  as  the rtandard spacificaticriS
        for Portland  cement.  ASTM C150  or A.'-5I10 3!H5.   Foreign
        ccrseatc vould probably have  to  bo s£:r.pled from a  ship,
        and  the cost  apprcp;riate  isathod'wouid be by tube sanipliujj
        froa, distributed  points of the  chij-i.rcnt.   Only by  such a.
        lactbod ccn  the entire depth  of  the ct:r.:snt be sc:^:?lcd \,-h:>le
        still  in  the  ship.  If this  is  not feasible,  I hen  cini'.plir.G
        Cfiii !-ci c!c-:io. froic  the  con\c=yor as  t.hf. cc.i.ii.if. is being
        unluadcd  frca a. shij.  into a  siJo or other contains-.:-:.
                                                         ,
                                H. A. Lindborg      (I
                                AsKOci::te A;!r...ini.".trcriJr for
                                          riTi3  Mid Traffic: Oj o"t

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/ \ {:.,                DIPARTMEMT OF TRANSPORTATION
 ~ "*NV •'
    ^
                            CIRCULAR LETTER


TO:
Changes to Pavement Design Criteria
April 30, 1978
CENTRAL OFFICE
ENGINEERING DISTRICTS
ENGINEERING CONSULTANTS
•
RESCINDS
*
DATE
April 28, 1976


Research Project No. 71-7, "An Evaluation of Pennsylvania's Flexible
Pavement Design Methodology" is now complete.  Results from this research
project coupled with results from other projects and research conducted
by the Bureau of Materials, Testing and Research have indicated a need to
change portions of our pavement design criteria.  Recent truck weight
studies -have indicated that the. 18 Idp equivalent factors for various
types of t -nicks considered in design should "be revised.  Annual main-
tenance costs and the interest rate to be used in the present worth
analysis for type determination have been studied and are revised.

The following criteria shall supersede the applicable portions of Chap-
ter 14 Design Manual Part 2 until such time this criteria is incorporated
into the Manual.

Torm D-4332, page 2, which is shown as page 2.14.H in the Design Manual.
contains the 18 kip equivalents for the various types of trucks considered
in pavement design.  The follovdng equivalents shall supersede those shown
on the form:

                            •   Rigid             Flex, and Mod. -Flex.

2 Axle - 6 Tire                  .24                      .24 .
3 Axle SU                       1.15                    -  .82
3 Axle ST                        .43                      .44
4 Axle ST                        .90                    •  .76
5 Axle ST                       1.59                     1.00

Existing supplies of Form D-A332 should be used until exhausted.  The old
factors should be crossed out and replaced by the above factors.

The structural coefficients ( relative strength factors, page ?.14.29) for
Aggregate - Cement and Aggregate - Lime - Pozzol fun
 0.40.  The structural coefficients for all other base courses shall regain
 as  they are.
                                   A-8

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     the economic  analysis  or engineering decision indicates that  a modified-
 flexible pavement  structure should be used and the design was completed for a
 bituminous concrete  or stabilized aggregate base course, the project  bid pro-
 posal shall incorporate an  alternate of Bituminous Concrete Base Course or
 Aggregate - Cement Base Course or Aggregate - Lime - Pozzolan Base  Course.
 As  an example, a pavement was designed to be !•§• inches of IB-2 Wearing  Course
 on  65- inches of Bituminous  Concrete Base Course, the bid proposal would read
 as  follows:

 KETKER

    Bituminous Wearing  Course,  ID-2
    l£ inch Depth,  SEL  - (H,M,G,L)

 AND

    Bituminous Concrete Base Course,  of- inch Depth

 OR

    Bituminous Wearing  Course,  ID-2
    1|- inch Depth,  SRL  - (H,M,GTL)

 AND

    Bituminous Binder Course,  ID-2
    T.L •;„«.«, n«^+u
   «LO ^«k4V«4A AXW L/Wli

 AND

   Aggregate - Cement  Base Course, 5 inch Depth

 OR

   Bituminous Wearing Course,  ID-2
   1-| inch Depth, SRL -  (H,M,G,L)

 AND

   O^ ^-—T T». *v^e T3-* n^«*« f^
   x^-u wUii*^-fcj!-j»j.3 i^_nCiCA  w
    i inch Dspth
AND

   Aggregate - Liiie - Pozzolan Base Course, 5 inch Depth


The slight difference in Construction Numbers that would be obtained with
these alternate designs is not considered significant.  It ic recognized
that the alternate bidding described above will not be possible with all
designs.  When the alternate bidding is not feasible the reasons should be
documented and included with the pavement design file.
                                            A-9

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                                                                   C-2810
The previous design approach to minimizing the effects of frost action was
to replace a portion of the frost-susceptible soils with non-frost-suscep-
tible materials consisting of surface, base, subbase and modified subbase
materials.  Available data now indicates that providing thicknesses of sub-
base over approximately 12 inches adds minimal increases in strength and

penetrate the subcrade.

More emphasis is now being placed on providing adequate pavement systems
to withstand the structural distress imposed by the frost phenomena of
heaving and subgrade softening.  The following is a revised procedure for  .
the structural design of Flexible and Modified-Flexible pavements:

          The Required Structural Number (SN) is determined as de-
          scribed in Chapter 14.  The pavement is designed so that
          the Construction Number (CN) is equal to or slightly greater
          than the Required SN.  If the resulting total pavement
          thickness is equal to or greater than the Required Total
 *         Thickness determined from Figure 1, no further design is
          required.  If the total pavement thickness is less than the
          Required Total Thickness, the difference, in inches, is
          multiplied by .10 per inch and the resulting value is added
          to the required SN to determine the Adjusted SN.  The pave-
          ment structure is redesigned so that the CN is again equal
          to or slightly greater than the Adjusted SN.  In doing so,
          the subboss courseshould have a maximum depth of 12 inches.
          Total pavement thicknesses resulting Trotn this procedure^
          which are less than the Required Total Thickness from
          Figure 1 are considered adequate.

Rigid pavement design procedures shall remain as described in Chapter 14
with the exception that the depth of subbase or combination of subbase  and
modified subbase should not exceed 12 Inches.

The above procedures do not preclude the use of additional granular  material
(subbase cr modified-subbase) or other design and construction techniques
as recc.T~er.dsd by the District Soils Engineer or in the Soils Report.

The table on page 2.14.33 shall be revised as follows:

                                           Flexible       Mod. Flexible
Interest Kate                 6%              6%
Ann-al Maintenance Cost
Per Lane '/.lie Per Year       $325            $500              $400
                                         A-10

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     tO
pavcnent designs for projects currently under design should be reviewed for
compliance with this new criteria.  Where there is a total thickness change
of 4 inches or less it will not be necessary to change individual cross-
sections ,  only the Typical Sections.  Exceptions to the use of this new
criteria on any specific project shall be documented as to why it cannot
be used and this documentation shall be forwarded to the Central Office,
Bureau of Design.

This criteria shall be used for all pavement designs approved subsequent to
the issue  date of this Circular Letter and for all projects scheduled for
letting after December 31,  1976.

If there are any questions concerning this revised criteria please contact
the Design Division,  Bureau of Design.
                                            David C. Sims, P.E.
                                            Deputy  Secretary for
                                            Highway Administration
                                       A-U

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STATE AND/OR FEDERAL  SPECIFICATIONS
                 A-12

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                               State of Illinois
                         Department of Transportation

                               SPECIAL PROVISION
                                      FOR
                        POZZOLANIC BASE COURSE, TYPE A

                            Effective April  1, 1964
                              Rev. April 1,  1980


DESCRIPTION.  This Item shall consist of a base course composed of Hme,
pozzolan, aggregate and water, plant-mixed and constructed on a prepared
subgrade, 1n accordance with the requirements of this special provision and
applicable portions of the Standard Specifications for Road and Bridge
Construction to the lines, grades, thicknesses and cross  sections shown on
the plans or established by the Engineer.

MATERIALS.  All materials shall meet the requirements of  the following
Articles of Section 700 - Materials:
                        Item                                 Article


      (a)  Water	702.01  -  702.02

      (b)  Aggregate (Note 1)  	        704.05

      (c)  L1me	        718.06

      (d)  Pozzolan (Note 3) 	        718.19

      (e)  Water Reducing Admixture  (Note 2)  ....        718.13

      (f)  Sand Cover  	   703.01(a), 703.01(e)

      Note 1.   The gradation requirements shall be as  follows:

           Passing 1 1/2 Inch sieve	     1002
           Passing 1 Inch sieve 	  90-1002
           Passing 1/2  inch sieve  	  60-100%
           Passing No.  4 sieve  	   40-702
           Passing No.  40 sieve	    0-25%
           Passing No.  200 sieve
             (gravel)	    0-10%
             (crushed stone and slag)  	    0-15%
                                     A-13

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      Alternate gradations will be considered provided mixture design data
      is furnished to the Department for analysis.  Specialized durability
      testing may be required for unique aggregate gradations or proposed
      combinations of materials for which the Department does not have
      historical performance data.  Production gradation tolerances shall
      be as stated in Articles 703.01 and 704.01.  The coarse or fine
      aggregate gradation which most nearly resembles the proposed gradation
      will be utilized for production tolerances.

      Boiler Slag.  In addition to the aggregates permitted in Article 704.05
      boiler slag may be used.  The slag shall be wet-bottom boiler slag
      produced as a by-product of a power plant burning pulverized coal.
      The slag shall be composed of hard durable particles and shall be
      free of excessive or harmful amounts of foreign substances.  Boiler slag
      in an oven dry condition shall meet the following gradation requirements.

           Passing No. 4 sieve .........  80-100%
           Passing No. 10 sieve  ........   55-90%
           Passing No. 40 sieve  , . ......    0-25%
           Passing No. 200 sieve ........    0-10%

      Note 2.  A water reducing admixture may be used if permitted by the
      Engineer.  No adjustments will be made in the required lime and pozzolan
      contents for this addition.

      Note 3.  A maximum of 15% of the gradation samples may be below the
      Minimum Percent Passing the No. 10 sieve.  No individual test shall
      be less than 65% passing the No. 10 sieve.
     ,The Contractor shall assure the Department that sufficient quantities
     ' of inspected materials are available to complete the work.

SAMPLES.  The Contractor shall at his own expense, submit to the Engineer
a minimum of 25 pounds of lime, 50 pounds of fly ash, and 100 pounds of the
aggregate which he proposes for use in the pozzolanic mixture.  The lime,
when sampled, shall immediately be placed in a sealed container and shall
be kept sealed.  Samples shall be furnished at least 60 days prior to the
construction of the pozzolanic base course.  The samples as submitted will
be tested for acceptance of materials and also to determine whether or not
they will produce a satisfactory mixture and will be used to determine
preliminary proportions for the mixture composition.

EQUIPMENT.  The equipment shall meet the requirements of the following
Articles of Section 800 - Equipment.
                                       A-13a

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               Item                                             Article

       (a)  Three-wheel Roller  (Note  1)  	     801.01

       (b)  Tandem Roller  (Note  1)  	     801.01

       (c)  Tamping Roller  (Note 2) 	     801.01

       (d)  Pneumatic-tired Roller  	     801.01

       (e)  Trench Roller  (Note  3)  	     801.01

       (f)  Virbratory Roller 	     801.01

       (g)  Pozzolanic Aggregate Mixture Equipment  ....     804

      Note 1.  Three-wheel rollers and tandem rollers shall weigh from
      6 to 12 tons and shall have a compression on the drive wheels of
      not less than 190 pounds  nor more than 400 pounds per inch width of
      roller.

      Note 2.  In addition to the requirements of Article 801.01, the'
      tampers shall be long enough to penetrate within one inch of the
      prepared subgrade on the  initial rolling.

      Note 3.  Trench rollers shall be self-propelled and shall develop
      a compression of not less than 300 pounds nor more than 400 pounds
      per inch of width on the  compaction wheel.

GENERAL CONDITIONS.  The pozzolanic aggregate base course shall be constructed
between April 15 and the transition date indicated in TABLE A and only when
the air temperature in the shade is above 40  F.  The Contractor shall submit
samples from July production representative of those proposed for use under
this provision no later than August 15.   The Contractor shall request, in
writing, specific mixture design modifications for extension of the transition
dates in TABLE A.  The Department may extend the construction season beyond
the transition dates indicated.  Approval will be based on consideration of
the cured strength development characteristics as determined by the Department's
test procedure and the predicted curing  degree days.   The amount of pozzolanic
aggregate base course constructed shall  be limited to that which can be
surfaced during the current construction season.  No mixture shall  be deposited
on a frozen or muddy roadbed.
                                  A-14

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        TABLE A   TRANSITION DATES FOR POZZOLANIC AGGREGATE BASE COURSE
                                   Required Compressive Strength, p.s.i
                                  	(14 Day Cure 9 72 F)  I/
        Transition Date            Northern Zonei/     Southern Zone!/
           Sept. 15                       700                 650
           Oct. 1                         850                 700
           Oct. 15                        950                 850
        I/
           The transition date must be verified by samples,  representing
           July production, submitted to the Department by August 15 for
           testing.


        -f Districts 1, 2, 3, 4.


        -' Districts 5, 6, 7, 8, 9.
COMPOSITION OF POZZOLANIC AGGREGATE BASE COURSE MIXTURE.   The  lime,  pozzolan,
and aggregate shall be proportioned within the following  approximate limits
on a dry weight basis:


                         APPROXIMATE PERCENT BY WEIGHT
                             OF OVEN DRY AGGREGATE



Ingredient
Lime
Pozzolan
Aggregate
Gravel, Crushed Stone,
Crushed Slag or Aggregate
Blend
2 to 6
9 to 20
74 to 89


Boiler Slaq
2 to 6
18 to 40
54 to 80
                                      A-14a

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       The  actual  proportions  of lime,  pozzolan, water,  and  aggregate  will
 be  set by  the  Engineer  before work begins  and will  be based on  tests
 conducted  on mixtures composed on  samples  of the constituent materials
 furnished  by the  Contractor.   The  Department's design method will  be
 utilized  (available on  request).   The  composition of the mixture will
 be  such that when molded  into cylinders  (as prescribed  in the Department's
 design method) and cured  at 72  F  £ 2° F (14-day cure), the cylinders will  have  a
 minimum average compressive strength of 600 p.s.i.  with no  individual test
 below  500  p.s.i..  The  minimum lime content shall be 3.5% or 3.0%  plus one
 standard deviation based  on ten (10) or more tests  of lime  content (by the
 Department's titration  procedure)  made by  the Contractor on production- samples
 from his plant.   The right is reserved by  the Engineer to make  changes in
 proportions during the  progress of the work as he may consider  necessary.

 MIXING.  Mixing shall be  accomplished  in accordance with Article 218.15
 except the control of the mixture  shall be of such  accuracy that the
 proportions of the mixture based on total dry weight will be maintained
 within the following tolerances:

          Lime	^0.5 percent  by weight

          Pozzolan	+_  1.5 percent  by weight

          Aggregate	+. 2.0 percent  by weight.

       If a water  reducing admixture is used, the automatic  dispensing system
 shall  be capable  of continuously introducing the desired quantity of '
 admixture within  the range of +. 0.03 gallons per minute.

 PLACING AND COMPACTING AND FINISHING POZZOLANIC AGGREGATE BASE COURSE MIXTURE.
The pozzolanic base course.mixture  shall be constructed in  layers not less
 than 4  inches (compacted) in  thickness.  If tests indicate  that the desired
 results are being obtained, the compacted thickness of any  layer may be
 increased to a maximum of 10  inches.  When the thickness specified is
more than 10 inches the mixture shall be placed in 2 or more approximately
equal  layers.  Each layer shall be  deposited,  full  width directly on the prepared
 subgrade or on the preceding  layer  of compacted mixture with a mechanical
spreader or spreader box of a  type  approved by the Engineer.  Where the
mixture must be placed in more  than one layer,  the previous  layer shall  be
maintained in a moistened condition until the  succeeding layer is placed.
After having been tested for density and approved by the Engineer,  the
previous layer shall  be dampened with water, if required by  the Engineer.
The second layer must be placed the same day as the first layer.  When placed,
the pozzolanic base course mixture  shall be free from segregation and shall
require minimum blading and manipulation.
                                        A-15

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      The pozzolanic base course shall be compacted to at least 97% of
maximum density except that If more than one layer is required the first
layer shall be compacted to 97% of maximum density and succeeding layers
shall be compacted to 100% of maximum density.  The maximum density will
be determined in accordance with AASHTO T-180, Method C, except that the
five lift requirement is replaced with three lifts.

      The density of each layer of the compacted base course will be determined
by the Engineer for compliance with these specifications in accordance with
the following test methods, AASHTO T 238 - Method B and AASHTO T 239, AASHTO T 191,
or by other methods approved by the Engineer.  If these tests indicate that
the layer does not comply with the density requirements, the condition shall
be corrected or the material replaced to meet these specifications.

      All pozzolanic base course mixture shall be placed and compacted the same
day it is mixed.  Compaction must be completed as soon as possible after the
mixture is placed on the grade.

      In constructing the top layer, the grade shall  be kept at sufficient
height so that the top surface, when compacted, will  be at or slightly above
grade, rather than below grade.  Finish grading shall be accomplished by
removing excess material followed by recompaction by rolling.  In the event
that low areas occur, they shall be reconstructed to the satisfaction of the
Engineer.

      If any subgrade material is worked into the pozzolanic base course
mixture during the compacting or finishing operations, all pozzolanic base
course mixture within the affected area shall be removed and replaced with
new material.  The Engineer may restrict hauling over partially completed
work after inclement weather or at any time when the subgrade is soft and
there is a tendency for the subgrade material to work into the pozzolanic
base course.

      If for any reason construction operations are delayed or suspended and
the Engineer orders any loose or uncompacted material removed and disposed
of, the Contractor shall perform this work at his own expense.  No pozzolanic
base course may be salvaged.

CURING.  After the pozzolanic base course mixture has been constructed,
the surface shall be kept continuously moist until  the bituminous curing"
cover is applied.  The bituminous curing cover shall  be applied no later
than 24 hours following final compaction unless in  the judgement of the
Engineer, it should be delayed.  The materials and  application of the curing
cover shall be in accordance with the requirements  of Article 303.14 for
bituminous protective cover.

      Surface course paving may proceed after the curing cover has been applied
and cured to the satisfaction of the Engineer.  At  least 14 hours shall elapse
between the time the curing cover material is applied and paving begins.
                                       A-15a

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 CONSTRUCTION  JOINTS AND  MAINTENANCE.  At the end of each  day's  construction,
 a  straight  transverse  construction  joint shall be  formed  by  cutting  back
 into  the completed work  to  form  a vertical face.   Damage  to  completed work
 shall  be avoided.  The pozzolanic base course mixture  shall  be  constructed
 and finished  full width  each  day without longitudinal  joints.

       The Contractor shall  maintain, at his own expense,  the entire  base
 course in a manner satisfactory  to  the Engineer until  the pavement has been
 completed.  Maintenance  shall  include immediate repairs of any  defective
 or damaged portions of the  base  course.  Repairs or replacements shall be
 made  in such  a manner  as to insure  restoration of  a uniform surface  and
 durability of the portion repaired  or replaced.  The Contractor shall also
 remove and replace at  his own  expense any pozzolanic base course mixture
 which  is unsatisfactory due to its  being placed over excessively wet or
 otherwise unstable subgrade;  damaged by rain, freezing or other climatic
 conditions; damaged by traffic;  or  which is unsatisfactory due to failure
 to comply with any of  the requirements specified herein.

 FINISHING OF  POZZOLANIC BASE  COURSE.  Prior to constructing the next layer
 of pavement the entire width  of  base course shall  be brought to true shape
 by mechanical means and shall  be tested for crown  and elevation by means of
 a  template.

       The Contractor shall  have  at  all times enough base course prepared ahead
 of the paving location so that paving will  be a continuous operation.

       If required by the Engineer,  the base course shall be sprinkled with
water  ahead of placing the  surface.
                                 COMPENSATION
TOLERANCE IN THICKNESS.  It is the intent that the base course shall be
constructed to the nominal thickness shown on the plans.  Thickness
determinations shall be made at such points as the Engineer may select.
When the constructed thickness is less than 90 percent of the nominal
thickness, it shall be brought to nominal thickness by the addition of the
applicable mixture or by removal and replacement with new mixture at no
additional cost.  However, the surface elevation of the completed base
course shall not exceed by more than 1/4 inch the surface elevation shown
on the plans or authorized by the Engineer.
                                      A-16

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METHOD OF MEASUREMENT.

      (a)  Contract Quantities.  When work is constructed essentially
           to the lines, grades or dimension shown on the plans and the
           Contractor and the Engineer have agreed in writing that the
           plan quantities are accurate, no further measurement will be
           required and payment will  be made for the quantities shown
           in the contract for the various items involved except that
           if errors are discovered after the work has been started,
           appropriate adjustments will be made.

           When the plans have been altered or when disagreement exists
           between the Contractor and the Engineer as to the accuracy of
           the plan quantities, either party shall, before any work is
           started which would affect the measurement, have the right
           to request in writing and  thereby cause the quantities  involved
           to be measured as hereinafter specified.

      .(b)  Measured Quantities.  Stabilized base course of the thickness
           specified will be measured in place and the area computed in
           square yards completed in  accordance with this  specification.
           The width for measurement  will  be from outside  to outside of
           the top of the final layer of the completed work as shown on
           the plans or as directed by the  Engineer.   The  liquid asphalt
           for the curing coat and any sand cover required will  not be
           measured for payment, but  shall  be  considered as incidental  to
           the contract.

BASIS OF PAYMENT.   This work will  be  paid  for  at the  contract  unit price
per square yard for POZZOLANIC BASE COURSE  of  the thickness specified.
                                      A-16a

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                                                               2/28/80
                       POZZOLANIC-AGGREGATE  MIXTURE  (PAN)
                    LABORATORY  EVALUATION/DESIGN  PROCEDURE
MATERIALS

      The material  components  used  in  Pozzolanic Aggregate Mixtures  (PAM)
evaluation/acceptance  shall  be representative of those intended for  use
on all  projects  for either base or  subbase  construction.  For the purpose
of this  specification,  pozzolan (fly ash) is a  siliceous or alumina
siliceous material  that in itself possesses little or no cementitious
value but that in finely divided form  and in the presence of moisture
will chemically  react with alkali and  alkaline  earth hydroxides at
ordinary temperatures  to form  or assist  in  forming compounds possessing
cementitious  properties.  Fly  ash is the finely divided residue that results
from the combustion of  ground  or powdered coal  and is transported from
the boiler by flue  gases.  Each of  the components shall be tested for
conformance with the requirements of Standard Specifications for Road
and Bridge Construction.

MIX DESIGN/EVALUATION

      The objective of  these mix design  procedures is to determine those
proportions of lime, flyash  and aggregate which when incorporated in a mixture
with water will  provide a workable, durable, support for, or element of
pavement structure  at economical cost.   To  this extent, a producer may
at his  own expense, evaluate trial  mixes under  criteria established by
the Standard  Specifications  and propose  a mix design.  However, this in
no manner shall  be  construed as to  imply acceptance by the Department
without  its written consent  or laboratory evaluation of the mix.

GENERAL  APPROACH

      For a given set of component  materials the significant factors
which may be  varied are the  ratio of lime to flyash and the ratio of the
lime plus flyash to the aggregate.  The  lime to flyash ratio affects
primarily the quality of the "matrix", and  the  ratio of lime plus flyash
to aggregate, primarily determines  the quantity of matrix available to
fill the voids of the aggregate and thus assuring that the matrix-
aggregate particle  contact is  maximized.

      The concept of providing sufficient matrix to fill the voids in the
aggregate is  applicable primarily to aggregates containing sufficient
amounts of coarse (+ No. 4)  aggregate  to create large void spaces, and
may be measured  in  a laboratory by  adding incremental amounts of a fixed
lime plus flyash ratio  to an aggregate,  until the compacted dry density
decreases slightly. However, in the event that  the aggregate contains a
high fraction of fine material  (- No.  4) the concern should shift to not
only providing sufficient matrix but to  the ability of the resultant
mixture to compact  and  remain  stable during construction.  Thus, it may
be necessary to  reduce  the amount of matrix in  the mixture or otherwise,
reduce the overall   fineness  of the aggregate through blending.
                                       A-17

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PRELIMINARY TESTING

      In addition to the testing of components required by the Specifications
for RAM mixtures, it may be desirable to perform preliminary evaluations
of lime and flyash, in order to select the lime-flyash ratio which provides
the greatest strength development.  This may be accomplished by procedures
outlined in ASTM C593, "Fly-ash And Other Pozzolans for Use With Lime,"
Section 7.

PREPARATION OF AGGREGATE/FLYASH

      1.  Sieve and discard if any, the aggregate retained on the 3/4
          inch sieve.

      2.  Determine the moisture content and absorption of the aggregate
          (- No. 4) and the moisture content of the flyash.

      In the event that the aggregate fraction between the 3/4 inch and
the No. 4 sieve does not contain free surface moisture, that fraction
shall be soaked 24 hours, and towel dried to obtain a saturated surface
dry condition. Fly ash which has agglomerated due to drying, shall be
crumbled with the fingers until the overall size is reduced to comply
with the Specifications.

PROPORTIONING

      Proportioning of components in PAM mixtures shall be on a dry
weight basis, considering the total dry weight as 100% of the batch.
Preliminary proportions for graded coarse aggregate mixtures are determined
from a grain size distribution curve for the coarse aggregate.   The
amount of lime plus pozzolan plus the minus No.  4 material is estimated
from Table A below.
                                    Table A
                                              Minimum % Passing No.  4 Sieve

      Maximum Nominal                          (Lime + Pozzolan + Minus No. 4
       Particle Size                                Sieve Aggregate)

           1"                                             45%
           3/4"                                           50%
           k"                                             60%
                                      A-18

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 Using an approximate 3 to 1 flyash to lime ratio and  a minimum of 3
 percent lime by weight, mixtures  are  blended  with the estimated preliminary
 proportions  at the amount from Table  A and, 2 percent above,  and 2
 percent below the preliminary proportions. If the densities  increase
 with increasing pozzolan contents (holding the lime content constant),
 the mix is deficient in fines; a  new  series of mixes  should be compacted
 with higher  pozzolan contents. When  the  unit weight  of three mixes are
 equal or decrease slightly with the higher pozzolan contents, the optimum
 pozzolan content has been determined.   The pozzolan content to be used
 in further testing should be the  amount which produced the maximum dry
 density plus an allowance for segregation and construction variability,
 based on the Engineer's judgement.

       The compacted density of each mixture shall  be  determined by AASHTO
 T180, the test for "Moisture-Density  Relations of Soils, Using 10-lb
 Rammer and 18-inch Drop", except  that  the 5-lift requirement  is replaced
 with three lifts, and Note 2 is not to be used.   In determining the
 moisture-density relationship, dry materials  should be mixed  for 1
 minute, or until the mixture is uniform in color and  texture,  in a
 Lancaster PC Mixer or its equivalent,  plus an additional 3 minutes  after
 the water is added, in order to obtain the first point on the  moisture-
 density curve.   The original  sample may be re-used  for subsequent  trials.
 The batch shall  be mixed for an additional minute  after the water  has
 been added for each subsequent trial.

 MIXING AND MOLDING TEST SPECIMENS

       After  the optimum moisture  content  is obtained  by the above procedure
 a  batch large enough.to make six  (6) each 4.0 by 4.6-inch (102  by 117 mm)
 cylinders, shall  be mixed in  the  following manner:  Mix  the dry materials
 for 1 minute or until  the mixture is uniform  in  color  and texture in a
 Lancaster PC Mixer or its equivalent.   Add enough water to bring the
 mixture to optimum moisture  content (corrected for  the  hygroscopic
 moisture  of  the  minus  No.  4 material).  Mix an additional 3 minutes.
 Mold  the  specimens  immediately in accordance  with AASHTO T180 Method C
 except as  previously noted.   Each layer should be scarified to  a depth
 of  h  inch  (6 mm)  before the  next  layer is  compacted in  order to  assure a
 good  bond  between the  layers.   Weigh a  representative  sample of  the
 mixture to determine the  moisture content  (use a container with a tight
 lid to prevent  loss  of moisture).   Then carefully remove from the specimen
 from  the  mold by the use  of  a  sample extruder  such  as  a jack or  lever
 frame.

 Curing  of Test  Specimens  - Immediately  after  the specimens are removed
 from  the mold,  re-weigh the specimens  and  place  in a sealed container
 to  prevent loss  of moisture.   The  sealed  container may be either a can
with  a  friction  lid, or double  sealed  plastic  bags.  Place three of the
specimens in the  sealed containers  carefully  in a room or cabinet with
forced  air circulation maintained  at 50°  F +  2° F (10° C + 1°  C) for a
7-day period.  Place the  remaining  three  (3j  specimens in a sealed container
                                      A-19

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in a room or cabinet with forced-air circulation maintained at 72° F +. 2°
(22° C +_ 1° C) for a fourteen day period, re-weigh, and allow to cool  to room
temperature.  After the required period, remove the specimens from the  container,
and cap the specimens for compressive strength testing.  Soak the specimens
in water for 4 hours, remove, allow to drain on a nonabsorbent surface  and
test within 1 hour of the time of removal from the water.

Number of Test Specimens - Six (6) specimens shall be tested in accordance
with ASTM Method C 39, Test for Compressive Strength of Cylindrical
Concrete Specimens; no 1/d correction will be considered in the computation
of the compressive strength.

VACUUM SATURATION

      If, in addition the Vacuum Saturated Compressive strength is specified
or otherwise required, the procedures outlined in ASTM C593, Section 9
shall be followed.

REPORT - Report of the compressive strength and/or vacuum saturation
strength tests shall include the following:

      (a)  Identification of each material used in the preparation of the
specimens,

      (b)  Percentage by dry weight of each of the constituents,

      (c)  Actual as compacted percentage moisture content of mixture,

      (d)  Actual dry unit weight of each specimen,  nearest lb/ft3 or g/cm3,

      (e)  Percentage of maximum dry unit weight of each specimen,

      (f)  Cross-sectional area of each specimen, inches2 or centimeters2,

      (g)  Maximum failure stress of each specimen,  to nearest 5 psi  or
35 kPa, and/or

      (h)  Vacuum saturation strength of each specimen,  to nearest 5  psi
or 35 kPa.

      The average compressive strength of three specimens tested at each
curing condition shall be designated as the test value for evaluation by
this specification.  The average vacuum saturation strength (if  required)
of the three specimens tested shall  be designated as  the test  value for
evaluation by this specification.  Co-efficients of  variation  within
groups at each curing condition which exceed 10% for  50° F (10°  C)  and
10% for 72° F (22  C) shall  be considered as cause for rejection  of the
samples, and a fresh batch shall  be  formulated, compacted and  tested  as
per procedures previously defined.   The corrected standard deviation
will  be estimated from Table B.  The co-efficient of  variation is
computed by dividing the corrected  standard deviation  by the mean  strength.
                                     A-20

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                                   Table B.


      ESTIMATING STANDARD DEVIATION.—If the number of values are not
large (say, less than 10), the standard deviation can be estimated by
either of the following equations:
      se   =  d  or se   =  Rm
      where:  se   =  estimated standard deviation
              R    =  range of values;  i.e.,  the  difference  between
                      the greatest value and  the  smallest  value
              d    =  factor (see Table C)
              m    =  factor (see Table C)
                        TABLE  C—FACTORS  FOR  ESTIMATING
                              STANDARD  DEVIATION
Number of
Values, n
2
3
4
5
6
7
8
9
10
Factor,
d
1.1284
1.6926
2.0588
2.3259
2.5344
2.7044
2.8472
2.9700
3.0775
Factor,
m
0.8862
0.5908
0.4857
0.4299
0.3946
0.3698
0.3512
0.3369
0.3249
                                    A-21

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PLOTTING OF DEGREE DAY (DP) VS. CURED COMPRESSIVE STRENGTH (CS)  CHARACTERISTIC
CURVE

      In order to evaluate the effect of curing at low to moderate temperatures
it is necessary to plot the best fit straight line relationship  of the
average cured compressive strength (PSI) obtained herein at both curing
temperatures, versus the curing degree days (40° F base) representative
of each average strength.

      Plots are to be arranged on 20x20/division graph-paper,  at a convenient
scale, with the number of degree-days along the -x-axis and the cured
strength (in PSI) along the y-axis.  Degree-days (40° F base)  are calculated
as follows:  (Curing temperature - 40) x number of days = DD.   Plots
will be appropriately labeled as to: producer, month and year  of analysis
and proportions of each component ingredient.

      The Department will analyze design test data and develop appropriate
construction cut-off dates.
                                      A-22

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                               State of Illinois
                         Department of Transportation

                          SUPPLEMENTAL SPECIFICATION
                                      FOR
              SECTION 804. POZZOLANIC AGGREGATE MIXTURE EQUIPMENT

                            Effective April  1, 1980


This Supplemental  Specification amends the provisions of the Standard Specifications
for Road and Bridge Construction, adopted October 1, 1979 and shall  be construed
to be a part thereof, superseding any conflicting provisions thereof applicable
to the work under the contract.
                                                 *;•
804.01  The pozzolanic aggregate mixture plant shall be a batch or continuous
type mixing plant.  The plant units shall be so designed, coordinated, and
operated that they will produce mixtures within the tolerances specified.   The
plant units shall  meet the following requirements:

  (a)  General Requirements.  The plant shall  be approved before production begins.
       It shall be equipped with adequate and  safe stairways to the  mixer  platform
       and sampling points.  The plant shall be equipped with a room of approximately
       200 square feet for performing the necessary tests for control  of the-mixture.
       The room shall be provided with sufficient heat, and  air conditioning,  natural
       and artificial light, and be equipped with a desk, chair, work  bench 3'xlO'x36"
       and 110 volt outlets.  First aid equipment, telephone, fire extinguisher having
       a minimum underwriters laboratory rating of 2A10BC and sanitary facilities  shall
       be available.  When approved by the Engineer a room with sufficient space
       .for performing the necessary tests for  control  of the mixture,  either in a
       building occupied by the operator or  in a separate building satisfactory to the
       Engineer, may be substituted for the  aforementioned facility-

       Guarded ladders shall be placed at all  points where accessibility to plant
       operations  is required.  Accessibility  to the top of  truck bodies shall  be
       provided by a platform or other suitable device to enable the Engineer to
       obtain samples.  A hoist or pulley system, if required by the Engineer,
       shall be provided to raise scale calibration equipment,  sampling equipment
       and other similar equipment from the  ground to the mixer platform and
       return.  All gears, pulleys, chain sprockets, and other dangerous moving
       parts shall be thoroughly guarded and protected.  Ample and unobstructed
       space shall be provided on the mixing platform.   A clear and  unobstructed
       passage shall be maintained at all times in and around the truck loading
       area." This area shall be kept from drippings from the mixing platform.
                                            A-23

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(b)  Storage Facilities.  The plant used in the preparation of the PAM mixtures
     shall  be located where it will have adequate storage and transportation
     facilities.   Sufficient space shall be provided for separate stock piles
     of each material type.  If necessary to prevent the intermixing of the
     different materials, or if stock piles join together, suitable partitions
     shall  be used between adjacent stock piles.  All aggregates shall be
     kept separated until they are fed in their proper proportions onto a belt
     conveyor.  The aggregates shall  be handled in such a manner as to prevent
     contamination and degradation.

(c)  Crane  or End Loader.  The crane  used in stock-piling the aggregates or
     conveying the aggregates to the  aggregate feeders shall be in first-
   '  class  mechanical .condition.  When compartment aggregate bins are used,
     the width of the crane bucket shall be not more than 1/2 the minimum width
     of the top of the bin compartments, and the maximum length of the bucket
     when fully open shall be at least 1 foot less than the length of the top
     of the bin compartment.

     When an end  loader is used to charge adjacent hoppers containing different
     materials, the maximum discharge width of the bucket shall be 2 feet less
     than the width of the top of the bin compartment surcharge.

(d)  Aggregate Feeder.  The plant shall  be provided with accurate mechanical
     means  for uniformly feeding aggregate in its proper proportion onto the
     main belt so that uniform production will  be obtained.   The controls  of
     the lime and fly ash fed to the  pug mill  shall  be by a variable speed
     system.  Other methods may be approved by the Engineer.   All .gates  shall
     be capable of being locked or bolted securely in the required position.

(e)  Material Control.  The plant shall  provide means for accurately propor-
     tioning lime and fly ash within  specified  tolerances.   Charts  shall  be
     provided showing the rate of feed of aggregate  per minute for the
     aggregate being used.

(f)  Weight Calibration of Lime, Fly  Ash and Aggregate Feeds.   The  plant shall
     include a means for calibration  by  weighing test samples.   Provision  shall
     be made so that the lime and fly ash fed  out of the feeder can be collected
     in an  individual test container.  The plant shall  be  equipped  to  conveniently
     handle individual test samples weighing not more than  200 pounds.   Accurate
     scales shall  be provided by the  Contractor to weigh such  test  samples.

     Adequate means must be provided  to  collect the  individual  or  combined
     aggregates or fly ash into a truck  after  the aggregates of fly ash  pass
     over the weigh belt or other proportioning device.

(g)  Synchronization of Lime, Fly Ash and Aggregate.   Means  shall  be provided
     to afford positive interlocking  control  along the flow  of aggregate,
     fly ash, lime and water satisfactory to the Engineer.
                                  A-24

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(h)   Mixer.   Ths plant shall  include a  continuous  or batch  mixer of an
     approved type,  and capable of producing  a  uniform mixture  within  the
     job-mix tolerances.  Continuous mixers shall  be equipped with  a discharge
     hopper  with dump gates which will  permit rapid  and complete discharge of
     the mixture. The paddles shall be adjustable to advance or retard  aggregate
     flow.   The spray bar of  the mixer  shall  be equipped with a pressure gauge.
     An adjustable baffle or  dam which  can be locked or bolted  in position shall
     be placed at the discharge end of  the pug  mill.  The mixer shall  have
     a nominal capacity, as determined  by the Engineer, of  not  less than 200
     tons per hour and shall  have a manufacturer's plate giving the net
     volumetric contents of the mixer at the  several heights inscribed on
     a permanent gauge.

(i)   Platform Scale  for Weighing Pozzolanic Aggregate Mixtures.   The scales
     shall be accurate to 0.4 percent of the  maximum load that  may  be  required.
     The scales shall be calibrated at  the beginning of each construction
     season  and as often as the Engineer may  deem  necessary to  assure  their
     continued accuracy.  The scales shall be inspected frequently  for
     sensitivity, sluggishness or damage.  They shall  be checked for accuracy
     at intervals of not more than one  week by  obtaining the net weight,  on
     another truck scale, of  a truck load of  pozzolanic aggregate mixture.
                                      A-25

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                             STATE OF OHIO
                      DEPARTMENT OF TRANSPORTATION

                     SUPPLEMENTAL SPECIFICATION 835
                      AGGREGATE LIME-FLY ASH BASE

                           January 13,  1977


     835.01 Description.  This  item shall consist of  a mixture of aggregate,
 hydrated lime and fly ash mixed,  placed and  compacted in accordance with the
 requirements hereinafter set  forth and  in conformity  with the linos,  grades
 and  cross sections  shown on  the plans.

     This construction may involve patents and if so  the provisions of  107.03,
 Patented Devices, Materials  and Processes of  the  Construction and Material
 Specifications of the Ohio Department of  Transportation  will  govern.

     835.02 Materials,  (a) Hydrated lime shall meet  the requirements of
 712.04(b).

     (b)  Fly ash shall meet  the  requirements  of  ASTM C  593,  with the exception
 of Section 7 for plastic mixes.   The maximum loss on  ignition shall be  10
 percent as determined in accordance with  ASTM  C 311.

     (c)  Aggregate.  Aggregate for this  course shall  be  sound and  durable  lime-
 stone, air-cooled blast furnace slag, or  gravel which  shall meet  the grading
 requirements of 301.02 except that a minimum of 35 percent shall  pass the No. 4
 sieve.

     When tested for  soundness  in accordance with Method of Test  for Soundness
 of Aggregates by use  of Sodium  Sulphate, AASHTO T  104, the weighted loss of
 the aggregate shall not exceed  15 percent except  in case of an aggregate where
 the major portion of  the unsound materials acquires a mudlike condition during
 the test, the soundness shall not exceed 5 percent.

     835.03 Composition.  Samples of the materials proposed for use shall be
 submitted to the Laboratory at  least 90 days before the planned construction
 of this item for evaluation,  approval and proportioning.

     Cylinders prepared from the submitted material samples will be tested
 for compressive strength and  freeze-thaw loss according to ASTM C 593.  The
 average compressive strength shall be not less than 400 psi with no individual
 cylinder being lower than 300 psi.  The loss in weight shall be not more than
 10 percent after 12 cycles of freezing and thawing.

     835.04 Construction Methods.  The aggregate,  hydrated lime and fly ash
 shall be accurately proportioned and thoroughly mixed  in  a mechanical mixer
 of the pugmill or other approved type.  The exact  material proportions shall
be fixed by the Engineer and  shall be maintained within the following toler-
ances in percent by weight of the total mix.

                           Lime           ±0.3
                           Fly ash        ±1.5
                           Aggregate      ±2.0

                                  A-26

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Means shall be provided for checking the accuracy of the proportioning.  Water
shall be added if necessary to insure that the mixture will be at optimum
moisture content when compacted.  The mixing operation shall be continued until
all the materials are distributed evenly throughout the mixture.  The mixture
shall then be discharged without undue segregation.  A sample of batched lime-
fly ash base material shall be obtained daily and compression specimens prepared
for testing according to ASTM C 593.  The average strength for each sample shall
be not less than 400 psi with no individual test being lower than 300 psi.  The
Engineer reserves the right to make such changes in mix proportioning during the
progress of the work as he may consider necessary.

     The aggregate lime-fly ash base, within an increment of work, shall be
placed and compacted within AS hours of mixing.  Where multiple layers are
placed, each layer shall be placed and compacted the same day as the first layer.

     The maximum compacted layer thickness shall be 4 inches except where vibra-
tory equipment is used in conjunction with other methods of compaction, the
maximum compacted layer thickness shall be 8 inches.  Where the total thickness
specified is more than 8 inches, the mixture shall be placed in two or more
layers approximately equal in thickness.

     Each layer shall be placed in full lane widths using a mechanical spreader
of a type approved by the Engineer.  When placed, the mixture shall be free from
segregation and when compacted the surface shall require a minimum of finish
grading to meet surface tolerances.

     Each layer shall be compacted using rollers or vibratory equipment and
rollers.  Compaction requirements shall be as specified in 304.OA of the
Construction and Material Specifications.

     After a layer has been compacted, tested for density and approved by the
Engineer, water shall be applied as required to maintain the moisture content
of the mixture near the optimum until either a succeeding layer of lime-fly ash
material or the bituminous curing coat is placed.  The equipment used for apply-
ing the water and bituminous curing coat shall be such that will not displace or
otherwise damage the surface.

     Prior to placing a layer on a previously placed layer, the surface of the
previously placed layer shall be loosened to assure interlocking of the aggre-
gate between the layers.

     In constructing the top layer, the grade shall be kept at sufficient height
so that the top surface, when compacted, will be at or slightly above grade,
rather than below grade.  Finish grading shall be accomplished by removing
excess material followed by recompaction by rolling.  In the event that low
areas occur, they shall be loosened, dampened with water immediately before
placing additional mixture, and then rolled to the satisfaction of the Engineer.
When this item is used as a subbase for 451 pavement, the surface tolerance
shall not exceed 1/4 inch in 10 feet.

     The Contractor shall remove and dispose of any mixture that has not been
compacted in place within 48 hours from the time it was mixed.  Any mixture
that has become contaminated with subgrade material or otherwise damaged by
rain,  freezing, traffic, or construction operations shall be removed and
discarded.
                                  A-27

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     The Engineer may restrict hauling over partially completed work when  such
hauling causes excessive deflection, cracking, displacement, or other damage
to the aggregate lime-fly ash base.

     A bituminous curing coat shall be applied to the surface of the completed
aggregate lime-fly ash base.  At the time the curing coat is applied, the
surface shall be tightly knit and free of all loose or extraneous material.
The bituminous curing coat, 702.02 RC-250, 702.04 RS-1, 702.09 RT-9 or RT-10,
shall be applied uniformly to the surface with a pressure distributor at a
rate of approximately 0.15 gallons per square yard.  The exact rate of appli-
cation and temperature shall be specified by the Engineer.  Cover aggregate
conforming to 703.06 shall be applied in accordance with 407.06.

     The Contractor shall maintain, at his own expense, the entire base in a
manner satisfactory to the Engineer until the pavement has been completed.
Maintenance shall include repairs of any defective or damaged portions of  the
base and shall be made in such a manner as to insure restoration of a uniform
surface and durability of the portion repaired or replaced.

     835.05 Construction Joints.  At the end of a day's work, a short tapered
construction joint shall be made at the end of the compacted base in a straight
line normal to the center line of the roadway.

     Where additional base course construction is to be joined to the previous
work, the end of the existing base course shall be scarified and moistened,
blended with new mixture, and compacted to form a continuous section without
a joint.

     835.06 Seasonal Limits.  Lime-fly ash base shall  be constructed between
April 15 and September 15 on pavements which are to be opened to traffic
during the summer, fall, or winter months of the construction year.   On  pave-
ments which are to be opened the following spring,  lime-fly ash base may be
placed later than September 15 but, after this date,  a bituminous curing coat
and a minimum of one overlying pavement course shall be constructed  within 72
hours of final base compaction.   In no case shall lime-fly ash material  be
placed during rain or when the atmospheric temperature is  below 40F  in the
shade nor shall this material be allowed to remain uncovered during  the  winter
months.

     835.07 Method of Measurement.   The quantity of  aggregate lime-fly ash base
course to be paid for shall be the  actual number of  cubic  yards,  computed  from
plan lines, of approved aggregate lime-fly ash base  course material  compacted
in conformity with the lines,  grades and cross sections shown on the plans.

     835.08 Basis of Payment.   The  quantity measured  as provided above shall
be paid for at the contract unit price per cubic  yard  bid  for Item  835,
Aggregate Lime-Fly Ash Base Course, which price and  payment shall constitute
full compensation for furnishing all materials for the aggregate lime—fly  ash
base, including hauling, incorporating admixture,  water, placing, compacting
and curing, and for all labor,  tools,  equipment and  incidentals necessary  to
complete this item.
                                  A-28

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              State of Pennsylvania
          Department of Transportation

322.1         Aggregate-Lime-Pozzolan        322.2(fl
                     Base Course
                   SECTION 322.
        AGGREGATE-LIME-POZZOLAN
                  BASE COURSE

322.1  DESCRIPTION—This work shall consist of con-
structing an aggregate, lime, and pozzolan base course in
accordance with these specifications and within reasonably
close conformity  to  the  lines, grades, width,  and  depth
shown on the drawings and as specified.

322.2  MATERIALS—

  (a)  Aggregate.  The aggregate shall be stone, gravel, or
slag, meeting the requirements of Section 703.3 for Type C.
or better, No. 2A material, except that a maximum of IS'*
may pass the No. 100 sieve, or the requirements of Section
321.2(a).
  (b)  Lime. Lime shall meet the requirements of Section
723  and ASTM  Designation C 207, Type N, Sections 2.
3(a), 6, and 7(a), and shall be capable of producing a mis-
turc meeting the requirements of Subsection (g).

  (c)  Pozzolan.   Pozzolan shall meet the requirements of
Section 724, and shall be capable of producing a mixture
meeting the requirements of Subsection (g).

  (d)  Water. Section 720.

  (e)  Bituminous Material.  Bituminous material for pro-
tection and curing shall meet the requirements of Bulletin
No.  25, and shall be one of the following:
        Class RT-2-C or RT-2-W
        Class E-l
        Class MC-30

  (f) Testing.  .  It  shall be  the  responsibility of  the
contractor  to do  the  preliminary testing required to de-
termine the compatibility and the quality of the respective
materials, the proportions required, and that the proposed
mixture meets the requirements of Subsection (g).
                     A-29

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322.2(0        Aggregate-Lime-Pozzolan        322.3(b)
                      Base Course

  The testing shall be performed in accordance with the re-
quirements of Sections 320.2(c)l. and 2.
  (g)  Mixuture.   The aggregatc-lime-pozzolan  mixture
shall meet the following requirements:
    1.  Liquid Limit and Plasticity Index. The liquid limit
of the mixture determined  in  accordance with AASHO
Designation T  89 shall not exceed 25  and the plasticity
index determined in accordance with AASHO Designation
T 90 shall not exceed 6.
    2.  Durability.  The proposed mixture shall be tested in
accordance with PTM, No. 110.

322.3  CONSTRUCTION REQUIREMENTS—

  (a)  Equipment. Equipment shall conform to the require-
ments of Section 320.3(a).
  (b)  Mixing.
    1.  Central Plant Mixing.  For central plant  mixing,
the materials shall be mixed in an approved continuous flow
or batch-type mixer equipped with batching or metering de-
vices designed to measure the  specified quantities of the
respective  materials.  Mixing shall be  continued  until a
thorough and uniform mixture is obtained.
  The mixture shall be transported from central mix plants
in clean,  tight vehicles and shall be  deposited  on the
moistened prepared area by means of approved mechanical
spreaders in a uniform loose condition for the full depth of
layer being place. Protective covers for the vehicles may be
required by the engineer.
    2.  In-Place Mixing.  For in-place mixing the required
quantity  of aggregate shall be spread on the prepared area
in a uniform loose layer. The specified  quantity of pozzolan
shall then be applied in a uniform spread to the aggregate in
place and be blended until the  pozzolan is uniformly dis-
tributed through the aggregate. At the time of application
of the pozzolan, the moisture content of the aggregate shall
not exceed the quantity which will permit uniform blending
of the materials.
                      A-30

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322.3(b)       Aggregate-Lime-Pozzolan        322J(b)
                      Base Course

  The specified quantity of lime shall then be applied in a
uniform spread and be blended until the lime is uniformly
distributed through the pozzolan and aggregate.
  After the  aggregate,  lime,  and pozzolan  have been
throughly blended, water shall be applied and incorporated
into the mixture. The application of water shall be so con-
trolled that there is no excessive concentration on or near
the surface of the mixture.  An adequate water supply and
sufficient  pressure distributing equipment shall be provided
to insure that the mixing operation is continuous. After  all
required water has been applied, mixing shall be continued
until a thorough and uniform mixture is obtained.
  On projects where  the  application  of lime and/or poz-
zolan creates a critical dust condition, the contractor may,
with the  approval .of the engineer, moisten the pozzolan
and/or  lime, or may pre-blend the specified quantities of
pozzolan  and lime (with  or without a  portion  of the ag-
gregate) with water prior to application to  the spread ag-
gregate or addition to the mixer.
  Water added to pozzolan and/or lime or to a pre-blend to
eliminate excessive dust shall not exceed the quantity  re-
quired in the final mix.

     3.  General. The moisture content at the time of final
mixing  shall not vary from  the  optimum moisture  de-
termined  in the  field by more than  2 percentage points, ex-
cept that  in no  case shall the moisture content  in the mix
exceed  the quantity which will  permit uniform blending or
cause the base  course to become  unstable  during  the
compacting or finishing operations.
   Bulk  lime  and bulk pozzolan may be used provided ap-
proved  equipment and handling methods are used.
  Pozzolan and/or lime shall not be spread nor shall mix-
ture be  placed when the aggregate or the base course area is
excessively wet, frozen, or  is at a temperature of 40 F or
less. No material shall be spread nor mixture placed unless
the  air  temperature is 40 F and rising and these operations
shall be discontinued when  the descending air temperature
falls below 40 F.
                    A""-

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322.3(b)        Aggregate-Lime-Pozzolan        322.3(h)
                     Base Course

  The  placing of Aggregate-Lime-Pozzolan Base Course
shall terminate August 15 and shall not be resumed prior to
May  1,  unless  otherwise approved in writing  by the
engineer.
  Only the  necessary shaping and processing equipment
shall be permitted to travel over the spread materials and
any lime,  pozzolan, or mixture that becomes displaced or
contaminated in any manner shall be removed and satisfac-
torily replaced at no expense to the Department.

  (c)   Compaction. Compaction shall conform to the re-
quirements of Section 321.3(c), except that PTM No.  106,
Method B shall be used  for optimum moisture content and
maximum dry weight density determination.

  (d)   Finishing.   Finishing shall be performed  in accor-
dance with the requirements of Section 321.3(d), except that
the finishing operation need not be limited to 3 hours.

  (e)  Construction Joints. Where additional base course
construction is to be joined to the previous day's work, the
end of the  existing  base  course  shall  be scarified  and
moistened, blended with new  mixture,  and compacted to
form a continuous section without a joint.

  (f)  Protection and Curing.  Protection and curing  shall
conform  to  the  requirements  of Section 321.3(f). If the
contractor so elects he may begin paving of binder and/or
surface courses immediately after placing the prime coat
without waiting for the completion of the 7  day curing pe-
riod.

  (g)   Density.  The density will be determined  in accor-
dance with PTM  No. 112, or  PTM No. 402. One density
determination shall be made for each 3000 square yards, or
less, of completed base course. No tolerance in density
below that specified will be allowed.

  (h)   Surface Tolerance.  The surface smoothness shall be
checked transversely with  approved  templates and longi-
tudinally with straightedges in accordance with the require-
ments  of  Section  310.3(d). Any surface irregularity that
                       A-32

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322.3(h)        Aggregate-Lime-Pozzolan          322.5
                     Base Course

exceeds '/z inch under a template or straightedge shall be
remedied to the satisfaction of the engineer.

  (i)  Tests for Depth of Finished  Base Course.  The depth
of the finished  base course shall meet the requirements of
Section 320.3(i).
                                              •s
  (j)  Maintenance and Traffic. The completed base course
shall  be  maintained  and traffic controlled  in accordance
with the requirements of Section 3l0.3(f).

322.4  METHOD OF MEASUREMENT—This work will
be  measured on the surface  using the  two-dimensional
method and include  all areas shown  on  the drawings or
otherwise approved by the engineer.

322.5  BASIS   OF   PAYMENT—Aggregate-Lime-Poz-
zolan Base Course will be paid for at the contract unit price
per square yard, complete in place, as specified.
  When  this  construction involves patent rights,  it is
mutually understood and agreed that without exception the
bid price is to include all royalties, costs, and/or license fees
arising from patents, trademarks, and copyrights in  any
way involved  in  the work and that the  requirements of
Section 107.03 will govern.
                    A-33

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                   Federal  Aviation  Administration
                      Newark  Airport Project

41 •        j.iMK-Ci^KNT  ri.YASII STABILIZED FILL SAND BASE.

          The  1 Jme-cerb'.Tit  flyash  stabilized  fill sand base shall be
,:s,:<\r mixed, anrt consist: of  a mixture  of  in-place fill sand, hydrate:!
'i-.ti. Portland cement, flyash, and  coarse aggregate if specified,  and
.•hail he mixed, -jlacud v.r.d compacted on a prepared subgrade in accord-
.i^c-' witn these Specifications and  to  the lines, grades and cross-
cc-ctions shown on the Contract Drawings.

          The Consolidated Edison Company of  New York, Inc. (herein-
after referred to as the "Company") has agreed  with the Authority
:«.• furnish flyash free of charge  to contractors requiring flyash in
;.•<:• performance or" their work under Authority contracts.   The Agreement
l-ctvcen '.he Authority and the Company   is    substantially in the
r.-r.T. attached hereto.

          The Contractor shall comply with the  terms  of the Agreement
b <.•:••.••_• .MI the Authority and the Company and shall assume all the risks,
i;;: ics .i:id obligations of the Authority under said  Agreement.   The
Cor.craotor and the Company shall mutually agree as  to the times,
pieces and conveyances to be used in the  removal of flyash.  The  fly-
..sh  ---jot be in accordance with the requirements for Lime-Cement Flyash
Stabilized Fill Sand Ease specified below.

                            Materials

          The coarse aggregate, called  "Aggregate"  on  the Contract
Drawings, shall be crushed trap rock and  shall  consist  of hard,
durable particles, free of an excess of soft  or disintegrated
pieces, dirt, or other objectionable material.   The coarse aggregate
shall conform to the following gradation  requirements:

          Sieve Sizes            Total  Passing  Per  Cent by Weight

              IV                                100
              1"                              90 -  100
              3/4"                            60 -  80
              No. 4                             0-5
                                  A-34

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          Lime-cement as specified herein shall be a mixture of one
part Portland cement and four parts hydrated lime, by weight.  The
cement shall be Type I conforming to the requirements of the Standard
Specifications for Portland Cement (A.S.T.M. C150) , and the line shall
be Type N conforming to the requirements of the Standard Specifications
for Hydrated Lime for Masonry Purposes (A.S.T.M. C207) and the modified
requirements specified herein:

          1.  Total oxide content (CaO + MgO) on a non-volatile
              basis shall not be less than 86% by weight.

          2.  A minimum of 75% shall pass a No. 200 sieve.

          3.  Substitution of high oxide lime (dolomitic hydrate)
              may be made provided that:

              a.  The total oxide in the mix shall not be less
                  than the specified hydrate lime assuming an
                  oxide content on a non-volatile basis of 92%
                  and the combined H20 is 25% (i.e. assuming
                  a 3.2% lime mix, the total oxide content will
                  be 3.2 parts x .75 x .92 = 2.2 parts).

              b.  The total amount of substituted lime in any
                  mix shall not be less than 2.8% by weight.

              c.  Quicklime shall be used only when the mixing,
                  performance and safety provisions of the slak-
                  ing mechanism are approved by the Engineer.

          Flyash shall conform to the requirements of the Tentative
Specifications for Flyash for Use as a Pozzolanic Material with Lime
(A.S.T.M. Designation:  C379) and the applicable testing procedures)
and the following modified requirements:

          1.  Loss of ignition shall not be more than 10%.

          2.  Combined content of silica (Si 02) and aluminum
              oxide (Al£0) shall not be less than 50%.
          3.  Lime-pozzo] an strength, minimum compressive strength
              shall be 600 psi at 7 days, 130° ±3° F.

          U.  Storap.c bins shall be provided when dry  powder fly-
              ash is used.

          5.  Moisture content of wet flyash shall.be  determined
              prior to placing in mix.
          6.  A  shredding machine  shall  be  used  to  pulverize  the
 conditioned  (moistened)  flynsli  prior  to its  use  in the  mix.

                                     A-35

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          Fill sand to be used in the LCF mixes shall be the suitable
material from the excavation and any deficiency in supply shall be
supplemented from the stockpile as directed by the F.ngineer.  The
suitable fill material shall consist of sand or a sand and gravel
mixture with fines .not more than 10% by weight passing No. 200 sieve
and shall have no particle size exceeding two inches in largest dimension.

          Water for use in mixing the lime-cement flyash stabilized fill
sand base courses shall be clean water without objectionable organic
content.

                               Proportions

          The materials in the lime-cement flyash stabilized fill sand
base courses shall be proportioned by weight in the percentages shown
herein.  The Engineer, however, may at his sole option vary the percentage
of materials.  The Contractor will be reimbursed for the actual net cost
delivery purchase price to him of any additional materials ordered by the
Engineer.  The amount of water used in the mix shall be determined by
tests for the optimum density and compaction as specified herein in the
subciause entitled "Compaction".

               Composition of Lime-Cement-Flyash (LCF)  Mixes

                            Percent by Weight
Type
A
B
C
Hydrated Lime
ASTM Type N
3.6
3.2
2.8
Portland Cement
ASTM Tvpe I
0.9
0.8
0.7
Flyash
12-14
14-16
14-16
Aggregate
V - 3/4" Size
30
—
— —
In-place i
Fill Sand
51.5-53.5
80.0-82.0
80.5-82.5
1
          Any ingredient of the mix shall  not  deviate more than 1/20 of the
figures shown above.

                          Change in Proportions

          If the Contractor elects  to place  lime-cement flyash stabilized
fill sand base courses  during the months of  September and October,  the
cement content shall  be twice the amount shown in the table above at no
additional compensation.

          Between November 1 and Marcli 1,  half of the cement shall  be
deleted and an equivalent amount by weight of  hydrntcd lime shall be sub-
stituted in lieu thereof.
                                  A-36

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                    (         Mixing

           The lime-cement flyash stabilized fill sand base course
 materials shall bcmixcd in a stationary continuous flow or batch
 type mixer equipped with batching or metering devices to measure  the
 specified quantities.  Mixing shall be continued until a thorough
 and uniform mixture of all materials incorporated in the mix is
 obtained.  The minimum mixing time determined from trial runs of  the
 central mixing plant shall be as directed by the Engineer.  For the
 batch type mixer,  prior to the introduction of water, the dry mix of
 lime-cement flyash and fill sand shall be blended uniformly for a
 period of not  less than 15 seconds per cubic yard or three revolutions
 of  the mixing  drum.  For a continuous  flow type mixer,  adequate devices
 shall be  installed to detect the changes  in the flow niateriali.  The
 moisture  content of the flyash,  aggregate  and  fill  sand  as  well  as
 all metering devices shall  be daily  tested and recalibrated.

           The  Contractor shall submit  in detail his anticipated pi*nt
 operation and  layout i'or the  approval  of  the Engineer.  As a guide lor
 the Contractor in  selecting  his  equipment,  the  central mixing plant
 shall be  equipped  with the  following:
    
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                          P re V.T rat ion of Subp.racle

        Prior  to placement of pavement materials  and  after grading,  the
  subgrade shall be compacted the same as specified  for  backfill in  the
  clause herein entitled "Backfill".

        In the event  that during or after compacting  the subgrade,  the
  Engineer determines that the material below such depths  is  unsuitable
  to  properly  support the permanent construction, the Contractor shall
  ON--.iv.ite to  such further depths and within '.such limits  a.°.  the  Enj'.inoc-r
  nay order and backfill and recompact to the extent  ordered  by  the
  Lnpinetr ir.  accordance with the clause entitled "Over-Excava-
        If,  in  the opinion of  the Engineer,  the material below  such
  .icpths  is  rendered unsuitable by  the Contractor's  opcrntions,  the  Con-
  tractor shall  receive no additional compensation whatever  for such
  retr.oval or backfill.

                            Placing of First Lift

        The  prepared subgrade  on which the mixture is  to be  placed
  sh ill  be thoroughly and evenly moistened,  as directed by the  Engineer
  L-ar-'cdiately prior to placing of the mixture.  The  mixture  shall be
  deposited  on  the moistened subgrade in a uniform loose condition  for
  a depth that will provide the compacted depth specified or. the Contract
  Drawings or as set forth in  the Specifications.


                              Compaction

       The roller used for the first two passes of  initial  compaction
shall be a vibratory roller as specified for backfill in the clause here-
in entitled  "Backfill".   The  final compaction shall be done with two  self-
propelled pneumatic-tired rollers equipped  for rapid  adjustment of  tire
inflation pressure.   Each of  these rollers  shall have a minimum gross weight
of 35 tons,  and hav a tire inflation pressure variable from 30  to  150 psi
(minimum) and shall be Bros.   SP-10000 self-propelled pneumatic-tired rollers
vich air on  the run,  as  manufactured by Bros. Inc.  or approved  equal.
                                     A-38

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       The number of passes of Che pneumatic tired roller shall be
determined by the Engineer when the deposited base courses reach a field
density at trial run at least 100 per cent of the maximum density in accord-
ance with AASHO Designation T-180 Method "D" Density Test.  The density
of compacted base courses in actual installation shall be determined by the
Engineer from in-place density tests or from undisturbed samples cut fron the
base courses.  During the course of placement construction, the Engineer c-.ay
increase or decrease the number of passes of the pneumatic-tired roller as
frequently as required to obtain the best density of the compaction.

       The Contractor shall furnish the necessary labor and materials to ob-
tain these samples and to patch areas from, which samples are taken.

       During the checking,  of  density  of base  courses,  the  Engineer
  will  also check  the  thickness of the  compacted  base  course.   Before
  proceeding  with  succeeding courses, the Contractor will  be  required
  to  correct  any portions  of the  base course  that do    not  meet the
  above density requirements or that dc    not meet in  thickness the
  requirements shown below.

       A  reasonably rippled surface with no  loose material,  is
  tolerable for the  integration of the  subsequent base  courses  and
  asphalt  concrete top  course,  as  long  as the following  tolerances
  are maintained:

                 Tolerances in Thickness of  Lifts

       First Lift         LCF  Mix "C"          ±1.0  inch

       Subsequent Lifts   LCF  Mix ''B"          ± 1/2  inch

       Top Lift           LCF  Mix "A"          ± 1/4  inch

       Total Thickness of All  LCF Lifts        -  1/2  inch
                                               + 1.0  inch
                                    A-39

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        Subsequent lifts sha'  be placed by means of  approve^  
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                        Rehandling of Material

         Within three days after the mixing, the lime-cenent flyash
stabilized sand may'be regarded, reshaped and reused in the work prr-
vided that the moisture of the mixture is within the range of optinur.
percentage +27. to -1%.  However, no lime-cement flyash mixture mav be
stockpiled for future use.

         During the construction period, the Contractor shall cx-'-rr : ••><_•
all necessary precautions to prevent air pollutions due to wind-Mown
flyash and in-place fill sand while these materials are being trans-
ported to the batching plant.

                         Weather Restrictions
         No lime-cement flyash stabilized fill sand base course shall
placed during periods of heavy or extended rainfall.  Base course or
courses shall be placed and compacted only if the day or night temp-
erature is not anticipated to be below 32  F- in the next twenty-four
hours after placement.  All exposed lime-cement flyash courses of
Mix "A" placed after November 1 and surfaces that will not receive an
asphalt concrete top course until April 1, shall be protected by an
asphaltic seal applied within two weeks after placement in accordance
with the provisions of the suhclause hereof entitled "Tack Coat".  All
exposed lime-cement flyash courses of Mix "B" or Mix "C" placed without
cover after November 1 to April 1, the Contractor shall remove the
top 2" of exposed lime-cement flyash in March or April bv scraping or
cutting prior to continuing paving construction, and the replacement of
the 2" of lime-cement flyash cut away shall be added to the thickness
of the subsequent lift.  At the resumption of pavement operations in
March or April, the base course or courses shall be recompacted
immediately prior to the placement of new lifts using the equipment and
number of passes specified in the sub-clause entitled "Compaction".

                      Protection and Maintenance

         After the base course has been completed as specified to the
required lines, grades and typical section as shown on the Contract
Drawings, no traffic, other than light personnel vehicle as approved
bv the Engineer shall he allowed on the course.  Any damage caused bv
i-quipmoiU nsovl in i In- const met ion of an adjoining section shall he tin-
responsibility of the. Contractor and shall be immediatelv repaired.

         The Contractor shall maintain the entire base course in a
condition  considered satisfactory by the Engineer.  Said maintenance
shall  Include i in- ri-pa I r of anv dt*(Vcrs rlint mav occur.
                                  A-41

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                       Water Curing
          The  Contractor will be required, after placement to apply moisture to
the lime-cement flyash stabilized sand base.  The determination'of said
raent shall be  at the sole judgment of the Engineer.
                             Tack Coac

           The Contractor shall apply tack coat to the compacted top
 lime-cement fly:ish layer (LCF "A")  within two wrrks .it tor its place-
 ment and to surfaces called for in  the subcinusc huroin entitled
 "Weather Restrictions".


           The cack coat shall consist of an 85 Co 100 penetration grade
 hot  asphalt cement or M3-70 which shall be placed by approved means at
 a rate  of  0.25  gallons per square yard.

           In addition, if the compacted top layer (LCF "A") Is left
 uncovered  of asphalt concrete top course over the winter months,  it
 shall receive a tack coat of 0.10 gallon per square yard after
 recompaction, prior  to the placement of the asphaltic top"  course.

                   Pavement  Joint  and Cushion  Mnturial

            The  preformed joint  filler  cushions  shall be a  closed-cell
  polyethylene foara of  the sizes and dimensions  shown on the  Contract
  Drawings.   The Contractor  shall  submit  a sample of material he  plans
  to  use for the Engineer's  approval.

            Joint sealer  shall be  "Sikaflcx T-68" ax manufactured by
  the Sika  Chemical Corp. or approved equal  and  shall he applied  in
  accordance with the manufacturer's  recommendations.

            Any  oversized cut  for  the installation of joint filler
  shall  be  backfilled with cement  mortar  consisting of one  portion of
  Type 1  portland cement  and 5 portions of LCF mix and not  more
  than 5  gallons  of water per sack of cement.
                                     A-42

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                    Inspection of Cement

     Portland cement will be inspected by  the Authority  at the  -.anu-
larturer's plant.  For nil cement dcsifinatod  for  this  Cor.:r.-.rc  nr.c  ;
unoctcd by the Authority at the manufacturer's  plant,  *.h-
Contractor shall pay to the Authority the  amount  of  f::;ccr.
cents per barrel of cement for cement delivered in carle?.!,:  lets,
the amount of thirty cents per barrel of cement delivered  in
truckloail lots and forty cents per barrel  of cement when re-
handled :hru a local distribution plant.   These charges will be
made on total amount of cement inspected even though the.quintity
shipped for the Contract be greater than the amount of concrete
incorporated in the permanent structure.   The operation c:
loading at plants and unloading at destination  will 'n* perfcrr.oc
during the daytime only.  The Authority shall,  from time to
time, render to the Contractor statements  of the  amounts to be
paid to the Authority under this numbered  clause  and within
fifteen days after receipt of each such statements, the Contractor
shall pay the amount thereof-  The Contractor,  however,  authorizes
the Authority to, and the Authority may at  its  option, collect
such amounts out of any sum payable under  this  Contract.
                            A-43

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                            Federal  Aviation Administration'
                               Toledo Airport Project

                         ITEM P-305 AGGREGATE-LIME-

                      FLY ASH SUBBASE OR BASE COURSE

                          '  (CENTRAL  PLANT MIXED)   '

                                            •"'
305-1.1  DESCRIPTION.  This  work shall consist.  of  the  construction, of a
stabilized subcase or base course on a  prepared and accepted underlying
surface.  The stabilized subbase or  base course shall be prepared  by mixing,
hauling, spreading, shaping, or compacting, and curing  mineral aggregate,
lime,  fly ash and water in accordance with the requirements of this specification.
The stabilized course shall be constructed  in reasonably -close conformity to
the lines, grades, thicknesses and typical sections shown on the plans or •
established by the  engineer.                             .        -  ;       "'

This construction may involve patents and, if so, GENERAL PROVISIONS 70-03,
Patented Devices, Materials and Processes shall  govern.


305-2-.1  LLME-FLY ASH CEMENTITIOUS FILLER MATERIAL.  The lime and fly ash
shall be supplied either separately or as a manufactured  blend.   The lime,  fly
ash or blend may contain admixtures such  as  water reducing  agents, portland
cement, or other materials  which are known to provide supplementary properties
to the final mix.  When admixtures   are to be included, they are to be used  in
the laboratory design  as required in Section 305.3.
        (a).  LIME shall meet  ASTM Specification C-207,  Type N,  Sections  2
and 3 (P.) when  sampled and  tested in accordance with Sections 6r and 7 and shall be
capable of producing a mixture which will meet  the requirements of Section 305.3.
A  minimum of 85% shall pass a No. 200  sieve when tested by wet  sieving as per
ASTM C110.
        (b).  FLYASH shall meet the  requirements of  ASTM  C-593 for fly ash  for use
with lime in non-plastic mixtures.  If ordered by the engineer, a shredding machine
shall be used to pulverize the conditioned  (moistened), fly ash prior to its use in
the mix.
        (c).  PORTLAND CEMENT, if used  as  an admixture, shall conform to
the requirements of ASTM'C"-rl50,...Type 1 fof ASTM- C-595, Type  IP.


305-2.2  WATER.   Water known to be of potable quality may be  used without test.


305-2.3  AGGREGATE."  The aggregate  shall'be  either stone,  slag or- sand, 100% .
crushed.  In. addition  to the fine aggregate naturally- contained in  the coarse
material, supplementary fly. ash may be used as a mineral filler to provide the
desired fines content.

The 100% crushed aggregate shall consist of hard, durable  particles, having
the gradation specified, and free from  an excess of flat,  elongated, soft or
disintegrated pieces,  dirt or other deleterious materials.
                                         A-A4-

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                           item P-305 Aggregate-Lime-
                         Fly Ash Subbase or Base Course


 The methods used  in processing such as  crushing,  screening,  and blending
 shall be such that  the finished product shall be as  uniform  as  practicable.
 If necessary to meet this requirement or  to  eliminate an excess of fine
 particles, the materials  shall be screened before and during processing,  and
 all stones, rocks,  boulders,  and other source material of inferior  quality
 shall be wasted.

 The aggregate shall show •  no evidence of general disintegration nor show a
 total loss of more than 12 percent when  subjected to five cycles of the
 sodium sulfate accelerated soundness test specified in1 ASTM C-88.   Aggregates
 failing  the sodium  sulfate test may be approved by  the engineer, providing
 they are from  a source  that  has proven  satisfactory service records of being
 used in cement or  asphaltic concrete pavement construction  in the same locality.

 All material passing the No.  4 sieve produced during crushing  or other processing
 may be incorporated in  the  base material to  the extent permitted  by the
 gradation requirements, unless it  is known to contain disintegrated'deleterious ....
 material, such as clay lumps, shale,  coal or other soft particles.   The aggregate
 shall meet the. gradation requirements given  in Table 1 when tested  in
 accordance with ASTM C-117 .and ASTM C-136.

                Sieve                        Percentage by Weight
                Designation                  Passing Sieve

                2 inch                              100
                1 inch                              75-100
                i inch                              50-85
                No. 4                               35-60
                No. 8                               15-45
                No. 16                              10-35
                No. 50                              3-18
                No. 200                        .     1-12


                Table l.v Acceptable'Gradation of Aggregates
                         for Aggregate-Lime-Fly Ash Base  •' *
                         and. Subbase Courses.      i:


The gradation in Table 1 sets limits which shall determine  the  general suitabiltiy
of the aggregate from a source of  supply. ;.The final gradations selected  for
use shall be within the limits designated in the table, and shall also be well
graded  from fine to coarse  and shall  not vary from  high to low limits  on
subsequent sieves.
                                   A-45

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                           Item P-305 Aggregate-Lime-
                        Fly Ash Subbase or Base Course


In addition to the gradations given in the table, clean sands and sand-sized
materials  such as boiler slags can be vised.   Also, if the aggregate has a
substantial portion passing the No. 4 mesh  sieve  (75 percent), the gradations
in the above table can be waived and the aggregate gradation adjusted with
the fly ash and fines  contents to produce the maximum dry density in the
compacted mixture.                                                    "

The portion of the base, material including  any blended material passing the
No.  40 mesh sieve" shall-have a liquid limit'of less  than 25  and a plasticity
index of less than 6 when tested  in accordance with AASHTO T  89 and AASHTO
T 90.


305-2.4  BITUMINOUS MATERIAL.  The types,  grades, controlling specifications
and  application temperatures for the bituminous materials used for curing the
aggregate-fly ash treated  base/subbase course-are given below.  The engineer
shall  designate the specific material to be used.

             Type and Grade           Specification         Application Temperature

             Cutback  Asphalt
                RC-70 or  MC-30        AASHO  M  81 & M 82      120°-loO°F.
             Emulsified Asphalt         Fed. Spec.
                RS-1, RS-2K           SS-A-674                   75°-130°F.


                               '•'•'      Laboratory Tests


305-3.1  LIME CONTENT.   The quantity of lime approximately 2 to 5 percent
by weight to be  used  with the  aggregate, fly ash,- and water, shall  be
determined by  tests for the materials submitted  by the-contractor, at his own
expense,  and in  a manner satisfactory to the engineer.


305-3.2" FLY ASH CONTENT^ .The':;'quan'tity:rof'fly'r ash' approximately"9 :t6 '15 percent
by weight to be  used  with the'aggregate,'-'lime,.''arid water,  shall'be  determined '•=
by tests for the  materials  submitted by the contractor, at his own .expense,  and
in a manner' satisfactory to the engineer.


305-3.3  MANUFACTURED BLEND  CONTENT.   The quantity of manufactured v'-'
blend to be used with the. aggregate and water  (and any .supplemental fly  ash)'.
shall be determined by tests for the materials submitted by the  contractor/ at  ':
his  own expense, and in a manner satisfactory to the engineer.
                                        A-46

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                           Item P-305 Aggregate-Lirne-
                        Fly Ash Subbase or Base -Course


 305-3.4  LABORATORY TESTS.  Specimens of the aggregate lime-fly.ash base
 7subbase course material  shall develop a minimum compressive strength of
 400 psi and demonstrate freeze-thaw resistance of a maximum of' 14% weight
 loss as specified in ASTM Specification C 593, Section 3.2, 'when tested in
 accordance •with Section 9 of that specification except that all compaction  .
 shall be done in accordance with FAA T  611, Section 2.2 .(a) and (b) for
 aircraft  weighing more than 30,000 pounds.


                              Construction  Methods

 305-4.1  WEATHER LIMITATIONS.  The  fly ash treated base/subbase shall
 not be mixed  or placed while  the atmospheric temperature is below 40°F. or
 when conditions indicate that the temperature may fall below 40°F. within
 24 hours.  Temperature requirements may be waived but only when so directed
 by  the  engineer.


 305-4.2  SOURCES OF SUPPLY. All materials shall be obtained from approved
 sources.


 305-4.3  EQUIPMENT.  All methods  employed in performing  the work and all
 equipment, tools, other plans  and  machinery used for handling  materials and
 executing  any part of the work shall be subject to the approval of the  engineer
 before the work is started.  If unsatisfactory equipment is found, it shall be
 changed and improved.  All equipment, tools, machinery, and plants must be
 maintained in a satisfactory working condition.


 305-4.4  PREPARING UNDERLYING  COURSE.  The underlying course shall be
 checked  and.accepted by the  engineer before placing and spreading  operations
 are started..._Any ruts..or soft,, yielding .places caused  by improper drainage
 conditions, hauling, .or any other cause,  shall be  corrected  and rolled  to\'the
required compaction before the base course  is placed thereon."" Grade control
between  the edges of the pavement shall be'accomplished by  grade stakes,'steel
pins, or forms placed in lanes parallel to the centerline of the runway and at
intervals sufficiently close that string lines  or  check boards may be  placed
between  the stakes, pins'or forms.  To protect the underlying  course and to--
insure proper drainage, the spreading of the base shall begin along the centerline
of the pavement on a crowned section or on the high side of the pavement with
one-way slope;  However, it shall  be the'responsibility  of the. contractor  to
construct adequate drainage to maintain the specified subgrade densities.
                                          A-4?

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                           Item P-305 Aggregate-Lime-
                        Fly-Ash Subbase or Base Course
305-4.5  MIXING.
        (a). General Requirements   Fly ash treated base/subbase shall be
mixed at a central mixing  plant by either batch or continuous mixing.  The
capacity-of the. mixing plant should not beless -than/50 tons per hour. -The
aggregates, lime, and fly  ash may be proportioned• either by weight'or "by --
volume.  The exact material proportions shall be fixed  by the Engineer and shall
be maintained within the following tolerances in percent by .weightvo£, the. total
mix.

                            Lime .             ±0.3
                            Fly  ash            ±1.5
                            Aggregate         ±2.0

In all plants, water shall be proportioned by weight or volume, and there  shall
be means  by which the engineer may readily verify  the amount of  water per
batch of the rate of  flow for continuous mixing.  .The -discharge of the water
into  th« mixer shall not be started before part of the aggregates are placed into
the mixer-.  The  inside of  the mixer shall berkept.free  from any hardened mix.

In alLplants, lime and fly ash (and. portland cement.when used in the mix)
shalL be- added in such a manner  that-it is uniformly distributed throughout
the aggregates during the mixing: operation.

The  charge in- a  batch mixer, or  the rate of feed into a continuous mixer shall
not exceed that which will permit complete mixing of all the material.  Dead
areas in the mixer, in which the  material  does  not move or is  not  sufficiently
agitated, shall be corrected either by a reduction in the volume of material •
or by other adjustments.

Means shall b-  provided for checking  the accuracyof the proportioning.   Water
shall  be added if necessary  to insure  that the  mixture  will kbe at optimum
moisture content  when-compacted. The mixing operation, shall be-continued until
all the materials  are distributed .evenly, throughout, .the.mixture.-': The .mixture--x
shall  then.be discharged without -.ondue-s'egregation-i-rr{ A sample;of ..batched -lime^-
fly-ash base material shall be obtained periodically-.and compression • specimens--r
prepared-,for testing  according to ASTM C 593. - The average strength for each
sample shall be not less than 400  psi with no individual test being lower_^than .-.-j
300 psi.  The Engineer reserves the right to make such changes in  mix " r
proportions during the progress of the work as he may consider necessaryv
                                       A-48

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                           Item P-305 Aggregate-Lime-
                         Fly Ash Subbaae or Base.Course


        (b). Batch Mixing. In addition to the "General Requirements" as
provided in '305-4.5(a), batch mixing of the materials shall conform to the
following requirements:            --.;.

The mixer shall be equipped with  a  sufficient number of paddles of a type
and arrangement to produce a uniformly mixed-batch.

The mixer platform shall be of ample size to provide safe and convenient
access to the mixefr and other'equipment.  The mixer and batch-box housing
shall be provided with hinged gates  of  ample size to permit easy sampling
of the discharge of aggregate from each of the plant bins and of the mixture
from  each  end of the  mixer.

The mixer shall be equipped with  a  timing device which will indicate by a
definite audible or visual signal the  expiration 6f the mixing period.  The
device shall be accurate to within two seconds.   The plant shall be equipped
with suitable  automatic device for counting the number of batches.

The mixing time of a  batch shall begin  after all ingredents are in the mixer
and shall end when the mixer is half emptied.  Mixing shall continue until a
homogeneous mixture  of uniformly distributed and properly coated  aggregates
of unchanging appearance is produced.  In general, the time of _' mixing shall
be  not less than 30 seconds,  except that the time may be reduced when tests
indicate that the requirement for lime-fly ash content and compressive
strength can .be consistently met.                    .      •

        (1). Weight Proportioning.  When weight proportioning ia used,  the
discharge gate 01 the weigh box shall be arranged to blend the different
aggregates as they enter the mixer.                        :

        (2). Volumetric Proportioning.  When volumetric proportioning is
used  for batch mixing,  the :volumetric proportioning device  for the  aggregate
shall  be equipped with separate bins, adjustable in  size, for the various
sizes  of aggregates.   Each bin shall have an accurately controlled gate or other
device designed so that each bin shall be completely filled  and accurately^"•-'•';-:^?'>
struck-off in  measuring the volume of aggregate;to  be used in the  mix.':'';Means
shall  be provided for/accurately calibrating the amount  of material in 'each' *
measuring  bin.
                                        A-49

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                           Item P-305 Aggregate-Lime-
                        Fly Ash Subbase or Base Course  •


        (c). .Continuous-. Mixing .  In addition, to the.--" General. Requirements"
as provided in 30 5-4. 5 (a),  continuous mixing of the materials shall conform
to the following requirements:

The correct proportions of each aggregate size introduced into  the mixer
shall be drawn from the storage bins by a continuous feeder, .which will
supply the correct amount of aggregate in proportion to the lime-fly ash  and
will  be so arranged that the proportion, of each material can be separately
adjusted.   The bins shall be- equipped  =with a vibrating unit which will '•;
effectively vibrate  the side walls of the bins and prevent, any" hang up" of
material while the plant is operating.  A positive signal 'system  shall be";
provided to indicate the' level of • material in each bin, and as the level  of
material in any one bin approaches  the strike-off capacity of the feed  gate,
the device shall automatically and instantly  close  down  the plant.  The plant
shall not be permitted to operate unless this automatic  signal is in good working
condition.

The drive shaft on the. aggregate feeder shall be equipped .with. a. revolution
counter accurate to 1/100 of a revolution, and of, sufficient : capacity to
register the total number of revolutions in a day's  run.
                                       . ..-* ~
The continuous,  feeder for the aggregate "may be mechanically or electrically .
driven.  Aggregate' feeders that are mechanically' driven shall be directly
connected ;with the drive on the lime- feeder.

The pugmill. for the continuous mixer .shall be equipped with  a surge hopper
containing sufficient baffles and gates to prevent segregation of. material
discharged into  the -truck  and to 'allow for closing of the hopper between
trucks without requiring shut down  of the plant.


305-4.6 PLACING, SPREADING,  AND COMPACTING.. The. use of mixers  having
a chute delivery shall not be permitted except as approved.  In all such cases,
the arrangement  of chutes, baffle plates, etc. ,. shall, insure the  placing "of the;
fly  ash treated:' base/withput.
The prepared underlying course shall be "free of all ruts or-' soft "yielding'
places.   The surface, if dry, .shall be moistened but. not to- the extent. of pro-
ducing a muddy condition , at the .time, the .base" mixture is placed.
                                            A-SO

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                             Item P-305 Aggregate-Lime-
                         Fly Ash Subbase or Base -Course


•  Trucks for transporting the mixed base material shall be provided with
  protective covers..' The material shall be spread on'the .prepared, underlying
v  course-to such depth that/when thoroughly compacted,'it will conform to  the
  grade  and dimensions shown on the plans.   The aggregate lime-fly  ash base,
  within an increment of'work, shall be placed and compacted  within  24  hours
  of mixing.  Where multiple layers are placed,  each, layer  shall be placed and
  compacted the same day as 'the first layer.

  The maximum compacted layer'thickness shall be 4  inches except where vibratory-
  equipment is used in conjunction with other methods  of'compaction, the •   '•'•••
  maximum compacted layer thickness  shall be 8 inches.  Where the total thickness
  specified is  more than '8 inches, -the mixture shall be placed  in two or more
  layers approximately equal in thickness, or as  specified on the plans.       '

  The "materials-shall-be spread  by a  spreader box,  self-propelled '• spreading .-'-•._
  machine or other method  approved by the engineer.  It shall not be placed in
  piles or windows without  the approval  of the engineer.  If spreader boxes or
  other spreading machines are used  that do not spread the material  the full
  width of the lane or the width being placed in one construction operation,
  care shall be taken to join the previous pass with the last pass of the spreading
  machine.  The machine shall be moved back approximately every 600 feet,  when
  staggered spreading machines  are not  used.  The first pass shall not   be
  compacted to the edge and,  if necessary, the loose material  may be dampened
  just prior to joining the next pass.  If portland cement is used in the mixture
  and the temperatures are more than 70°F.,  the materials shall be spread
  within 4 hours  and worked  into the adjacent material.  When portland  cement
  is used in the mixture and  the temperatures are less than 70°F., the materials
  must be spread  within 8 hours and  worked into the adjacent material.   Additional
  moisture may be required during the reworking operations as directed by the
  engineer.

  The equipment  and methods  employed in spreading  the base  material shall insure
  accuracy and uniformity of ;depth and width.   If conditions  arise  where
 such uniformity  in the spreading ds not being obtained, the  engineer may
 require additional equipment or modification in  the  spreading procedure-to
 obtain satisfactory results.   Spreading equipment'"shall be-no more-than "30-feet-
~nor less than 9  feet,in  width, unless approved by .the engineer.

"After 'spreading,: 'the "material shall'be  thoroughly "compacted  by rolling."•>'"'-The- ~"<
 rolling shall progress gradually from one side toward  previously placed material
 by uniformly, lapping  each preceding rear-wheel track by one-half  the width
 of such track'.   Rolling shall continue until  the base  material has been uniformly
 compacted for its full depth to not less than 100%  density, as determined by
 the  compaction-control tests specified in FAA T 611.   Blading and rolling shall
 be done alternately,  as required or directed,  to obtain a smooth, even,- and .
 uniformly compacted  base.  Finishing operations shall continue until the surface
 is true to the specified cross section and until the surface shows no variations  of
 more than 3/8 of an  inch from a 16-foot straight-edge laid in any location  parallel
 with, or at right angles to  the longitudinal  axis of the pavement.
                                            A-51.

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                           Item  P-30S Aggregate-Ldme-
                         Fly Ash Subbase or Base Course


 After  a layer has been compacted, tested for density and. approved by the.
 Engineer, water-shall be applied  as required to. maintain the moisture content
 of the mixture near  the optimum until  either a succeding- layer of liine-fly ash
 material or the bituminous curing coat is placed.  The equipment used for
 applying the. water, .and bituminous curing coat shall be  such that will-not.displace
 or otherwise damage the surface...

 Prior to placing-a layer on a previously placed .-layer, the surface of the
 previously placed layer shall be  loosened to- assure interlocking of the aggregate
 between the layers. '.

 In constructing the  top  layer, the. grade shall be kept at sufficient  height
 so that the top surface, when compacted, will be at or  slightly above grade,
 rather than below grade.  Finish grading shall be accomplished .by removing
 excess material followed by recompaction by rolling.   In the  event, that low
 areas occur, they shall.be loosened, dampened with water immediately before
 placing additional--mixture, and then rolled to  the satisfaction of the Engineer.

 Any dusting or surface ravelling caused by traffic on the sealed base course
 material shall be  the responsibility of the contractor  and shall  be taken care
 of as directed by the engineer.


 305-4.7  CONSTRUCTION JOINTS.  The protection provided for  construction
"joints shall permit, the placing, spreading, and compacting of base material
"without injury to the work previously  laid.   Care shall  be exercised to insure
 the specified 'density of the  base material immediately adjacent-to. all construction
 joints,  existing pavements, structures and unsupported pavement or lane edges.


 305-4.8  PROTECTION  AND  CURING.   After  the base  course  'has been finished
 as specified herein and  approved by-the engineer, it shall be  protected
 against drying until the surface course is  applied by the application of the
 specified bituminous material.

" The bituminous material specified shall be uniformly "applied to the surface of the
 completed base course at the rate-of approximately 0,20 gallons per square
 yard  using approved heating and''distributing"' equipment in  accordance to
^Specification P-602. ' The exact rife- and temperatuxe-of applicatiort-to^give
 -complete coverage without excessive runoff, shall be^as  directed. by;.the engineer.

• At the  time the bituminous material is  applied, the surface shall be  dense,
 free of all loose and extraneous  material, and  shall contain  sufficient  moisture
 to prevent penetration, of the  bituminous material.  All  surfaces shall be
 cleaned of all dust and  unsound materials to the satisfaction of the  engineer.
 Cleaning shall be done- with rotary  brooms and/or blowing the  surface with
 compressed air, with the surface reasonably moistened to prevent  air pollution.
 Water shall be applied in sufficient quantity to fill the  surface voids immediately
 before the bituminous curing material is applied.  •
                                      A-52

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                           Item P-305 Aggregate-Lime-
                        Fly Ash Subbaae or Base Course


Should it be necessary for  construction equipment or other traffic to use the
bituminous-covered surf ace' before the bituminous material  has  dried sufficiently
to prevent pickup, .sufficient granular  cover shall be applied before such use.

No traffic shall be allowed on the fly ash base/subbase course other than that
developing from the operation of essential construction equipment, unless other-
wise directed by the engineer.  Any defects which may develop in the
construction of the base course or any other damage caused by the operation
of the job equipment is the responsibility of the contractor and shall be
immediately repaired or replaced to  the satisfaction of the  engineer, at no
expense to the sponsor.
              -"> * •

305-4.9  COLD WEATHER PROTECTION.  During cold weather if the air temperature
unexpectedly drops below  40°F. and remains there for-a period of several
days  or  more, the completed base course shall  be protected from  freezing by
a method approved by the engineer prior to the application of the bituminous
surface course.   Any light surface  frost caused by overnight below freezing
temperatures  shall be treated by rolling  the surface with a light steel wheel
roller as directed by. the engineer.


* 305-4.11  TOLERENCE IN BASE/SUBBASE THICKNESS.
See General  Notes on the Plans. **


                             Method of  Measurement

305-5.1  The quantity-of aggregate-lime-fly  ash.base course to be paid for shall be
the actual number of cubic yards (computed from plan lines, within the
actual width of the existing underpavements) of approved  aggregate lime-fly as"h
base  course  material  compacted in conformity with the lines, grades and typical
sections shown on the plans.


                                Basis of Payment,

305-6.1  Payment shall be made at the contract unit price per cubic yard for
aggregate-lirae-fly ash base/subbase course.  This price shall be full compensation.
for furnishing all materials and for all preparation.manipulation,  and placing
of these materials and for all labor, equipment, tools and  incidentals necessary
to complete the item.


Payment will be made under:

        Item P-305-6.10  Aggregate-Ldme-Fly Ash Base Course
                         per cubic yard.
                                             A-53

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               4. THE ROAD RESEARCH LABORATORY FROST TEST

 The test adopted at the Laboratory is based on one originally developed by Taber in the
 United States.^)  Compacted cylindrical samples of the material under test are frozen from
 one end while the other end is in contact with free water maintained at a temperature slightly
 above freezing point.  The heave Js'recorded over aperiod of 10 days.

.4.1  Preparation of samples

       The samples tested are 4 in diameter and 6 in long.  They are compacted in a cylin-
 drical mould provided with a slight taper for easy extrusion. Details of the mould and the
 extruders are shown in Fig. 6 and Plate 1.

       For cohesive soils the usual level of compaction adopted corresponds to 5 per cent
 of air voids at the natural moisture content or,  if the latter is not known, at a moisture content
 of 2 per cent above the plastic limit.

       Non-cohesive  soils and other granular materials of maximum size less than 1 in are
 normally tested at the maximum dry density and optimum moisture content of the British
 Standard compaction test using normal compaction.'^'  For coarser granular materials the
 fraction retained on the 2 in sieve is removed prior to  the preparation of the freezing samples.
 The selection of the appropriate  moisture content and  dry density for the compaction of such
 coarse materials presents some difficulty.  A.E.S. compaction test carried out on material
 finer  than % in gives a useful guide,  but some  adjustment to the dry density may ce necessary
 to achieve  a sample which is sufficiently stable  but at the same time is not subject to
 crushing of the  particles when compacted by the  procedure described below. This adjust-
 ment  must be made by trial and error  at the time of compaction.

       For all materials, tests at several dry densities can  be carried out to investigate the
 effect of dry density, but in granular  materials  care should be taken to  avoid crushing the
particles during compaction.
       Classification tests adopted include liquid and plastic limits, particle size distribu-
tion and particle specific gravity. For aggregates of porous structure the saturation moisture
content of the particles greater than the Vi  in sieve size is determined.  From a kilogram of
the material not less than ten particles in this  size range are selected at  random.  The
particles are immersed in water for at least 24 hours after which they are  surface-dried and
the wet weight of  each is measured.   From the oven-dry weights subsequently determined,
the moisture content of each particle  and the average moisture content are quoted.

4.2 Compaction of samples

      The  mould  is assembled in the vertical position with  the lower ram in the bore but
held half to one inch from its innermost position by  suitable spacers. The weighed amount
of material  necessary to give the required dry density in the compacted sample is placed
slowly into the mould accompanied by continuous dynamic compaction with  a flat-ended
wooden rod of about 11A in diameter.   When all the weighed material has been tamped into
the mould the upper ram is placed in the bore and the complete mould transferred to a com-
pression type testing machine of  maximum capacity  30  tons (Plate 2).  The spacers are
removed from the lower ram and the sample is compressed statically using a rate of strain
not exceeding 2 in per minute.  During compression  the side of the mould is struck period-
ically with a rawhide mallet. This compaction  procedure is  adopted to  reduce density grad-
ients  within the specimens to a minimum.
                                         A-54

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       The sample is extruded from the wide end of the mould using the short extruder
 mounted in the testing machine to start the extrusion process.  Final extrusion is affected
 by hand using the full-length extruder.

       Immediately  after extrusion a waxed paper sheet 14 in long and 8 in wide is wrapped
 round the curved face of the sample and secured with adhesive  tape, to give a 2 in upstand
•at the upper face. A waxed cardboard disc 3V. in in diameter and provided with a  central
 dimple  to accommodate a 3/16 in diameter push road is placed on the top of the sample.
 Finally the sample  is placed on a ceramic plate,  Yi in thick and 4 in in diameter, of average
 pore size 100 microns  (Grade  1),  located in  a spun copper collar (specimen carrier) of the
 dimensions given in Fig. 7. An extruded  sample  ready for wrapping and mounting is shown
 in Plate 3.

 4.3 Freezing cabinet

       The freezing cabinet (Plate 4), which is designed to  take nine specimens,  is shown
 in cross-section in  Fig.  8. A  removable wooden specimen container is located in  a lagged
 cabinet provided with wheels  to facilitate movement into and out of the refrigeration room.
 The base of the specimen container is provided with nine recessed holes into which the
 copper  specimen carriers fit.  The space between the samples is filled with a coarse dry
 sand to a level slightly higher than the top of the  samples.  Vertical push rods 3/16 in in
 diameter, supported by transverse metal bars  in which they are free 10 slide, are located
 with their lower ends in  the dimples provided in the sample cover discs (Plate 5).
                                i
       When  the specimen container is in position in the lagged cabinet, the upper faces of
 the ceramic discs are in the surface of the water in a thermostatically-controlled electrically-
 heated  water bath in the bottom of the cabinet.  An overflow  pipe prevents water rising above
 the level of the plates and water  can be added to maintain this level  through a stand-pipe
 passing through the base of the specimen  container.  The adjustable  thermostat for controlling
 the temperature of the  bath is  fixed to the outside of the cabinet.

 4.4 Test procedure

       The compacted  specimens  are placed in the cabinet, and  the sand filling added.  The
 transverse bars and push rods are put in position and water add  d to the bath until overflow
 occurs.  After 24 hours at room temperature further water is added to replace any absorbed by
 the samples.  The push rods are pressed firmly in contact with the sample covers and the
 distance between the top of each  rod and the transverse bar is recorded.  With the  thermostat
 set to + 4°C  the equipment is wheeled into a refrigeration roo-n  operating at -17°C and the
bath heating circuit is  connected  to the appropriate mains supply.

      After 24 hours the push rods are again  firmly pressed in contact with the specimen
covers and the protrusion of the rods above the transverse bars is again measured, any heave
which has occurred  being deduced by subtraction.   Water at + 4°C is added until overflow
occurs.  This process is repeated until the specimens have been in the refrigeration room
for  10 days.

      At the conclusion  of the test the cabinet is taken from the cold room and the frozen
samples are removed from the specimen container and their copper rings. The waxed paper
is removed and the samples are photographed, while still frozen, together with an  unfrozen
specimen for comparison.
                                      A-55

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 4.5  Temperature conditions in the specimens during test

       The temperature distribution in the test specimens once equilibrium conditions have
 become established varies slightly with the material under test.  The average temperature
 distribution measured in several materials not susceptible to appreciable frost heave is shown
 in Fig. 9(a) and the suction distribution imposed by this temperature gradient (assuming no
 moisture flow) is given in Fig. 9(b).  Under the conditions of the test the equilibrium temp-
 erature distribution is  established after about 6 days of freezing.

       The effect of heave on the temperature distribution is to elongate the depth scale
 approximately in proportion to the heave which occurs.

       Comparison of Fig. 9(a) with  the distribution of temperature with depth in the ground
 during severe winter conditions, Fig. 4(a), shows that the temperature gradients with  depth
 in the vicinity of the zero isotherm are greater in the test than in practice.  This means that
 the suction gradient's also greater.  Both figures show, however, that once the  zero isotherm
 has penetrated into a moist soil or granular material a considerable suction gradient is presen
 at the depth of penetration. It is probable that the precise magnitude of this gradient is of
 secondary importance in determining frost heave.  A more important factor is likely to be the
 high water-table used in the laboratory test.  In soils other than unfissured heavy clays the
 height of the water-table has a profound effect on the ability of the unfrozen soil to transmit
 water.  If it be assumed that  the depth of the zero isotherm below a road  surface during a
 prolonged cold spell is 18 in,  the test would  represent  a water-table about 3 in lower than the
 depth i.e. at 21 in below road surface.  This would represent a high water-table condition for
 a modern motorway or trunk road provided with an effective drainage system, although this
 would not necessarily be the case on older roads with ditch drainage. The  test  is therefore a
 rather severe one in relation to the conditions likely to prevail in practice in Britain  during a
 very cold  winter.

       It is important to appreciate that the test conditions give a freezing front  which is
continuously descending in relation to the top of the sample.  This is because the sample is
allowed to heave  above the level of the surrounding sand. Once the position of  the zero isotherm
has become stable with relation to the bottom of the sample, the addition of more sand packing
to bring the level up to the top of the sample stabilizes  the position of the zero isotherm relative
to the top of the sample and completely inhibits further heave.

4.6  Criteria adopted to assess frost  susceptibility

      Most road materials heave to some extent when subjected to the Road Research Laboratory
freezing test.  It is therefore necessary to establish heave criteria from  which the frost suscep-
tibility can be judged.  Experience during the severe frosts of 1940 and  1947 was used to develop,
these criteria.  Subgrade materials from sites where frost failures had occurred were  subjected
to the test together with other materials which had apparently been satisfactory under similar
conditions.  From this  work it  was concluded that materials which heaved 0.5 in or less during
the 10-day period of the test were satisfactory, materials which heaved between  0.5 and 0.7 in
were marginally frost-susceptible and those which heaved more than 0.7 in were classified as
very frost-susceptible.  Since a main function of a sub-base is to  replace frost -susceptible- soil
the same criteria  were subsequently applied to sub-base and base materials.
                                      A-56

-------
       Criteria such as these can clearly only distinguish broadly between  the actual performance
of the materials in a road structure, which will depend not only on the drainage conditions but
also on the type of pavement used.  The early experience was  based largely on the performance
of roads with relatively weak pavements consisting of crushed stone or pitched bases surfaced
with the open-textured bituminous materials widely used at that time.  The  load-spreading ability
of such a pavement would be much smaller than,  for example, that of an asphalt surfacing on a
bound base, and the  danger of failure during the thaw period consequently greater.  It is felt, how-
ever, that there is not sufficient information to permit the use of different criteria depending on
the type of pavement used.   Apart,from the question of actual failure following the thaw, it is clear
that the inevitable weakening of frost-susceptible foundations  will impose additional stresses on
the upper layers of the pavements, the effect of which may be long-term and not necessarily imme-
diately apparent. This is particularly likely to apply to pavements with lean concrete bases and
possibly to concrete roads generally, where the tensile stresses at the bottom of the  concrete are
known  to be influenced by changes in the effective elastic moduli of the foundation.

     ;A further point to be considered in relation to frost- susceptibility  criteria is the need to
avoid significant differential heave even on pavements unlikely to suffer any serious  structural
weakening following the thaw.  Such differential heave where pavements join structures or at
edge-beams and hard shoulders  gives rise to the opening of cracks and joints which subsequently
present a maintenance problem if the ingress of water and its attendant difficulties are to be
avoided.
                                         A-57

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                                                         EM 1110-2-1906
                                                               10 May 65
                             APPENDIX VII:

                        PERMEABILITY TESTS


1.  DARCY'S LAW FOR FLOW OF WATER THROUGH SOIL.   The flow of
water-through a soil medium is  assumed to follow Darcy's law:

                                q = k i A

where    q = rate of discharge  through a soil of cross-sectional area A
          k = coefficient of permeability
          i = hydraulic gradient:  the loss of hydraulic head per unit
              distance of flow

The application of Darcy's law to a specimen of soil in the laboratory is
illustrated in,Figure 1.  The  coefficient of permeability, k  (often termed
                                    WATER SUPPLY
  OVERFLOW
  TO MAINTAIN
  CONSTANT HEAD
J^—
3 <£L


L
SCREE
1
•—
(T**



N —
j

' ' • •'•'.'
. '.' A '. ' .
•''•': 1 :'•."•
j -^ — — « _ ^.





•^——

h



*• ' — •"
                                                      =-^= kiA
WHERE q = RATE OF DISCHARGE
       = QUANTITY OF FLOW, Q,
         PER UNIT OF TIME, t
      k = COEFFICIENT OF
         PERMEABILITY
      i = HYDRAULIC GRADIENT
         = h/L
      A = CROSS-SECTIONAL AREA
         OF SPECIMEN
                                                GRADUATE
                  Figure 1.  Flow of water through soil
                                           A-58

-------
 EM 1110-2-1906
 Appendix VII
 10  May 65

 "permeability"), is defined as the  rate of discharge of water at a tem-
 perature of 20 C under conditions of laminar flow through a unit cross-
 sectional area of a soil medium under a unit hydraulic gradient.  The
 coefficient of permeability has the  dimensions of a velocity and is usually
 expressed in centimeters per second. The permeability of a soil depends
 primarily on the size and shape of  the soil grains, the void ratio of the
 soil, the shape and arrangement of the voids, and the degree of saturation.
     Permeability computed on the  basis of Darcy's law is limited to the
 conditions of laminar flow and complete saturation of the voids. In turbu-
 lent flow, the flow is no longer proportional to the first power of the
 hydraulic gradient.  Under conditions of incomplete saturation, the flow is
 in a transient state and is time-dependent.  The laboratory procedures
 presented herein for determining the coefficient of permeability are based
 on the Darcy conditions of flow.  Unless otherwise required, the coefficient
 of permeability shall be determined for a condition of complete saturation
 of the specimen. Departure from the Darcy flow conditions to simulate
 natural conditions is sometimes necessary; however, the effects of turbu-
 lent flow and incomplete  saturation on the  permeability should be recognized
 and taken into consideration.
 2.   TYPES OF TESTS AND EQUIPMENT,  a.  Types of Tests. (1) Constant-
 head test.   The simplest of all methods  for determining the coefficient of
 permeability is the constant-head type of test illustrated in Figure 1.  This
 test is performed by measuring the quantity of water, Q,  flowing through
 the soil specimen, the length of the soil specimen,  L,  the head of water,
 h,  and the elapsed time,  t.  The head of water is kept constant throughout
 the test. For fine-grained soils, Q is small and may be difficult to mea-
                   k
 sure accurately. Therefore, the constant-head test is used principally for
 coarse-grained soils (clean sands and gravels) with k  values greater than
 about 10 X  10"* cm per sec.
           (2)  Falling-head test.   The principle of the falling-head test
is illustrated in Figure 2.  This test is conducted in the  same manner as
                                   A-59

-------
                                                 EM  1110-2-1906
                                                     Appendix VII
                                                        10 May 65



DPIPE



OW
r==^=




	

—
l
•_•



r^


"~"


A







— a
j

















hc






L
ne





r
1





ho











L
X









— • -—•_-"



7
^^^^
7


'." A ' -
•.--•.-








7


        (a)
(b)
USING SETUP SHOWN IN (3), THE COEFFICIENT OF PERMEABILITY IS
DETERMINED AS FOLLOWS:
                               LQ
USING SETUP SHOWN IN tbl, THE COEFFICIENT OF PERMEABILITY IS
DETERMINED AS FOLLOWS:
WHERE:  HC = HEIGHT OF CAPILLARY RISE

         a = INSIDE AREA OF STANDPIPE

        A = CROSS-SECTIONAL AREA OF SPECIMEN

        L = LENGTH OF SPECIMEN

        h  = HEIGHT OF WATER IN STANDPIPE ABOVE
            DISCHARGE LEVEL MINUS h  AT TIME, t
        L                         C        ' O
        h. ± HEIGHT OF WATER IN STANDPIPE ABOVE
            DISCHARGE LEVEL MINUS HC AT TIME. tf
         t = ELAPSED TIME, tj - t
                          '   O
  Figure 2.  Principle of falling-head test
                           A-60

-------
EM 1110-2-1906
Appendix VII
 10  May 65

the constant-he ad test, except that the head of water is not maintained
constant but is permitted to fall withiji the upper part  of the  specimen
container or in a standpipe directly connected to the specimen.  The quan-
tity of water flowing through the specimen is determined indirectly by
computation.  The falling-head test is generally used for less pervious
soils (fine sands to  fat clays) with k  values less than 10 X 10~^ cm
per sec.
       b.   Equipment.  The apparatus used for  permeability testing may
vary considerably in detail depending primarily on the condition and
character of the  sample to be  tested.  Whether the  sample is fine-grained
or  coarse-grained,  undisturbed, remolded, or compacted, saturated or
nonsaturated will influence the type of apparatus  to be employed. The
basic types of  apparatus, grouped according to the type of specimen con-
tainer (permeameter), are as  follows:
            (1)   Permeameter cylinders
            (2)   Sampling tubes
            (3)   Pressure cylinders
            (4)   Consolidometers
The permeability of remolded cohesionless soils is  determined in
permeameter cylinders, while the permeability of undisturbed cohesion-
less soils in a  vertical direction can be determined using the sampling
tube as a permeameter.  The permeability of remolded cohesionless soils
is generally used to approximate the permeability of undisturbed cohesion-
less soils in a  horizontal direction. Pressure cylinders and consolidome-
ters are used for fine-grained soils in the remolded, undisturbed, or
compacted state. Fine-grained soils can be tested with the specimen
oriented to  obtain the permeability in either the vertical or horizontal di-
rection.  The above-listed devices are described in  detail under the
individual test  procedures.  Permeability  tests utilizing  the different types
of apparatus, together with recommendations regarding their use, are
discussed in the following paragraphs.
                                    A-61

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EM 1110-2-1906
Appendix VII
10 May 65
4.   FALLING-HEAD PERMEABILITY TEST WITH PERMEAMETER
CYLINDER,   a.   Use.  The falling-head test with the permeameter
 cylinder should in general be used for determining the permeability of
remolded samples of cohesionless soils  having a permeability less than
about 10 X 10"^ cm per sec.
        b_.  Apparatus.  The apparatus and accessory equipment should
consist of the following:
           (1)  A permeameter cylinder similar to that shown schemat-
ically in Figure 3b, or modified versions thereof.   The permeameter
cylinder should be constructed  of a transparent plastic material.  The'in-
side diameter of the cylinder should be not less than about 10 times the
diameter of the largest soil particles. The use of two piezometer taps, as
shown by Figure 3b, connected  to a standpipe and discharge level tube
eliminates the necessity for taking into account the height of capillary rise
which would be necessary in the case of a single standpipe of small size.
The height of capillary rise for a given tube and condition can be mea-
sured simply by standing the tube upright in a beaker full of water.  The
size of standpipe to be used is generally  based on experience  with the
equipment used and soils tested.  In order to accelerate testing, air pres-
sure may be applied to the  standpipe to increase the hydraulic gradient.
           (2)  Perforated metal or plastic disks  and circular wire
screens, 35 to 100 mesh, cut for a close  fit inside  the permeameter.
           (3)  Glass tubing, rubber or plastic tubing, stoppers, screw
clamps, etc., necessary to make connections as shown in Figure 3b.
           (4)   Filter materials such as Ottawa sand, coarse sand, and
gravel of various  gradations.
           (5)   Deaired distilled water,  prepared according to para-
graph 3b_{6),
           (6)   Manometer board or suitable scales for measuring levels
in piezometers or standpipe.
          . (7)   Timing device,  a watch or clock with second hand.
           (8)   Centigrade thermometer, range 0 to 50 C, accurate to 0.1 C
           (9)   Balance, sensitive to 0.1 g.
                                  A-62

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                                                        EM 1110-2-1906
                                                            Appendix VII
                                                              10 May 65
                                                    \a
           (10)  Oven (see Appendix I, WATER CONTENT - GENERAL).
           (11)  Scale, graduated in centimeters.
       £.   Placement and Saturation of Specimen.  Placement and satu-
ration of the specimen shall be done as described in paragraph 3c_.
Identifying'information for the sample and test data shall be entered on
a data sheet similar  to Plate VII-2.
       d.   Procedure.  The procedure shall consist of the following steps:
            (1)  Measure and record the height of the  specimen,  L,  and
the cross-sectional area of the specimen,  A.
            (2)  With valve  B open (see Fig. 3b), crack valve  A  and
slowly bring the water level up to the discharge level  of the permeameter.
            (3)  Raise the head of water in the standpipe above the dis-
charge level of the permeameter. The difference in head should not result
in an excessively high hydraulic gradient during the test.  Close valves
A and  B.
            (4)  Begin the test by opening valve  B.  Start the timer. As
the water flows through the specimen, measure and record the height of
water in the standpipe above the discharge level,  hQ,  in centimeters, at
time  t0,  and the  height of water above the discharge level,  h.£,  in
centimeters, at time   tr.
            (5)  Observe and record the temperature of the water in the
permeameter.
            (6)  Repeat the  determination of permeability, and if the com-
puted values differ by an appreciable amount, repeat the test until con-
sistent values of permeability are obtained.
       e.   Computations.  The computations consist of the following steps:
            (1)  Compute the test void ratios as  outlined in paragraph 3e(l).
            (2)  Compute the coefficient of permeability, k, by means of
the following equation:
                        k= 2.303——log —X R-
                                 A/t
                                   /
                                      A-63

-------
EM 1110-2-1906
Appendix VII
10 May 65

where      a = inside area of standpipe, sq cm
           A = cross-sectional area of specimen, sq cm
           L = length of specimen, cm
            t = elapsed time (tf - tQ), sec       "                 •
           h0 = height of water in standpipe above discharge level at time
               t ,  cm
                o
           hf = height of water in standpipe above discharge level at time
               tf, cm
          R_ = temperature correction factor for viscosity of water ob-
               tained from Table VII-1, degrees C
If a single standpipe of small diameter is used as shown in Figure 2, the
height of capillary  rise, h ,  should be subtracted from the  standpipe
readings to obtain  hQ and hr.
        _£_.  Presentation of Results.  The results of the falling-head
permeability test shall be reported as described in paragraph 3_f.
5.   PERMEABILITY  TESTS WITH SAMPLING TUBES.  Permeability
tests may  be performed directly on undisturbed samples without removing
them from the sampling tubes.  The sampling tube serves  as the per-
meameter cylinder.  The method is applicable primarily to cohesionless
soils which cannot  be  removed from the sampling tube  without excessive
disturbance.  The permeability obtained is in the direction in which the
sample was taken,  i.e. generally vertical.  The permeability obtained i*i a
vertical direction may be  substantially less than that obtained in a hori-
zontal direction.
     Permeability tests with sampling tubes may be performed under
constant-head or falling-head conditions of flow, depending on the esti-
mated permeability of the sample  (see paragraph 2a).  The equipment  ,
should be  capable of reproducing the conditions of flow in  the constant-
head or falling-head tests. It is important that all disturbed material or
material containing drilling mud be removed from the  top and bottom of
the sample.  The ends of the sample should be protected by screens held
in place by perforated packers.  The test procedure and computations are
                                              A-64

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                                                        EM 1110-1 -1906
                                                            Appendix VII
                                                              10 May 65

the same as those described previously for each test.
6.   PERMEABILITY TEST WITH PRESSURE CHAMBER.   In the perme-
ability test with a. pressure chamber, see Figure 7, a cylindrical specimen
is confined in a rubber membrane and subjected to an external hydrostatic
pressure during the permeability test.  The advantages of this type of
test are:  (a)  leakage along the sides of the specimen, which would occur
if the specimen were tested in a permeameter, is prevented, and (b) the
specimen can be tested under conditions of loading expected in the field.
The test is applicable primarily to cohesive soils in the undisturbed,
remolded, or  compacted state.  Complete saturation of the specimen, if it
is not fully saturated initially, is  practically impossible.  Consequently,
this test should be used only for soils that are fully saturated, unless
values of permeability are purposely desired for soils in an unsaturated
condition.  The permeability test  with the pressure chamber is usually
performed as a falling-head test.
     The permeability specimens  for use in the pressure  chamber generally
should be 2.8  in. in diameter, as rubber membranes and equipment for
cutting and trimming specimens of this size are available for triaxial
testing apparatus (see Appendix X, TRIAXIAL COMPRESSION TESTS).  A
specimen length of about 4 in. is adequate. (The dimensions of a test
specimen may be varied if equipment and supplies are available to make
a suitable test setup.) The  pressure in the chamber should not be less
than the maximum head on the specimen during the test.  The other test
procedure and computations are the  same as those described for the
falling-head test.  The linear  relation between permeability and void ratio
on a semilogarithmic plot as shown in  Figure 6 is usually not applicable
to fine-grained soils, particularly when compacted.  Other methods of
presenting permeability-void ratio data may be desirable.  x
7.   PERMEABILITY TESTS WITH BACK PRESSURE.  Gas bubbles in the
pores of a compacted or undisturbed specimen of fine-grained soil -will
invalidate the results of the permeability tests described in the preceding
                                    A-65

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EM 1110-2-1906
Appendix VII
10  May 65
                   -LEVELING BULB
                                                 GRADUATED
                                                 STANOPIPC
                                                               .WIHC NUT
              MOTE: OOUPRESSEO AIM USED ran
                 HIGHER LATERAL  PRESSURES
                 IN PLACE Of LEVELING BULB
                               IJIUU-lLIJ-U-LllL
                COARSE
                POROUS PLATE
                                                                       PLASTIC SLEEVE AMD
                                                                            useo
                                                                       SATURATION Of
                                                                       SPCOUEN.
                COARSE
                POROUS PLATE
             Figure 7.  Pressure chamber  for permeability test
                                          A-66

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                                                        EM 1110-2-1906
                                                            Appendix VII
                                                              10 May 65

 paragraphs. It is known that an increase in pressure will cause a reduc-
 tion in volume of gas bubbles and also an increased weight of gas dissolved
 in water.  To each degree of saturation there corresponds a certain addi-
 tional pressure (back pressure) which, if applied to the pore fluid of the
 specimen, will cause complete  saturation. The permeability test with
 back pressure is performed in  a pressure chamber such as that shown in
 Figure 7, utilizing equipment that permits increasing the chamber pressure
 and pore pressure simultaneously, maintaining their difference constant.
 The method is applicable to fine-grained soils which are not fully saturated.
 An apparatus which has been used for permeability tests with back pres-
 sure has been described by Bjerrum and Huder.t
 8.   PERMEABILITY TESTS WITH CCNSOLIDOMETER.   A permeability
 test in a consolidometer {see Appendix VIII, CONSOLIDATION TEST) is
 essentially similar to that conducted in a pressure chamber, except  that
 the specimen is placed within a relatively rigid  ring and is loaded verti-
 cally. The test can be  used as  an alternate to the  permeability test in the
 pressure chamber.  The test is applicable  primarily to cohesive soils in
 a fully saturated condition.  Testing is usually performed under falling-
 head conditions.
     A schematic diagram  of the consolidation apparatus set up for a
 falling-head permeability test is shown in Figure 8. Identifying informa-
 tion for the specimen.and subsequent test data are entered on a data sheet
 (Plate "VTI-3 is a suggested form).  The specimen should be placed in the
 specimen ring  and the apparatus assembled as outlined under Appendix VIII,
 CONSOLIDATION TEST. The specimen is consolidated under the desired
load and the falling-head test is performed as previously described.  The
t L. Bjerrum and J. Huder, "Measurement of the permeability of com-
  pacted clays," Proceedings, Fourth International Conference on Soil
  Mechanics and Foundation Engineering (London, August 1957), vol. 1,
  pp. 6-8.
                                     A-67

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EM  1110-2-1906
Appendix VII
 10 May 65
                          STANOPIPE AREA =O
                            NOTE: VALVE BETWEEN OEAIRED DISTILLED WATER
                                JUS AND CONSOLIDATION APPARATUS IHOULD
                                1C CLOSED DURING THE PERMEABILITY TEST.
          Figure 8.  Schematic diagram of falling-head device for
                   permeability test in consolidometer
net head on the specimen may be increased by use of air pressure; how-
ever, the pressure on the pore water should not exceed 25 to 30 percent
of the vertical pressure under which the specimen has consolidated.  Dial
indicator readings are observed before  and after consolidation to permit
computation of void ratios.  The determination of the coefficient of perme-
ability may be made in conjunction with the consolidation test,  in which
case the test is performed at the end of the consolidation phase under each
load increment.  Computations are similar to those described for the
                                            A-68

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                                                         EM 1110-2-1906
                                                            Appendix VII
                                                               10 May  65

falling-head test with the permeameter cylinder.
     The permeability may also be determined indirectly from computa-
tions using data obtained during the consolidation test; however the as-
sumptions on which the method is based are seldom satisfied, and conse-
quently, the direct determination of permeability  should be employed
where reliable values of permeability are  required.
9.   POSSIBLE ERRORS.   Following are possible errors  that would cause
inaccurate determinations of the  coefficient of permeability:
        a_.   Stratification or nonuniform compaction of cohesionless soils.
If the specimen is  compacted in layers, any accumulation  of fines  at the
surface of the layers will reduce the  measured coefficient of permeability.
        b_.  Incomplete initial saturation of specimen.
        c_.   Excessive hydraulic gradient.  Darcy's  law is applicable only
to conditions  of laminar flow.
        d_.   Air  dissolved in water.   No other source  of error is as
troublesome as the accumulation of air in  the specimen from the flowing
water-  As water enters the specimen, small quantities of air dissolved
in the water will tend to collect as fine bubbles at the  soil-water interface
and reduce the permeability at this interface with increasing  time. The
method for detecting and avoiding this problem is described in paragraph
3d_(6).  (It should be noted  that air accummulation will not  affect the coef-
ficient of permeability determined by the constant-head test if piezometer
taps along the side of the specimen are used to measure the head loss.)
        e.   Leakage along side of specimen in  permeameter.   One  major
advantage to the use of the triaxial compression chamber  for permeability
tests (see paragraphs 6 and 7) is  that the specimen is confined by  a
flexible membrane which is pressed tightly against the specimen by the
chamber pressure.
                                      A-69

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                EM 1110-2-1906
                   Appendix VII
                      10 May 65
FALLIHG-HEAD
pnn.TPTT


Sample or Specimen Ho.
p Tare plus dry soil
so
a Tare
£ Dry Soil Ws
Specific gravity G
Vol of solids, cc =WS + G V
Area of standplpe, sq cm a
Test No.
Height of specimen, cm
Void ratio =(AL - V J+ V

Initial time
Final time
Elapsed time, sec = tf - to
Initial head, cm
Final head, cm
Log(h(j + hf)
Water temperature, °C
Viscosity correction factor
Coefficient of permeability/2'
cm/sec
L
e

*o
*f
t
J\,
hf

T
\
k20
Avg

PERMEABILITY TEST
D
tyr




Diameter of specimen, cm
Area of specimen, sq cm
Initial height of specimen, cm
Initial vol of spec, cc » AL
Initial void ratio =(v- vj+ Vg
Constant =(2-303 x a) + A
1


la









lb










2


Zs.









2b










0
A
L
V
e
C
3


3a 3*










(1) Correction factor for viscosity of water at 20 C obtained from table VH-1.
(2) *»' 2-303 ft log JSx^-SJ! lag j£ XK,..
*
•Rernn-TVe . . ._.

1><:>"Tlc-i»n r.n

mputed
ENC FORM ,0 ,c
1 JUN 6S 3845
by rh.^lted liy

PLATE VII -2
A-70

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EM 1110-2-1906
Appendix VII

10 May 65
FALLING -HEAD
PERMEABILITY TEST

WITH CONSOLIDOMETER



DATS


BOETUT, NO.
Sample or Specimen No.
1 Tare plus dry soil
to
c Tare
£ Dry soil Ws
Specific gravity °s
Vol of solids, cc « Ws+G Vs
Area of standpipe, sq cm a
Capillary rise, cm c
Height of tailvater, cm t
Test No.
Load increment, T/sq ft
Dial reading at start, in.
Change in ht of spec, in. = Do - D^_
Ht of spec, cm L - 2.5^ £D
Void ratio =(AL - vj+ Vg
P
\
^D
L
e

Initial time
Final time
Elapsed time, sec - tj - to
Initial height, cm
Final height, cm
Water temperature, C
Viscosity correction factor^
Coefficient of permeability,^
cm/sec
*o
*f
t
"l
h2
T
^T
^20
Avg


Diameter of specimen, cm
Area of specimen, sq cm
Initial height of specimen, cm
Initial vol of spec, cc = AL
Initial void ratio =(v - Vs)+ Vs
Constant =«(2. 303 x a)+ A
Initial dial reading, in.
Corrected tailvater, cm, h^ + hj
1





la








Ib









2





2a








2b









D
A
L
V
e
C
Do
Ah
3





3a 3b



-





(1) Correction factor for viscosity of water at 20 C obtained from table VII- 1.
(2) *„ - 2.303 | £ log h . ^ x ^ = S_i log * _ ^ x J^, .
OJ n o 2 "" g

Technic1an ^

omp,
ted by_


Checksd bv

PLATE VII-3   EHC FORM
               I JUN SS
                               A-71

-------
PATENTS
   A-72

-------
 Patented Au». 21, 1951
                                 2
                                 £j
       UNITED    STATES   PATENT    OFFICE

                                          2,564,690
                              HYDRATED LIME-FLT ASH-FINE
                                   AGGREGATE CEMENT
                         Jules E. Havelin, Haveriown, and Frank Eaha,
                                      Philadelphia, Pa.
                           Application June 30,1948, Serial No. 36,048
                                   4 Claims.  (CL 106—120)
                      1
  This Invention relates to novel hydrated lime-
fly ash-flne aggregate  cements especially useful
for masonry mortar, protective coating, soil sta-
bilization and  grouting compositions and  par-
ticularly to hydrated lime-fly ash-ftne aggregate
compositions of this type having early compressive
strengths exceeding the corresponding early com-
pressive strengths of the lime-fine aggregate mor-
tar compositions of the prior art.
  For many years the masonry mortar and  pro-
tective coating art has operated on the supposi-
tion that the compressive strength of lime mortars
Is increased by adding lime and is decreased  by a
reduction in the proportion of lime to fine aggre-
gate. This decrease in compressive strength  with
reduction in lime and the extent thereof is well
known In this art and the various attempts to re-
duce the lime proportion without loss in compres-
sive strength have been unsuccessful.  In its broad
aspect the present Invention is directed  to the
provision of hydrated lime fly ash-fine aggregate
cements  useful as masonry  mortars,  protective
coatings such  as plaster, soil stabilization  and
construction filling materials such as groutings
having compressive strengths exceeding those of
the prior art lime mortars of corresponding  lime
proportion. For some applications the magnitude
of  Improvement  in  early  compressive strength
need not be large, since a relatively small Increase
in early compressive strength will provide a ce-
ment having characteristics equal to or better
than a prior art lime mortar of very much higher
lime content.  However, for other applications,
particularly in the field of industrial construction,
a mortar of very much higher early  compressive
strength Is required and in these fields lime mor-
tars have been largely displaced because early
compressive strengths of the magnitude required
are not obtainable In a lime-fine aggregate mor-
tar even with very large proportions of lime. This
characteristic  of  low compressive strength  has
been considered by the art as Inherent In llme-
flnm aggregate  mortars  and consequently the art
has turned to Portland cement mortars and the
like.
  As used throughout this specification and claims
the terms "hydrated lime" and lime are used in-
terchangeably  to Indicate a dry powder obtained
by "treating quicklime with water enough to  sat-
isfy Its chemical aflnity for water under the con-
ditions of Its hydration.  It consists essentially of
calcium hydrate or a mixture of calcium hydrate
and magnesium oxide and magnesium hydroxide.
In the above definition quicklime  is used to Indi-
cate a calcined material the major portion of
which Is calcium oxide or calcium oxide In natu-
10
   ral association with a lesser amount of magnesium
   oxide capable of slaking with water.
     As defined above  and  as used throughout the
   present specification and claims, the  term "hy-
   drated lime" or "lime" is not intended to include
   hydraulic lime or the free lime made available In
   the hydration of -Portland cement, natural ce-
   ments and the like.  Lime from such sources dif-
   fers from the hydrated lime of the present inven-
   tion and does not give the results hereinafter de-
   scribed.
     The term "fly ash" as used In the present speci-
   fication Is Intended to indicate the finely divided
   ash residue  produced by the  combustion of pul-
15 verized coal which ash is carried off with the gases
  • exhausted from the furnace in which the coal is
   burned  and  which  is collected from these gases
   usually  by means of suitable  precipitation appa-
   ratus such as electrical precipitators.  The fly
20 ash so obtained Ls in a finely divided state such
   that at least about 70% passes through a 200
   mesh sieve.
     The term  "fine aggregate"  as used throughout
   this specification and the claims hereof Is intend-
25 ed to indicate natural or artificial substantially
   chemically inert inorganic materials such as nat-
   ural sand, sand prepared from stone, blast-fur-
   nace slag, gravel, or other inert materials having
   similar characteristics, substantially as defined in
30 A. S. T. M. Tentative Standard Specifications for
   Concrete Aggregates, Designation C33—37T, and
   having a fineness modulus of at least substantially
   1.7, substantially all of which will pass a % Inch
   sieve, substantially 95%  or more of which will
   pass  a No. 4 sieve, substantially 45% or more of
   which will pass a No. 16 sieve, and substantially
   5% or more of which will pass a No. 50 sieve.
     So far as we are aware no  lime mortars have
   been made  available to  the art which have set
   under  normal  conditions  to  a  compressive
   strength of  the order of about 225 pounds per
   square Inch and above In a period of seven days.
   As used In  the  present specification and claims
   the term "high compressive strength" is intended
45 to cover the range from about 225 pounds per
   square inch and above after 7 days and the term
   "low  compressive strength" Is Intended  to cover
   the range from about 225 pounds per square inch
   and below after 7 days.
50   The principal object of the present invention
   is  to provide hydrated lime-fly  ash-flne aggre-
   gate  cement compositions  having  greater early
   compressive strengths than the lime mortar com-
   positions of the prior art  having comparable lime
£5 content.
     A further object of tte present Invention la to
33
40

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                                           2,664,690
 provide hydrated lime-fly ash-fine aggregate ce-
 ment compositions having high early compressive
 strengths of the order of 225 pounds per square
 men and above.
   A further object of the present invention is to
 provide  a  hydrated  lime-fly  ash-flne aggregate
 cement comparable in early compressive strength
 to the known cement mortars.
   Heretofore, the  addition of fly ash to Portland
 cements has been investigated and certain advan-
 tageous results based upon the so-called "puzzol-
 anic''  effect have been referred to in the  art.
 While the  reaction underlying the puzzolanic ef-
 fect is not entirely  understood It is said to in-
 volve a chemical reaction between the lime con-
 tent of the cement and the silica content of the
 fly ash.  However. th<« reaction does not Involve
 hydrated lime and fly ash and should not be con-
 fused with the present invention.  So far as we
 are aware the prior art has not successfully com-
 bined hydrated lime and fly ash in the ^airing of
 a useful hydrated lime cement, capable of devel-
 oping practical high early strengths when allowed
 to set under ambient conditions within the range
 of normally occurring atmospheric temperatures
 and humidities.  Moreover, in the Portland ce-
 ment art the addition of fly ash has not produced
 particularly significant increases in early com-
 pressive strength  which is  one of the principal
 advantages of the  present invention.
   The effect of puzzolanic materials in Portland
 cement concretes is  evidenced by their producing
 an increase In  long-time  compressive strength,
 «"iri it is indicated  that their use may result in
 decreased early compressive strength.
   In contrast with the low early strength char-
 acteristic of the puzzolanic effect, applicants' in-
vention  produces  a high   early  compressive
 strength.  In fact, the high early strength feature
              Table II (parts by volume)
10
15
20
Hydrated
Lime
5
5
6
S
5
6
8.25
0.25
0.25
Fir
AJi
0
19
38
47.6
47
70
0
37.5
44.873
Sand
95
70
57
47.6
38
19
93.75
56.29
48.375
Per Cent Fly Ash (of Fly
Ash and Lime)
0
79.2
88.4
90.4
92.0
83.7
0
85.9
88.0
Ratio of 7
Day Com-
pressive
Strength
LOO
3.12
10.50
8.01
7.01
6.05
LOO
10.7
15.4
             Table III (parti by volume)
Lime
3.84
5.0
4.3
£5
48.08
38.0
37.6
Sand
48.08
57.0
4ft. J
Llffie/Fly ^ «h and Sand
1 part lime to 25 para fly
tab and and.
1 put lime to 19 parti fly ash
and aand,
1 part lime Co 15 parts By ash
«nH fflTlfl
7 Day Cora
pressive
Strength
OBP.I.L)
230
427
273
     It will be noted from the curves of Figs. 1 and
   2 that the optimum 7 day compressive strengths
   occur in the range from one part hydrated lime to
   about 5 parts fly ash to one part hydrated lime to
30 about 15 parts  fly ash which values correspond
   to about 82% fly ash and 93.7% fly ash respective-
   ly calculated on the sum of the hydrated lime and
   fly ash.  In obtaining the novel hydrated lime-fly
   ash-fine aggregate cements of the present inven-
35 tlon within this range a suitable proportion of fine
   aggregate must  be  used. High early ccrapressive
   strengths are obtained  in the particular range
   lying between one pan hydrated lime to about 15
                                                  parts fly ash and sand by volume and one part
 of applicants' Invention can be used to increase 40 ]jm» to about 25 parts fly ash and sand by volume
 substantially the early strength characteristic of
 Portland cement mixes.
   We attain the objects of the present Invention
 by means of a dry mix comprising hydrated lime,
 fly ash  and a suitable fine aggregate to which 45
 water is added In suitable proportion in making
 up the final working composition.
   In the drawings Fig.  1  shows in the  curve
 marked  A a plot of the compositions specifically
 set forth in Table I which follows. Curve Brepre- 30
 .sents a hypothetical curve which is the relation-
 ship that would be normally expected from knowl-
 edge of the prior art.
   In Fig. 2 the curve marked A is  the same as
 curve A  of Fig. 1 but plotted on a different scale. 55
 Curve C is a plot of "the compositions specifically
 •et forth ha Table IL
   The data set forth In the following tables taken
 In conjunction with the curves of Fig. 1 and Fig. 2
   as indicated in the data listed in Table HL  The
   data plotted in curve C is devoted almost entirely
   to a high compressive strength type mixture hav-
   ing a lime to fly ash and sand ratio of one to 19.
   there being one  point lying directly  above the
   peak which represents a composition in which
   the ratio of lime  to fly ash and sand is one to 15
   and a second point corresponding to the next to
   the last composition of Table n in which the ra-
   tio of lime to  fly  ash and sand is one to 15.  The
   optimum ratio of hydrated lime to fly  ash is not
   materially changed by variations in the  amount
   of water used in  preparing the flriql cement mix
   although the absolute compressive strength values
   will be stronger where  the amount of water is not
   greater than that required to give the desired flow
   of 100 on a standard flow table.
     The proportions given in the tables and in the
   examples which follow are  based upon the fol-
 will serve  to illustrate  the present invention as  80  lowing weights per cubic foot for the solid ingre-
 herelnafter described.                              dients:
           Table I (party by volume)
Hydrated
Lime
50
40
20 '
ao
10
2.5
L25
Fly
Aah
0
10
20
30
40
43
47. <
48.75
Sand
50
to
to
to
SO
BO
to
to
Per Cent Fly Ash (of Fly
Ash and Lime)
0
20
40
W
80
90
95
97.5
Ratio of 7
Day Com-
press! re
Strength
1.00
LOO
LOS
L13
L13
L30
0.79
0.38
                                               70
                                     Pounds per
                                      cubic foot
   Lime	45
   Fly ash	60
   Sand	80
     It will be apparent to those skilled in the art
   that in the tables and in the examples parts by
   volume can easily  be converted  to  parts  by
   weight and that parts by weight can easily be
   converted  to parts by  volume using the  above
   weight per cubic foot values in calculating the
   conversions.
     In preparing the compositions set forth In the
                                      A-74

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                                          3,564,600
above tables, several mixing procedures were fol-
lowed.  For example, the compositions of Tables
n and in were prepared  by  following the gen-
eral procedure for mixing  test specimens as out-
lined In A. 8. T. M. C109—44.  Specimens of each
mix were prepared In cubes measuring 2 Inches
In each dimension and these cubes were stored
In molds In laboratory air for seven  days after
which  they were   removed  and  tested  for
compresslve  strength  following  the  standard
A. 8. T. M. compressive strength procedure.  In
each case water was added to give a flow of 100
u measured on  an  A. 8. T. M. standard flow
table.  In  order  to obtain optimum  results  In
                                                                      6
                                              10
It will be noted that the compresslve strength
Is lower than that of Example I although It still
exceeds 225 pounds per square Inch.  This com-
parative decrease in compresslve strength prob-
ably results from the  Increased amount of sand
In Example  m where the ratio of lime to fly
ash and sand by volume Is 1 to 25.  In this case
we have found that where the ratio of lime to
fly ash Is selected In the range between about
one to 5 and about one  to  15 high early com-,
presslve strength results  are obtained  by using.
the amount of fine aggregate calculated to hold*
the ratio of lime to fly ash plus fine  aggregate
between one  to  15 by volume to one  to 25 by
the practice of the present Invention the amount is volume, provided, however, that the ratio of fine
of water added to the dry mix  should  be the
minimum amount required to obtain the  desired
flow but as pointed out above the optimum ratio
of fly ash to hydrated  lime is not changed  by
using more or less water.  We  have found that
other mixing procedures produce results  follow-
ing the  same general curve which gives the rela-
tive compressive strengths although the absolute
values may differ and in fact may be materially
Increased by Intimate Intermixture as described
In detail In the examples  below.
  As preferred  examples for obtaining hydrated
lime-fly ash-fine aggregate cements having high
early compressive strengths, we direct attention
to the  following  examples:

                 EXAMPLE I

Hydrated lime	parts by volume..   5
Fly ash	do	  38
Sand (fineness  modulus, 1.7)	do	  57
Water to lime ratio (by weight)	5.40 to 1
Compresslve  strength (7 days)	p. ».  I	437

  The dry  mix of the above example was pre-
pared by following the procedure outlined  in
A. 8. T. M. C109—44 referred to  above .and the
compresslve strength was measured on the two
inch test cubes using the A.  8. T. M. standard
compresslve strength test procedure.

                 EXAMPLE n
Hydrated lime	parts by volume   5
Fly ash	do	  38
Sand (fineness  modulus, 1.7)	do	  57
Water to lime ratio (by weight)	4.17 to 1
Compresslve  strength (7 days)	652
  The dry  mix of Example n  was prepared  by
intimately mixing the hydrated lime and the fly
ash In  a ball mill for  15  minutes after which
these ingredients were thoroughly mixed,  while
dry. with the sand.  The dry mix thus obtained
was converted to a masonry mortar having a de-
sired  consistency  by  the addition of water  as
Indicated.  The 7 day compresslve strength  of
Example II  was about 650 Ibs.  per square inch.
It will be noted that this example has a higher
compressive strength and requires a smaller pro-
portion  of water than the earlier  example which
Is attributable  to the ball  milling step in  place
of the hand mixing step of the A. 8. T. M. pro-
cedure.
                EXAMPLE m

Hydrated lime	parts by volume.. 3.84
Fly ash,—	-	-	do	48.08
Sand (fineness  modulus, 1.7)	do	48.08
Water to lime ratio (by weight)	8.1 to 1
Compresslve strength (7 days)	  230
  The mixing procedure followed for Example
                                                 aggregate to fly ash plus fine aggregate Is main-
                                                 tained In the range from about 1 to 1.5 to about
                                                 1 to 2.5,
                                                   From the above It will be apparent, particu-
                                              20 larly  to those skilled hi the art. that we have
                                                 provided a new hydrated  lime cement having
                                                 wholly unexpected properties and In certain cases
                                                 surprisingly large  early compressive  strength
                                                 values.  We have pointed out  above the sharp
                                              25 Increase  In  compresslve strength which  occurs
                                                 In a relatively narrow range hi which the ratio
                                                 of fly ash to hydrated lime is  very high.  The
                                                 degree of improvement is likewise partly depend-
                                                 ent on the manner of mixing and on the propor-
                                              30 tlon of hydrated lime and of fine aggregate to fly
                                                 ash plus fine  aggregate.  In the prior art the
                                                 proportion of hydrated lime to aggregate has
                                                 covered the range (in parts by volume) from one
                                                 part of hydrated lime  to from about 2 Mi parts
                                              36 to about 4 parts aggregate.   For many years the
                                                 art has considered that any substantial decrease
                                                 In hydrated lime relative to aggregate material
                                                 would result In mortars and plasters having un-
                                                 desirable characteristics Including low early com-
                                              40 presslve strengths.  From the foregoing detailed
                                                 description of the present Inventon. It will be
                                                 noted that the ratio of hydrated lime  to other
                                                 solid  Ingredients  of the mix  employed  In the
                                                 practice  of  the present Invention where high
                                              43 early compresslve strengths are required Is of
                                                 the order of from one part hydrated lime to
                                                 about 15 parts  of other solid ingredients  to one
                                                 part hydrated lime to about 25 parts  of other
                                                 solid Ingredients.   So far as we are aware, these
                                              w proportions  are not only unknown In  the lime
                                                 mortar art but are contrary to the previously
                                                 held teachings thereof.
                                                   It will be seen that the present Invention pro-
                                                 vides  a choice of  hydrated lime-fly ash-fine ag-
                                              M gregat* cement compositions which may vary de-
                                                 pending upon the particular requirements of the
                                                 specific use  to  which the cement is  to be  put.
                                                 Where relatively low early compresslve strength
                                                 is all that Is required, the prior  art lime to other
                                              oo solid  ingredient  ratios  may be  employed. In
                                                 which case  the  resulting hydrated  lime-fly
                                                 ash-fine  aggregate  cement  will have Improved
                                                 characteristics  as compared to prior art lime
                                                 mortars of comparable lime content.   Composl-
                                              Oa Uons  such as shown in Examples I,  n and HT
                                                 may be employed where a cement of high early
                                                 compresslve strength is  required.  So far as we
                                                 are aware hydrated lime  mortars  having the
                                                 characteristics  of the embodiments referred to
                                              70 above have  not been available  to the art prior
                                                 to our Invention  which therefore represents a
                                                 new development in the hydrated lime mortar
                                                 art and particularly provides a novel hydrated
                                                 lime-fly ash-fine  aggregate  cement composition
HI waa the A. 8. T. M. procedure given above. 19 suitable for masonry mort&r. protective coating*
                                         A-75

-------
                                          9,804,600
such as plaster, soil stabilisation and filling ma-
terials such as grouting.
  It wUl be understood that the basic ingredi-
ents comprising hydrated lime, fly ash and sand
may vary as to specific volume from the values 5
given but it is Intended that such variations shall
be Included  within the scope of  the present in-
vention as hereinafter claimed.  It will likewise
be understood that various additive ingredients
may be used in addition to the basic ingredients 10
referred to without departing from the present
invention as hereinafter claimed.
  This application is a continuation in part of
our  prior application Serial No. 546,208. filed
July 22, 1944. and now abandoned.              15
  Having thus described our invention, we claim:
  1. A  hydrated  lime-fly ash-fine   aggregate
cement having high early compressive strength
when mixed with water in suitable amount and
allowed to set, consisting essentially of hydrated 20
lime, fly ash and an aggregate of substantially
chemically inert  inorganic  material  having  a
fineness  modulus of  at least substantially  1.7,
substantially all of which will pass  a % inch
sieve, substantially  95% or more of  which will 35
pass a No. 4  sieve, substantially 45%  or more of
which will pass a No. 16 sieve, and substantially
5% or more of which will pass  a No. 50 sieve,
the ratio of  hydrated lime to  fly ash being from
about 1  to 5 to about 1  to  15 by volume, the 30
ratio of  hydrated lime to fly ash plus fine ag-
gregate being from about  1 to 15 to  about 1 to
25 by volume and the ratio of fine aggregate to
fly ash  plus fine aggregate being from about 1
to 1.5 to about l to 2.5 by  volume.               z&
  2.  A cement and protective coating composi-
tion having  high  early  compressive  strength
when mixed with water in suitable amount and
allowed to set, consisting essentially of hydrated
lime about 1 part by volume, fly ash from about 40
7.5 to about 12.5 parts by volume and from about
7.5 to about 12.5 parts by volume of an aggregate
of substantially chemically inert Inorganic ma-
terial having a fineness modulus  of at least sub-
stantially 1.7, substantially all of which will pass 45
a H  inch sieve, substantially 95% or more  of
which will pass a No. 4 sieve, substantially 45%
or more of which will .pass a No. 16 sieve, and
substantially 5% or  more of  which will pass  a
No. 50 sieve.                                  M
                                                                      8
   3. A cynent and protective coating composi-
 tion  having  high  early  compreislve strength
 when  mlzed with water in suitable amount and
 allowed to set, consisting essentially of hydrated
 lime about 5 parts  by volume, fly ash about 38
 parts  by  volume and  an aggregate of substan-
 tially  chemically inert inorganic material hav-
 ing a  fineness modulus of at least substantially
 1.7, substantially all of which will pass a % inch
 sieve,  substantially  95%  or more of which  will
 I««8 a No. 4 sieve, substantially 45% or more of
 which will pass a No. 16 sieve, and substantially
 5% or more of which will pass a No. 50 sieve.
   4. A structural material possessing high early
 compressive strength, produced  by tnHrfng  hy-
 drated lime, fly  ash. an aggregate of substan-
 tially chemically Inert inorganic material having
 a fineness modulus of at least substantially 1.7.
 substantially  all of which will pass a %  inch
 sieve,  substantially 95% or more of which  will
 pass a No. 4 sieve, substantially 45%  or more of
 which will pass a No. 16 sieve, and substantially
 5% or more of  which will pass  a No. 50  sieve.
 and a suitable  amount of water, the ratio of
 hydrated  lime to fly ash  being from about 1 to
 5 to about  1  to 15 by volume, the ratio of hy-
 drated lime to fly ash plus aggregate being from
 about  1 to 15 to about 1 to 25 by volume and the
 ratio of aggregate to fly ash plus aggregate  be-
 ing from  about 1 to 1.5 to about  1 to 2Jj by vol-
 ume, the  mixture being subjected for  a suitable
 time to ambient conditions within the range of
 normally  occurring atmospheric temperatures
 and humidities.
                       JULES  E. HAVELJN.
                       PRANK  KAHN.

            REFERENCES CITED
  The  following references are of record In  the
 file of this  patent:

         TJNTTSD STATES PATENTS
 Number        Name               Date
  1,886,933    Askenasy	Nov. 8. 1933
  1,942.770    Peffer  et aL	Jan. 9  1934
 2,250,107    Nelles	July 22, 1941

             FOREIGN PATENTS
Number         Country             Date
   381,223    Great  Britain	 1932
                                       A-76

-------
Aug. 21,  1951           j. E. HAVEL1N  £TTAL           2,564,690


                 HYDRATED LIME-FLY ASH-FINE AGGREGATE CEMENT


Filed June  30, 1943                                   2 Sheets-Sheet  1
          1.4-
     X _

     K o
2f
C «/)
I- K 1-0
in Q.
  5
uj S

£ =
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          0.6
     >z
     2    a2
   WITNESSES
                  \

                                            \
                    ZO       40        60       80   90  100


                 % FLY ASH(BT vot.)or  FLY ASMS LIME
                                                  Jules JP.
                                                     INVENTORS:
                                                         ATTORNEYS.
                             A-77

-------
Aug. 21, 1951          J. E. HAVELIN  ETAL           2,564,690


               HYDRATED LIME-FLY ASH-FINE AGGREGATE CEMENT


Filed June 30, 1948                                  2 Sheets-Sheet 2
         16.0
         14.0
     L«
     UJ O



     SI
     UJ "! 10.0
     •x. (C
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     tn 2

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     or ><
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                   20       40      60       .BO  90   100



                % FLY ASH (a* VOU.)OF FLY ASH & LIME
                                                       INVENTORS:
                                                     ATTORNEYS.
                         A-78

-------
  United  States  Patent  Office
                                            2,693.252
                            Patented Dec.  28,  1954
                       2,698.252

  UME-FLT ASH COMTOSmONS FOR STABILIZING
    FINELY DIVIDED MATERIALS SUCH AS SOILS

       )a\o E- HaTettB, Havertowa, mad Frmmk Kaho,
                    FfcfladclpUa, Fm.

       No Drawiat.  ApeUaooa \aftat IS, 1951,
                   Serial No. 245,652

                7 CbUan.  (CL 1M—120)


    This invention relates to composition] for effecting ibe
  stabilization of finely divided material) such as soils and
  the I'te, and  more  particularly relates to compositions
  whereby substantially chemically inert fine  mineral  ma-
  terials are  stabilized by treatment with lime tad fly  ash.
    This  application  b a  continuation-in-pan  of our co-
  pending application,  Ser  No  "16.048, filed June 30. 194$
  entitled  "Hydrated Lime Fly Ash Fine  Aggregate," nov.
  U. S. Patent  No. 2.364,690.  issued October 21.  I9J1
  In  the  aforesaid co-pending  application we have  dis-
  closed cementitious  compositions useful  as  mortars  and
  the like  which contain fine aggregate in the form of fineiy
  divided  sand  or  other  chemically  inert aggregate  hav
  ing a fineness modulus of 1.7 or above.   Repeated expen-
  ments in the labonto'Y as well  as  practical applications
  in the field have dernouv.rated  that,  within specific ranges
  of relative proportions of those ingredients,  a mixture
  having unexpectedly h;?n early compressive strength  was
  obtained.
    We have now  discovered that unexpected advantages
  are attained by mixirg iirne and fly ash  in controlled pro-
  portions  with  a  finely divided  soil  having  a  fineness
  modulus less than 1 7.  We have further found tha:. for
 ceitain soils of rincress modulus below  1.7. certain  opti-
 mum relative propoi uons of lime and fly  ash  give  unex-
 pected  peak* when  ioil  characteristics  relating to  dur-
 ability and bearing power of the soil are plotted against
 percentage.  For example, the  plasticity  index, shrink-
 age characteristics,  water  retentivity  and capillary  po-
 tential of uncured samples is well as  modulus of elasticity,
 uncooflned  compressive streogib  and resistance to  alter-
 nate cycles  of freezing and  thawing  and wetting And dry-
 ing of cured  specimens  vary critically  within definite
 ranges for  definite  soils.   These materials axe of  such
 fineness that they are  outside the class of materials usually
 referred  ro as  aggregates.   The compositions of this in-
 vention are extremely useful for  many  purposes and are
 found paiticularly useful  in the field of  soil  stabilization
 for building load-supporting  *ui faces such  as air  field
 runways, roads, highway or the like.
   Cenain materials whi-.h have pre>iously been iugge.iteJ
 fur other purposes wholly unrelated to soil stabilization
 involve the  incorporation of lime with  fly ash. as exem-
 plified by the V.  S. patent  to  Pefler. No. 1,942,769. is-
 sued January  9,  IQ34  Peffer's compositions do not in-
 clude finely divided  materials  such  as  soils or the like
 and are nrcessarily indurated, or subjected to the action
 of  heat,  in order to  cause a  chemical  interaction  be-
 tween the lime and (he fl> ash.  Such  induration ordinarily
 involves  intimute  contact with sieam,  which  would be
 difficult if not impossible to accomplish  in  building roads
 •>r  highways.   Moreover  an" process involving indura-
 tion would be exi-exsively costly and  of no practical merit
 whatsoever in road or highway building operations.
  Another prior patent, issued to Jones and Swezey (U. S.
 Patent  No. 2.3«2.154, August 14,  1945 '.discloses a build-
 ing Mock or brick comprising lime,  fly ash,  and cenain
 •jl'jmino:iJicic  acid materials such as shales, slates and
clays.  However, substantial proportions of lime, on  the
order of  •*0'% lime,  far in  excess of the proportions of
lime ir. applicants' compoiiiions. are included in the Jones
and Swe^ey composition,  and this has a profound effect
on the  properties and character of the final composition
45 well as its cost.
  Th: development of the field of soil stabilization is oi
          importance in ^onstruaion of  roads, highways
    knd the like.  Such stabilized soils are effectively utilized
    to form load-fupponinx  bases, by which  we mean base
    courses under highways and  roads, and for road shoul-
    ders, secondary roads.parking aims, airport runways and
    the like.  Several different  compositions  are  being de-
    veloped for stabilization of roads and highways, the con-
    struction of which is one of the largest industries in the
    United  States.   One  soil stabilization  composition in-
    volves the admixture of  bituminous  materials such a*
 10 road oils,  tars, emulsions and  the like with the soil.  Cer-
    tain soils  have  been stabilized by mixinp with lime, or
    with  birumin-bydrated   lime  compositions.   Portland
    cement, has also been employed for soil stabilization, as
    well  as various other materials tuch  as organic  resins.
 IS calcium chloride and various proprietary materials.  How-
    ever,  these materials have not exhibited certain advan-
    tageous properties peculiar to this invention, and in most
    instances are  relatively expensive as compared with  our
    i oppositions.  A further disadvantage ID connection  with
 20 the use of Portland cement is  that the cement component
    of ;he soil mixture  sets quite rapidly and  it  is therefore
    necessary  for  persons using the mixture to  adhere closely
    10 time schedules  in forming the soil  mixtures and  in
    finishing the stabilized mixture
 2S   The surfacing of tirport runways has presented diffi-
    culties in  that the jets of jet propelled airplanes using
    the ninways are frequently directed against  the runway
    surface.   The surface  temperature is  almost  instantly
    brought to a value sufficient to cause spal!:ng of concrete
 30 and cement-like surfacing materials. Un the  other band.
    bituminous materials  such  as asphalt  and  oil-treated
    aggregates are inadequate surfacing materials for airport
    use since  the bituminous content of  me surface urune-
    di.uely burns  under the intense hiat of the jet.
 33   The primary object  of the  invention  is  to provide
    economical compositions  tor  stabilizing soil to couvert
    it to a composition well suited as a construction material
    for use in roads, highways and the like.
      Another object  of the present invention is to provide
 40 'siaMi.ied fine mineral  material  having high compressive
    •.trength.   Still  another  object of the  invention is to
    picvide a  stabilized  soil or equivalent fine  material hav-
    ing superior  durability,  wetting and drying  resistance,
    freezing and  thawing  resistance, and  weathering  re-
 43 sisunce
      Another object ii  to provide compositions for convert-
    ing soils which  have high  plasticity, excesaive shrinkage
    and poor drainage characteristics  tn composition having
    lou plasticiry index and improved dimensional stability
 |O and drainage properties
      Still  another  object  of the  invention is  to provide a
    composition of matter  for  incorporation into  a finely di-
    vided  inert material with  capacity to  form a  stabilized
    mixture having modified and improved engineering char-
    .ii'teristics.
      Still  another  object  of  the  invention is  to provide a
    itlarvely inexpensive .solid  mixture which, when  mcor-
    fA.riicd  into  finely  divided joil or equivalent  mineral
    having a fineness modulus less thau 1.7, in the presence
.„,  of moisture, will form  a stabilised mixture  having  resist-
    
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lime.**  *oth bydrated !lm« and slaked lime may ba
elated with excess wa:er. resulting ic a moist or alurned
state  or condition.
  The term "fly uh" as used in the  present specification
ii intended to indicate the £/ely aividcd  ash residue pro-
duced by the combustion of pulverized  coal, which  ash
is cairied off  with the gaaes exhausted from the furnace
ia which the coal is burned and which is collected from
these gases usually b>  rae^ns of suitable precipitation
apparatus  such as eiecuical  precipitators.  The  fly  uh
so obtained is in a finely divided state such that at least
about 70% passes through  a 200 mesh sieve.  The fly
ash  coUecteo  from  the  exhaust gases is hereinafter re-
ferred to ai crude fly ash.
  The term "soil" is  used throughout this specification
aad  the claims hereof U intended to indicate natural or
artificial substantially  inorganic  materials having a fine-
ness modulus below 1.7.  While we designate these msf-
terials as "inorganic,"  the presence of minor proportions
of organic  materials is  not excluded, provided the fine
material is predominantly inorganic.
  By "fineness modulus" we  refer to a standard panicle
size designation determined by sieve analysis.  The stand-
ard  sieve*  employed  are H  inch.  No.  4 sieve  (4760
micron), No.  8 sieve (13*3 micron), No. 16 sieve (1190
micron). No.  30 sieve i59C micron). No.  50 sieve (297
micron),  and  No.  !00  sieve (149  micron).  Fine no*
modulus of a matenal ii determined  by  adding the total
percentages retained on  each of the specified sieves and
dividing  the sum by 100.
  Our invention embraces a wide  variety of naturally
occurring soils which have a ftucrwM modulus below 1.7.
Such sous  are well classified  in accordance with  the
Public  Roads  AdmuiijtrtMoo  classification into  sevea
groups identified is  Group A- 1  through A-7, with sub-
grouping under A-!. A-2 ar»i A -•»   Fhe principal groups
covered in  kcc-jrilance with .(.is invention, and as defined
in Bulletin 39 of the Commonwealth of Prnnsylvania
Department of Highwayi.  lune 1948, are  Group* A—*
through A-7,  and A-2-4 if.rnugh A-2—7, as w«U u cer-
tain A-3 soils  having fln»acs*  modulus below 1.7.  Group
A—4 soil* art  non-plastic or moderately plastic silty soils
usually having a  nigh  percentage passing the No.  200
sieve.  The group includes also mixtures  of  floe silty
soil aad up to v*^  und and gravel  retained oa the No.
200 sieve.  These v-iiis ordinarily contain small amounts
of colloidal clay.  In performance as sub-grade material,
Group A-4 soils of themselves  are  subject to objection
in that they are difficult to compact, are subject to frost
heavini. and  have undesirable  elasticity (or poor  com-
pressibility) and volumetric  shrinkage characteristics.
  Group A-5 soil* .ve micaceous and diatotnaccous ma-
terial*, are flneiy  divided, and arr subject to the principal
objections  noted above  in connection  with  A—4  soils.
They are particularly obir-c'Jonable as nib-grade materials
by reason of therr ela.'tio'y ind  instability
  Group A—6 soil* are esaen!:aJJy plastic clay soDs usually
having 73% or more  pasting  the No. 200 sssr*.  Simi-
larly  Group A-7  soils are tlayey materials  and  exhibit
undesirable elasticity  as well as volumetric  ahrmkaire.
A-6 and A-7 soils are  generally regarded as poor sub-
grade material* for road  and highway construction.  The
aforementioned Bulleiin  39, on page 9 thereof, indicates
that  the  A--4.  A-5, A-6, and A-7  soils  are  sflty  aad
davey, all  being characterized by the fact  that at least
36%  by weight of  the  aoQ puses  a standard No.  200
   Sub-croups A-2—< and A-2-5 include travels or coarse
sands havinc  fineness moduli above 1.7 but also irvdode
fine sands havi"« fineness  moduli  below 1.7 which are
effectively stabilized in accordance with  this Invention.
The aforementioned Bulletin 39. on pages 7 and 9 thereof
Indicate*  th»» the A-2—* and A-2-5 soils are envois or
sands contaHint a elastic component of clay or cOt, aad
that th« A-2—4 soils are characterized by the f»ct rhut
a maximum of ?5% by weight passes * staadard No, 200
lie-re, and thm portion of the  toil which o**aes a stand-
ard No. 40 sieve has a maximum  Ikjukl  limit of 40 and
BAS « rnaiimu"! elasticity- index of  10.  The same bulletin
simflorlv  identifies A-J-5 soils, with the  exception that
the minimum  liquid  limit r>( the fraction Duaing a itsnd-
ard No. 40 sieve  is <'   Suh-rroups A-2-6  and A-2-7
coots to sand  »nd travel tijcether with a clayey binder
component and  many of these  toils have fineness rood nil
beiow  1.7 aad are advantageously treated ia accordance
                                                            with  this Invention.   On page 9.  ih«  sforexnentioneJ
                                                            Bulletin  39 specific*  that A-2-6  and A-2-7 stxis  are
                                                            chuacterlzed by  the fact that they are silty  and ciayfy.
                                                            *nd that portion of the soil  pajoing a standard  No. 40
                                                         3  sieve  has a  minimum  plasticity index of  11.   A-3 soils
                                                            art essentially very fine sands, and those A- 3  toils having
                                                            fineness  moduli below  1.7 are  within  the scope of this
                                                            invention.   Natural A-3  soils,  though occasionally con-
                                                            sidrred  satisfactory as sub-grade  materials  ia confined
                                                         ID  spaces, are generally too mobile  or lacking  in cementitious
                                                            materials for avcrag* use. The aforementioned  Bulletin
                                                            39, on pages 7 and 9 thereof, indicates that A-3 soils  are
                                                            fine sands  having no  binder content,  at  least 51%  by
                                                            weight passing a  staadard No. 40  sieve, and a maximum
                                                         IJ  of 10%  by  weight  [~**T;if a  standard No. 200 sieve.
                                                              Finely divided  materials other than natural  soils, which
                                                            are equivalent to the  sods falling within  the above  de-
                                                            fined soil classifications, nevertheless are included within
                                                            the scope of  this  invention.   These  material*  include
                                                         •JO  fine sand, stooe screenings, slags, gravel screenings, min-
                                                            eral deposits, fine screenings  from quarry  operations sod
                                                            the like, having fineness modulus  below  1.7. as  well as
                                                            Diner  similar soil-like materials  all  of which are included
                                                            within the meaning of the term  "aofls" as  n**4 herein.
                                                         '-3    The relsiive  proportions  of the three  principal  com-
                                                            ponents  of  the  compositions are  important, in that a
                                                            wholly  unexpected peak  is  attained, when  certain toil
                                                            chaiacteristics are plotted against the relative  proportions
                                                            of fly aah and lime in  the mix. such peak oei.-.g of  me
                                                         3V  same  general character as that  trpreaected in Fig. 2 of
                                                            our aforementioned cnpendinj  application.   Moreover.
                                                            optimum results are attained  for toils  of  different  ivpei
                                                            by providing lime-fly  ash ccmnosilipns  within  iritk.al
                                                            ranges of different scopes.  Thus,  while the lime, fly ash
                                                         3.">  and *ofl of our oonjpoution may advantageouslv br pres-
                                                            ent in amounts by weight within the ranges of about lime
                                                            2-5.  fly  ash about  10-30 »nO soil  about 70-90,  very
                                                            ad vantage--us results are anuned  in  different ranges  for
                                                            different .oils, as indicated in the following table:
                                                                             Optimum proportion!
                                                                       SoAClM
                                                        43
                                        Pvra BT »«tctit
                                         T
                                          i
A -4 	

*->-» 	
\-J-7 	
A-4 	

A-4. 	
A-'' 	 	 	

	 . 1-7 i 16-JO
	 	 *-T i 10-X

	 i »-* i i«-»
	 i *-* j ic-so
	 i 1*1 io-x
	 1 >-• 1» »
	 1 t-9 1 10-Z
	 	 »-t 1 »-»
! i
                                                                                                               W-M
JO
      In the ranges shown  above,  very advantageous results
    are  obtained, with pronounced opchr.ums occurring par
    ticularly  with  respect to  the relative  percentages  of  fly
    ash.  Preferably the parts fly ash and soil, as expressed
00  above,  total 100.
      The  advantage* and  characteristic!  of these  composi-
    tions are readily determined by  testing  samples thereof
    for plasticity index, rt-mr>n.-c to penetration by standard
    Dcedl«, shrmkan  characteristics,  water  retentjviry »nd
U  capillary  potential, for example, such characteristics being
    measurable Immediately after the mixture is formed. Th«
    stabilized soil  mixes which show  optimum performance
    as tested by the above characteristics  are found to havt
    the  most advantageous  properties upon  aging or curing
70  «s reflected by tests for  modulus  of  elasticity,  freezinc
    and  thawing resistance, wetting and drying resistance, and
    unconnacd coopresssrve  tti *t^grH
      The  plasticity Index of  soil  is  conventionally defined
    as the numerical difference betwrer. the  liquid limit and
74  the plastic limit of a sofl.  It indicates  the range of mois-
    rure contact ia which the toil  is  in the  plastic, or semi-
    aolid stata.  TB« liquid limit  Is conventionally denned
    as the  water cosuaat at which the mil  passes  from the
    plastic state to the liquid  stale, while the plastic limit of
M  a  sofl ia  the lowest water content  at which the soil be-
    comes  ptastfc,  or  ta« content  «t  which a voil  changes
    frocn a «oiid stata to a aemi-soiU  state.  The.ie tests may
    be carried out  in accordance with AASHO Designations
    T-14-49. T-90-49. and T-91--41.
U    The rohanctric shrinkage of a aofl  is tested by
                                                           A-80

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 uring the volume  loss of a soil  sample on  drying, ana
 may be determined .n accordance  with AASHO Detig-
 nation T-92—42.
   The water retentiviiy ot a Mil i* its ability to bold wa-
 ter, and  may be determined  by  applying standard suc-
 tion to a soil  sample of standard  size,  and  measuring
 the time required  for removal of a unit  amount of wa-
 ter.
   The capillary potential of a soil  is the direct measure
 of the property of the soil to  raise water above the free
 ground  water  level by  capillary  action.   It  i*  deter-
 mined oy placing  a wet soil  sample of  definite  size  in
 the top of a funnel the  stem of  which contains water
 The open bottom of the stem  is submerged in  a mercury
 reservoir.  Water  is  permitted to  evaporate  from  the
 soil surface, the height of the mercury column thus drawn
 up is  measured.  Capillary potential is  usually expressed
 in terms of  feet of water.
   Another  important  characteristic of  stabilized  soil,
 which is measurable after a curing or aging period, is  its
 modulus of elasticity, which  is often  determined by  a
 conventional dynamic method based  upon  resonance
 The test for modulus  of elasticity,  or  nitio  of stress  to
 strain, is of particular importance because many of the
 other  important  characteristics  of stabilized soil  are
 related to its modulus  of elasticity.
   The aged or cured  stabilized soil  specimens may alxj
 he tested for capacity  to resist alternate cycles of freez-
 ing and thawing and/or welting and drying.   The speci-
 men is subjected to successive cycles and the condition
 of the specimen is observed  at the end of each  cycle.
 After each cycle the surface  of the  specimen  is  brushed
 with a wire brush  to  remove  loose panicles.   The loss
 in weight is  recorded  as an indication  of the  durability
 and quality  of the soil composition.
   Another  important  test  which  constitutes  a  definite
 factor, specifically  relating to  thr  proportions of our ma-
 terials, is the test  for unconfined compressive strength
 Unconfined  compressive strength is measured  on un-
 confined  cured and dried  samples using conventional test-
 ing equipment  such as that used  for mortars, concrete,
 and the like.  This test conveniently  demonstrate* the im-
 provement in bearing capacity which  is  developed by
 the use of this invention as contrasted with the very low,
 and in many instances negligible bearing capacity of un-
 treated soil  expresaed  in terms of unconfined compres-
 sive in-ength.   In  fact, the  superior strength  developed
 by this invention improves  it  beyond the range measura-
 ble by the conventional teit which involves measurement
 of deflection under load
   Ingredients of our  compositions  may be  prepared  in
 any conventions! manner, such as  by simple  milling  of
 the solid component,  preferably  in  'he presence  cf wa-
 ter.  However the  muing is preferably carried  into effect
 by breaking  up the soil and mixing the soil with liine and
 fly ash in predetermined proportions,  utilizing  suitable
 toil-breaking and  mixing equipment such as  that con-
 ventionally  used  for  farm  and  construction  purposes.
 with water added to the  mixture  in  an  amount substan-
 tially  equal  to  that  proportion  of water  known and
 defined  as the optimum moisture  content.  Optimum
 moisture  content is determined by the well known modi
 fled Proctor  test.
   Optimum  moisture content  of a sofl  or stabilized soil
 mixture is that moisture content at which the soil-moisture
 mix has  the maximum dry  density, or  maximum drv
 weieht of solids per unit  volume.  In practice, the opti-
 mum  water  content varies with each particular wil and
 stabilired toil mixture, ordinarily within  fhe  range of
 8-25% moisture by weight, based  on the total dry weight
 of  lime,  fly ash,  and  soil.    Preferably,  in  Incorporat-
 ing moisture into our stabilized soD mixes, the water con-
 tent should be controlled within the range  of 70%- H0%
of the optimum water content.   Thus the water content of
 the stabilized road  base may vary from about  5%-32%
 by weight, based on the weight of total lime,  fly ash, and
 soil, for different soDs.
   After  mixing, the toil  may  be  formed  to  the desired
 shape, which may  be  of any desired  character.   After
curing for  teverml  weeks it   wil]  develop considerable
compressive  strength,  but the  cemeatitiou* bond of the
mix develop*  to  slowly  that  even  after a week, the
formed mix  can readily be deformed and  re-shaped.
   The following example* are ttlustratiTe  of the  inven-
 tion:
                               6
                           Ejuunplt 1
        A  toil wai  selected composing a  cltyey  and,  fine-
      ness modulus below 1.7, secured from the southern pert
   -   of  Maryland, having a relatively high plasticity index of
      11.4%.   It* Highway Research Board classification  wa*
      A-2-6.   The soil wa* mixed with lime, fly aih and opti-
      mum water, the proportfco* of tolids being a* follow*:
  lu
  ->t»
  3.1
      A-2-6 sou-
      Lime  ...	
      Fly  ash	
                                           Parts by weight
                                          	90
                                          	   9
                                          	  10
      The  resulting  material at oace showed the foUowing
1J  properties a* contrasted to mote of tb« natural  A-2-6
    soil:
      The  pUtdaty  bdex erf 11.4%  for the nararaj wQ wm«
    reduced to 3.5% for the stabilized toil.
      The  water retenuSity of 8.4 tecood* for the natural

                    to penetration wa* increued.   A stand-
    ard needle penetrated the natural  toil a depth of .07 mm..
    while  under the tame  te*t condition* it peactraud  the
0_  stabilized soil to a depth of only .023 ""•)
-J    Specimen* were prepared from  the above mixture utiliz-
    ing moisture at optimum  moisture  content and com-
    pacted  and cured for 28 days.  These ipecimeai showed
    an unconflned compressive strength  of  300  p. «- i.  as
    contrasted to 20 p. s. i. for the natural toil.   Rexutance to
30  freezing and  thawing  and wetting and drying wa*  alto
    radically unproved as iodicaied by a itaadard wire brush
    test which showed that the stabilized material mods up
    after numerous  cycle*  a*  contrasted to  the  native soU
      which fails to stand up for one cyck.
                           Example 2

      Soil description: Plastic clay soil tccurcd from  a  loca-
        tion north of Hagerstown,  Maryland.
      Highway Research Board classification:  A-7.
      Proportions of mixture:
          A-7 toil
          Lim« ....
          Fly aih ..
                                         Pan*  by weight
                                        	90
                                        	  9
                                        	_	10
        The  resulting material at  once showed  the  following
      properties as constrasietj to those  of the natural  A-7 soil.
  ,-,.,    The plasticity index of 38.5%  for the natural soil was
      reduced to 4.0% for the stabilized toil.
        The volumetric  shrinkage of 89% for the  natural soil
      was reduced to 15% for the stabilized toil.
        The capillary potential of  17 feet fur the  natural soil
  .-,-,  was reduced to 10.2  feet for the biabQizrd toil.
        Specimens of the above mixture, combined with opti-
      mum water and compacted and cured for 28 days, showed
      in unconfined compresaive strength of 2000 p. s. i. &j con-
      trasted  to 700 p. s. i. for the natural Mil, and  a  resistance
  1^1  to  alternate cycle* of  freezing and (hawing and  wetting
      and drying for numerou* cycle* as contrasted to the nat-
      ural toil which failed  in the first cycle.
        The dynamic modulus of the cured specimen  expresvd
      as  the product of the  weight of  the specimen  times  the
  0-(  square of the natural frequency was J.I X IV pounds/sec.1
      while  that  of  the  natural   soil was  below  O.lxlO*
      pounds/sec.1.
                           Example 3

  "(>    Separate umples were compounded with varying pro-
      portion* by weight of lime, Sy ash, aad A-2-6  toils  a*
  75
  go
84    La  the
                      UflM
                                                     8n"






10
10
x
30 i



BO
80
90


                        toil sample* a* aboro prepared,  th«
A-81

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                           7
         	cbaraeteritdct of the toil were Improved
         the range being a function of the composition:
       ' Iwtos	
       •T« ttrmctb
Wftur rvUoUTllr	
Drm^e Modmk».
                               N«lurmJ
                                tell
                             11.4%
                             Up. §. I
                             ,07mm	
                             1.0-LIX10*
                                         ntblUMdSol)
                                        aoo-aoo p. i. L
                                        1.4 me. (tU mat-
                                            i).
                                                0.1X10*
                                         UM/M.I.
                      Example 4

   Separate sampks were prepared in the  manner de-
 scribsd in Example 3, using u A-7 toil of fineness modu-
 lus  below  1.7.  The  soil was  effectively stabilized by
 HM  action of lime ud fly ash. in proportions by weight
 M foOowi:
Umt







JIT 1*
10
M
10
X
»
X

Soil
U-T)
90
90
w
tO
an
•>


Ffcatltdty Tnd«i
Vnooofisad mmprcailTi rtrmfth
(at 
10
10
10
RRRSSiZ
»
x>
>
M
10
M
i
                                                             All of the foregoing compositions of Example 13 have
                                                          compressive strengths in the range of 400-600 p. s. i. after
                                                       70 aging for 28 days, and  ihow  ability  to  resist about 12
                                                          cycles of alternate  freezing and  thawing or wetting and
                                                          drying tn accordance  with conventional tests.
                                                             From the foregoing description and examples It will be
                                                       _   appreciated that  our lime-fly  ash-toil  compoaitions «re
                                                       13 novel generally and applicable to a wide variety of uses.
                                                          They are of great advantage by reason of their relatively
                                                          low  coat, engineering properties  and strength character-
                                                       80
                                                                 ,                                g   caracter-
                                                         «*«•  The stabilized, oncwed toil product k particularly
                                                         advantageous  to that considerable time (on  the order of
                                                         a week or more) eiapaet before the mixture  sets up more
                                                         or lesa completely.  During this period the  mix it read-
                                                         ily  handled, spread  and compacted,  and yet due  to tha
                                                         immediate changes in toil properties which are produced.
                                                         the  compacted  mixture has  a turprisingly  »reat  Joadl
                                                      U bearing capacity during this period, even before compku
                                                         A-82

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                            9
 setting,   to  our experience  the  load-bearing  character-
 istic  of  this  newly formed composition  has been  suffi-
 cient to permit the use of a road or highway, for example,
 beture setting is complete,   i he addition  of the lime and
 fly <"sh.  in the  proportions disclosed,  immediately con-
 verts a natural  soil which is relatively poor as a  load-
 supporting base  to a composition  having  structural  char-
 acteristics ideally suited for the purpose.
   The property  of our compositions to set slowly  is of
 prime importance  in  road  and highway construction, in
 that constructions  schedules  need not necessarily be ad-
 hered to  rigidly.   Moreover, work may be discontinued
 or postponed due  to rain  and  resumed  at a  later date
 without  harm  to  the stabilized soil  due  to  setting or
 erosion  during  the  intervening  period.  By  contrast,
 soils  stabilized with Portland cement set up rapidly under
 such  conditions.
   Another  advantage  of our stabilized lime-fly ash-soil
 compositions is that they may be  recompacied after sev-
 eral weeks, while soils treated with Portland cement are
 found to set up quickly and  can not satisfactorily  be
 recompactcd  several weeks after they are first compacted.
 Our  material is also an ideal  patching material, which
 is an  additional advantage  over  Portland  cement.
   While lime alone or fly ash alone, when  mixed with soil,
 may  in certain  cases  improve certain characteristics of a
 soil,  for  use  as  a  load-supporting base, the combination
 of lime with fly ash produces radically changed character-
 istics far  beyond any results that might  be predicted  from
 the behavior of lime alone, or of fly ash  alone.  The  bene-
 ficial effects achieved are far in excess of the sum of  those
 attributable to the presence of either lime  or fly ash.
   Additional  materials such  as  Portland  cement, special
 grades of clay soils and alumino silicates and the like may
 be incorporated into soil stabilized in accordance with our
 invention without detrimental effect to  certain  of the ad-
 vantages of the invention.  However, the  novel stabilized
 soil  road bases  themselves  consist essentially of  the  in-
 gredients set forth  in the appended claims.
   The above description and examples are presented as
 illustrations of  preferred embodiments of the  invention.
 All modifications and variations  which conform to the
 spirit of the invention, including the substitution of equiva-
 lents  and  other changes in  the  particular form  of the
 method and  product, ai well as the use of certain advan-
 tageous features of  the invention without the use of  other
 features, are  within the scope of the invention  as defined
 in the appended claims.
   Having thus defined our invention, we  claim:
   1. A stabilized soil composition of  matter  consisting
 essentially by weight of about 10% to  about 30% inclu-
 sive of crude fly ash,  about  70%  to about 90% inclusive
 of sofl having a fineness modulus below  1.7, the sum of
 the percentages of crude fly  ash plus soil  being substan-
 tially equal to 100,  and about 2% to about 9% inclusive
 of lime,  tlvc percent lime being based  on the  weight of
 crude fly ash plus soil.
   2. A stabilized soil  compoaitioa of  matter  consisting
 essentially by weight of about 15% to  about 30% inclu-
 sive of crude fly ash, about 70%  to about 85%  inclusive
 of «oQ  having  a fineness modulus below  1.7,  said sofl
 comprising fine sand having substantially  no binder con-
 tent,  at lent  51%  by weight of which  passes a stajadard
 No. 40 sieve,  aad a maximum of 10% by weight of which
 passes a  standard  No.  200 sieve, the  sum of the  per-
 cent* «e»  of crude fly ash plus soil being substantially equal
 to 100, aad about 2% to about 7% inclusive of lime, the
percent lime being based on the weight of crude fty ash
 plush sofl.
   3. A stabilized loQ  composition of  matter  consisting
 essentially-by weight of about 10% to about 20% inclu-
 chv of crude  fly ash. about 80%  to about 90%  inclusive
of sofl having a f •"•*«•>«• modulus below  1.7,  said soQ
  10
  20
 30
 3>>

 40
 , (
 '*"
 „..
 00
 
-------
United  States  Patent  Office
                                        2,815,294
                          Patented  Dec. 3, 1957
                      2,815^94

                 STABILIZED SOIL

     Jn\ei F. Uarclin, IJnvertown, »nd Frank K»ttn,
                   1'hilnrfrlphU, Pn.

     No Drawing.  Application December 22, 1954,
                  Serial No. 477,122

               « Claims.  (CL 106—118)

  This invention relates to the stabilization of fine, plastic
silts or clay soils.
  This  application  is a continuation-in-part of our co-
pending  applications Serial Nos. 245,651  and 245,652,
now U.  S. Patent No. 2,698,252, both  filed August 18,
1951, wherein we  disclose stabilized soil compositions
including lime and fly  ash  which are incorporated into
the soil.  Various  soils, even including highly plastic
soils, can be successfully stabilized by reacting  them with
lime and fly ash causing the product to set in accord-
ance with the inventions disclosed in  the aforementioned
copending applications.  Although  the  compositions set
relatively slowly, they  have good  compressive  strength
even during the early stages of the  setting period.  After
setting for a sufficient time, the compositions develop ex-
cellent compressive strength and  have sufficient stability
as load supporting bases for road building and other op-
erations.                                          .
  However, it has  now been found  that certain of the
more plastic soils,  when stabilized in  accordance with
the disclosures of the aforementioned  copending  appli-
cations,  are lacking in  durability under certain adverse
weather  conditions during the early stages of the setting
period.   It is desirable to provide a road base  which has
good  stability  immediately  after the road  base  is laid
down,  and such base must have the  property  of retain-
ing its stability even  when it is exposed to severe weather
conditions, such  as alternate cycles of wetting and dry-
ing, frost action, or freezing and thawing, for example.
The ability of a stabilized soil mixture to stand up under
severe  weather conditions during the  early stages of the
setting period, while said mixture  is also  subjected  to
heavy engineering loading, is referred to. hereinafter as
the durability of the soil mixture.
  Attempts  to improve the early durability characteris-
tics of plastic soils, by adding lime and fly  ash, are not
successful.  In fact,  when an A-6 or A-7 clayey soil is
combined with fly ash, for example, the  progressive addi-
tion of  lime  decreases the water retentivity  of the com-
position, which indicates that the lime  is  not  acting in co-
operation with the  other components of the mixture to
improve  its early durability.
  It is  accordingly an  object of this invention to pro-
Tide an  improved  soD  stabilization composition  lor
stabilizing plastic soils.   Still another object of this in-
vention is to provide a stabilized soil composition includ-
ing plastic soil, which composition has  capacity to support
heavy loads during  the early stages  of the setting period.
Still another  object of this invention is to provide an in-
expensive means for stabilizing very plastic soils in such
manner  that the stabilized soil  composition  has suffi-
cient pliability during the early stages of the setting period
to permit compacting and re-shaping after  compacting,
but which composition has  sufficient durability  during
the early stages of the setting  period to support heavy
loads without  excessive deformation, even when  sub-
jected to severe weather conditions such as repeated wet-
ting and drying or freezing and thawing, for example.
  It is still  another object of this  invention to provide
• means for stabilizing  plastic silts  or clay soils to pro-
Tide compositions having excellent early load-bearing and
durability properties, and without adversely effecting the
10
 IS
20
ZS
80
88
4tf:
  *
50
Ta
 compressive strength or other engineering properties of
 the final product after setting.
   Other objects and  advantages  of this invention  will
 farther become apparent hereinafter.
   We have now discovered that very plastic sods, when
 stabilized with  specific proportions  of lime, aggregate
 particles and fly ash, have remarkably improved durability
 during the early stages of the setting period.
   The relative proportions of the  ingredients are critical,
 as will  further  become apparent  We have found  that
 the water retentivirj^oX the composition decreases with
 lime addition when .a -small proportion of aggregate is
 incorporated into the composition, but surprisingly, the
 water retentivity increases with lime addition when the
 proportion of aggregate is in the range of about 20%—
 50% by weight, based on the total weight of fly ash plus
 soil plus aggregate.
   As used throughout this specification and claims, the
 term "lime" is used to indicate quicklime, hydrated lime,
 and slaked lime.  The term "hydraled lime" indicates *
 dry powder obtained by treating quicklime with  water
 enough to satisfy  its chemical  affinity for  water under
 the conditions of its bydration.  Hydrated lime consists
 essentially of calcium hydrate or a mixture of  calcium
 hydrate and/or  magnesium oxide and/or magnesium hy-
 droxide.  In  the above definition quicklime is  used to
 indicate a calcined material  the major portion of which
 is  calcium oxide (or calcium  oxide  in  natural  associa-
 tion with a lesser amount  of magnesium otic^e)  capable
 of slaking with water. The term "slaked lime" is used
 interchangeably with  "hydrated lime."  Both hydrated
 lime and slaked  lime may be associated with excess water,
 resulting in a moist or slurried state or condition.
   The term "fly ash" as used in the present specifica-
 tion is intended  to  indicate the finely  divided ash residue
 produced by the combustion of pulverized  coal, which
 ash is carried off  with the gases exhausted from  the
 furnace in which the coal is burned and which is col-
 lected from these gases usually by  means of suitable pre-
.;cipitation apparatus such as electrical precipitators. The
 ny ash so obtained is in a finely divided state such that
 at least about 70% passes  through a 200 mesh sieve.
   The  term "plastic soil" as used  throughout this speci-
 fication and the claims hereof is intended  to indicate
 natural  substantially inorganic material  of  the type of
 clay, loam or silt,  which soil is so fine that  the normal
 method of soil evaluation does not  include fineness modu-
 lus  determination.    The  majority  of  the   sofl  passes
 through a  standard  100-mesb  sieve.  While we desig-
 nate this material as "inorganic," the presence of minor
 proportions of organic materials is not excluded, provided
 the fine material is  predominantly inorganic.
   Plastic soil, within  the  meaning of the term as ap-
 plied to this invention, includes all  soils which  have a
 plasticity index of more than 15, all soils which have a
 plasticity index of about 9—15 when more than about 15%
 by weight of the sou" passes  a  standard 200-mesb sieve,
 and all  soils which have a plasticity  index 'of less than
 about 9 when more than about 35% by weight of the
 soil passes a standard 200-mesh sieve.
   The  plasticity  index of  a soil  is the numerical  dif-
 ference between the liquid limit and the plastic limit of
 the toiL
   The liquid limit of a soil  is that water content at which.
 the soil passes from the plastic  or semi-solid state to a
 liquid state.  The plastic limit  of  the soil is the lowest
 water  content at which the soil becomes plastic or the
 content at which the soil changes from a solid to a temi-
 solid state. Tests for liquid limit and plastic limit are
 standard in the art   ASTM specifications D423-54T and
 D424-54T as well  as  AASHO designations T-89-49,
T-90— 49  and  T-91-49, which  are incorporated  herein.
                                                    A-84

-------
                                                2,819,204
                          3
 by reference, define standard procedures for determining    20%  by weight the progressive addition of lime to the
 the liquid  limit and plastic  limit of a soil, and hence    soil plus fly ash plus aggregate increases the water reten-
 its plasticity index.                                       tivity.   This was  entirely unexpcted, and  probably ex-
   The term "aggregate" in accordance with this inven-    plains why the compositions of this invention function as
 tion refers to  natural or artificial  inorganic materials  5  well as they do.   Repeated tests have established the
 which  are substantially chemically inert with respect to    fact of  the existence of this phenomenon, as well as its
 fly ash and lime,  and substantially  insoluble in  water.
 such as limestone screenings,  natural  sand, sand prepared
from stone, blast furnace slag, gravel, or other equiva-
                                                       practical merit.
                                                         The ingredients  of our compositions may be prepared
                                                       in any  conventional manner, such as by simple mixing
lent materials having similar characteristics.  In accord-  10  of the solid  components,  preferably  in the presence of
ance with this invention a relatively coarse aggregate is     water.  However,  the mixing is preferably carried into
included, as well as fine aggregate.  An aggregate, within     effect by breaking up the  soil and mixing the  soil with
the meaning of the term as used in this specification, is     lime, fly ash and aggregate in predetermined proportions,
a mixture of finely divided particles which may include     utilizing suitable soil breaking  and  mixing equipment
limited amounts of relatively coarse particles, and may  15  such  as equipment conventionally used  for farm  and
even include particles  up to about  V4 inch in size.     construction purposes.  Water is added  to  the mixture
                                                       in  an amount substantially equal  to  that proportion of
                                                       water known and defined as the optimum moisture con-
                                                       tent  Optimum  moisture  content is  determined by the
                                                    20  well known modified Proctor test
                                                         Optimum moisture content of a soil or stabilized soil
                                                       mixture is that moisture content at which the soil-moisture
                                                       mix has the  maximum  dry density,  or  maximum  dry
                                                       weight of solids per unit volume.  In practice, the opti-
                                                    25  mum  water content varies  with each particular  soil and
                                                       stabilized soil mixture, ordinarily within  the  range  of
                                                       8-25% moisture by weight, based on the total dry weight
                                                       of solids.  Preferably, in incorporating moisture into our
                                                       stabilized soil mixes, the water content should  be con-
  Tie relative proportions of the principal components  30  trolled within the range of 70%-130% of the optimum
Approximately the majority of the  aggregate  preferably
consists of particles ranging in size from about 40 mesh
to about V4 inch.  Preferably, the sizing of the aggregate
falls within the following range:
SereaitlM
\f. 	 	 	 	 	 	 „ 	
ft 	
no 	 ....... 	 .... „ 	
MO . „„. 	 	
1200 	 	

Percent by
weight
puslnc
(0-100
75-100
40-40
6-36
0-16

of the compositions are important  When the propor-
tions are maintained  within a limited range,  surprising
durability improvement is  obtained in the  early  stages
of the setting period.  The preferable proportions  are as
follows, percentages being by weight:
                Materiel
                                       Percent (based
                                       on total of fly
                                       uh, sou. ana
                                         aaretate)
71y AJ
SoU .

T Irnfl



»t* ....


S-2S
SS-75
20-80
3-8

                                                       • water content  Thus the water content of the stabilized
                                                       road base may vary from  about  S%-32% by weight,
                                                       based on the weight of total lime, fly ash, soil and aggre-
                                                       gate, for different soils.
                                                         After mixing, the stabilized soil product may be formed
                                                       to the desired shape.  After curing for a very short period
                                                       of time, for example two to five days, it develops  con-
                                                       siderable stability even  when wet. but the  cementitious
                                                       bond  of the mix develops so slowly that even after a
                                                       week, the formed mix can readily be deformed and re-
                                                       shaped.   After setting for a considerable period, such as
                                                       one month for example, the mix has a very substantial
                                                          ipressive strength and after one year the product is
                                                         ;eedingly strong.
                                                             following examples are illustrative of the inven-
   As expressed  above, the sum of the percentages of    tion:
 fly ash  plus soil  plus aggregate are substantially equal                       EXAMPLE 1

 ri 3^%MS±ri?w£: „ ^SSMSS •£%&'££
 nents of our compositions.                            «• lowtne sieve analysis-
   The durability characteristics of these compositions are         g         y
 readily  determined by testing samples thereof for under-
 water disintegration.  One such method consists of form-
 ing  a  standard  test block of- the  composition  under
 investigation, allowing the block to  set for  a relatively 55
 short period, such as three days for example, under sub-
 stantially dry conditions, and then  submerging the block
 for several hours under  still  water.  A sample  having
 relatively poor durability tends to  disintegrate,  and a
 rough measure of its value is obtained by weighing the 00
 block after removing it  from  the water, to determine
 the loss of weight due to underwater disintegration.  In      The soil had a plasticity index of 14 and a liquid limit
 accordance with this invention, even very plastic soils     of 32.  The soil was mixed with hydrated lime, fly  ash.
 are converted to products having such excellent durability     and dolomitic limestone  screenings, in the presence of
 that in some cases the weight loss due to disintegration  65 optimum water, the proportions of solids being as follows:
 under water is substantially zero.
   Underwater  disintegration tests illustrate that at about
 20% by weight of aggregate, the aggregate coacts with
 the lime, fly ash and soil in such manner that the four
 ingredients act as a  mixture rather  than separate, dis- 70
 tinct materials.  At proportions below  about 20%  by
 weight aggregate, the progressive addition of lime to the
 sofl plus fly ash plus aggregate tends to decrease the
water retentiviry  of  the  composition; however, when
the proportion  of agftreiflte Is increased to a value above. T8

                                              A-85
Saves No.
W
jm .—. — .« - ~- 	
1*
1A
40 ... - -—.«.-.——.---«
flO _,.....................,. ,.
300 m 	 	 	

Percent by
welgbt
panlTif
100.0
99 0
98.0
87 6
97 3
97 0
94.5




AHItofl ........ T 	 	
fm* 
-------
                                                   2,818,394
   Hie resulting material, after compaction, was allowed
 to set under natural ambient  conditions for  three days.
 Samples (compacted cubes) of the stabilized product were
 submerged in water for three hours and showed substan-
 tially zero weight loss.  In addition, the mix had sufficient
 durability to support heavy trucks  which were driven
 over it. even when subjected to repeated cycles of alter-
 nate wetting  and drying, as contrasted to the very poor
 stability of the natural A-6 soil.  Test cubes  of the nat-
 ural A-6 soil, when tested  for underwater disintegration
 after exposure for three days under natural ambient con-
 ditions,  substantially completely  disintegrated  within a
 few minutes when submerged in water.
   After setting for twenty eight days under natural am-
 bient conditions, the stabilized product showed excellent
 compressive strength on the order of about 300 Ibs. per
 square inch, as contrasted to substantially zero compres-
 sive strength for the natural  soil.  The stabilized product
 also had radically unproved resistance to  freezing and
 thawing and wetting and drying as indicated by a standard
 wire brush test which showed that the stabilized material
 stands up after numerous cycles, as contrasted to the nat-
 ural soil which fails to stand up after one cycle.
                     EXAMPLE 2
   The  following compositions further  illustrate compo-
 sitions within the scope of this  invention which have high
 early stability (3  days) and have excellent engineering
 properties after setting for twenty eight days:
                       TabU I

Type Aggregate

Do. ............
Do. ...„„....
Doizninzzziinz
Do 	
Limestone Screening!.
Do 	
Boiler SUc 	
Do"i™m~i"
Do 	
Limestone Screenings.
Do 	
Do. .....—..._„
Do 	 	

Boiler Slag. ...... 	 .
Do..... 	
I
PI
zo
zo
zo
8.0
8.0
8.3
8.3
It
8.9
9.1
9.1
9.9
9.9
10. 0
11.0
14.0
14.0
17 0
24.0
24.0
k>a
Percent
P using
2UO
Uab
47
47
47
17
17
40
40
37
37
It
It
86
86
63
21
98
96
23
46
48

Percent
by wt.
Uffll







Percent
by-,wt-
10
26
10
18
10
28
10
a
10
28
10
5
10
10
10
16
10
10
18

Percent
70
76
88
00
46
68
40
eo
eo
86
86
88
46
80
80
46
38
88
80
36
Percent
by wt.
A «re-
a
a
a
28
40
28
38
30
a
28
20
36
60
40
30
43
60
38
40
60
                    EXAMPLES
                            «
  A mixture was prepared consisting of 90% by weight
plastic A-7 soil, 10% by weight fly ash and 5% by weight
lime. After mixing with optimum water and setting under
natural ambient conditions for three  days, if was tested
for durability by submerging standard test cubes in water.
The test cubes disintegrated so rapidly that no quantita-
tive measurement of loss was obtainable.
  A composition was prepared  consisting of  60% by
weight of the same A-7 soil,  10% by weight fly ash, 5%
 10
 15
 20
 by weight lime and 30% by weight limestone screenings.
 After mixing with optimum water and setting under nat-
 ural ambient conditions for three days, test cubes of the
 resulting mix were submerged in water and tested for dis-
 integration.   Substantially  no weight loss was observed
 after submerging the cubes for three hours.

                     EXAMPLE 4

   In a series of tests, a plastic kaolin (A-7) was stabi-
 lized with varying quantities of lime, fly ash and limestone
 screenings.   The samples were allowed to set for a short
 time, water  was added, and each sample was tested for
 water retentivity.  According to this test, each soil sample
 was placed on top of a piece of filter paper supported on
 the flat perforated ceramic bottom of a Buchner funnel,
 and a standard suction was  applied.  After a certain time,
 the filter paper or ceramic  support became wet,  and  this
 fact  was visually observed.  Increments of time were
 measured and reported as  water retentivity count  The
 following results were obtained.

 Table II.—Effect  cf Ume on water rttentivity count of
                    stabilized kaolin
 25
30
                                                       30
                                                       40
wt.
KaoUn
to
00
«
W
TO
TO
TO
TO
EO
60
10
60
30
30
30
30
Wt.
a
10
10
10
10
10
10
10
» .
.•10
10
10
10
10
10
10
10
wt.
AnretBt*
(Sacra*
top)
0
0
0
0
30
20
20
20
W
40
40
40
00
eo
BO
so
wt
Lime
0















Water
Re tea-
tlvlty
Count
31
31
21
27
28
24
It
29
20
20
21
21
U
17
20
IB
                                                      46
                                                      SO
60
   The above example illustrates that, although the water
retentivity count of the composition decreases with lime
addition when a small proportion of aggregate is present,
this  effect is reversed and the water retentivity count of
the  composition increases with  lime addition when the
proportion  of aggregate  is  in  the  range  of  about
20%-50% by weight  This effect indicates that an inter-
action takes place among the lime, fly ash, soil and aggre-
gate.
                    EXAMPLE 5

   A series  of underwater disintegration tests was run.
using a Maryland A-7 clay.   Various specimens were
prepared,  containing  various  proportions  of  limestone
screenings as aggregate, and all  specimens were sub-
merged  in water for 60 hours, after  which they were
checked for hardness and compressive strength  as well
as underwater disintegration.  The results  are tabulated
in the following table:
        TabU III
8 Test
No.
i
Percent by weltbt
T.lm.
3
8
8
8
25
10
10
10
10
10
10
Boa
n
to
80
70
80
80
Afire-
0
0
10
a
30
40
Hardnesi
Very poor™
~Kor..TT!Z
Veryfood_
.,,*• .-'-.

Conpresire
Strength
S^pUcrannUd.
<80 p. «.!_._...
488 P. 1.1 	
4»p.«.l 	
Percent Disintegration
w
18
8
3.6
0
0
0
24 fan.
38
28
18
. 0.6
as
80 fan.
Almoet oom-
30.
s.
OJ.
                                                       A-86

-------
                                                   9,810,984
   The foregoing table illustrates that the underwater dis-
.inlcgration is sharply reduced and almost entirely elimi-
. nated when the percentage  aggregate approaches about
.20%  by weight, when lime and fly ash proportions are
.maintained constant  This indicates that an interaction 6
 takes  place at about 20%  by weight aggregate.
   When a plastic soil, having  high water  retentivity, is
 mixed with aggregate in an effort to improve  the  soil
 to provide a road  base, the  results  are unsatisfactory
 even  though a  very large  proportion  of aggregate is ,10
 added.  For example, when over 50% aggregate is added
 to a plastic silt or to a plastic  clay, the product quickly
 fails when subjected to alternate cycles of wetting  and
 drying or freezing and thawing, when also subjected to
 heavy loads.  It is accordingly surprising that the same IS
 soil can be stabilized to form a product having excellent
 durability under the same  conditions, when  small pro-
 portions  of lime and fly ash and as little as 20% by
 weight of aggregate are incorporated into the soil.  While
                                                                                    8
                                                          those soils having a plasticity index of about 9-15 when
                                                          more than about .15% by  weight of .the soil passes a
                                                          standard  200-tnesh sieve, and ,to .those,soils .having a
                                                          .plasticity  index of above,about. 15.
                                                            ..4. The  stabilized .soil.composition.defined in claim 1,
                                                          wherein the aggregate  has the following  screen analysis:
rStandaoi MCMD MM
If 	 	
«_ 	 ;
ho ..„......._„.„............„ . ..........
in . ...
woo .._. ... 	 .. . .. .

;Peneat by wdcbt
• pftfypg
90-100
75-100
40-90
5-35
0-1S

                                                             5. A stabilized soil  composition of matter consisting
                                                          essentially of about 5  to about 25%  by weight fly ash,
                                                          about  35 to about 75% by weight soil, said  soil being
                                                          limited to  those soils  having a  plasticity index below
 »X££*^«^^»^rt SZ; 20 ab°«'  » when more than about ;35%  by weight of the
                                                          soil passes a standard 200-mesh sieve, to those soils hav-
                                                          ing a  plasticity  index  of about 9-15  when  more  than
                                                          about  15% by weight of the soil  passes a standard 200-
                                                          mesh sieve,  and'to those soils having a plasticity index
costly  because  of the large quantity of aggregate re-
quired to create  a  good road  base, the same  soils are
efficiently and economically stabilized in accordance with
this invention,  which requires  much  less aggregate, to-     .      .   , ,,   .   .  _-_      ,     »„_
gether with small amounts of fly ash and  lime,  at  a 25 ab°ve  about I5-  abou?  20Jf  to about 50% aggregate,
drastically reduced total cost.                              said aggregate.compnsing discrete particles  of predomi-
  It will  be appreciated  that  large  aggregate, as dis-    nantly inorganic mineral material selected from the group
tinguished from the aggregate  in  accordance with this    «*«'Un8 °f iTtnn^' K"  "^         8 T^jS
invention  and hereinbefore referred to, such  as  V*  inch    I*"*  ^£-££?.f* W?5ht P3SMJ a *?*?*„*A
stones  or even  larger,  may be  incorporated  into  the *0 ««ve, about 75-100% by we.ght passes a standard No 4
stabilized  soil mixture without departing from the scope    $leve' abo"  ?££?**?** paMes a *"*"* *°' ]°
of this invention.  The expression  "consisting essentially    s!eve' •bSutll"5*.'Jr T"81".*£"* * SUndard N°' 4°
or as used  in the claims  docs  not imply that the com-    sieve' and about °"15%  by wei*ht ***** a standard
 positions of the invention must be free of other additives;
                                                                        sum   f  **   ercenu«f
                                                                              ,   .
 his intended as a definition of those components which I .-*> J* •nd«"1 *«»* ^anual y equal to 100%, and about
 must be present in order to obtain the benefits of the in-
 vention, and these benefits are obtained whether our com-
 ponents are present alone or mixed with one or  more
 compatible additives.
   Having  thus described our invention, we claim:
   1.  A stabilized  soil composition of matter consisting
 essentially of about 5% to about 25% by weight fly ash,
 about 35% to about 75% by weight plastic soil, about
 20% to about 50% aggregate, the sum of the percentages
 of fly ash, soil  and aggregate being substantially equal
'to 100%,  and about  2%  to about  9%  lime, the  per-
 centage of lime being based on the  total  weight  of fly
 ash, sojl and aggregate, said aggregate comprising a plu-
                                                          2% to about 9% by weight lime, the percentage of
                                                          being-based on the total weightr.of fly ash, soil and aggre-
                                                          gate.
                                                            6. A stabilized compact supporting coune-for a road,
                                                          highway  or.the  like,  characterized by  early durability
                                                          and pliability sufficient for re-compacting,, consisting  es-
                                                          sentially of about 5% to about 25% bywetzht fly ash,
                                                          about 35% to about 75% by weight plastic soil, abt-ut
                                                          20% to about 50%  by weight aggregate, said a—regale
                                                          comprising a plurality of discrete  particles .which  are
                                                          substantially chemically inert with respect to fly ash and
                                                          lime, and  substantially insoluble in water, the majority
                                                          of said particles ranging in size from about 40 mesh  to
 cally inert with respect to fly ash and lime, and substan-
•tiaily insoluble in water, the majority of said particles
•ranging in size from about forty mesh to about one half
 inch.
   2.  The stabilized soil composition of matter defined in
 claim 1, wherein the soil is selected from the group con-
.sisting of clay,  loam and silt
   3. The stabilized soil composition defined .in  Claim 1,
 wherein the soil is limited to those soils having a plasticity
.index below about 9  when more  than  about  35%  by
.weight of the soil passes a  standard 200-mesh sieve, to
                                                      00
                                                          about  2%  to about 9%  by weight lime, the percentage
                                                          of lime being based on the total weight of fly ash, soil
                                                          and aggregate, and about 5% to 32% by weight of water,
                                                          a percent water being based on the total weight of lime,
                                                          fly ash, soil *nd aggregate,

                                                                 References Cited in. the. file of this patent
                                                                     UNITED  STATES  PATENTS
                                                           2,564,690  , Harelin et «L	Aug. 21, 1951
                                                   A-87

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United  States  Patent
                                                                                     2,937,53!
                                                                      Pntented May 24, I860
                      2437,581

            ROAD BUILDING  METHOD

Jnie* E. Harelta. 216 Walcut Place, Harertown, Pa., and
    Frank Kahn, 186S Edmund Ro*d, Ablagtae, Pa.

  No Drawing.   Filed Jooe 2*.1997, Ser. No. 668,627

               6 Claim*.   (CL  94—21)
   This invention relates to a method of making stabilized
load-supporting bases, and more particularly relates to a
method of improving a stabilized road base composed of
lime, fly ash and finely divided soil.
   This application is a continuation-in-pan of oui appli-
cation, Ser.  No. 36.048,  filed June 30, 1948, entitled
"Hydrated Lime Fly  Ash Fine  Aggregate." now U.S.
Patent No. 2,564,690, issued August 21, 1951, and  is also
a continuation-io-part of our application Ser. No.  245. 652,
filed  August 18, 1951, now U.S.  Patent No. 2,698.252,
and is also a continuation-in-part of our co-pending patent
application Ser. No. 245,651. filed August 18, 1951, now
abandoned.  In the aforesaid patents and co-pending ap-
plication we have disclosed cementitious compositions use-
ful as structural materials, stabilized soils and  the  like
which contain fine aggregate in the form of finely divided
sand  or  other  chemically  in:rt  aggregate,  or soil.  Re-
peated experiment!) in the laboratory  as well as practical
applications in  the field have demonstrated  that,  within
specific ranges of relative proportions of those ingredients,
a mmure having unexpectedly high early comprcs»ive
strength  was obtained
   We have now discovered that unexr'ected advantages
are attained by mixing lime and fl> ash in controlled pro-
portions  with  a finely  divided soil having  a  fineness
modulus  less than  1.7,  compacting the mix.  partially
setting, then re-working  and recomputing the mi*,  and
then  setting it completely.  Soils having fineness  modulus
below 1.7 are of such fineness thai  they are cutsids the
class  of material usually referred to us aggregates  The
formation of our mixtures changes the engineering prop-
erties of  the soil  at  once, convening it  to an excellent
stabilized material  for building lond- supporting  surfaces
such  as roads,  highways,  airfield  runways and  the like.
After curing for an appropriate time, this stabilised  ma-
terial develops  advantageous strength characteristic* for
service as a load-supporting base, but these advantages are
greatly enhanced  by the method  which comprises  this
invention.
   It  is an object of this  invention to provide a method
of improving the ultimate strength of a mixture composed
of lime, fly ash and soil.
   Another object  is to provide a  method of making an
improved road or other load-supporting base.
   Further objects and advantage* of the invention  wi'l
further become apparent hereinafter.
   The foregoing and other objects are  attained  in ac-
cordance  with  this invention b> incorporating lime  and
fly ash into a finely divided soil, said finely  divided soil
having 3  fineness modulus less than 1.7, in the  presence
of moisture, compacting  the resulting composition, sub-
jecting the comparted  composition  to  partial  setting,
breaking  the partia'.ly-sct mix down  into a  plurality of
separate and divrreic particUs. recompacting the  separate
and discrete particle',  and then completing the setting of
tbs resulting recor.ipacted mix.
Th;
r^j "lime,"
                                 "soil,"  and "fineness
                             2
   modulua" are expressions well known in the ait and have
   been  discussed in  considerable detail in our aforemen-
   tioned US. Patent No. 2,698,232.
      Finely divided materials other than natural soils, which
5  are equivalent  to  the soils falling within the above  de-
   fined  soil classifications, nevertheless are included with the
   scope  of  this invention.  These  materials include fine
   sand, stone screenings, slags, gravel screenings, mineral
   deposits, fine screenings from quarry operations and  the
10 like: having fineness modulus below 1.7, as well as other
   similar soil-like materials all of which art included with-
   in the meaning of  the term "soils" as used herein.
      The relative proportions of the three principal com-
   ponents of the compositions  are important, in that a
15 wholly  unexpected peak is attained,  when  certain soil
   characteristics are  plotted against the relative proportion*
   of fly ssh  and lime in the mix, such  peak  being  of  the
   same  general character as  that represented in Fig. 2 of
   our aforementioned Patent No. 2,564.690.
20    Accordingly  the relative proportions of the  ingredient?
   are substantially 10-30 parts fly ash and 2-10 purts lime
   (expressed as Ca(OH>j)  for  each 70-90 parts of fine
   inert  msteriM.  However, prenter  proportions  of lime
   may  be employed for some soils without excessive  de-
25 trimcntal effect for the stabilization of highly plastic soils
   such  as clays and the like although as lime content is
   increased  the desirable characteristics of the composi-
   tion are rapidly lost.  Lime contents of 20% or above
   are to be  avoided  since the advantages of our invention
30 are not realized.   For certain A-7 soils and other highly
   plastic soils,  lime  contents  up  to  15 parts lime per 100
   pans soil  plus fly ash may be etnH^cd  to  advantage.
   Preferably, the lime content of the mix is within the range
   of 2-10%  lime per 100 pan;,  soil plus fly ash.
33    This  invention  is also applicable to compositions  in-
   cluded in  our  co-pending patent  arolicatron  Serial  No.
   477,122  filed December"::. 1"5-. n~w U S. Patent Vo.
   2.815 294,  i;sued D:cemher 3. I957. eotiM-Tii; essential-
   ly of about 5"£ to about  :5<^. hy w»irht fly ash. about
40 35%  to about 757e by weigh' pbrtic soil, about 1»f' to
   about 5n*£ aggregate,  the sum  of th? percentages of fiv
   ash. soil and aggregate being substantially equal to !00">
    ash and lime, and  substantially  in-
   soluble in  water,  the majority of  said panicles ringing
   in si/e from  about forty mesh  to  about one half inch.
50    Ingredients of our compositions may he  initially pre-
   pared in  any conventional manner, such as by simple
   mixing of  the  solid components,  preferably in the pres-
   ence of water.  However the mixing is preferably carried
   into effect by breaking up the soil and mixing the soil
53 with  lime and fly ash  in predetermined  proportions.
   utilizing suitable soil-breaking and  mixing equipment such
   :is that conventionally used for farm  rind construction
   purposes,  with water added to  the mixture in an amount
   substantially equal to  that proportion  of  water known
60 and defined as the optimum moisture content. Op'tmc^i
   moisture content is determined by the well known  modi-
   fied Proctor  test.
      Optimum moisture  content of a soil or stabilized soil
   mixture is that moisture content at  which the soil-moispire
gj mix has the maximum dry density,  or maximum  dry
   weieht of solids per unit volume. In practice, the optinrm
   water content varies with  each particular soil and stabi-
   lized  soil mixture,  ordinarily within the range of 8-25 ~.
   moisture by weight, based or. the total dry weight of lime.
70 fly ash. and  soil.  Preferably,  in  incorporating moisture
   into our stabilized soil nixes,  rhe waser evmrnt should
   he ecatrol'ed within  the  ripce of 70%-130%  of the
                                                       A-88

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 cs»U.
 pro;"orroning of materials  is preferably carried  out so
 that the composition  conforms  quits closely to the opti-
 mum mixture established in the  previously described tests
 cf sample mixes.
   Where the material is mixed in place, the use of a pulvi-  •"><>
 mixer or similar road construction equipment  will result
 in a  thorough and rapid blending of the materials to a
 cier'h of <>" to 8".  Usually when depths greater than 8"
 «re desired  the  application and  mixing process is prefer-
 ably carritd out ic layers.   The depth of material used  •'"'
 will depend lo a considerable  extent on the  service lo
 which the base will be subjected and on the surface cover
 placed over the base.
   The composition should preferably contain the  proper
 smouni of «ater to develop adequate density after com.  •'•"
 paction  'A'i'ere the composition is prepared in a raixir.g
 pi:.at the water may convementh be added to  the mixer.
 Tor  the  "mix-in-place" procedure the water  may  be ap-
 plied either  by  means of watering tanks or by addition of
 water to one or more of the ingredients prior  to mixing.  .,5
 regardless of the method of addition of water.  It  is usu-
 ally  esv.-uial to check  the  water content prior to com-
 paction of the base.   If the water concentration is not
 close enough to the optimum value, an adjustment thould
 he made—cither by blading or mixing material too high  ;vl)
 in moisture content or  by addition of water for further
 mixing for material too  low in water.
   Compaction of the base is accomplished by using con-
 ventional gradir.g and rolling equipment for some of the
 more plastic  t> pe soils.  A sheeps foot roller may be used  j.j
 to advantage. Flat fteel rollers or rubber wheeled rollers
 such as wobble wheel rollers may be also used to develop
 the desired compaction. Where possible the compaction
 should be checked in the field to determine whether or not
 the compaction  of the  base is adequate.  Preferably the  ands pro-
 duced in the first reaction stage.
   In accordance with this invention, the 
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                          5
                                                   2.^37,631
relatively slowly but has usually b«3 found to ttJte ?U-.c
in the tinie period u-ferred to  above in voncsctioa with
water of immobility.  A »ubsi«ntial mineral fi»canent
chaogc  occurs  in  the  first  reaction stage, as compared
to the ctunge occurring in the second  reaction stage.     5
  After the base has been  finally compacted, « final sur-
face treatment  may be applied.   In some instances no
surface treatment msy be necessary if the base ia to serve
in an application where severe traffic  or climatic condi-
tions  are not anticipated.  Usually some  form of  wear-  lo
ing or seal coat is applied to the compacted base.  This
may ccnsiM of  a coating of oil or tar with or without
additions of stone  chips.  The composition may  also be
placed directly  under bituminous or  Portland  cement
pavements  o: in some types of  road construction may act  18
a* the sub-base under other base  competitions such as
water bound macadam and the like.
  The compositions may  also be  added to larger size
aggregates  such as ballast  road stone to bind the  coarse
agregate together and thereby develop greater strength  20
aad improved stability in the base.  Many variations of
the above  sre possible.
  The method  used in the construction of the  base re-
quirts essentially convenrional road building equipment
aad therefore the  irvcn'ion may be practiced ic both a  25
convenient rnd scot-.omifsl  manner.
  The following examples arc illustrative of the invention:
                      Example 1
  A street -was  constructed for a development, utilizing  30
a mixture  consisting essentially by weight of about i%
lime, about 10% fly  ash  and  the  balance soil having a
flaecess modulus below  1.7.   After suitably mixing  the
ingredients of the composition together with water,  the
road  was compacted in an unconfined  condition and was  35
tubjected to ambient conditions for a period of 6 months.
After  6  months a  sample was removed  from the road
and disintegrated, then recompactrd and subjected to cur-
ing until it developed its final coir.pressive strength. This
produced a  conipressive  strength  of  1200  pounds per  40
square inch.  Another sample of the material which was
used  in  bui'uin? the  'ond wax taken  and such sample
was simply compacted nnd cured unit!  i* reached its fir.M
tomprsssive   ciuved H> :he two-stage process
involving breaking up the mix and recompactir.g it.

                      Example 3                       rt5
  A base was laid for a  storage area at a large  refinery.
The project consisted of a road supporting base consisting
of about 5% by weight  lime,  about 10%  by weight fly
ash, and about  85%  by  weight of A-2-4 soil having a
fiaenes^ modulus below  1.7.  At the time the base was  70
prepirrd and compacted,  representative samples of the
mixture  were taken and  these were  compacted  in the
laboratory  under controlled conditions accurately repre-
sentative of tht icnditioss in  th.~  field.  The final com-
pressive strergu1 neisurec'  -52 pounds per square inch.  75
                           Q
                 *d b*«a  *ul«j'xvd to a •»•«•*
condition: in iht field for a period of 1 ne.-jib, : sample
of ii»e base  was taien and was disintegrated and teccm-
pacteU and tested for its final comrres3tve itrcr.pth.  Such
disintegration  wes accomplished as follow*: the sample
of base was broken down, according 10 siindard  proce-
dures for preparing toil satr.pici, to a point where  it sub-
stactially met the giadation of the origical  soil  used for
construction of  the base.   The lest after  recompacting
was conducted under the same conditions as  the test with-
out recompacting and indicated an improvement of final
comprusive strength  from 452 pounds per square inch
to 570 pounds per square inch.
  One of the important advantages of our invention  is
that  it prcvidea a new concept in road building in which
the road is initially installed in a temporary way in rough
condition for immediate  use  as a  construction  road
(usable even while installing it) and then  at  some con-
venient later period it is reworked and recompe  hearing  strength of the soil,
the steps which comrris? mi\ir.g said !ime, crude fly ash
and water with the soil in rriaii-.c quantities  forming said
composition, compacting said composition, subjecting said
compacted composition to conditions within  the range  of
natural ambient  conditions for a  limited period of time
of about a  week to a year until partial setting of said
composition occurs  and the bearing strength of the com-
position  is substantially m.rcai;d. disintegrating and re-
mixing  the  partially-set composition and  distributing it
along  a  predetermined  rood course,  reccrnpacting raid
palially-set  composition ia situ, and then <.ubjer;mg said
compacted partially-set composition  to narj-il  a~bient
conditions for a  suitable time until reaction cf iaia lime.
f.y ish and soil u complete.
  2.  In a method of building a  road of u slow-setting
composition consisting essentially of about 10^c-30% by
                                                          A-90

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                           7
h»- r, a Sr-fiw moiufcs MC.-JT 1.7, the rein of iV p«r-
ce^'ajis of -.-o:! plus fiy ash  being sufc-ssat-f'&liy ecuj! to
'".<.  *i'J ilrout ITc to about  9?? by isajjb'. icclu.-ive of
ii;rs, said  con«'.ositiop. having an esrly  bcarin;  strcsgtii
which is much gresicr  than  the bwiog szrtoyth of the
>«?, the step*  which comprise looatr.ing the toii along a
predetermined course, mhtng said !i:nc, crude fiy ash and
water  with the soil in relauve  quantities forrrJag  said
cociposirion, compaeiins .'.aid '.omposition, subjecting the
compacted comr3?:::on to natural ambient conditions for
a limited period of  time of about a week to a year until
substantial partis! setting of said composition occurs and
the besring strength of the composition is increased while
isid ics-.posiooa i<  in a re-workaNe condition, looxn;rf
lit parually-sct compacted compo«itipn before ssid setting
is cor-iri'iete. dixiniesratirsg and tenuiag the lessened p*r-
tiaHy-stJ coniyxjsiaoo,  and then  subjtctios *a«d  rey aih sod soil is complete.
  ?. The rri-:hnd defined in claim 2. v.-hertin the original
mix  is compacted in an un.-anfined conditior,. by down-
wa.-dl) directed pressure only.
  4  !n a  mcth'Xl  of building a road of  a composition
           evv?ir:a!l> r>f aiit IOfc-30^  b>  weight fiy
           TCi-Wf hy wcich: soil h^vin; a fineness modu-
           li  th*  sum of tl.j pctseT-.g*;  of soil plus

          ^ by  we-ignt inclusive of  litae, acirr.:rA  to tlir '.:me required to proUucc  a compre.ssive
str.-^eth of about ot.-half  toe to:np-«:ssi\e strenfth tliat
would be provlucol atter cc:;ip!i.:ii.'a of  »iJ ia1
Mb. sbo-.i
lu» Vrlr*
5y »»L '
u> about
          Ur.f U.e r.'1"r ;>i t"r ^•••j'tnce of rc'Vi1'!
   5  TSs tretbc-i rfcfi^v 1 ia cL'-ir *•, 'j-hcrein tnt •?!
stl ;i!i.iv ,a\, afsir having beer Jivritepr.-.trd, M r?-ih:r>?d
and r^-cornpictst* in  tu.c prc»?r;c  of riio^U'rc ar.-? -.ub-
jected to REOU-a! ambient roodit'cru ur.t:! said intsrac^on
is ccoipieted.
   6.  A wo-iiage aiethod of  bwilding a road of a liow-
settms  comrcsition  cca««:ng  csstntiaiiy  of   aN>ut

•oil having a fineness  modulus be!ow 1.7. the sur»> of '.he
percentages of soil plus fly <**h being 'urstanutlly  equal
to 100, and about 2s subsion-
tiaily iocrcascd, ?ersiinat:ng the fi.-M ?tige of sai- setticg
by disinsejra'inj the parua'h  set mix fnto a p'urali.y of
separate and divrrcie oai:>.!•:'•  " :Ltic a  pericw of about a
wfvk to al-jtit .  >cai  af'.i-r -.STJ vottij .-..tjon, «.uch period
being limited a> a miVTrurf t" ;be !irrc r^qa.'tfd  tc pro-
Juce  a compressive »:r^ac'-h of ahoiit one-half the  core-
picssive strength  that would be frjduce- aficr com^ietion
of  said  setting,  re-shaping the disintegrated  nix,  then
commencing the  seccnd setting Magi *y re-c>~i,ipacon$
'be disintegrated  re shaped mix io ;he presv^r* c»f .•*•,•.;•.•
ture, and subjecting the  resultirg r.;b to csta-j' eir.^.-'.'-:
conditioas until  :he setting rcacuon b-i:»'ee"<  s.-;d  !unf.
fiy ash and soil is complete.

        Refzreocrji C.'ited in the f.le oi ih«- prttst
             UNITED STATE.': i ATLNTS
                                                          A-91

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          ASTM STANDARD SPECIFICATIONS AND STANDARD TEST METHODS
          The following is a list of ASTM standard specifications and test
materials which are relevant  to this study.  The complete specifications
can be found  in the pertinent ASTM documents.
ANSI/ASTM C29-78
ANSI/ASTM C88-76

ANSI/ASTM C127-80

ANSI/ASTM C128-79

ANSI/ASTM C131-76


ANSI/ASTM C311-77


ASTM C593-69

ANSI/ASTM C593-76a

ASTM D422-63
ANSI/ASTM D558-57

ANSI/ASTM D698-78



ANSI/ASTM D1557-78



ANSI/ASTM D1883-73
ANSI/ASTM
ANSI/ASTM

ANSI/ASTM

ANSI/ASTM

ANSI/ASTM
ANSI/ASTM
D2049-69
D2435-70

D2850-70

D3080-72

D1074-76
D1075-76
ANSI/ASTM D1138-73
ANSI/ASTM D1559-76
Unit Weight and Voids in Aggregate
Soundness of Aggregates by Use of
  Sodium Sulfate or Magnesium Sulfate
Specific Gravity and Absorption of
  Coarse Aggregates
Specific Gravity and Absorption of
  Coarse Aggregates
Resistance to Abrasion of Small Size
  Coarse Aggregate by Use of the Los
  Angeles Machine
Sampling and Testing Fly Ash or Natural
  Pozzolans for Use  as a Mineral Ad-
  mixture in Portland Cement Concrete
Fly Ash and Other Pozzolans for Use
  with Lime
Fly Ash and Other Pozzolans for Use
  with Lime
Particle-Size Analysis of Soils
Moisture Demsity Relations of Soil-
  Cement Mixtures
Moisture Density Relations of Soils
  and Soil-Aggregate Mixtures Using
  5.5 Ib (2.49-kg) Rammer and 12-in.
  (305-mm) Drop
Moisture-Density Relations of Soils
  and Soil-Aggregate Mixtures Using
  10-lb (4.54-kg) Rammer and 18-in.
  (457-mm) Drop
Bearing Ratio of Laboratory-Compacted
  Soils
Relative Density of Cohesionless Soils
One-Dimensional Consolidation Properties
  of Soils
Unconsolidated, Undrained Strength of
  Cohesive Soils in Triaxial Compression
Direct Shear Test of Soils Under Con-
  solidated Drained Conditions
Compressive Strength of Bituminous Mixture!
Effect of Water on Cohesion of Compacted  •
  Bituminous Mixtures
Resistance to Plastic Flow of Fine-Aggre-
  gate Bituminous Mixtures by Means of
  the Hubbard-Field Apparatus
Resistance of Plastic Flow of Bituminous
  Mixtures Using Marshall Apparatus
Recommended Practice for Use of Process
  Waste in Structural Fill
A-92

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vO
U>
     *POZ-0-BLEND - THE SECOND GENERATION OF P02-0-PAC*

                        L. John Hinntck-7




                      HISTORICAL BACKGROUND

     The original  efforts  In  the early forties of HavelIn and Kahn?/
(engineers with the Philadelphia Electric Company)  to develop lime-
fly ash-"soll" mixtures  for structural purposes has resulted in a ma-
jor Industry In the field  of  road construction.  Since the composi-
tions Mere first produced  at  the Plymouth Heeling plant of the G. t
V. H. Corson company, approximately fifty Million tons of Poz-0-Pac«
have been placed,   licensees  have produced material In twenty states,
and roads and highways of  all types have now been in service fur many
years (some In excess of twenty years).  Major airports, parking lots.
highway embankments, reservoirs, and  dams all have  used the Poz-0-Pac
compositions.  Specifications have been drafted by many state and
federal agencies,  the most recent being the specification Issued by
the Federal Aviation Administration covering this product.

     The properties of the Poz-0-Pac  compositions have been carefully
studied In numerous laboratories and  evaluation programs of field Jobs
have been reported many times in the  literature.!/  The product cow-
petes with other types of stabilized  base compositions, namely cement
aggregate base and asphalt aggregate  base.  Figure  1 shows a recent
photograph of a feeder road that was  placed  In Salem County. N. J.
In 195*.  Figures 2 and 3 show views  ul   set, durability, etc. such  as is often done
  In  Portland ceuenl concrete.   Control ol optimum density in the final
 nu can also be  influenced by  proper prcaiixlng and adjustment of the
  fly ash nali't*.

  S.Mji.iiaf  (Yi.>«fr*a/«vM»   extensive  investigations have been carried
 out over  the  last  five  years to  develop a so-called "winter mix* Pui-
 0-Pac.   The purpose  of  this  is to allow lor  late season construction

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    •nd avoid problems  ctuscd by tow temperature  curing.   The new concepts
    of "degree days" which have been reported In  the  literature*/ can  be
    substantially modified by using the Poz-0-Blend formulations.   In  ef-
    fect, this means that sever*) classes  of  Poz-0-Pac  can be designed In-
    stead of a single formulation as used  In  the  past.   This Is  analogous,
    for example, to the use of different types  of portland cement In  the
    design of concrete  mixtures.

    tnvlnonmtfitAt PnoptAtitAi  Poi-0-Olend Is attractive since  It does not
    use a significant quantity of energy sensitive materials.   In view of
    the high cost of energy today, this results therefore In a  Poz-0-Pac
    composition that Is very competitive to tho other products  specified
    for road base use.   In addition, the large quantities of ash used In
    the mixtures provides an outlet to assist In the  disposal  (and  utili-
    zation) of power plant waste.

    Jtchnical fitU Supporti  The Poz-0-Blend concept also uses highly
    trained technicians for field support purposes.  This covers such ar-
    eas as providing assistance In drafting specifications for  the  base
    Material, establishment of suitable test  procedures for quality con-
    trol, and providing technical data to develop proper design of  the
    road base.  In this connection. It should be mentioned that in  the
    state of Pennsylvania the merit factor for Poz-0-Pac has now been set
<*"  at a value of 0.40 which places It on an  equivalent design  basis  with
vo  Portland cement or asphalt stabilized compositions.

                             FIELD ACTIVITIES

         An Important evaluation program was  undertaken In 1973 in  cooper-
    ation with  the Pennsylvania Department of Transportation.   A number of
    sections of roadway were designed and placed at two separate times of
    the year; the first section early In the month of September, and the
    second section late In the month of October.  The highway  department
    utilized a road rater as one of its evaluation methods.  This  device
    Measures variations In the roadway surface caused by deflection under
    load and establishes  In  this manner the performance of the road base.
    Figure 5 shows the equipment used for this purpose.  While it  Is not
    the  Intention of this paper to provide specific data of the tests,
    the results have clearly indicated that the Poz-0-Blend formulations
    gave superior results to some of the conventional mixtures.  In addi-
    tion, cores have been taken out of the roadway at various  times and
       Thompson. H.R.. and B. J. Oempsey.   Final Report - Durability
       Testing of Stabilized Materials.  Illinois Cooperative Highway
       Research Program Series No. 152,  1974.
measurements have been made on these cores and on laboratory prepared
specimens.  These data have been used to assist in the development of
ultimate design criteria of Poz-0-Blend and Poz-0-Pac for future use.

     During the year of 1975 a full -.cale plant has been constructed
at Kansas City, Missouri which uses fly ash from Kansas City Power
and Light Company.  The plant Is located adjacent to the Hawthorne
Station and can therefore supply Poz-0-Dlend for an area that can use
considerable quantities of the Poz-0-Pac road base.  Figures 6 and 7
show photographs of the plant at Kansas City.  One Interesting aspect
of the Kansas City program Is the use of some lignite fly ash which
Is a quite reactive material.  Tbe production of Poz-0-Blend with this
fly ash provides a means of controlling this reactivity so that it will
perform In the final composition In an optimal manner.  Previous expe-
rience with this type of fly ash has shown that It is sometimes diffi-
cult to control the reactions in road base Mixtures.

     While It is not yet appropriate to refer to other plants that are
now being proposed, It is anticipated that at least two More of these
blending systems will become operational In 1976.  Conversion Systems
is cooperating with the utilities in constructing a complete system
for utilizing fly ash in the manufacture of Poz-0-Blend.  This In-
cludes the financing, construction, and operation of the plant by
Conversion Systems who also serves as a supplier of the product to the
local stabilized base producers.  Marketing Is also carried out using
local Conversion Systems' organizations.  This program therefore re-
presents a major step forward In the development of a reputable fi-
nancially strong alliance of pertinent groups in the Marketing of the
final Poz-0-Pac base.

                               SUMMARY

     As a result of many years of experience and use of lime-fly ash-
aggregate mixtures known as Poz-0-Pac road base, a new concept has been
formulated to assist in the growth of this important product.  Poz-0-
Blend cement Is a quality controlled mixture of all Ingredients exclu-
sive of the aggregate.  It is produced in a centrally located plant
usually on or adjacent to the power plant.  Conversion Systems is
offering to the utilities an ash utilization program including fi-
nancing, construction, and operation of the Poz-0-Blend plant.  The
company also provides marketing and technical services to assist in
the production and placement of the final Poz-0-Pac composition.

     Results to date show that the new generation of Poz-0-Pac produces
a product with improved structural properties, durability, and quality
control.  The Poz-0-Pac road base, produced with Poz-0-Blend cement, is
economically competitive with the leading base course materials.

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                                Appendix B

                     SUPPORT DOCUMENTATION - KILN DUST
          This appendix contains copies of three patents cited in Chapter 6
of Volume 1.  They relate to the  use of kiln dust in stabilized road bases.
                                   B-l

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                                             4,018,617
                        1                                                    2
                                                     lion. Such bases have been used in limited geographical
MIXTURE FOR PAVKMENT BASKS AND THE LIKE    .ircas of the  United Stales where  they can compete
                                                     economically because of availability of lime and fly ash.
  Tliis invention relates to materials which are capable      Thus, the picdominantly used stabilized  bases utilize
of supporting surfacing such as-pavement bases.       3 materials th.it .ire in short supply and require substan-
      HArKCHOUND OF THF IN VPlsniON          lial Muaillil'«» "f w'Kf'«»pnxluce them. The materials
      BACKGROUND OF  TTHL INVENTION          ma? ^ lCMncd cncrgy ;n,cnsivc .|lierc i$ a necd  ,o
  hi road  paving, at one time it wus  thought thai the    avoid or minimi/e  the use of such energy intensive
base for the surfacing material should  comprise a gran-    materials in road paving.
ula» or  gravel base.  However, more recently, it has  10   Accordingly, among the object* of the invention are
been  concluded that there wus a considerable differ-    In provide a mixture of materials for producing a stabi-
cncc  in the performance between such bases and cc-    lizcd  base comprising a  hard, strong, durable mass
mcnl-a^gTcgalc  or  bituminous   (asphalO-afyjrcpaic    cnpnhlc of supporting surfacing which avoids or mini-
bases. As reported in  the  Highway  Research Board    mi/es the use of materials which are cncrgy intensive
Special Report 6IE, tilled The AASHO Road Test.  15 and, moreover,  utilizes  materials  that normally are
Report  5, Pavement Research, publication 954 of Na-    waste materials that arc readily available.
tional Academy  of  Sciences  -  National  Research             ct 1MMARY OF THE INVENTION
Council, there is a clear sujxriority of such treated             SUMMARY Of THE INVENTION   .
bases over untreated bases. In recent  years, treated      Basically, the invention  comprises a mixture consist-
bases have  become commonly known u  stabilized  30 ing essentially of fly ash.  cement kiln dust and aggre-
bases.                                               gate which through pnzzolanic  reactions  produces a
   In subsequent work, for example, use of asphalt mix-    hard, strong,  durable mass capable of supporting sur-
tures in aJI courses of pavement above the subgrade has    facing.
been proposed. The Asphalt Institute. Information Sc-           ni-'SrairnON DP THF  nn Awiwrc
rics No. 146, June 1968. Asphalt stabilized bases have  J5        DESCRIPTION OF THE  DRAWINGS
become the  most dominant stabilized base utilized  to      FIGS. 1-3 arc curves of comprcssive strength versus
support a flexible surfacing such as asphalt concrete.  In    age at lest for various compositions.
addition, asphalt concrete has found extensive use as a      FIG. 4 is curves of cncrgy requirements for various
resurfacing material for concrete pavement.              pavement materials.
   It has also been proposed  that a lime-fly ash-aggrc-  30                  nncrDnrnnvi
gate stabilized base be used in road paving. Such a base                     Uf^t-KlPTlON
consists of a mixture of proper quantities of lime, fly      In accordance with the invention, the p^zzolanic load
ash, and graded a££rccalc at opiimum  moisture con-    supposing composition utilizes cement kiln dust.
tent,  in which the stability is greatly enhanced  by the      The solid waste generated by cement manufacture is
cementing action which results from complex chemical  33 primarily kiln dust. This dust contains a mixture of raw
reactions between the lime-and the fly ash in the prcs-    kiln feed, partly  calcined material, finely  divided ce-
CHCC of water.                                        nurnt  clinker and  alkali  sulfatcs (usually  sulfates).
  Stabilized bases arc usually employed as base coursrs    There is economic value  in returning the  dust to the
under wearing surfaces such as  hot  mixed, hot  laid    kiln, but when the alkali content of the returned dust is
asphaltic concrete. A wearing surface is necessary  to  40 loo high for the product klinker to meet specifications,
resist the  high shearing stresses which  are caused by    the dust must  be discarded. Up to about 15% of the raw
traction, but the stabilized base provides the required    maicrials processed may be collected as dust and of this
stability to support wheel  loads.                        alxiut half may be low enough to alkalis to  be returned
  A serious obstacle to the expanded use of stabilized    to the  kiln. The  rest is usually stockpiled u a waste
bases is the high energy costs for making the materials.  43 material which must  be disposed and may be a nuisance
   For example, it is well known that the production  of    and po.-aibly a hazard.
portland cement which is used in stabilizing bases re-      Although the chemical reactions occurring in  the
quires substantial quantities of coal in manufacture.  In    resultant cement kiln dust are not well known, typical
fact the United States Department of Transportation    cement kiln dust has a chemical  analysis as follows:
has suggested that fly ash be substituted for a portion  of  50   SiO,
the portland  cement utilized in concrete or cement-      AI,O,
aggregate bases, Federal Highway Administration No-      Fc
-------
3
4,018,617
4

-continued
biwltl
U|iulKM i^'
S0_ 26J
NN0 ^ 3.11^)
j.Q- V^ilV^
l|niiiim ^32.^
Sotiici
l^
10.7
/ooiN
VJ-OlX
<5j^)
Souice^
i^C
1.12
/Ci\
1^.3 >*
<2^0>
' Soviet Sonic*
2.4 13.6
02 /OT«\
4J L^2.9^y
36.6* (f^vP
Sfl
-------
                             4.018.617




                        EXAMPLE I
Cement Kiln Own
Fly A«h
LJmritonc
Tout
Prite-nl
	 ITST
12.0%
10.0%
~I56.(ri
Wci|hl of
Hatch
•OTIS 	
1.6 IM
24 0 IU
JoTJW
Specimen
Nu.
A
B
C
D
E
F
Percent
W.icr
10 I
10.1
IO.S
lO.t
101
10.1
Wi. At
Molded (LU.)
4.7)
4.72
4.73
4.71
4.73
4.73
Wei WL Dry Wl Arts
Pri CM. Ft. Per Cu H. (^. In )
HI.
141.
141.
141.
|4|.
141.
121.
127.
121.
171.
12S.
121
I2.J7
12.37
I2J7
12.57
I2.J7
I2.J7
Due
Tc.ird
10-16
10-16
• 10-23
1023
11-06
11-06
Mach.
\a*4
13.140
14.370
1 3.7 JO
15.330
17.100
17.800
P.S.I.
10)0
1140
1260
1240
1420
1420
l Wi*. ml -•
                        EXAMPLE 11
Cement Kiln Dtn
FlyAU
UmcMonc
Reorder
Tout
Specimen Pcicenl
Me. W.icr
A
U
c
D
E
F
10.1
10.1
10.2
10.2
10.3
,10.3
, -*F
12
10
Wd|htof
ent Batch
0% 2.4 ib*.
0* 3.6 Ibv
0* 24.0 Ib*.
0.96 ox
100.0* 30.0 Ib*.
Wt. Ai Wet WL Dry WL
Molded 
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                                              4,018,617
                                  EXAMPLE IV-conlinued
                                                                              8
XVcifhl at
Pricent DJU h
Ccmcni Kiln Duat ID* "24 Ib
Suet Dual 3.0% 0.9 Ib
FlyAih 13.0% 3.611)
Limciioiw 77.0% 73 I Ib
Toul 100X4" ICTHE
Specimen Pminl Wl Al Wcl W|. Dry Wt
No. • W.ui Molded (Lba.) Per Cu. Ft. Pel Cu. Ft.







Aiti Due Mack.
(Sq la.) Tnlcd Load P.S.I.
           9.0
                     4.36
                                   136.1
                                                123.3
                                                            12.37
                                                                11-07    14.150
                                                                                      IIIO
•.•XlL

K. »ta.<«
                                        EXAMPLE V
Ccmcat Xun Dual
FlyAah
Tulal
                                    Wcithl at
                                    Batch	
                            12
                            M.0%
 3.6 Ib
26.40i
30TTIG	
Specimen
No.
A
B
C
D
E
F
Fficeal
Waur
9J
9.7
9.7
9.7
9.7
10.0
WL A*
Molded (Lba.)
2.17
2.90
2.90
2.90
2.90
2.96
Wet Wu
Pet Cu. Ft.
S6.I
S7.0
17.0
17.0
17.0
11.1
Dry Wt.
Per Cu. Ft.
71.6
7VJ
79J
79.3
79.3
10.7
Area
(Sq In.)
12.37
12.57
11.57
12.57
12.57
1257
Date
Tcaled
10 17
10 17
1074
1024
11-07
11 07
Mach.
Load
2J50
2.300
2.075
1.900
3.040
3.230
MX
117
113
165
151
240
260
                                                                to«w«ly "IWfly"
                                       EXAMPLE VI
Crmeal Kite Dual
Fly Aib
LinolOM
Uimctioac Finca
Toul
Percent
— nw
1.0%
79.0%
'100.0%""
Wei.M at
Daicn
2415
2.4 Ib
23.7 Ib
1.3 Ib
30TJTE
  WmUl »Uc
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                                        4,018,617
                                                                    10
                                EXAMPLE VIII
Fly Aih
Kiln bull
No. 304 l.imritnnt
Prrcrnt
~ 10.01
»0*
X201
Weight of
natch
3.00 rt»
2 40 lh
74 Ml |h
   (Screened o»ei V* KICCO)
Tuial
                                    30.00 lh
at
4
3
6
Percent
Waiet
9.4
9.3
9.6
9.3
Wi. Ai
Molded (Lba.)
4.72
4.71
4.7 1
4.69
4.61
4.69
Wet Wl.
Per Cu. Kl.
141.6
141.3
I41.J
140.7
1404
140.7
Or, Wl.
Pel Cu. Ft.
129.6
1J9.2
12'U
1313
12H.I
121.3
Atra
(Sq. In )
12.37
12.37
1J.37
12.37
12.57
12.57
Dale
Tested
4.01
401
401
4.22
422
4-22
Maeh.
l-oad
1060
7750
1000
9730
10450
11490
PA1.
640
613
615
773
130
915
A. SaUBpk* f«Ul*«J tlMpC I«IU«W|

1. N» (M* *tMI MUC44 *
                          tnim
                                EXAMPLE IX
Fly Aah
Kiln Dull
Fill Sand
Total
Cyl. Percent
No. Waict
1 9.1
7 10.0
3 9.9
4 V.9
5 10.0
6 9.1
Percent
1.0%
10 oa
R20*
I ub.b*
Wl. Ai
Molded (Lba.)
4.09
4.12
4.10
4.11
4.10
4.09
Weight of
natch
j'no ib
24 60 Ib
30.00 Ib
Wet Wt.
Per Cu. Ft.
122.7
123.6
123.0
123.3
123.0
122.7

Dt> Wl.
Pet Cu. Ft.
II 1.7
112.4
111.9
112.2
II 1.1
111.7
Area
(Sq In.)
12.37
12.37
12.57
12.57
12.57
12.37
Hate
Teiicd
301
3-31
3-31
4-21
4-21
421
Maeh.
Load
1100
1700
1690
2010
2110
2670
PAL
145
133
133
223
230
210
A H« kW«tfm| •/ •*•*»!• tf»mn| cwfltf acln*
a Utwml •uy«4 * • Wfi «kc« p«cl<4 ft? k*ft*J.
C SU|ki WU«.| *MK<4.
l> UMI!) COMf«TMj.
                                EXAMPLE X
Wcithl ol
Percent Batch
Fl» Aih U.W "CTOTS
Kun Dual 100% 3.00 Ib
Clau (Cnuhed to
anmot. *" me) 32.0O. 9.60 Ib
Kill Sutd 30 » 5.0 Ib
Toul TOO.tflt 30~.00 Ib
CyL Percenl Wt, A« Wet Wt.
No. Water Molded (Lba.) Per Cu. Ft.
1
2
3
4
5
A. UftiffMj
0 Su»|t»
9.4
9.4
9.3
9.2
9.1
9.1
?£££
4JO
4.50
4.31
4.52
4.51
4.47
4 u 10 J» ».
(Krr Ihwi tip*
133.0
133.0
135.3
135.6
133.3
134.1
IHI«««. L*Acd ••!. pmaab
r V.4% ••*!«««. rfid Ml ft*
• «lU> llM UMMk (Mil •!
t«4. Ju»|kl UK ma »n«l
Dry WL
Per C». Ft
123.4
123.4
123.1
124.2
1240
122.9
ly b.r>.> ••».<
tf llip <«
-------
11
                4,018,617
12
          EXAMPLE XII

Ccmcnl Hil« Dtul
Fly Ai»
Nil J04 CiuihcJ LimctUMte
Ti

    -------
    
    
    13
    Cement Kita Dual
    Fly A»h
    Limolunc Sticrnin|t
    No. )7 Cnuhed UmoioAC
    Water
    Teul
    Specimen
    No.
    A
    B
    C
    D
    E
    r
    G
    u
    i
    )
    t
    L
    M
    N
    O
    4,018,617
    EXAMI'Lli XV
    14
    
    
    Weichi . ~TWIb'
    1 1.7% 240 Ih
    J9 0* ROO Ih
    ]9.