AEROSPACE REPORT NO.
)059(6781)-1
Final Report
Technical and Economic Factors
* ' • i •
Associated with Fly Ash Utilization
71 JUL 26
Prepared for SPECIAL PROJECTS SECTION
DIVISION,OF CONTROL SYSTEMS
OFFICE OF AIR PROGRAMS
ENVIRONMENTAL PROTECTION AGENCY
Contract No. F047.01-70-C-0059
Office of Corporate Planning
-------
Report No.
TOR-0059(6 781 )-1
FINAL REPORT
TECHNICAL AND ECONOMIC FACTORS
ASSOCIATED WITH FLY ASH UTILIZATION
71 JUL 26
Office of Corporate Planning
THE AEROSPACE CORPORATION
El Segundo, California
Prepared for
Special Projects Section
Divis ion of Control Systems
OFFICE OF AIR PROGRAMS
ENVIRONMENTAL PROTECTION AGENCY
Contract No. F04701-70-C-0059
-------
FOREWORD
The study of the technical and economic factors associated with fly ash
and limestone-modified fly ash involves many different types of industries,
technologies, agenc ies and individuals, such that the results given her ein
cover a broad range of data and interests. To simplify the reading of the
results, a comprehensive summary of the study is provided in Section 1.
Included in that section is a statement of conclus ions, Section 1. 3, and a
listing of recommendations for future efforts necessary to improve the fly
ash market, Section 1. 4. The main body of this report is presented in
Sections 4 and 5. These provide the basic details of the survey and study
efforts of this program. Supporting data and listings of relevant literature
and data sources are given in the appendices.
The per iod of performance for this study was October 1970 through June 1971.
Appreciation is acknowledged for the assistance and guidance provided by
Dr. J.S. Bowen and Mr. T.A. Kittleman of the Environmental Protection
Agency, Office of Air Programs, Division of Control Systems, Special
Projects Section (formerly Process Research Section), for whom this study
was conducted.
The following technical personnel of The Aerospace Corporation engaged in
the surveys and contr ibuted to studies performed under this contract:
Mr. F. E. Cook
Mr. O. Bamber g
Dr. R. C. R 0 s s i
Mr. A. K. Smalley
g~
APPROVED BY:
Fly Ash Study Program
eltzer
. ector of Pollution and Resources
Programs
Office of Corporate Planning
-iii-
-------
FOREWORD. . . . .
CON TENTS
............
. . . . . .
.......
S UMMA.R Y . . . . . . . . . . . . . . . . . . . . . . . . . . .
1. 1 Scope of the Study. . . . . . . . . . . . . . . . . . . .
1.2 Study Approach and Procedures. . . . . . . . . . . . .
1. 3 Summary of Results, and Conclus ions. . . . . . . . .
1. 3.1 Fly Ash Unmodified. . . . . . . . . . . . . .
1. 3. 1. 1 Specifications and Fly Ash
Quality Assessment. . . . . . . .
1.
1.3.1.2
1.3.1.3
1.3.1.4
1.3.1.5
1.3.1.6
1.3.1.7
1.3.1.8
1.3.1.9
1.3.1.10
1.3.1.11
1.3.1.12
1.3.1.13
1.3.1.14
1.3.2
Concrete. . . . . . . . . . . . . . .
Mass Concrete and Concrete
Products. . . . . . . . . . . . . . .
LightweightAggregate . . . . . . .
Portland Cement Manufacturing. . .
Br icks . . . . . . . . . . . . . . . .
Bituminous Filler
Road Construction.
.........
.....
. . . .
Agriculture and Land
Reclamation. . . .
........
Remote Filling of Mine Cavities. .
Land Fill. . . . . . . . . . . . . . .
Mineral Wool. . . . .
. . . . . . .
Gas Concrete
.......
. . . . .
Miscellaneous Uses and Potential
New Use s . . . . . . . . . . . . . .
Limestone-Modified Fly Ash
. . . . .
. . . .
Summary of Recommendations
1.4
1. 4. 1
1. 4. 2
. . . .
.........
Regular Fly Ash. . . . . . .
.........
Wet-Collected Limestone-Modified
Fly Ash. . . . . . . . . . . . . . .
. . . . . .
-v-
ill
1-1
1-1
1-2
1-3
1-6
1-6
1-8
1-11
1-12
1-12
1-12
1-13
1-13
1-15
1-15
1-16
1-16
1-17
1-17
1-18
1-19
1-19
1-20
-------
2.
CONTENTS (Continued)
IN" TR ODUC TION . . . . . . . . . . . . . . . . . . . . . . . .
2. 1 Purpose of Study. . . . . . . . . . . . . . . . . . . .
2.2 Significant Factors Pertaining to Fly Ash
Utilization. . . . . . . . . . . . . . . . . . . . . . . .
2.2. 1
2.2.2
2.3
2.4
Regular Fly Ash. . . . . . . . . . . . . . . .
Wet-Collected Limestone- Modified
Fly Ash. . . . . . . . . . . . . . . . . . . . .
Organization of Study. . . . . . . . . . . . . .
Scope of Effor t. . . . . . . . . . . . . . . . .
.....
. . . . .
LITERA TURE SUR VEY AND PERSONAL CONTAC TS . . . .
3. 1 Literature Survey. . . . . . . . . . . . . . . . . . . .
3.2 Per sonal Contacts. . . . . . . . . . . . . . . . . . . .
3.
4.
FLY AS H SUR VE Y . . . . . . . . . . . . . . . . . . . . . . .
4. 1 Fly Ash Production. . . . . . . . . . . . . . . . . . . .
4. 1. 1 Fly Ash Geographic Distribution and
A va ilab il ity . . . . . . . . . . . . . . . . . . .
Fly Ash Disposal Costs. . . . . . . . . . . .
Freight Rates Versus Shipping Distances. . .
Fly Ash Quality and F. O. B. Utility Costs. . .
4. 1. 2
4. 1. 3
4. 1. 4
4.2
4.2. I
Utilization and Economics.
Concrete
. . . .
..........
......
4.2.2
........
.......
4.2.1.1
4.2.1.2
4.2.1. 3
Structural Concrete
. . . .
. . . .
Mas s Concrete
.....
. . . . . .
Concrete Products
.....
. . . .
Lightweight Aggregate. . . . . . . . . . . . .
4.2.2. I Technology - General Charac-
teris tics and Process ing . . . . . .
4.2.2.2
4.2.2.3
Technology Limitations. . . . . . .
Inhibitions For Use of Fly Ash in
Lightwe ight Aggregate. . . . . . .
-vi-
2-1
2-1
2-1
2-1
2-3
2-4
2-4
3-1
3-1
3-1
4-1
4-1
4-4
4-6
4-7
4-8
4-11
4-15
4-16
4-29
4-31
4-33
4-34
4-36
4-38
-------
4.3
CONTENTS (Continued)
4.2.3
4.2.4
Portland Cement Manufacture. . . .
Br icks
. . . . . .
. . . . .
........
.....
. . . .
4.2.4.1
4.2.4.2
4. 2.4. 3
Fly Ash Br ick Technology
. . . . . .
Economics
. . . . .
.........
Potential Utilization
.........
4.2.5
Filler in Bituminous Products
.........
4.2.5.1
Utilization Potential
. . . . . . . . .
4.2. 6
4.2.7
Remote Filling of Mine Cavities. . . . . . . . .
Mis c e llane 0 us Use s. . . . . . . . . . . . . . . .
4.2.7.1
4.2.7.2
Agriculture
. . . . . .
........
Land Fill
......
.........
4.2.8
Gas Concrete
......
. . . .
. . . . . . . .
4.2.8.1
Material Requirements and Gas
Concrete Properties. . . . . . . . .
4.2.8.2
4.2.8.3
4.2.8.4
4.2.8.5
Manufactur ing Proces ses .
. . . . . .
Applications
Economics
. . . .
. . . . . . . . .
. . . . .
. . . .
. . . . .
Usage Potential for Fly Ash and
Limestone-Modified Fly Ash in
Gas Concr e te . . . . . . . . . . . . .
4.2.9 Foreign 'Utilization. . . . . . . . . . . . . . . .
Fly Ash Specifications and Properties. . . . . . . . . .
4.3. 1 Introduction....................
4. 3. 2 Specifications Applicability. . . . . . . . . . .
4.3.3 Fly Ash for Use in Portland Cement Concrete. .
4.3.3.1 Develo-pmentofSpecifications.....
4.3.3.2 Provisions of Specifications. . . . .
4.3.3.3 Specifications Versus Fly Ash
Properties. . . . . . . . . . . . . .
4.3.3.4 Specifications Versus Fly Ash
Utilization. . . . . . . . . . . . . .
-vii-
4-39
4-43
4-43
4-45
4-46
4-47
4-47
4-49
4-50
4-51
4-51
4-52
4-53
4-55
4-57
4-58
4-60
4-61
4-67
4-67
4-68
4-68
4-68
4-69
4-71
4-79
-------
4.4
4.5
4.6
4.7
CONTENTS (Continued)
4. 3. 3. 5
Adequacy of Exis ting Spec ifi-
cations. . . . . . . . . . . . .
. . . .
4.3.3.6
Proposed Specification Modi-
fications . . . . . . . . . . . .
. . . .
4.3.4
Fly Ash for Use in the Manufacture of Portland
Cement and Portland Cement Concrete
Products. . . . . . . . . . . . . . . . . . . . .
Fly Ash for Use in Products Other Than
Portland Cement Concrete. . . . . . . . . . . .
Fly Ash Concrete - Advanced Technology. . . . . . . . .
4.4. 1 Advantages and Disadvantages. . . . . . . . .
4.4. 2 Subs titution Ver sus Ingredient. . . . . . . . . .
4.4.3 Quality-Specification Relationship. . . . . . . .
Fly Ash in Paving. . . . . . . . . . . . . . . . . .
4.3.5
4. 5. 1
4.5.2
Pavement Design. .
. . . . . . . .
. . . . . . .
Fly Ash Utilization in State Highway
Pr 0 gr ams. . . . . . . . . . . . . . . . . . . . .
Fly Ash in Airport Construction. . . . . . . . .
Unique Fore ign Applications. . . . . . . . . . .
Potential Utilization. . . . . . . . . . . . . . .
4.5.3
4.5.4
4.5.5
Development Programs. . . . . . . . . . . . . . . . . .
Fly Ash Use - Inhibitions Summary. . . . . . . . . .
WET-LIMES TONE-MODIFIED FLY ASH SURVEY. . . . . . .
5. 1 Scope of Survey. . . . . . . . . . . . . . . . . . . . . .
5.1.1 Limestone-Modified Fly Ash Research Per-
formed at the Coal Research Bureau. . . . . .
5.
5.2
5. 3
Dry-Collected Limestone-Modified
Fl y Ash. . . . . . . . . . . . . . . .
5.1. 1. 2 Wet-Collected Limestone-Modified
Fly Ash. . . . . . . . . . . . . . . .
Modified Ash Production and Cons iderations . . . . . . .
5.1.1.1
Survey of Wet Process Systems
. . . . . . .
. . . . . .
-viii-
4-81
4-84
4-87
4-88
4-91
4-92
4-93
4-98
4-101
4-101
4-102
4-112
4-112
4-114
4-11 7
4-119
5-1
5-1
5-1
5-1
5-2
5-3
5-4
-------
1-
CONTENTS (Continued)
5.4
Wet Process Limestone-Modified Fly Ash
Properties and Quantities. . . . . . . . . . . . . . . .
Wet-Scrubbed Limestone-Modified Ash Research. . . .
Bas ic Qualities of the Modified Ash Affecting
Utilization. . . . . . . . . . . . . . . . . . .
5.5
5. 6
. . . . .
5. 7
Evaluation of Utilization with Significant Use
Par aine ter s . . . . . . . . . . . . . . . . .
......
5. 8
Re sear ch Cons ider ations
. . . .
. . . . . .
. . . . . .
5. 8. 1
5. 8. 2
Character ization . . .
. . . . . . . .
.....
Mass Usage of Limestone-Modified
Fly Ash. . . . . . . . . . . . . .
......
5. 9
5. 8. 3 Toxicology...................
5. 8.4 Mineral Recovery. . . . .' . . . . . . . . . . .
Utilization Inhibitions. . . . . . . . . . . . . . . . . .
APPENDICES:
A: BIB LIOGRAPHY. . . . . . . . . . . . . . . . . . . . . . . . . .
B: ACKNOWLEDGEMENTS TO SOURCES OF FLY ASH DATA. . .
C: BASIC PORTLAND CEMENT CONCRETE PROPOR TIONING
TECHNOLOGY AND ECONOMICS OF FLY ASH CONCRETE. .
D: DESCRIPTION OF TWO FLY ASH LIGHTWEIGHT
AGGREGATE PLANTS. ; . . . . . . . . . . . . . . . . . . . .
E: CEMENT PRODUCTION PLANT UTILIZING FLY ASH. . . . .
F: DESCRIPTION OF FLY ASH BRICK PILOT PLANT. . . . . . .
G: DRY-COLLECTED LIMESTONE-MODIFIED FLY ASH. . . . .
H: SAMPLE SPECIFICATION AND USE DATA FOR FLY ASH
AS AN ADMIXTURE IN CONCRETE FURNISHED BY THE
TENNESSEE VALLEY AUTHORITY DIVISION OF
ENGINEERING DESIGN. . . . . . . . . . . . . . . . . . . . .
-ix-
5-6
5-8
5-9
5-11
5-13
5-13
5-14
5-15
5-16
5-17
A-I
B-1
C-l
D-l
E-l
F-l
G-l
H-l
-------
1-1
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
TABLES
Es timated Fly Ash Utilization Potential (Million
Tons Per Year) .. .. .. .. .. .. .. " " " " " " " " " " "
" " " " "
1970 Fly Ash Utilization
" " " " " " "
......
" " " " "
Potential Fly Ash Utilization
" " " "
.....
.......
Advantages and Disadvantages of Fly Ash in Concrete. . .
Fly Ash Concrete - Minimum Cement Proportions and
Economic Proportions. . . . , . , , . . , . , . , ., , . , ,
ACI Fly Ash Concrete Proportions
.......
" " " " "
American Concrete Institute Fly Ash Concrete Pro-
portions for Mix C (Non-Air -Entrained, I-in. .
Aggregate, 4- in, Slump) , , , , , , . . , . . . . , , , . .
Foreign Production and Utilization of Bituminous
Ashes - 1967 (Fly Ash, Bottom Ash and Boiler
Slag)" " " " " " " " " " " " " .. .. " " " " " " " .. " " " .. " "
Specifications for Fly Ash as an Admixture in
Concrete.. " " " " " " .. " " " " .. .. .. .. " " "
" .. " " " .. "
Comparisons of EEl Fly Ash Sample Data with
Chemical Specifications, , . . . , , . , . . . .
.. " " " " ..
Compar ison of OHIO Fly Ash Sample Data with
Chemical Specifications, , , , , , . . , . . . ,
" " .. .. .. ..
Compar isons of EEl Fly Ash Sample Data with
Phys ical Specifications. . . . . , . . . , . . ,
......
Compar isons of OHIO Fly Ash Sample Data with
Phys ical Specifications. . . , . . . . . . , , , .
" .. .. .. ..
Summary, Fly Ash Samples Conforming to Key Provision
of Various Specifications for Use in Portland
Cement Concrete.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. " .. .. ..
Fly Ash Utilization in State Highway Programs
-x-
1-5
4-13
4-15
4-17
4-22
4-24
4-25
4-64
4-72
4-73
4-74
4-75
4-76
4-77
4-106
-------
5-1
C-l
C-2
C-3
C-4
C-5
C-6
C-7
G-l
G-2
G-3
TABLES (Continued)
Wet-Adsorbed Limestone-modified Fly Ash - Theoretical
Var iations in Chemical and Phase Compos ition with
Var iations in Sulfur and Ash Content of Coal Burned. . . . .
Age-Strength Relationship of Air-Entrained Concrete.
ACI Recommended Maximum Permiss ible Water-
Cement Ratios for Different Types of Structures and
Degrees of Exposure. . . . . . . . . . . . . . .
Standards of Concrete Control. .
. . . . . . .
. . . .
Amount of Water in Concrete Mixes
. . . . .
. . . .
. . . .
Economic Factors (Non-Air-Entrained Concrete,
1- in. Aggre~ate, 4-in. Slump, Type I Cement) .
. . . . . .
Example Cos t Var iations of Fly Ash Concrete Compared
to Portland Cement Concrete (28-Day, Non-Air-
Entrained, 3000-ps i Concrete) . . . . . . . . . .
Air -Entrained Concrete. . . . .
......
. . . . . . . . .
Spark Source Mass Spectrographic Analysis of TVA
Dry-Collected, Limestone-Modified Fly Ash by
Shell Development Company. . . . . . . . . . . .
. . . . .
Dry-Collected Limestone-Modified Fly Ash Trace
Analysis by Shell Development Company. . . . . . .
. . . .
Oak Ridge Spark Source Mass Spectrometry Analysis of
TV A Dry-Collected Limestone-Modified Fly Ash. . . . . .
-xi-
5-5
C-2
C-5
C-9
C-IO
C-15
C-19
C-20
G-l
G-2
G-3
-------
I ----~.
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
C-l
C-2
C-3
C-4
C-5
FIGURES
United States Coal Consumption
. . . . .
......
. . . .
Coal Consumption and Fly Ash Production
. . . .
......
Power Stations
-.............
. . . .
......
National Fly Ash Production by Plant Size (Developed
from Use Data in 1970 Keystone Coal Industry Manual) . . .
Fly Ash Production and Utilization. . .
. . . . . . .
. . . .
TV A Fly Ash Concrete Proportions. . .
.......
. . . .
Economic Proportions of Fly Ash for 28-Day Strength
Cone rete. . . . . . . . . . . . . . . . . . . . . . . . . . .
TV A and ACI Fly Ash Concrete, Example Proportioning
Compar is ons. . . . . . . . . . . . . . . . . . . . . . . . . .
Typical Construction Applications
. . . .
. . . . . .
. . . .
Compressive Strength of Various Concrete Mixtures
Age at Test - 28 days. . . . . . . . . . . . . . . . .
. . . .
Proportioning and Curing Time Effects on Compressive
S tr en g th . . . . . . . . ~ . . . . . . . . . . . . . . . . . . .
Typical Highway Construction. .
. . . . .
......
. . . .
Fly Ash in Airport Construction
.....
.....
. . . . .
Typical Base Deflection Pattern Under a Moving Load
Moist Curing of Portland Cement Concrete. . .
. . . . . . .
Water /Cement - Strength Relation of Concrete. .
......
Tes t Results Var iations . . .
......
.....
Design Requirements. . . . . .
..........
.....
Concrete Production Dis tr ibution
. . . .
. . . .
-xii-
4-2
4-3
4-5
4-6
4-14
4-20
4-22
4-26
4-59
4-94
4-96
4-103
4-104
4-109
C-2
C-4
C-6
C-8
C-Il
-------
C-6
C-7
C-8
C-9
D-l
D-2
E-l
F-l
FIGURES (Continued)
R~ady- Mix Concrete Consumption
. . . . . .
........
Fly Ash Transportation Cost. . . . . . . . . .
.......
Fly Ash Concrete Economics, 2500-3500 psi
. . . .
. . . .
Fly Ash Concrete Economics, 3750-5000 psi
........
Fly Ash Lightweight Aggregate Production Flow
. . . . . .
Fly Ash Lightweight Aggregate Production - Material
Flow. . . . . . . . . . . . . . . . . . .
. . . .
. . . . . . .
Portland Cement Production. . . . . .
. . . .
. . . .
. . . .
Flow Diagram of Fly Ash-Brick Pilot Plant
. . . . . . . . .
-xiii-
C-12
C-14
C-17
C-18
D-2
D-5
E-3
F-l
-------
~
~I
~.
~I
-------
SECTION 1
SUMMARY
1.1
SCOPE OF THE STUDY
This report contains the results of a study performed to determine charac-
ter istics pertaining to the current and potential us e of fly ash, the particu-
late res idue produced from burning pulver ized coal. Because of the great
number and var iety of industries and individuals involved in total production
and use of fly ash, this study was directed toward that produced by the coal
burning power utilities. This constitutes the major portion of fly ash pro-
duced in this country and is the source of ash collected and sometimes used
as a raw material for various products or applications. Presently, of the
26.5 million tons produced annually, approximately 1. 6 to 2 million tons
are utilized. Additionally, the power utilities have in some instances
installed systems to remove gases of sulfur which result from coal combus-
tion. Some of these systems employ wet limestone scrubbing of the resulting
fly ash and effluent gases. This process appreciably modifies the fly ash
such that it is not amenable to most utilization schemes to which the unmodi-
fied (regular) fly ash is applied, and it increases the amount of fly ash
produced by as much as one and one-half to three times. This process, if
widely used, could have an appreciable impact on the existing and potential
unmodified fly ash market.
The objectives of this study were to investigate the current and potential uses
of regular fly ash and to: (a) identify the factors which inhibit its use, (b)
investigate the applicability of substituting wet-limes tone-modified fly ash in
the regular fly ash market, and (c) make recommendations for developing
both the regular and wet-limes tone-modified fly ash markets.
1-1
-------
1.2
STUDY APPROACH AND PROCEDURES
It has been established through development and actual practice that fly ash is
a valuable mineral resource and as such has been successfully used in
numerous applications. However, this usage has been rather limited (i. e.,
1. 5 to 2. 0 million tons per year over the past four year s), and does not show
any sign of attaining rapid advancements. Although the possibility of new
discoveries or developments was not neglected in this study, the principal
approach taken to investigate inhibitions and potential uses of the regular ash
was to cons ider those uses for which it is already applied and where the us e
could consume large quantities of fly ash. New or modified developments,
however, are a signiiicant factor in the as ses sment of modified ash utiliza-
tion.
The production and utilization of fly ash involves many organizations and
individuals throughout varying geographic regions of the United States. There-
fore, since no set conditions or circumstances are generally applicable to
all cases, it was necessary to select significant circumstances and relate
them to the appropriate organizations and geographic areas as best suited to
the attainment of the objectives of this study. The emphasis of these efforts
was placed on what is best for the nation as a whole and not necessarily on
what may be des ired in isolated areas.
The review of limestone-modified fly ash was limited to the ash produced by
the wet limestone process. Other systems produce a dry limestone-modified
ash which has been studied in other programs in considerable detail (see
Section 5.1).
The major portion of this study was directed toward the production and utili-
zation of regular fly ash. In addition to its being a principal consideration in
the objectives of this study, an understanding of fly ash, of the inhibitions to
its use, and of its present and potential market are basic to the determination
of the potential utilization of modified fly ash. This is due to the fact that for
1-2
-------
many uses conceived for the modified ash, its marketing processes will be
similar to those of regular ash. This relationship, when cons ider ing use
inhibitions, should appreciably aid the determination .of: (a) the efforts to be
expended on modified ash developments for existing fly ash uses, (b) the
neces s ity for developing new uses, and (c) the methods and potential of
marketing modified ash.
After the foregoing study approach was established, the study was conducted
according to the following procedures:
1.3
1.
Review the literature pertaining to fly ash production,
utilization, technology, and marketing.
Review the status of fly ash production, utilization,
technology, and mar keting with individuals significantly
involved with fly ash in power plant operation, sales,
research and development, product manufacture, product
use, trade associations, technical societies, and govern-
ment agencies. (A list of these contacts can be found
in Appendix B. )
2.
3.
Determine fly ash uses having high technical utilization
potential and assign priorities for further study.
Analyze current and potential use inhibitions on the bas is
of technology, economics, and producer and user attitudes.
Make recommendations for improvement of fly ash market.
Review known and projected qualities of wet-collected
limestone-modified fly ash.
Determine potential uses for modified ash and es timate
its use inhibitions and impact on regular ash market.
Make recommendations for the programs or tasks which
should be performed for development of a modified ash
market.
4.
5.
6.
7.
8.
SUMMARY OF RESULTS, AND CONCLUSIONS
Although ny ash is used in var ious applications, those utilizations consume
only a small portion of the total amount of fly ash available. Through a
review of the current technology via the literature and through contacts with
individuals in the industry, an estimation was made of the amount of fly ash
1-3
-------
that could be technically utilized in the vanous applications used today
regardless of any other circumstances such as supply, economics, etc.
This was done for the purpose of identifying those areas that could best
benefit from the increased mas s utilization of fly ash, thereby indicating
where effort, if any, should be applied for the improvement of the market.
Maximum technically feasible uses of at least one million tons per year
are listed in Table I-I, column 1.
It should be noted that this is based on
ash composition and possible product utilization alone. The 1970 actual
utilization values for each use are listed in column 2, and total 1. 6 million
tons per year. As a result of this survey, it is estimated that if fly ash
were used in the. applications listed in Table 1-1 such that the maximum
practical potential would be utilized under current technology and associated
market conditions, approximately 7 million tons would be utilized, as
shown in column 3. It must be realized, for clar ity, that this study was not
a marketing analysis and that these values are merely best estimates. The
significance of this list is that it indicates approximately 75 percent of the
fly ash produced in the United States is not marketable without significant
changes being made to reduce or eliminate the following limitations: (a)
inadequate technology and knowledge dissemination related to known uses,
(b) geographic limitations on transportation economics, (c) insufficient
marketing efforts, (d) lack of control of fly ash production and supply, (e)
cost effects of other materials or processes, and (f) insufficient develop-
ment of new technologies.
The values given in column 4 of Table 1-1 are estimates of the amounts of
fly ash that would be consumed if all the limitations just noted were removed,
except some geographic limitations on transportation. These factors are
discussed in detail in Section 4 of this report. Again, these values are
estimates, but they indicate areas where it is believed fly ash can be used
in large quantities if appropriate steps are taken. This approach limits the
area of concern to: (a) fly ash concrete, (b) lightweight aggregate, (c)
road base cour ses, (d) new uses or developments such as gas concrete
building construction, ceramic products, and miner al recovery, and (e)
control of mine subsidence and fires.
1-4
-------
Table 1-1.
Use
Fly Ash Concrete (Structural,
Mas s and Concrete Products)
Lightwe ight Aggregate
Raw Mater ial for Cement
Br icks
.....-
I
V1
Filler m Bituminous Products
Base Stabilized for Roads
Agriculture and Land
Reclamation
Control of Mine Subs idence
and Fires
Structural Fill for Roads,
Construction Sites, Land
Reclamation, etc.
Others
Total (Million Tons/Year)
Estimated Fly Ash Utilization Potential
(Million Tons Per Year)
1
2
3
,"
4'"
Maximum Utilization 1970
Te chnically Feas ible Utilization
10-15 0.54
13 0.21
13 O. 16
10 -- --
1-2 0.13
> Annual Production 0.11
> Ann ual Production - - --
> 1 0.01
> Annual Production 0.32
----------
O. 16
1. 64
Estimated Utilization
Potential
Current hnproved
Conditions Utilization
..'....'..
3. 5 6. 0 .,--~
..'....'....,..
O. 5 >3. 0"""'"
O. 25 ~::: ~:~ ::::: :::::
- - - - - - --
O. 75 -.1..........'.....'..
.,"","",""1"
O. 3 >10. 0
- - - - - - --
O. 75 >1. 0
O. 6 ::::::::::::::::::::
0.25
6.9
:;:::::::::::::::::::::::
- - --
,..
"'The values in Column 4 are scaled against the current market, but may take as much as
5 to 10 years for realization with maximum efforts.
.......'..
"--"Value can be increased cons iderably with use of fly ash gas concrete in building construction.
.......,...,.1..
-'--'--"Has potential for accelerated future growth well beyond the proportions shown here.
.1.. ..I.. ..'....1..
""''''''''N 0 a ppre c iable incr eas e.
..1....'....'....'..,1..
""'''''''''''Significant increases are possible through new developments such as ceramic products
and mineral recovery.
-------
Becaus e of limited operational exper ience with the wet scrubbed proces s, data
pertaining to modified fly ash properties and potential uses is limited. Based
on the limited theoretical analyses performed dur ing this study and those
collected from researchers in the industry, it was concluded that there may be
certain potential uses for the modified ash, but that research and development
are required to establish any of them as being technically and economically
feas ible. The potential impact of modified ash on the total regular ash mar-
ket cannot be estimated since the extent to which the wet limestone processes
will be used is not known. Its potential impact would be best estimated in
terms of what effect it would have as a replacement for the regular ash in a
particular locality, and this can be done accurately only after technical and
economic study, research, and development of the modified ash is made.
Early indications are that technically, the modified ash may be able to sub-
stitute (with appropriate alterations) for the regular ash in road base con-
struction and cement production, lightweight aggregate (accompanied by
sulfur collection), fill material, autoclave products, and possibly gas con-
crete if the market exists. It does not appear to be a reasonable replace-
ment in portland cement concrete without cons iderable benefic iation. New
potential uses include gypsum pr oducts, pres sure s intered products, new
asphalt filler mater ials, sulfur production, and mineral extraction.
1.3.1
Fly Ash Unmodified
1.3.1.1
Specifications and Fly Ash Quality Assessment
All known specifications for fly ash used as a material for product manufac-
ture or application, and for fly ash products were examined for the purpose
of assessing the extent to which they inhibit the utilization of fly ash. It was
determined that except for the specifications on fly ash as an admixture in
portland cement concrete, specifications do not inhibit the use of fly ash.
Detailed discus s ion on spec ificatlons can be found in Section 4. 3.
There are individuals and organizations who, by combining the production or
procurement of quality fly ash, appropriate concrete technology, and dis-
semination of the knowledge, have marketed fly ash readily within the limits
1-6
-------
1-
I.
of existing specifications (ASTM or Federal Bureau Specifications) or have
wr itten their own (e. g., TVA). The general fly ash community has not done
this and therefore the use of fly ash concrete is not widespread. The lack
of under standing of fly ash concrete by the general community, isolated cases
of misuse of fly ash, and the dissemination of inaccurate or misleading in-
formation concerning fly ash (e. g., broadcast of the term "waste product, II
intolerable low early strength, bad color) has inhibited potential dealer s,
contractors, ar chitects, and engineer s. The power companies (with few
exceptions) have not taken the initiative to improve the quality of fly ash or
to maintain a cons istent quality. Improvement in that area would undoubtedly
relax the inhibitions to the use of fly ash by giving potential users the
assurance of having a readily available supply of a quality grade of fly ash.
It is believed that a considerable portion of the fly ash produced today is
usable as an admixture in portland cement concrete. Section 4.3 presents
a comparative analysis of existing fly ash sampling data with existing speci-
fications for fly ash as an admixture in portland cement concrete. Table 4-13
shows that approximately 60 percent of the fly ash is usable in concrete,
with 6-percent loss on ignition (LOI) and 20 to 22-percent residue on 325-
mesh sieve being the key considerations. A significant factor which could
not be ver ified dur ing this study was obtained from unoffic ial information.
This information indicated that the 60-percent usability factor noted above
could be increased to approximately 80 percent by us ing existing power plant
personnel and equipment more efficiently through improved maintenance and
operation of combustion and ash collection equipment. A well-recognized
result of that would be an improvement in power production efficiency.
It is interesting to note in Table 4-13 the effect of a proposed change in ASTM
Specification C - 618 which would make acceptable approximately 78 per cent of
fly ash produced. Certain reservations to this are discussed in Section
4.3.3.6.
1-7
-------
Because the specifications for fly ash as an admixture in concrete are numer-
ous, conflicting, and irrelevant in many respects, recommendations are
made that new specifications or procedures be written that will recognize
properly proportioned fly ash concrete as a standard technology which relates
various grades of fly ash to structural concrete usages, and includes design
strength beyond 28-day cure. A procedure which avoids the current time-
consuming process of specification writing, verification, and approval is
advisable.
1.3.1.2
Concrete
Fly ash is used in portland cement concrete for the improved pr operties it
imparts to the concrete. Among these improvements is pumpability, com-
pres s ive strength, long-term strength, workability, finishability, and
resistance to sulfates and alkali-aggregate reaction; it decreases the heat of
hydration, drying shrinkage, particle segregation, bleeding, permeability,
and leaching. These qualities are well-documented (see Section 4.2. 1. 1)
and have been demonstrated repeatedly in actual practice. The net effect is
a stronger and more durable product which requires less cost to put in
place and finish. It is significant to note that for properly proportioned fly
ash concrete, early strength, form removal per iods, and cur ing require-
men ts ar e not us e - inhib itions.
Pr incipal inhibitions to the use of fly ash in concrete are the lack of a
dependable supply of usable quality ash, and the nonrecognition of the techno-
logical gains and potential improvements (see Section 1. 3. 1) which would
allow the use of various qualities (or classes) of fly ash and greater than
28-day design strength criteria.
As noted earlier, a fly ash concrete technology (now practiced by only a few
individuals in the concrete industry) which allows the use of more and coarser
fly ash should be recognized and publicized through a new set of specifica-
tions or procedures, including the recognition of the long-term cur ing
strength of fly ash concrete.
1-8
-------
[.
The choice of concrete cure time should be based on the economics involved
with construction. Since the cost impact on mater ials by us ing fly ash is
often small relative to the cost of placing and finishing the concrete, the
des ign conditions should be dependent upon the requirements of cons truction.
However, the state-of-the-art in concrete construction requires design
compressive strengths of 28 days and does not include an optimal cure time
in the total economics. A cure time of 28 days represents that point at which
portland cement concrete will attain up to 90 per cent of its ultimate strength
and is considered representative of the true strength of the concrete. How-
ever, in concrete containing fly ash, 28-day cure times are arbitrary and
meaningless since the strength tested at that time does not represent the
ultimate strength of the concrete when fully cured, which occur s after 28
days. Using a 90-day cure, for example, allows more fly ash, less cement,
provides higher strength, and affords advantages in pouring, pumping, and
finishing. While the concept of 28-day des ign strengths lar gely dominates
the concrete construction industry, there are few examples that can be cited
in which structur~s under construction will experience their design loads in
28 days. Until the concrete construction industry becomes aware of the
increased latitude in concrete mix design that is offered by a technology using
fly ash in an effective, economical manner, an inhibition to the use of fly
ash in concrete will pers ist. The architects, engineers, contractor s, and
concrete producers must be educated in this respect.
The continued development and acceptance of properly proportioned fly ash
ir.. concrete is likely to provide the basis for renewed interest in fly ash as a
concrete ingredient. Intensive sales campaigns, although beneficial, have
been effective only in local regions. When the user s of concrete become
fully aware of the range of advantages and properties that properly propor-
tioned fly ash concrete offers, their reluctance to use fly ash in concrete
should diminish and an increase in demand may be expected.
Significant deter rants to the massive use of fly ash in concrete, assuming
the supply is made adequate (see Section 1. 3. 1) and the technology is
1-9
-------
improved, are the requirements for additional storage and handling equip-
ment at the ready-mix plants, and hauling costs. A study of the economics
of fly ash concrete related to the ready-mix operation was performed to
determine if that is an inhibitory factor since the literature is weak in this
respect. A detailed, comprehensive cost analys is could not be performed
within the extent of this study because of: (a) the numerous, variable fac-
tors involved plus the variation in costs from region to region; (b) the use
or nonuse of beneficiation of the fly ash, brokerage fees, and financ ial
assistance to ready-mix dealers for new equipment; and (c) sliding costs
related to local competition. The analysis was therefore limited to estimates
of the more significant factors, i. e., costs of fly ash F. O. B. utility, cement,'
truck hauling, new equipment, and chemical admixtures. Strict conclusions
cannot be drawn from this analys is because of the many cost var iations
involved for each case; however, indications are that (based on Table C - 6 in
Appendix C) a dealer can increase his profit before taxes by approximately
50 cents per cubic yard if high quality fly ash concrete is delivered within
10 miles of the fly ash source, or he can break-even at about 150 miles.
On the other extreme, there is the poss ibility of a combination of circum-
stances, including the use of low-grade fly ash, which indicates that he will
not be able to match portland cement air-entrained concrete on an equal
production economics bas is.
In most cases, however, the dealer should be
able to produce fly ash concrete to compete with portland cement concrete
for haul distances of approximately 50 to 150 miles, depending on the many
cost factor s involved. Since the profit, before taxes, on portland cement
concrete is in the range of $2 to $3 per cubic yard (according to various
personal contacts), a potential increase of 20 to 50 cents per cubic yard
would be appreciable to the dealer. If circumstances, as noted above,
lncreas e the cos t to the dealer, that increase is generally small enough to
be absorbed by the contractor who stands to benefit from the economic and
technical advantages of using fly ash concrete.
1-10
-------
In cons ideration of the utilization of "greater -than-28-day" design strengths
described earlier, the production costs of fly ash concrete can be reduced
rather dramatically. Using this technology where applicable, cost reduc-
tions can be attained for any type of concrete, and for some it can be well
in excess of one dollar per cubic yard.
I'
Bar ge or rail transport provides ales s expens ive means of hauling fly ash
than truck, but is applicable to only certain peculiar geographic situations.
It should be noted that the development and acceptance of a standardized fly
ash concrete technology by the concrete industry would expand the market
and bring a large percentage of the power companies into the supply market;
consequently, any transportation inhibition would be significantly decreased
in most of the eastern half of the country.
1.3.1.3
Mass Concrete and Concrete Products
Fly ash is used in much of the mass concrete construction in dams and
spillways conducted by the U. S. Army Corps of Engineers and the Bureau of
Reclamation. Specifications exist for this use and fly ash is proportioned
accordingly, principally to lower the heat of hydration and also for its pump-
ability feature. Technically, a larger percentage of fly ash could be used in
these structures; however, the present proportioning is adequate. With the
bulk of this type of work being performed in the western United States where
fly ash must be transported for long distances, its use is not a strong
economic incentive. With new coal-burning power stations opening in the
West, it is poss ible that fly ash may become more economically des irable.
Usage may increase, but the small number of such projects make this
potential use a small percentage of the national supply.
Concrete products such as building blocks, pipe and precast units represent
a very attractive field for fly ash usage. Fly ash is used for this application
and is well accepted; its pr inci~al inhiblitions are the lack of guar anteed
quality ash, and transportation cost limits. It was estimated that if this
industry were exploited to its fullest extent, it would consume a maximum
of 5 percent of fly ash production.
1-11
-------
1.3.1.4
Lightwe ight Aggregate
The predicted high future demand for lightweight aggregate is based on
dwindling supplies of natural aggregates plus the increas ing recognition
by architects and engineers of a future demand for large-scale usage of
lightweight concrete. Present developments of fly ash lightweight aggre-
gate production technology in the United States, Canada, and Germany
have been reviewed. All are still in various phases of development and
are attempting to solve technical problems of production. Lightweight fly
ash aggregate in the U. S. is not yet cons idered to be an economically
competitive product.
This is an infant industry, and solutions to its problems are being sought
and incorporated in the process. It has been shown that a quality product
can be manufactured. Whether the manufacturing process and market can
be sufficiently developed to economically compete with other lightweight
aggregates remains to be seen. A significant increase in the utilization of
fly ash for this application appears possible, but cannot be expected in the
near future.
1.3.1.5
Portland Cement Manufacturing
Fly ash lends itself economically to the production of portland cement only
under certain special situations where the manufactur ing plant cannot be
located adjacent to the major raw mater ial source or wher e pos s ibly the
required mineral depos its are located close to a utility. However, in most
cases such special situations do not exist. This, coupled with the fact that
there is no need for new cement plants since the present market demands
considerably less than production capacity, indicates that the potential for
utilizing fly ash in large sums for the manufacture of portland cement is
relatively low.
1.3.1.6
Br icks
Although fly ash can be used technically for making bricks, there is no
shortage of clay deposits for brick making. The principal sources of fly ash
in the United States are all close to ample sources of natural raw mater ials
1-12
-------
for br ick manufactur ing. Whether the coinc idence of a depleting source of
natural raw mater ials, a dependable local source of high quality fly ash,
and a knowledgeable entrepreneur will soon co-exist may determine whether
fly ash will eventually find an application as an ingredient in brick. This is
not expected on a wide scale. Additional factor s indicating that this utiliza-
tion potential will not mater ialize to any appreciable extent include: (a) fly
ash br ick manufactur ing requires new handling equipment and production
machinery, (b) fly ash bricks are not especially cheaper than ordinary
bricks, and (c) the present United States brick production capacity exceeds
demand.
1.3.1.7
Bituminous Filler
There are numerous uses for fly ash in bituminous products, however, its
use as a mineral filler in asphalt concrete (black top) pavement is the major
application for large tonnage usage. Low quaJity fly ash can be used, and
current technology is sufficient. The competition to fly ash includes an arr ay
of low cost, abundant mater ials, all of which are adequate as a mineral
filler. Although this is a good use for fly ash, particularly in cons ider ation
of the mileage of new asphalt roads (2 to 4 in. thick) or resurfacing of old
roads (1 in. thick), the potential usage is not large, probably much less than
one million tons per year. This limitation is caused by competition and is
aggravated by the special problems of storage and handling.
1.3.1.8
Road Construction
Except for use as a mineral filler in asphalt, or occasional use as a struc-
turalland fill, road base course applications appear to be the only practical
large-scale use for fly ash in road building. Although this application has
an extremely large potential, supported by the facts that the technology is
developed and a technical super ior ity over competing mater ials has been
demonstrated, certain inhibitions are preventing a substantial growth of
this application. It is not widely used in road contracts even though its cost
is less than or equal to competing materials of equal strength for urban
1-13
-------
construction. Proven applications are das s ified as lime -pozzolan-aggregate
base courses (pozzolan base), which involve patent rights. Factual data which
would substantiate the inhibition of the use of this mater ial because of royalty
payments were not found; however, such an excuse has been given for nonuse
on occas ion. An example of competition which a pozzolan base course can-
not meet is the use of a gravel or crushed rock base 6 in. thick under 2 to
4 in. of asphalt paving. Some municipalities, after allowing this form of
construction, have later been faced with the continual problem of repair of a
failing roadway.
The pozzolan base course is used mostly for urban applications. Portable
mixers are not widely used, and hauling costs are often limited by the use of
mater ials available at or near the construction site. . However, the amount
of paving urban roadways, subdivis ion streets, parking lots, and airports
represents an extremely large market. Present usage appears to extend as
far as 40 to 50 miles from the mixing plant. Almost any fly ash produced
today is adequate for this application, and it can be stored outdoors during
the winter months and, with mini~al processing, can be used during the
construction season.
The true inhibitions to the use of pozzolan bases is not apparent even after
contact was made with over two dozen state highway departments.
Most
states are aware of its benefits but have chosen not to use it.
The reasons
given were almost always vague. The pr incipal inhibition may be that most
potential users have not had exper ience with it and are reluctant to make a
change. A thorough, detailed marketing analysis of road construction would
be required for the var ious regions of the country within range of potential
pozzolan base cour se supplies to determine the justification and advisability
of action by government road contracting agencies as regards the consump-
tion of fly ash for this purpose.
1-14
-------
1.3.1.9
Agr iculture and Land Reclamation
Although this application appears to be a method for utilizing large amounts
of fly ash, it is not economically attractive when compared to the use of
lime or other additives to adjust soil pH. The transportation and handling
costs for the large amounts of fly ash that would be required appears to be
prohibitive. Generally, the proportionate amounts of fly ash to limestone
required to achieve an equivalent soil condition or crop yield is sufficiently
high (as much as 30 to 1) as to be beyond c~ns ideration. Moreover, the
presence of certain trace elements often found in the fly ash would be detri-
mental to the growth behavior of many common types of vegetation. It may
find usage in certain local areas, but is not expected on a wide scale basis.
1.3.1.10
Re.mote Filling of Mine Cavities
In the coal mining areas, mine subsidence damage to homes, bridges, and
roads is an increasing problem. The increase is due only partially to addi-
tional mining. It can also be attributed to the growing need for urban and
suburban land which has extended building over old mines, where slow
deterioration of supporting conditions results in surface subsidence many
years after mining has occurred. In addition to the subsidence, abandoned-
mine fires have also become a ser ious problem in coal mining areas. The
technology for remote filling of mines has been developed and the cost is
estimated at $2.00 to $4. 00 per ton within 30 miles of the source if the fly
ash is provided free of charge by the utility. Since many large coal-burning
power plants are located near the coal mining areas, the filling of abandoned
mines appears to be an excellent means, for utilizing/disposing of the entire
amount of fly ash produced by these utilities. Many utilities are currently
incurr ing cos ts of up to $2. 00 per ton to dump fly ash and as much as $4. 00
per ton where local regulations require the utility to landscape the land fill
area. This factor plus the economic cons ider ations of land value improve-
ment resulting from the elimination of mine subsidence could possibly justi-
fy the economics of this form of utilization, particularly during the time
when more profitable uses cannot or are not being employed.
1-15
-------
1.3.1.11
Land Fill
Where structural land fill is required and hauling distances are short, fly
ash can often be used more economically than other fill materials and can
provide technical advantages. It is handled and hauled in a wet condition,
thereby eliminating special handling provis ions. Among these advantages
are ease of handling and spreading, low compaction density, and shear
strength that continues to increase with time (a consequence of pozzolanic
reaction with residual lime content in the ash). Fly ash, when covered with
soil, provides excellent drainage for vegetation. Also, any grade of fly ash
is adequate and does not have to be s tor ed, handled, or hauled in an
enclosed and dry condition. However, the use of fly ash for land fill (exclud-
ing fly ash disposal) is not widely applied in this country. It has demonstrated
its usefulness in the United States in embankments and abutment backing in
highway construction, but it is not widely used for these purposes because of
the availability of natural fill mater ials. Except for special c ir cumstance s
such as extremely high fill embankments for roadways built over weak sub-
soils, or other cases where local fill mater ials are not available, little use
of fly ash as a land fill is expected except for disposal purposes.
1.3.1.12
Miner al Wool
The use of fly ash as the raw material for mineral wool manufacture requires
no deviation from the state-of-the-art commercial manufacture of mineral
wool, and there appears to be no technical inhibitions to the use of fly ash
in this application.
Inhibitions are apparently in the comparative economies of manufacture and
in the likelihood of overcapacity in competition with mineral wool and fiber-
glass insulation materials. To date, a market position for fly ash mineral
wool has not been found.
1-16
-------
1.3.1.13
Gas Concr e te
Gas concrete, a porous concrete building material which is approximately
one-fourth to one-third the density of ordinary concrete, utilizes fly ash up
to 80 per cent of the solid constituent we ight. It is made in patented European
processes and is widely used in many fore ign countr ies but not in the United
State s.
European utilization of gas concrete has proven it to be a highly desirable
form of building material from the standpoint of construction economy and
structural qualitie s. It is used in at least 20 countr ies; for example, it is
used on a wide scale in Denmark; in West Germany, gas concrete is used in
the construction of 80 per cent of all new factory buildings, while in Sweden
such use approaches lOO per cent. Additionally, in the Philippine Islands it
is now being used for the construction of low-cost hous ing projects, and in
England, it is expected that in 1971, one million tons of fly ash will be con-
sumed in gas concrete. Since fly ash improves the quality of gas concrete,
reduces capital and production costs, and is available in abundance in urban
areas, it could conceivably find a large market throughout the United States
as a constituent of gas concrete. Additionally, fly ash used for this purpose
does not have to be fine quality and it can be hauled and applied in a wet state,
thereby allowing simplicity of handling.
The future of gas concrete in this country is not readily assessable. As a
new industry, it would have to compete with numerous well-established
building techniques us ing conventional mater ials. To es tablish fly ash con-
crete as a building construction material on a wide scale would require sub-
s tantial technical and economic surveys, coupled with the dissemination of
the technology. Such a program is recommended.
1. 3. 1. 14
Miscellaneous Uses and Potential New Uses
Other uses such as in foundries, groutihg, pipe coating, oil well cementing,
etc., are considered to have a low potential for the consumption of large
quantities of fly ash. A large potential exists for poss ible new uses such as
sewage filtration/ soil supplement applications, ceramics and mineral recovery.
None of these' has been developed.
1-17
-------
1.3.2
Limestone-Modified. Fly Ash
The wet-collected limestone -modified fly ash differ s cons iderably, both
chemically and physically, from the regular ash and as such does not lend
itself to the direct substitution for the regular ash as it is used today.
Additionally, the chemical and physical properties of the modified ash vary
to alar ge degree based upon the sulfur content of the coal burned and the
percentage of coal burned which becomes fly ash.
There are numerous potential uses for the modified ash, some the same as
for the regular ash and some not yet developed. Programs of research and
development are necessary for the determination of the technical and
economic feas ibility of utilization schemes for this mater ial. This is dis-
cussed in some detail in Section 5. Specific problems confronted in seeking
these uses include: (a) var iable quality of the ash, (b) it is wet collected,
therefore subject to concreting; (c) it contains sulfur which would be released
during some processes involving heating the raw materials; (d) is pozzo-
lanic properties are decreased compared to the regular ash; (e) the volume
of fly ash is greatly increased compared to regular ash; and (f) toxic trace
elements may be released with contained soluble sulfites and sulfates. On
the plus s ide, the ash does contain: (1) pozzolanic proper ties; (2) unreacted
lime; and (3) appreciable amounts of gypsum.
General areas of potential technical utilization include autoclave products,
structural or land fill, bituminous filler, pozzolanic mater ials, cement
manufacture, pressure sintered products, gypsum products, and mineral
recovery. Immediately promising areas are autoclave products (sulfur
would not be released), gypsum products (it contains lar ge amounts of gyp-
sum), road base course material (it contains lime and pozzolanic properties
and the potential market is lar ge), and sulfur recovery (although the econo-
mics are not promis ing, it could suppleme,nt a sinter ing process). Charac-
terization and utilization research are recommended.
1-18
-------
Since the modified ash cannot replace regular ash in its utilization, it can be
said that its immediate impact on the regular ash market would be negative.
It is pos sible, however, that proces ses can be developed that would make it
usable by the time its production quantities become appreciable.
1.4
SUMMARY OF RECOMMENDATIONS
1.4. I
Regular Fly Ash
The existing inhibitions to the utilization of regular fly ash are of such mag-
nitude that only a small per centage of the ash produced today is utilized.
It is believed that the inhibitions will continue to prevent an appreciable
growth of the fly ash mar ket if appropr iate resear ch, development, and sur-
vey programs are not carried out. Properly conducted, these programs
have the potential for removing inhibitions such that all or a major portion of
the fly ash could be profitably used.
The major areas of concern for new efforts are structural concrete, road
base cour se mater ials, and new products such as gas concrete, ceramics,
and mineral recovery. It is felt that sufficient effort is already being
applied to the advancement of the fly ash lightweight aggregate technology.
Additionally, an effort should be directed toward the extended use of fly ash
as a mine void fill, particularly since it could serve as an interim measure
until the efforts requiring more lead time are completed and put into practice.
The recommendations are:
1.
A new set of specifications or a handbook should be
expeditiously developed for the use of fly ash in portland
cement concrete which would provide a standard utiliza-
tion to produce predictable r'esults. This would include the
application of var ious grades of fly ash (pertinent para-
meters such as residual carbon, fineness, and pozzolanic
activity) to concrete usage and encompass cure times
beyond 28 days. This could be modeled after TV A speci-
fications G-2 and G-30 (Refs. F-80 and F-8l) to expedite
the process. A testing program will be required to
provide statistical data to support this program.
1-19
-------
1. 4.2
2.
A marketing survey should be conducted for various regions
within the fly ash supply areas to determine the economic
feas ibility of fly ash gas concrete in var ious forms of
building construction in the United States.
A technical and marketing survey should be conducted in
various regions of fly ash producing areas to determine
the justification for an advisability of action by government
road contracting agencies as regards the use of fly ash in
the base course section of federal, state, and local paving
program contracts.
Research should be performed for mineral recovery from
fly ash.
A survey study should be conducted to evaluate the net
economic effects of coal-washing or gasification on the fly
ash market and on the cost of ash disposal.
A technical and economic survey should be conducted
related to land reclamation and to the remote filling of
mine voids for control of mine subsidence and fires. This
would include the economics of fly ash usage and land
reclamation values; in addition, it would include the effects
of fly ash on ground waters. The use of empty coal cars
or a fly ash slurry should be considered for transporta-
tion.
3.
4.
5.
6.
7.
Research and development should be conducted to develop
or improve uses for fly ash such as ceramic products,
optimized fly ash gas concrete, and those uses not yet
identified.
Fundamental research should be conducted that can identify
the intrinsic characteristics and properties of fly ash to
provide the basis for subsequent research into new uses of
fly ash. This has been performed in part at var ious
organizations, but results of complete characterization
are not published.
8.
Wet-Collected Limestone-Modified Fly Ash
The determination of the potential use of the modified ash is dependent upon
research and development programs and marketing surveys to determine an
understanding of the potential marketability of developed products in terms
of public acceptance and ability to compete with other products, including
those produced from regular fly ash. The following programs are recom-
mended:
1-20
-------
1.
The mos t cr itical resear ch to be conducted on wet-
limestone-modified ash is the fundamental characteriza-
tion of its chemical and phys ical proper ties to provide
the basis for subsequent utilization and toxicology research
described in Recommendations 2, 3, 4, and 5, as appli-
cable.
Research and development programs should be conducted
on potential mass uses of modified fly ash to include filler
materials, autoclave products, pozzolanic materials,
pressure sintered products, and gypsum products (specific
products are discussed in Section 5). These programs
should be broad enough to allow the possible emergence of
uses not yet identified. Additionally, these programs
should cons ider the mas s usage of modified ash in situ
and beneficiated in processes in which sulfur is not released
and in processes in which sulfur is released and recovered.
Research should be conducted on the recovery of mineral
ore from the modified fly ash.
Research should be conducted to determine the phys ical
state of toxic elements within the modified fly ash and the
source of these elements (coal ash or limestone), the role
of wet collection in the prevention of mass contamination
via particulate and gaseous effluents, and the potential
hazards that may exist, particularly through leaching, in
the disposal and utilization of the ash.
Surveys should be conducted to determine the potential for
marketing recovered sulfur and products to be developed
for the use of modified fly ash. Cons ideration should also
be given to the development of products which are already
partially developed; e. g., mineral aggregate and road base
cour se materials.
2.
3.
4.
5.
6.
An economics survey should be made of the phase of elec-
tr ic power production involving the effects of fuel prepara-
tion and delivery, pollutant removal, res idue disposal and
product credits. Examples of trade -offs which should be
made, include: (a) scrubbing of fly ash and gases resulting
from the combustion of untreated coal, (b) scrubbing of
fly ash and gase s resulting from the combustion of cleaned
coal, (c) gasification of coal, and (d) liquefaction of coal.
1-21
-------
0;-.>
z
--i
:::0
o
o
c::
n
:::::!
o
z
-------
SECTION 2
INTRODUCTION
2. 1
PURPOSE OF STUDY
The Office of Air Programs of the Environmental Protection Agency, in its
association with the development of schemes for the removal of sulfur gases
from the stacks of coal-burning power companies, has expressed an interest
in the present and potential utilization of fly ash as well as any impact on
that utilization caused by modification of the fly ash during the sulfur removal
process. The fly ash modifications to which this study was directed in part
is caused by the wet scrubbing of the fly ash and stack gases. Presently,
only a small percentage of the fly ash produced is marketed; no modified ash
is marketed at all. The non-marketing of the modified ash is due to the fact
that the limestone modification systems are still being developed; therefore,
the modified ash is produced in relatively small amounts of varying quality in
only a few locations. Additionally, uses for modified ash have not been
developed. Hence, this study has concentrated on forming an understanding
of the present utilization of the regular (unmodified) fly ash, inhibitions to
its use, and means of removing those inhibitions. To that was added a survey
of the qualities of the modified ash, potential utilizations, and recommenda-
tions for development programs.
2.2
SIGNIFICANT FACTORS PER TAINING TO FLY ASH
UTILIZA TION
2.2. 1
Regular Fly Ash
Fly ash is used principally as an admixture in applications such as concrete,
concrete products, and road base materials, providing qualities or charac-
teristics superior to those products not using fly ash. Additionally, it has
excellent compaction qualities and is amenable to sinter ing and autoclave
2-1
-------
processes for manufacturing certain construc~:ional materials. In spite of
the many advantages, the use of fly ash is limited':', pr incipally because
(a) it is a by-product of power production and consequently is generally
produced with little or no regard for quality or consistency, (b) it is difficult
to handle, (c) utilization technology has not reached a level near its potential
and some major technological advancements have not been widespread, and
(d) previous misuse, incorrect criticisms, and fears of risk have marred
its reputation.
Through the research and perseverence of certain individuals
in The Chicago Fly Ash Company, the TVA, and the G. and W. H. Corson
Company in Plymouth Meeting, Pennsylvania, as well as numerous others
in both the United States and foreign countries, fly ash utilization technolo-
gies have been developed and practiced which prove the value of this mater ial
and dis count false impress ions held by many individuals both in and out of
the fly ash business. Additionally, a few power companies have demonstrated
that quality fly ash can be produced consistently (concurrently improving the
efficiency of power production) and some have participated in the development
of fly ash products or applications and are using fly ash in their own construc-
tion. Still other individuals have developed methods and procedures for
beneficiating fly ash for various utilizations, and numerous universities and
government agencies have advanced the utilization technology through
research activities. To these activities has been added the National Ash
As soc iation, which was founded in 1968 for the purpose of promoting the sale
and us/e of all types of coal ash. This Association, consisting of membership
from the power utilities, coal companies, researchers and consultants,
collects and distributes all forms of ash information, publishes an ash
newsletter, wr ites and presents' relevant ash utilization paper s, sponsors
technical and marketing meetings, coordinates the Amer ican ash utilization
,'.
"'An exception is the Chicago area where a combination of a,vailable high
quality fly ash, technology, and sales promotion accounts for utilization of
approximately 75 percent of the fly ash produced by Commonwealth Edison.
2-2
-------
community' with foreign ash production and utilization groups, and provides
information to those individuals or groups interested in ash utilization.
With all of these efforts, the national fly ash market is generally inhibited
and is not exper iencing an appreciable growth. In the interest of utilizing
fly ash, the need for identifying the inhibitions and determining means of
removing them is apparent.
2.2.2
Wet-Collected Limestone-Modified Fly Ash
The modified fly ash is quite different from the regular ash, so much 80 that
it could eas ily be cons idered a new mater ial. Except pos s ibly for use as a
filler mater ial, it cannot be substituted for the regular ash in cons ideration
of today's technology without extensive research and development. As a
filler, it would require some development work to satisfy all cons iderations
of use and performance. Study and research programs that have been per-
formed to date indicate that there are numerous potential uses for the
modified ash. The major portion of research has been performed by Com-
bus Hon Engineer ing, Inc., of Windsor, Connecticut, and by the Coal
Research Bureau of West Virginia University. These efforts have identified
many characteristics of the material and potential uses, but research is not
complete, and developments are minimal or nonexistent. Some develop-
ments of a proprietary nature, such as at the Corson Company, are progres-
s ing and have been reported in technical papers (Ref. D-I).
Modified ash, therefore, is appreciably different from regular ash, both
chemically and physically; it will be produced in much larger quantities per
pound of coal burned than regular ash and its utilization potential can only be
determined through extensive research and development programs. Its
marketability, once products are developed, will resemble that of the regular
ash in many respects.
2-3
-------
2.3
ORGANIZATION OF STUDY
This study was performed in the following four steps:
l.
2.
3.
4.
Literature survey
Contacts with individuals and organizations
Inhibitions analys is
Determination of necessary actions to eliminate
inhibitions
The literature survey was conducted to provide a factual background for the
study and to aid planning of continuing activities. The contacts with the fly
ash community provided considerable actual practice data and guidance for
the study. The inhibitions analysis was based on the information obtained
from the literature and personal contacts. With the exception of some
minimal efforts on economics, most of this analys is effor t cons is ted of
obtaining pertinent factual data, placing it in proper perspective, making
rational compar isons and follow-up inquir ies, and forming rational judgments.
The recommendations for removing use-inhibitions are considered the most
feasible and rational of all possibilities determined by the study members
and those suggested by members of the industry. Many suggestions were
not used because it was believed that they involved programs which either
were more elaborate than necessary (e. g., "form a national fly ash research
center"), or were considered inadequate for wide scale mass utilization
(e. g., "depend on promotion and' salesmanship"); or were based on nondedi-
cation to the utilization of fly ash (e. g.,
"bury it").
2.4
SCOPE OF EFFOR T
It is impor tant to the unders tanding of this study to note that it cons ists
principally of a compilation of facts as they appear in the industry today,
and that it was not a research program to test or develop materials or pro-
ducts. Neither is it an attempt to provide information on how to produce or
construct anything such as concrete, roads, or aggregate. Its purpose is to
provide an insight as much as possible into the total fly ash production and
2-4
-------
utilization picture, to make rational es timates of the nature of situations or
problems, and to make recommendations for solutions. It is realized that
the "total picture" could not be obtained within the scope of this study, in
light of the vast nwnber of individuals involved, conflicting points of concern
or interest, the many different technologies involved, varying geographic
cons iderations and limitation, and ever -changing economic conditions. It is
believed, however, that sufficient coverage has been made to provide rational
statements of the situation and recommendations considered necessary to
appreciably improve the fly ash market.
2-5
-------
~
"'tJr
ITI-'
:;Q-i
enlTl
~~'
~-il
rC::1
C'):;Q
olTl
:zen
-iC::1
~~I
C')ITI
-i-<
en.........
-------
SECTION 3
LITERATURE SURVEY AND PERSONAL CONTACTS
3. 1
LITERATURE SUR VEY
Appropr iate literature pertinent to this study has been collected, surveyed,
and compiled into a fly ash library. A survey of this literature was per-
formed merely to obtain information; therefore, literature reviews are not a
par t of this repor t. A bibliography is provided in Appendix A. It is sub-
divided into the following sections: Fly Ash Production, Fly Ash Properties,
Fly Ash Utilization, Limestone-Modified Fly Ash Technology, Foreign
Technology, Specifications and Regulations, Sulfur Dioxide Control, and
Miscellaneous. Because there is some overlap in the indexing system,
cross-referencing is provided as necessary.
All literature references
within the body of the report are made to the documents listed in Appendix A.
3.2
PERSONAL CONTACTS
A listing of all contacts made during this program is given in Appendix B.
That appendix is subdivided as follows: Fly Ash Production, Beneficiation,
and Mar keting; Fly Ash Utilization, Specifications, and Technology; and
Limestone-Modified Fly Ash. Because of the overlap of interests, some
individuals are listed more than once. Approximately 65 of these were visited
personally and the remainder were contacted by letter or telephone. The
cooperation of all of these individuals is commendable, and the time and data
provided is appreciated. Sincerest apologies are offered to those who
participated but whose names may have inadvertently been omitted from
this list.
3-1
-------
f'"
...,.,
I
-<
):0
'"
:J:
'"
c::
~
<
I'T1
-<
-------
SECTION 4
FLY ASH SURVEY
4.1
FLY ASH PRODUCTION
Since this study considers fly ash as the particulate residue that results
from the burning of pulver ized coal to gener ate electr ic power, the quantity
of fly ash produced necessarily becomes a function of the energy require-
ments from the combustion of coal. The growth in demand for electr ic
power in recent years has been phenomenal. According to Ref. H-15, the
total energy consumption in the United States per capita has increased
almost 300 percent from 2500 kwhr in 1950, to 7150 kwhr in 1970. Also,
from statistics collected in Ref. A-19, the United States presently consumes
over one-third of the world's 4.2 trillion kwhr of electricity with coal-
burning power plants providing almost one -half of this country's yield. Of
the total amount of coal consumed for all purposes, the proportionate
quantity utilized by the electric power generating companies has shown a
steady increase since 1945, and as illustrated in Fig. 4-1, this currently
represents 56 percent of the total United States coal consumptLon.
Although it is recognized that a saturation point must be eventually reached,
the present rate of expansion in electric power is expected to continue to
the year 2000 (Ref. H-15). The coal industries participation in this expan-
s ion appears to be well as sured despite the increased amount of power
expected to be produced by nuclear and petroleum fuels. With the United
States possessing one-third of the earth's estimated 5. 1 trillion tons of coal
reserves (Ref. A-19), this country's coal consumption is expected to increase
rapidly year by year due pr incipally to the anticipated vast increase in elec-
tr ic power generation. The increased power demands dur ing this per iod will
also, in all probability, result in the necessity for increased consumption of
lower quality coals.
4-1
-------
100
STOCKPILE
EXPORT
80
RAILROADS
60
HEATING
I-
Z
W
U
a:
w
a... 40
ELECTRIC POWER UTILITIES
MANUFACTURING
20
o
1935
1940
1945
1950
1955
1960
1965
1970
YEAR
Fig. 4-1.
United States Coal Consumption
The past, present, and projected consumption of coal and fly ash production
by the electric utilities in the United States is shown in Fig. 4-2. The basic
data for these curves were obtained from Brackett (A-2 and A-5) and the
Edison Electr ic Institute. The requirements for power plant ener gy for the
combustion of coal was 300 million tons in 1970, with expected increases to
400 million tons per year by 1975, and 480 million tons per year by 1980.
In addition, this figure shows the actual fly ash production for the year s
1956 through 1970, with the projected production based on coal consumption
estimates. The ab.rupt increase in the rate of fly ash production between
1969 and 1970 can be attributed to the energy crises that prevailed during
4-2
-------
1000
400
(f) 40
:z
o
~
LL...
o
~ 20
o
.-J
.-J
::2:
.",.-"""
",:".....0'"
",
"
COAL CONSUMPTION ~...... ............."""
"
,;;
"
.,/
/'
",
",
FLY ASH PRODUCTION~/,/'
"
"
"
600
200
100
60
10
6
4
2
I
1950
1960
Fig. 4-2.
1970
YEAR
1990
1980
2000
Coal Consumption and Fly Ash Production
4-3
-------
this per iod which compelled power plants to burn a lower quality of coal than
had been previously acceptable. The utilities affected by these crises
reported increases in fly ash production in the range of 25 to 50 percent.
As stricter standards for particulate control devices are imposed on the
coal burning utilities, the amount of fly ash removed from stack emissions
will also result in significant increase.
4. 1. 1
Fly Ash Geographic Distr ibution and Availability
As might be expected, a major factor in the marketing of fly ash is distribu-
tion and availability. The availability of fly ash is greatest in those large
urban or metropolitan areas presently served by electr ic utilities us ing coal
to generate power. Figure 4-3 indicates those states and metropolitan areas
where the largest coal-burning utilities (exceeding 400,000 tons per year)
are located. The Middle Atlantic area, which includes New York, New
Jersey, and Pennsylvania, and the East North Central area, which includes
Illinois, Indiana, Michigan, Ohio and Wis cons in, consume the largest
amounts of coal in the generation of electr ical energy (Ref. A-2). These
are followed in order by the South Atlantic, East South Central, West North
Central, New England and Mountain areas.
Although the large utilities in the Middle Atlantic and East North Central and
East South Central areas are in rather close proximity and therefore afford
fly ash availability, large areas still exist where fly ash is totally unavailable.
As can be seen in Fig. 4-3, very little fly ash is available west of the
Miss is s ippi River, in the New England area, and in parts of the South. As
a further illustration of the concentration of fly ash availability, data from
the 1970 Keystone Coal Industry Manual wer e used to develop the curves
presented in Fig. 4-4. This figure indicates that of the 489 power plants in
the United States that burn coal, only 195 or about 40 per cent consume over
400,000 tons of coal per year. However, these 195 power plants supply
approximately 90 percent of the total quantity of fly ash produced.
4-4
-------
>l::-
I
\.1l
'-"--'-"'-"--["T -.- ----.- ..-..-.-
f \ -----'-'--"-'-'-'-"-"-"r'-~
i \ I i ~...
.-?!;~ L_~:_._--J .
"'-''-i'---'-'--;.-----.-.J \
'- ! ! ! i
'~'-'- I I I .
'-'7"-.~--._.1__._._. i L_.__- ,1---.-.-.-.-.-.
/ T'~--'-'/ i ._._._._-~
i ! i ! '\
i I ..--...-...--._! .
i ! ; '''.-.-.---.L.__, \
. I ..
'. ; ! .. i \-.---.-.-.-.
'. i ! j-.-.-.-.-....-.---.""-.
'. ; ! i ,
\ ! ! i .~
\! Ii'
\1\ : .-.-.-.-.-....-.-.!-:.-.......- '-'-. --... T- j --....-....- .-.-.-.-.-.-.-.1
. ! t.---.-.! \'-'-'-'-'-'-'-1
; !! .
; !! I
"-.. i i ~ I
, ! ~
", i ! .
"..... ; !
',. I
"""---..L_!-'-' .-.-.---.;
. = DENOTES POWER STATIONS WITH ANNUAL COAL
BURN EXCEEDING 400,000 TONS PER YEAR
j"
i
. i
;-,,--:--<(-~~:..- -~':'-_.
../"~ ,-_..~~.-.-
~-'-'1'--'-";;\-''''''-' - . '....
! .. \.
I \ ..
. '~l_---
Fig. 4-3.
Power Stations
-------
489
100
400
80
-
-' -'
"- u...
u... u...
o 0
a:: I-
w Z
co 200 t$ 40
::e a::
::> w
z "-
100 20
o
o
o
1000
2000
3000
4000
PLANT SIZE IN ANNUAL COAL USE. KTONS/yr
Fig. 4-4.
National Fly Ash Production by Plant Size
(Developed from Use Data in 1970 Key-
stone Coal Industry Manual)
4. 1. 2
Fly Ash Disposal Costs
The costs presently associated .with the dumping or disposal of power plant
fly ash in settling ponds or land fill areas, at the current production rate
of 26.5 million tons per year, varies from as low as $0. 50 per ton to as
high as $2. 00 per ton. With new regulations prohibiting the dumping of fly
ash, fewer available disposal sites in the metropolitan and urban areas,
and rising land costs, fly ash disposal costs are continuing to rise. From
Fig. 4-2, it is estimated that 40 million tons of fly ash will be produced in
1975.
At this rate, a conservative estimate of the average disposal cost
of $1. 00 per ton will amount to approximately 40 million dollars per year
by I 975 .
4-6
-------
4.1.3
Freight Rates Versus Shipping Distances
Fly ash is in direct competition with many highly competitive bulk products
which are bas ically low in unit pr ice. As such, quality fly ash must be
delivered to the sites for use at a sufficiently low price to insure that it is
competitive. Therefore, freight rates become a major factor affecting the
economic availability of fly ash for utilization purposes.
The extreme fineness and easy flowability of fly ash necessitates that it be
shipped in air tight containers for many uses. In addition to shipping rates,
the mode of transportation will depend on the location of the power plant
and the site at which the fly ash is to be used. Currently, var ious modes,
including truck, rail, and barge, are used in transportation.
Despite the higher shipping rates, the most common mode of transporting
fly ash is by truck. Usually this mode is dictated by the relative locations
of the fly ash source and the plant where it is to be used. A truck can nor-
mally transport 20 to 30 tons of fly ash per trip at a cost of $0.06 per ton/
mile. For short haul distances, local shipping charges include a $1. 00
loading and $1. 00 unloading fee per ton. These costs were found to be quite
uniform throughout the United States.
In transporting fly ash by rail, each car, containing two hopper s, can
accommodate 55 to 60 tons. Except for a few special cases, the rate for
transporting fly ash by rail is about $0.02 per ton/mile with an additional
fee for shaking the car to complete the unloading. In some isolated cases,
the rate for rail transportation was found to be as low as $0.01 per ton/mile.
The shipment of fly ash by barge requires that both the source and user be
conveniently located to connecting waterways. Although barge shipping rates
are relatively low, the necessity of trans loading to and from the barge by
truck or special conveying equipment results in this mode of transportation
becoming competitively economical only for long (greater than 200 miles)
distances. A barge 'can haul 1500 tons of fly ash over long distances at an
4-7
-------
approximate average of one-half cent per ton/mile. Also, because of the
finene s sand flowability character is tics, provis ion for cover ing fly ash will
be an added requirement in transporting by barge.
4. 1. 4
Fly Ash Quality and F. 0. B. Utility Cos ts
In order for fly ash to gain acceptance by potential users, it must not only
be available economically, but at a uniform quality as well. The phys ical
properties and chemical composition of fly ash produced by each coal-
burning electr ic utility is dependent upon the characteris tics of the coal that
is used as fuel, the type of equipment employed, and the manner in which it
is operated and maintained. Since these character istics vary from plant to
plant, it is not unexpected that fly ash properties vary from source to source.
In addition, fly ash collected at anyone sour ce will change as the demand
on the power plant var ies from base to peak loading conditions and as condi-
tions within the producing plant change. The::>e considerations, as well as
the fact that coal-burning electric utilities are primarily concerned with the
production and sale of electric power, contr ibute to the difficulty in produc ing
a fly ash of uniform quality. Added to this is the further obstacle that each
product with fly ash utilization potential has individual quality requirements.
As indicated in Section 4. 3, specifications have been wr itten for the use of
fly ash in concrete and concrete products. From a technical standpoint,
these specifications permit fly ash with a carbon content of 6 to 12 percent.
The manufacture of lightweight aggregate from fly ash or blended ash requires
a consistent carbon content of between 4 to 6 percent, although fly ash used as
a bituminous filler can tolerate carbon contents as high as 12 percent, and in
road base courses, 15 percent. In addition, the fineness of fly ash to be
used in most concrete mixtures requires that 78 to 90 percent of it pass
through a 325 mesh sieve, whereas others allow as little as 68 percent to
pass; and, for bituminous products, 75 to 80 percent passing a 200 mesh
sieve is adequate. High Fe203 is undesirable in lightweight aggregate from
a weight standpoint. It has an effect on concrete color, but much less than
that of carbon (Ref. B-l8). Although uniformity is a major requirement for
4-8 .
-------
all users of fly ash, it can be seen that the definition of quality will vary
depending on the use or product to which it is being applied.
In order to market an acceptable product, some utilities have incorporated
additional equipment, operating procedures, and controls to assure the
production of a uniform quality fly ash. These measures and controls
include: the washing and/ or blending of coal to reduce the amount of ash
or aid fly ash chemical consistency; frequent maintenance and calibration
of coal pulver izer s for cons istent fineness; maintenance of high combustion
efficiency in boilers to limit carbon content; and maintenance of fly ash
collector efficiency within design limits to attain a fineness consistency.
The latter does not appear to be technically feasible for either older plants
and/ or those plants frequently operating at peak loading conditions. Of the
newer base-loaded plants, only a few have selected these approaches to
produce fly ash of marketable quality.
Two unique operations exist in which the fly ash is beneficiated. In one,
the Dayton Fly Ash Company in their Atlanta, Dayton, Pittsburgh, Terre
Haute, and Wilsonville plants, pass the ash through mechanical air classi-
fier s which reduce the 325 mesh res idue to about 5 per cent. This allows
the fly ash company to meet its present supply needs without depending on
the power company for high quality ash, but at the expens e of the clas s ifica-
tion process.
In the other operation, a somewhat different approach to beneficiation has
been developed by Ener con, Ltd., of Hamilton, On tar io. This company,
in conjunction with the Stirling Sintering Company of Pittsburgh, has
des igned and built a modern, integrated facility adjacent to a power plant
for the purpose of processing fly ash for total utilization (Ref. C-30). When
fully operational, the plant will separate as -rece ived fly ash into (a) a very
fine fraction for use as a pozzolan, (b) an iron oxide concentrate, (c) a car-
bon fraction, and (d) inter -feed fraction for use in making lightweight
aggregate for concrete.
4-9
-------
At the time of this wr iting, the aggregate operation is not yet operational.
Moreover, the value of the iron concentrate is les s than the cost of
separating it but is justified on the basis that iron removal upgrades the
other fractions.
The profitability of the Enercon plant has not yet been demonstrated. How-
ever, it appear s that the total utilization concept has cons iderable mer it,
particular ly if excellent quality pozzolan and aggregate feed result from
the operation.
The largest volume of fly ash is currently marketed by brokers that either
process fly ash produced by the utilities and/or have the capability to
selectively choose from numerous power plants that under known operating
conditions will result in a specific quality of fly ash for a particular market.
Regardless of the process that is used in supplying a user with uniform fly
ash that meets a particular product quality specification, the F. O. B. cost of
quality fly ash at the sour ce was found to vary between $3. 50 and $4.50 per
ton. Where the ash is marketed directly by the utilities, lower F. O. B.
charges generally prevail.
4-10
-------
4.2
UTILIZATION AND ECONOMICS
As indicated in Section 4. 1, the continual increase in demand for electr ical
power in this country with the related increase in the quantity of coal burned
yearly has resulted in the accumulation of fly ash at a remarkable rate.
Alternatives for disposing of this accumulating by-product of power genera-
tion have become more and more restrictive as public and governmental
pressure increases for better control of environmental pollution. Confronted
with new regulations containing further prohibitions on the dumping of fly
ash, this traditional disposal method has become less and less satisfactory
with fewer disposal sites available in urban areas and disposal costs,
already in exces s of $2. 00 per ton in some areas, continuing to climb. In
addition, current cons iderations governing the choice between nuclear and
fos s il-fueled power plants include the economics as sociated with the disposal
of the by-.products of the combustion process. As a result, concentrated
efforts to attain a feas ible solution to this ever - increas ing problem have been
directed to the search for and development of applications in which fly ash
can be utilized.
The efforts to find markets for fly ash have resulted in the development of
numerous uses. On the basis of technical feasibility many of these uses can
accommodate only small amounts of fly ash whereas others could account
for the use of appreciable quantities.. Currently, fly ash in this country is
utilized in the manufacture of cement, concrete, and concrete products,
land reclamation and construction fill, road base and soil stabilization,
lightweight aggregate, and mineral filler for asphalt pavement. Miscellaneous
uses for fly ash include grouting, oil well cementing, mine fire and subs i-
dence control, pipe coating, . sewage plant treatment and foundry filters, and
manufactured products. The Fuel and Ash Subcommittee of the Prime
Movers Committee of the Edison Electric Institute conducts a survey each
year to obtain details of the annual production and utilization of fly ash from
the coal-burning electric utility plants. From the latest survey results,
the quantity of fly ash used in each major category dur ing 1970 is presented
4-11
-------
in Table 4-1. These results indicate that the properties of fly ash are
commercially useful and utilization varies greatly with the type of
application.
Figure 4-5 illustrates the trend of fly ash production and utilization in the
United States during the past 15 years. Although, the utilization of fly ash
advanced steadily from the early 1960' s to 1968, the past few year shave
exper ienced a leveling off and even a slight decline while the rate of fly
ash production has increased beyond expectations due to the recent energy
crises.
The foregoing data indicate that although numerous uses of fly ash have
been developed and are currently available, utilization still remains at less
than seven percent of the total production tonnage. In order to assess the
prospects for possible further growth in fly ash utilization, the high volume
use potentials were investigated on the basis of economic and technical con-
siderations. Table 4-2 lists high-volume fly ash uses which were selected
on the bas is of a United States total theoretical technically feas ible applica-
tion in exces s of a million tons per year based on current fly ash production.
These were selected on the basis that only in the application where there is
the potential for mas s marketing could a significant increas e in the utiliza-
tion of fly ash be realized. New uses or developments could, of course,
increase this list. It is recognized that the potentials are overly optimistic
in view of the varying degrees 01 economics, technology, and fly ash
access ibility throughout the United States; however, for mass utilization
to become possible, fly ash must be capable of being marketed as a quality
product over large areas at sufficiently low prices to be competitive with
low-cost bulk products such as sand, gravel, clay, and shale.
4-12
-------
Table 4-1.
1970 Fly Ash Utilization
Tons
Foundries - manufactured products
Pipe coating
Mis cellaneous
26,538,019
1,631,009 ':'
536,320
320,304
207,019
158,484
131,270
111,309
75,872
14,000
7,523
4,260
1,603
64,044
Total Fly Ash Collected
Total Fly Ash Utilized
Partial replacement for cement in concrete
Fill mater ial for roads
Lightweight aggregate
Raw material for Portland cement
Filler in bituminous products
Base stabilizer for roads, parking areas, etc.
Grouting
Control of mine fires
Oil and gas well conditioning agent
.~
-"Not included is the reported fly ash removed from plant sites at no cost
to utility but not covered in use categories shown: 526,347 tons. Unof-
ficial estimates by the Edison Electric Institute are that some of this
tonnage may be dumped at no cost to the utility, some may be used, and
some may be stored for later use.
4-13
-------
6
en
Z
0 4
.--
LI...
0
en
Z
0 2
......J
......J
~
FLY ASH MARK ETED OR
USED BY UTILITY
0.6
0.4
100
60
40
20
10
0.2
0.1
1950
FLY ASH
""
""
/
""
"".
PRODUCTION ~ ./ ./,,"
./
1960
1990
2000
1970
1,980
YEAR
Fig. 4-5.
Fly Ash Production and Utilization
4-14
-------
Table 4-2.
Potential Fly Ash Utilization
Application
Amount of Fly Ash (Tons /Year)
Bricks
Filler in Bituminous Products
10-15,000,000 (C95, C55, C120, C87)
13,000,000 (B15, ClO, C31)
13,000,000 (Cll)
10,000,000 (C87, C99, C53)
1-2,000,000 (A9, B15, C49)
> Annual Production (C87)
>Annual Production (C19, B15)
>1,000,000 (C5l, C133)
Fly Ash Concrete
Lightwe ight Aggregate
Raw Mater ial for Cement
Base Stabilizer and Fill for Roads
Agr iculture and Land Reclamation
Control of Mine Subs idence and Fires
The following paragraphs treat each of the selected uses of fly ash separately.
In view of the fact that concrete appeared to offer one of the greatest techni-
cal and economic advantages for the use of fly ash, and has a high potential
for near -term utilization improvement, a greater por Hon of the effort was
concentrated in this area.
4.2. 1
Concr ete
One of the most widely accepted uses of fly ash is as a raw mater ial ingre-
dient in concrete. Structural and mass concrete, concrete block, pipe and
precast products have consumed the largest quantity of fly ash in recent
year s. The use of fly ash as a raw mater ial in the production of concrete
serves two primary purposes: (1) to supplement or replace fine aggregate,
and (2) to provide effective pozzolanic action. In addition to its physical
properties which allow the concrete mix to flow easily, fly ash also possesses
pozzolanic proper ties. Pozzolans are siliceous or siliceous and aluminous
mater ials which pos ses s in themselves little or no cementitious properties,
but which in finely divided form will, in the presence of moisture, react
chemically with calcium hydroxide at ordinary temperatures to form insoluble
compounds possessing cementitious properties.
4-15
-------
The currently available information indicates that, in general, when fly ash
is used in portland cement concrete mixes, many of the concrete properties
are improved. On the bas is of findings published in the literature, and
personal communications with representatives in the field of concrete tech-
nology, the effects of fly ash are summarized in Section 4.2.1. 1. Although
some differences of opinion in the industry exis t as to the proper ties of con-
crete in which fly ash is used, the character istics presented in Table 4-3
are cons idered a reasonable cons ensus of available information to date.
These advantages and disadvantages are categor ized by subject with refer-
ences to source materials. Although these characteristics will vary in
degrees depending upon the quality of fly ash and the proportioning of the
concrete mixtures, the improvements afforded by fly ash can be realized
when it conforms to the phys ical and chemical specifications is sued by the
Corps of Engineers, Bureau of Reclamation, TVA, etc., and when the con-
crete mixes are designed in accordance with those developed by Lovewell,
Hyland, et al (C-58) or by R. W. Cannon (C-55).
4.2. 1. 1
Structural Concrete
The use of fly ash in ready-mix concrete is cons idered to be one of the more
promising potentials for achieving mass utilization. In this application fly
ash can be used to partially replace cement which is the highest cost bulk
product with which fly ash can compete. According to the National Ready
Mixed Concrete Association (C -:92), the total production of ready-mix con-
crete in the United States dur ing 1969 was approximately 186 million cubic
yards. In addition, the market demand for ready-mix concrete is relatively
stable.
The ingredients used to produce conventional portland cement concrete are
por tland cement, water, gravel or stone, sand, and a var iety of chemicals
to either increase the air content of the concrete or reduce the amount of
water required for the proportioning of the concrete mixture.
of each of these ingredients affect the concrete properties.
The amounts
4-16
-------
Table 4-3.
Advantages and Disadvantages of Fly Ash in Concrete
Advantages
Character istics
Increased pozzolanic action
Improved workability
Higher long term strength
Decreased particle segregation
Decreased bleeding
Reduced drying shrinkage
Reduced a.lkali-aggregate reaction
Reduced cement-aggregate reaction
Improved res istance to sulfate action
Decreased permeability and leaching
Lower heat of hydration
Improved formability and su~face
wear res is tance
4-17
Sour ce
A-9, B-15, C-l, C-5. C-15, C-18,
C-20, C-2l, C-26, C-33, C-55,
C-58, C-81, F-40
A-2, A-9, B-15, C-5, C-15, C-18,
C-21, C-26, C-48, C-56, C-81
A-9, B-14, B-15, C-l, C-5, C-2l,
C-26, C-58, C-81, F-40, G-lO
A-9, B-15, C-18, C-2l
A-9, B-15, C-18, C-2I,
A-9, B-15,
A-9, B-15,
C-26
C-26,
C-58,
C-8I
C-8I
C-15,
C-21,
C-26, .
C-2I,
C-26,
C-58
A-9, C-21,
A-9, B-15, C-20, C-21, C-26,
C-33, C-58
A-9, B-15, C-I, C-15, C-20, C-2I,
C-33, C-48, C-56, C-58, C-8I
A-9, B-15, C-20, C-26, C-58,
C-80, G-lO
A- 9, B-14, B-15, C-33, C-56,
C-58
-------
Table 4-3.
Advantages and Disadvantages of Fly Ash in Concrete
(Continued)
Disadvantages
Character is tics
Difficulty of transporting, handling,
and stor ing fly ash as a separate
material which runs like "liquid smoke"
Extra effort in batching and control of
an additional ingredient in the concrete
mix
Additional fac ilities, equipment,
operations, overhead, etc., for extra
ingredient
Additional air entrainment agents
necessary to meet durability require-
men ts
Maintaining uniformity in fly ash
finene s s
Maintaining uniformity in chemical
compos ition of fly ash
No generally accepted specifications
4-18
Sour ce
A-9, B-15, C-15, C-26, H-13
A-9, B-15, C-26
A-9, B-15, C-26
A-9, B-15, C-l, C-5, C-26,
C-81, F-40
A-2, B-15, C-l5, C-20, C-2l,
C-26, C-33, C-58, C-8l
A-2, C-l5, C-26, C-33, C-58,
C-81, F-40
A-2, B-l5, C-33, F-40, H-13
-------
The material flow through all ready-mix plants is basically similar. To
accommodate the use of fly ash in a ready-mix concrete plant, additional
equipment is required such as storage silos, conveyor sys terns, modifica-
tions to the batching control sys tern, and, pos s ibly, modifications to the
liquid raw materials supply system.
In order to obtain a more realistic evaluation of the potential utilization of
fly ash in ready-mix concrete, a review of the technology of producing and
utilizing concrete was conducted (see Appendix C). In Appendix C, the
technical factors considered in proportioning the ingredients used in producing
concrete include the effect of us ing fly ash as an admixture. Economic
proportions of fly ash are then established and used to compare the relative
costs of producing concrete with and without fly ash. These data are
presented parametrically to allow evaluation of the economics of fly ash
concrete as a function of fly ash cost and transportation distance for dif-
ferent strengths of concrete.
4.2. 1. 1. I
Fly Ash Concrete
The following two sections deal with 28-day-strength, fly ash concrete pro-
portioning and ready-mix economics. This portion of the study was per..
formed to provide a better understand,ing of the correlation between two
prominent fly ash proportioning procedures (TV A and that published by the
ACI) and to determine if pos sible whether the economics related to ready-
mix concrete production inhibits the use of fly ash. As a result of this
survey, a close correlation was found between the two methods investigated,
which removed any doubts about selecting proportions to use in an economics
survey. The results of the economics survey are given in 4.2. 1. 1. 2.
Additionally, fly ash concrete advanced technology and technology improve-
ments are discussed in Section 4.4.
The proportioning of ingredients for fly ash concrete in this survey were
derived from experimentations conducted at the Tennessee Valley Authority
(C-55) and at the Chicago Fly Ash Company (C-58). For these references,
the work performed at TVA was conducted over the past eight years, while
4-19
-------
experimentations by the Chicago Fly Ash Company, whose results are
reported by the American Concrete Institute, has spanned a 20-year period.
An expansion of the technology for design strengths beyond 28 days is
discussed in Section 4.4. Figure 4-6, derived from the TVA data, presents
the amounts of cement and fly ash required in non-air -entrained concrete
having equal 28-day strength as compared to pure portland cement con-
crete. Type I portland cement, I-in. aggregate, 4-in. slump, and a ratio
of 1. 25 for required-to-specified compressive strength were used for the
example illustrated in Fig. 4-6.
1.0
MINIMUM CEMENT CONTENT
FOR EQUAL 28 day STRENGTH
0.9
C = PURE CEMENT, Ib leu yd
Cm = MIXTURE CEMENT, Ib leu yd
F = FLY ASH I Ib/eu yd
.&;)
........
.&;)
u
........
E
u
~ 0.8
0.79
2000 psi
0.7
0.34
0.88
0.6
o
0.2
0.4
0.6 0.8
F I Cm I I b I I b
1.0
1.2
1.4
1.6
Fig. 4- 6.
TV A Fly Ash Concrete Proportions
The ordinate is expressed as the ratio of the cement in the mixture of fly
ash portland cement concrete to the cement in non-fly ash concrete (C I C);
m
the abscissa is expressed as the ratio of f~y ash to mixture cement (F/Cm).
The diagonal line, labeled "minimum cement content for equal 28-day
strength, II represents the minimum amount of cement required in a mixture,
relative to pure portland cement to obtain equal 28-day strength.
4-20
-------
The following is an example of proportioning for non-air-entrained 28-day
fly ash concrete. To obtain 3000-psi concrete requires a minimum ratio of
mixture cement to a pure cement of 0.79. By reference to Fig. 4-6, this
would require a ratio of fly ash to mixture cement of 0.88. The amounts of
cement and fly ash in the mixture would be computed as follows: For a port-
land cement concrete, the amount of cement is 470 lb as shown in Appendix
C.
The amount of mixture cement is obtained from
C = (C /C)C
m m
and would be 0.79 (470) = 370 lb/yd3 for the minimum mixture cement pro-
portions. The corresponding amount of fly ash is obtained from
F = (F / C )C
m
and would be (0. 88) (370) = 326 lb/yd3. This, however, is not an economical
proportioning.
Figure 4-7 (C -55) shows a TV A relationship for economic proportioning of
fly ash for 28-day strength concrete. These proportions are claimed to
obtain minimum total cost of the fly ash concrete for a given strength. As
an example, if it is assumed that fly ash costs 36 percent as much as pure
portland cement per pound delivered, and that it is intended to produce
3000-psi concrete, the figure indicates that a ratio of fly ash to cement in
the mixture that would be most economical would be O. 34. By referr ing to
Fig. 4-6 and entering at the 0.34 F/C ratio, it can be noted that this
m
intersects the 3000-psi line at approximately 0.85 Cm/C.
Therefore, for 3000-ps i, non-air -entrained concrete, us ing Type I cement,
and the 0.36 fly ash/cement cost ratio, the amount of cement and fly ash
in the fly ash concrete are:
C
=
470lb/yd3,
0.85 (470) = 400lb/yd3
0.34 (400) = 136lb/yd3
C
m
=
F
=
4-21
-------
1.2
0.2
o
o
10
20
30
40
50
60
!'!
I
:!
,
~ 0.4
"-
PERCENT FLY ASH I CEMENT COST
Fig. 4 - 7.
Economic Proportions of Fly Ash for 28-Day
Strength Concrete
Table 4-4 compares the amounts of cement in conventional concrete with the
minimum proportions and with the economic proportions for the 0.36 fly-
ash-to-cement cost ratio.
Table 4-4.
Fly Ash Concrete - Minimum Cement
Proportions and Economic Proportions
Minimum C Economic Proportions
m
Proportions Fly Ash = 36% Cement Cost
28- Day C Ic F/c C IC F/C
Strength Concrete, m m m m
psi lb lIb lb lIb lbllb lb lIb
2000 0.62 1. 15 O. 80 0.47
3000 0.79 o. 88 I 0.85 0.34
4000 0.85 O. 62 0.90 0.28
5000 0.93 0.32 0.94 0.33
4-22
-------
The Amer ican Concrete Institute published Table 4-5 (C-58) providing the
proportions of cement and fly ash in air -entrained and non-air -entrained
concrete. Mix A uses only portland cement, Mix B uses portland cement
plus water reducing agent, Mix C uses portland cement and fly ash, and
Mix D uses portland cement, water reducing agent, and fly ash.
,
I
I I
: I
As explained previously, in comparing fly ash concrete with conventional
concrete, it is neces sary to obtain approximately equal strength at equal
time periods in the curing cycle for the same design conditions. Tests
conducted on proportions approximating the ACI fly ash concrete proportions
(C-132) indicate that in general the one day early strength of the non-air-
entrained concrete is somewhat higher than the conventional, the three -day
strength i.; approximately equal to the conventional, and the seven-day
strength is roughly 10 to 15 percent lower. At 28 days the strengths are
equal, and at 90 days the fly ash concrete has a cons iderably higher strength
than conventional concrete. The strength at which forms can be removed
from the concrete vary from 500 psi to 1500 psi for normal type of construc-
tion work. These strengths occur in the one- to three-day period for most
types of concrete. Since during this time period, the fly ash concrete either
exceeds or equals the strength of the conventional concrete, it can be seen
that for the ACI proportions the early strength of the fly ash and conventional
non-air -entrained concrete can be cons idered equal. The somewhat lower
strength of fly ash concrete at s~ven days is not considered important. For
air -entrained concrete, the early strength of fly ash concrete is somewhat
less than that of portland cement concrete, by as much as 20 to 25 percent
in the one-- to seven-day period, then equal at 28 days, and considerably
higher thereafter. This is not seen as a deterrant to usage, particularly
since curing conditions and form removal in actual practice are the same as
for portland cement concrete.
4-23
-------
I
Table 4-5.
ACI Fly Ash Concrete Proportions
1
2
3
4
5
6
Mix C
Non-Air Entrained Concrete
4 P.C. + W.R. 3% P.C. + F.A".
4\14 P.C. + W.R. 4\14 P.C. + F.A....
4% P.C. + W.R. 4% P.C. + F.A".
5 P.C. + W.R. 5\14 P.C. + FA.
5\14 P.C. + W.R. 5\4 P.C. + FA.
6\14 P.C. + W.R. 6\4 PC. + FA.
Air Entrained Concrete
2500 1" 34 4\4 Bags P.C. 4 P.C. + W.R. 3% P.C. + F.A....
3000 1" 34 5 Bags P.C. 4\14 P.C. + W.R. 4\14 P.C. + F.A....
3500 1" 34 5% Bags P.C. 5 P.C. + W.R. 5\14 P.C. + FA.
3750 1" 34 6\14 Bags P.C. 5\4 P.C. + W.R. 5% P.C. + FA.
Table showing suggested trial mixes in combination with admixtures.
P.C. = Portland Cement
W.R. = Water Reducer as defined in ASTM C-494.
F.A. = Fly Ash as set forth in ASTM C-S18, Class F.
Note: W.R. amounts should be used according to manufacturers directions (usually a specified amount per bag
of Portland cement). Fly Ash should be 75 Ibs where marked *: 100 Ibs where marked **: and 125 Ibs
where marked ***.
Class 01 Concrete Max. Size Max. Total Water
Compressive Str. Aggr. per cu. yd. 01
at 28 days, psi Inches Concrete gallons
2500 1" 36
3000 1" 36
3500 1" 36
3750 1" 36
4000 1" 36
5000 1" 36
Equivalent Minimum Cementing Material Contents per cu. yd. lor 4 inch slump
line
No.
Mix A
Mix B
Mix 0
4\4 Bags P.C.
5 Bags P .C.
5\4 Bags P.C.
5% Bags P.C.
6 Bags P.C.
7 Bags P.C.
3\14 P.C. + W.R. + FA"
3% P.C. + W.R. + FA"
4\14 P.C. + W.R. + F.A."
4\4 P.C. + W.R. + F.A."
4% P.C. + W.R. + FA"
5% P.C. + W.R. + FA..
11
12
13
14
3\14 P.C. + W.R. + F.A."
3% P.C. + W.R. + FA"
4\4 P.C. + W.R. + F.A."
5 P.C. + W.R. + FA"
Simply stated, the adjustments to the straight cement mix to secure equal
28-day strength are as follows. Approximately 3/4 to one bag less portland
cement per cubic yard of concrete is used. This reduction is replaced
with approximately 1-1/2 times as much fly ash by weight':'. In order to
correlate the TV A propor tions with the proportions given by ACI, Table 4- 5
has been converted into Table 4-6 and provides the amounts of cement, fly
ash and water in terms of Ib/yd3, us ing non-air -entrained Mix C concrete
as an example.
The last two columns show the results of an analysis that was performed to
convert the values into the ratios used in the TV A economic proportioning
system; namely, ratios of the amount of cement in the fly ash-cement mix-
ture relative to pure cement, and the ratio of fly ash to the amount of cement
in the fly ash-cement mixture.
,'-
-"The technology related to us ing fly ash as an admixture in portland cement
concrete is discussed further in Section 4.4.
4-24
-------
.-
I
Table 4- 6.
American Concrete Institute Fly Ash Concrete
Proportions for Mix C (Non-Air-Entrained,
I-in. Aggregate, 4-in. 'Slump)
Conventional Analys is of
Fly Ash Concrete Concrete Propor tions
Mixture Cement Fly Ash Water Cement
Specified 28-Day "Cm" "F" nw" "c" C IC ylc
Strength, ps i lb/yd3 Ib/yd3 lb/yd3 Ib lyd3 m ' m
2500 353 125 300 422 0.83 0.35
3000 400 125 300 470 0.85 0.31
3500 446 125 300 516 I 0.86 0.28
3750 494 75 300 540 0.91 0.15
4000 517 75 300 564 0.92 0.14.
5000 611 75 300 659 0.93 0.12
Figure 4-8 compares the TVA ang the ACI data to determine how closely they
relate to each other. The lines identified by the squares depict the minimum
amount of portland cement in the mixture, represented by the d~agonal line
in the TV A proportioning curve, Fig. 4-7. The lines identified by the circles
are plots of the TV A economic proportions for an assumed cost of the fly ash
equal to $8/ton delivered and a portland cement cost of $22/ton. The lines
identified by the solid dots are the proportions published by ACI shown in
Table 4-6.
For the amounts of mixture-cement to pure-cement ratios, it can be seen
that a close relationship exists between the economic proportions advocated
by TV A and the proportions recommended by ACI. Minor var iations in this
example would be caused by varying the costs of cement and fly ash. Since
the ACI proportions are generally accepted by industry, these were used for
the following economic analysis.
4-25
-------
~ 2
....
I
o
><
:I:
~
c.::>
~ 0
a::
~
en
I.JJ
>
en
en
I.JJ
g: 5
~
o
u
~ 4
I.JJ
a::
u
6 3
u
NOTE:
NON -AIR - ENTRAINED CONCRETE
EQUAL 28 DAY STRENGTH + SLUMP
TYPE I CEMENT, I" AGGREGATE,
4" SLUMP
5
4
MIXTURE CEMENT TO PURE CEMENT RATIO
Cm/C
3
FLY ASH TO MIXTURE CEMENT RATIO
F/Cm
. AMERICAN CONCRETE INSTITUTE
TABLES
o TVA (CANNON) ECONOMIC PROPORTION
FLY ASH COST = $8/ton DELIVERED
o TVA(CANNON)MINIMUM Cm/C
2
o
o
1.2
1.4
0.8
1.0
0.2
0.4
0.6
Fig. 4- 8.
TV A and ACI Fly Ash Concrete, Example
Proportioning Comparisons
4-26
-------
,------
4.2.1.1.2
Fly Ash Concrete Economics
A cursory study of the economics of fly ash concrete related to the ready-
mix operation was performed to determine if cost is an inhibitory factor.
Details of this analys is are provided in Appendix C. A comprehens ive cost
analysis was not considered appropriate within the extent of this study
because of the numerous, variable factors involved plus the variations in
costs from region to region; the use or nonuse of beneficiation of the fly ash,
brokerage fees, and financial assistance to ready-mix dealers for new
equipment; and sliding costs related to local competition. The analysis was
therefore limited to the more significant factors, us ing es timates made for
costs of fly ash F. O. B. utility, cement, truck hauling, new equipment, and
air entrainment. Several cases were cons idered, us ing var iations in the
parameter s just mentioned. The results of that analys is indicate that non-
air -entrained fly ash concrete costs approximately the same to produce as
por tland cement concrete at haul distances as low as 35 miles or as much as
150 miles, depending on the costs of the various input parameters. The
effect of air-entrainment tends to increase the cost of fly ash concrete if
the fly ash is high in carbon content, or high in particle surface area (Ref.
B -18). An example case cons idered a four per cent LOr fly ash, and accord-
ing to the available literature, the cost of air entrainment agents could be as
much as 20 cents per cubic yard. According to various users consulted,
this may be somewhat conservative. However, applying this to the values
determined for non-air -entrained concrete, the approximate fly ash con-
crete (4 percent carbon) comparison with portland cement concrete costs
varies from a 7-cent cost increase if used at the fly ash source to a break-
even cos t at about 100 miles, depending on the inputs. It should be noted
that most air-entrained concrete using one percent carbon fly ash for example,
costs the same as non-air-entrained fly ash concrete. Also, the use of fly
ash does not appreciably affect water reducing agent costs.
4-27
-------
Strict conclusions cannot be drawn from this analysis because of the many
cost var iations involved for each case; however, indications are that (base d
on Table C-6 in Appendix C) a dealer can increase his profit before taxes
by approximately 50 cents per cubic yard if high quality fly ash concrete is
delivered within 10 miles of the fly ash source, or he can break-even at
about 150 miles. However, if he acquires cement at $22/ton and fly ash at
$4/ton F. O. B. utility, buys good quality or sophisticated storage and handling
equipment which is replaced. in five years, and uses a "poor" grade of fly
ash, indications are that he will not be able to match portland cement con-
crete on an equal production economics basis.
In most cases, the dealer should be able to produce fly ash concrete to
compete with portland cement concrete for haul distances of approximately
50 to 150 miles. Since the profit, before taxes, on portland cement concrete
is in the range of $2 to $3 per cubic yard (according to var ious per sonal
contacts), a potential increase of 20 to 50 cents per cubic yard would be
appreciable to the dealer. If circumstances, as noted above, increase the
cost to the dealer, it is generally small enough to be absorbed by the con-
tractor who stands to benefit from the technical and economic advantages of
us ing fly ash concrete.
As noted in Appendix C, in cons ideration of the utilization of "greater -than-
28-day" design strengths described in Section 4.4.2.1, the production costs
of fly ash concrete for some applications can be reduced rather dramatically.
Using this technology where applicable, cost reductions can be attained for
any type of concrete, and for some it can be well in excess of one dollar
per cubic yard.
In summary, fly ash concrete has technical advantages over conventional
concrete, including improved workability, higher long-term strength,
reduced drying time, reduced shr inkage, increased impermeability, increased
resistance to sulfates, etc., as detailed in Section 4.2.1. These technical
advantages result in a better finished product and some, such as improved
workability, can result in lower placement costs for the user.
4-28
-------
The technical disadvantages of fly ash concrete, including more complex
handling and s tor ing, more complex operations and equipment to produce
the concrete, and fly ash quality problems, etc., generally affect the cost
of producing the concrete. However, as long as the producer can sell
fly ash concrete at approximately the same cost as conventional concrete
(as indicated herein and in Appendix C), these factors have relatively little
influence as economic inhibitions to the utilization of fly ash concrete.
Limitations of haul distances are noted above.
4.2.1.2
Mass Concrete
Although the technical advantages that result from the use of fly ash in con-
crete are applicable to mass concrete, of primary interest is the reduction
of heat generation. Portland cement concrete mixes containing fly ash that
replace an equal amount of portland cement have a lower heat of hydration.
Although the partial replacement of fly ash for an equal amount of portland
cement in concrete mixes result in slow early strength development, this is
not considered to be a disadvantage in mass concrete since it is generally
not highly stressed. In most cases the stresses produced are the result of
its own we ight which is applied slowly as the structure is built.
The technical incentive for reducing the heat of hydration in mass concrete,
which is well known throughout the industry, results from two basic prob-
lems. Fir s t, as the concrete near the surface cools, the differential in
temperature between sui-face and interior may produce thermal gradients
which result in tens ile s tresses exceeding the tens ile strength of the early
age concrete. Secondly, the interior concrete must eventually cool to the
mean temperature of its environment and if it is cured at a high temperature
and restrained against volume change, the cooling inevitably results in the
development of tensile stress. Mass concrete structures which are not
normally reinforced cannot hope to wi~stand the resulting temperature
drops that approach 13SoF without cracking. Although the total heat generated
is similar to that of conventional portland cement concrete, fly ash concrete
applied to the interior will defer a portion of the heat generation until the
4-29
-------
r ---
I
center of the mass has started to cool.
Thus, the peak temperature is
reduced as is the temperature drop to ambient.
Large construction jobs such as concrete dams, flood walls, retaining walls,
and navigation locks offer an uncertain market for fly ash. Since the mass
concrete market is irregular, the potential application of fly ash for such
purposes can only be anticipated as opportunities appear. Each such pro-
ject represents a separate potential with no continuing demand. As indicated
in Section 4.3, fly ash utilized in mass concrete projects is purchased under
specification with its use controlled to reduce the risk of improper applica-
tidn. In addition, since the specifications are somewhat strict as to the
carbon content and finenes s of fly ash, the supply may neces sar ily be limited
to one or two sources with their locations a considerable shipping distance
to the job site. Furthermore, considerable storage facilities are also
required to fulfill the demand for large quantities of fly ash in a relatively
short per iod of time. For example, the Dworshak Dam presently being
constructed at Orofino, Idaho, is planned to utilize 200,000 tons of fly ash
in the remaining 6.5 million yd3 of concrete over the next four years. The
fly ash is being shipped by rail from Chicago to Idaho in special covered
hopper cars for a reported delivered cost of approximately $16. OO/ton, most
of which is transportation cost at one cent per ton/mile.
Fly ash concrete competes with artificially cooled portland cement concrete
(e. g., ice placed in the mix) in mass concrete. With much of the mass
concrete work today being performed in the western part of the United
States, the use of fly ash is particularly sensitive to transportation costs.
As these costs rise, the economic feasibility of fly ash usage rapidly declines.
A partial solution to such a problem would be the utilization of lignite fly ash
which is produced mostly in North Dakota and has been shown to be adequate,
although not covered by present spec ifications, and the use of increas ing
supplies of fly ash from the Southwest.
A further improvement of fly ash usage for mass concrete would result from
the incorporation of proportioning criteria such as that now used by TVA
4-30
-------
(see Section 4.3.2.6). For example, current fly ash concrete usage in
Corps of Engineers and Bureau of Reclamation mass concrete projects
employs an equal substitution of fly ash for cement on a 35 percent volume
bas is which is adequate for the purpose of reducing heat .of hydration.
Greater reductions of cement and additions of fly ash can be used technically,
with the proportioning depending on the quality of the var ious constituents.
This technology has been demonstrated by the U. S. Army Corps of Engineers,
but is not used. However, it is used by the TV A where the fly ash supply is
adequate and controlled by TVA, and transportation distances are compara-
tively short.
Although it is recognized that fly ash is a valuable admixture for mas s con-
crete, and is used as such, the sporadic demand for this purpose and the
limits on number s of projects of this type do not allow for large increases
in fly ash usage. The incorporation of new specifications plus the use of
lignite, and an expanding economy all add up to increased fly ash usage;
however, it is not expected to provide alar ge impact on the future growth
or mas s utilization potential of fly ash when cons ider ing the total volume
produced.
4.2. 1. 3
Concrete Products
As might be expected, the allied concrete products industry which manufac-
ture building block, pipe, an~ precast units, represents an attractive market
potential for fly ash. Although most of the preceding general discussion
regarding concrete applies to these products in varying degrees, there are
certain features as soc iated with the use of fly ash in the ir manufacture that
distinguish them from general concrete construction. The cur ing used in
the concrete product operations is usually conducted at elevated tempera-
tures using saturated steam to produce heat and at the same time to main-
tain high humidity conditions, and in some cases high pressures. For these
cur ing conditions, an equal replacement of fly ash for cement reduction can
be tolerated without the disadvantage of low early strength. Also, since these
processes are repetitive with the end product being duplicate units produced
4-31
-------
over and over again, the advantages of fly ash to these operations in reducing
wear on forms and better molding qualities become considerably more sig-
nificant.
Estimates for the concrete block industry (B-13) indicate a current annual
production total of approximately 3 billion concrete building block units
(8 x 8 x 16 in. equivalent). At an average rate of one pound of fly ash per
block, which is in accordance with the accepted (25 percent) replacement of
portland cement with fly ash by the American Concrete Institute, the theo-
retical fly ash utilization potential for this use becomes about 1. 5 million
tons per year. Although information is not available to determine the
acces s ibility of fly ash to the block production plants, it is reasonably
assumed that a more practical potential would not exceed one million tons
per year. From information available in the literature and discussions
with producers of concrete block, it appears that a savings on the order of
0.2 cents per block can be realized by the partial replacement of cement
with quality fly ash costing $7. 00 to $8. 00 /ton delivered.
No readily available information was located upon which to base an estimate
for the fly ash utilization potential in the production of pipe and precast
concrete. However, typical mix designs presented in the 1970 Concrete
Industries Yearbook provide for a maximum replacement of 15 percent
portland cement with fly ash.
From a technical viewpoint it appears that the concrete products industry
represents a very attractive field for the utilization of fly ash. Based on
the best currently available cost information, the transportation of quality
fly ash to a concrete block plant beyond approximately 130 miles would
become uneconomical. Therefore, it is estimated that if the concrete
products industry were exploited to its fullest extent, this field would
probably consume a maximum of 5 percent of. the total annual fly ash pro-
duction.
4-32
-------
4. 2. 2
Lightweight Aggregate
The primary market for lightweight aggregate is in the manufacture of
bulk and structural concrete as well as concrete block. Although its
advantages in certain applications have been recognized only recently, the
annual output in the United States is over 13 million tons (Ref. C-3l),
with the manufactured lightweights (e. g., made with clay, shale, slate or
fly ash) experiencing the most rapid growth. The consumption of lightweight
aggregates is expected to reach 55 million tons /yr within the next decade. (B-15)
while at the same time the supply of natural aggregate in many parts of the
country is diminishing rapidly. Therefore, this growing industry offers
what may be the best outlet known for the consumption of large quantities
of fly ash. Additionally, with adequate developments, it may offer a
market for the utilization of limestone-modified fly ash. To help meet
this need for lightweight aggregate, several commercial processes for its
manufacture from fly ash have been developed. However, these develop-
ments have not been extended to the stage that fly ash aggregate can compete
economically with other lightweight aggregates.
In spite of the potential for the rapid growth of a lightweight fly ash aggregate
market, the experience of six production plants built so far in the United
States has not been good. Three have discontinued operations permanently:
two for a variety of technical and economic reasons and the third because
the utility providing the fly ash switched from burning coal to gas. A fourth
plant is attempting to resume operations after being closed down for 3 years.
The two remaining plants are in operation and are continuing in their
development efforts to produce and competitively mark~t a quality lightweight
aggregate manufactured from fly ash. Although they use the same basic
proce ss, the type of equipment employed is different and has resulted in
separate problems and development app~oaches. (There is one plant,
Enercon, Ltd., near Toronto, Canada, now in its initial shakedown period;
it is designed with substantial differences from the others and has not yet
demonstrated its projected capabilities.) In order to appreciate production
4-33
-------
difficulties, the operations and some of the problems encountered 1;>y the
two operating American plants are reviewed and discussed in Appendix D.
4. 2.2. 1
Technology - General Characteristics and
ProcessIng
Lightweight aggregates are generally defined as any solid material included
within a concrete mix weighing 115 lb/ft3 or less. Concrete made with
conventional sand, gravel, or crushed stone has a unit weight of 140 to
l50lb/ft3. However, structural concrete using lightweight aggregates can
be produced with equal strength and a unit weight of as low as 80 lb/ft3.
Thus the use of lightweight aggregates permits architects and engineers
greater flexibility in designing longer spans, larger floor areas, added
height or simpler foundations, and this lightness of structural concrete
has enabled it to be competitive with structural steel frames in high-rise
buildings.
The various lightweight aggregates used in the United States are normally
classified in three general categories: (I) natural, (2) by-product, and
(3) manufactured. Natural lightweight aggregates are those derived from
naturally occurring materials such as pumice and diatomite, and volcanic
ash, cinders and scoria. Although these aggregates are very light, they
produce concrete relatively low in strength. By-product aggregates are
derived from the combustion of coal or coke and include slag and cinders
which are used primarily for the production of concrete blocks. The
manufactured aggregate category includes expanded clay, shale, and slate.
Lightweight aggregate produced from fly ash is also included in this
category. In general, the manufactured aggregates are highest in strength
and can be used in both structural concrete and lightweight masonry blocks.
The two methods which presently account for about 95 percent of the
manufactured lightweight aggregate (non-fly ash) produced in this country
(Ref. C- 97) are the rotary kiln and sintering pr~ce s se s. In both of these
processes, clay, shale or slate are heated rapidly to the point of fusion;
4-34
-------
while the material is in this state gases are evolved within it which produce
bloating, and this results in a porous structure when the material is cooled
which provides strength and a low bulk density. The sintering proces s is
also used for manufacturing lightweight aggregate from fly ash. The use of
fly ash has several advantages compared to clay and shale. This is because
raw fly ash is a finely divided material which does not normally require
pulverizing before sintering; it can be obtained without mining, and it contains
carbon for the sintering reaction, which reduces fuel costs.
All processe s for manufacturing fly ash lightweight aggregate are es sentially
identical. Fly ash is agglomerated, formed, sintered, and sometimes
ground and screened. Agglomeration requires the addition of water (about
20 percent) and usually clay or organic binders depending upon the process.
The wetted fly ash is usually pelletized so that the material will be held in
the burner grates and so combustion gases can easily pass through the bed.
Alternative forming by extrusion has been tried in one process but this
technique has been replaced by a roll forming method using serrated roller s.
Pelletizing of the fly ash is one of the more important steps since variations
in pellet size can affect the quality of the aggregate made in the subsequent
sintering operation. Moreover, the conditions required to provide adequate
sintering in one size fraction differ sufficiently from those for other size
fractions. For example, at a. given set of conditions a small pellet may
overs inter, producing a hard, dense, nonreactive aggregate; the identical
conditions may not provide an adequate degree of sintering in the center of
a large pellet, producing a poorly formed, weak aggregate. Because the
control of the sintering process is not absolute (chemical composition
provides control limits, see following section 4.2.2.2), the operation
requires close control of the pellet size. This control is provided by the
pelletizing equipment.
After forming, the pellets are transferred to a continuously travelling grate
that pas ses through a fire box where the residual carbon within the fly ash
4-35
-------
is ignited. This carbon provides an important source of power for
sintering of the fly ash in two of the processes. In the Enercon, Ltd., process,
residual carbon is burned away before pelletizing and all power for
sintering is provided by gas or oil burners. After sintering at 1800 to
21 OOoF, the pellets are eithe r transferred to a stockpile or screened, or
crushed and screened before stockpiled. The sintered pellets can be stored
in the open where they are not affected by the weather, and sophisticated
hauling equipment is not required.
As for product quality, a recent report by the portland Cement Association
(Ref. C-33) concludes that measured physical properties of the several
concrete samples made from commercially available fly ash aggregate
fall within the ranges shown in the "Guide for Structural Lightweight
Aggregate Concrete" of the American Concrete Institute.
4.2.2.2
Technology Limitations
The most important step in the process for manufacturing lightweight
aggregate is the sintering operation. Nevertheless, when the carbon content
of the fly ash is used as a primary source of heat, the draft control on the
combustion air is the only operational control. This control requires
limits on the carbon content of the fly ash which can be sintered into
acceptable aggregate. These limits are a function of the de sign of the
sintering furnace and can be influenced by the sinterability of the fly ash.
The sinterability is dependent upon the finenes s of the fly ash and the iron
oxide content that acts as a flux. Since neither the carbon nor iron oxide
contents nor the fineness of the fly ash are properties for which the process
has control, the succes s of the operation has been totally dependent upon
the quality of the pelletized material.
The quality of the ash that is acceptable for lightweight aggregate manu-
facture contains a narrow range of carbon content of nominally 5 (.:t. 2)
percent. The actual range that is acceptable depends upon both the iron
oxide content and fineness. For most fly ashes, these sinterability factors
do not vary significantly and since their effect on the proce ss is not strong,
4-36
-------
they serve a secondary role in the sintering operation. However, their
effect becomes important when the carbon content is close to its functional
limit. For example, if the carbon content is low within its acceptable
range and the iron content decreases or the fineness decreases, the ability
to continue to make acceptable aggregate may be lost. On the other hand,
at high carbon contents, an increase in iron content or an increase in
fineness may oversinter or fuse the aggregate and it again may be unacceptable.
The process for making lightweight aggregate from fly ash being developed
by Enercon, Ltd. (see Section 4. 1.) does not use carbon as a primary
source of fuel. In this proces s the residual carbon within the fly ash is
burned off in a preheater, and sintering is accomplished by auxillary
burners external to the sinter bed. In this way, direct control of the
sintering operation is attained but at the expense of an additional operation
and a significant increase in fuel costs. A further measure of control is
attained through beneficiation of the fly ash which provides to the sintering
operation a controlled fraction of particle size s. This proces s has the
potential for providing greater reliability and reproducibility in product
performance but, at the time of this writing, the process has not operated
on a production schedule to provide the data necessary to evaluate its
capabilities.
A lightweight fly ash aggregate operation observed in Germany is limited
by an inability to consistently form the required size pellets and,
occasionally, to obtain adequate strength. That operation blends fly ash
having a 2 to 3 percent carbon content with pulverized coal to bring the
total carbon content up to 5 to 6 percent for sintering. The finenes s
requirement for the ash is 30 to 35 percent retained on a 1 70-mesh sieve;
for the coal, which is purchased in the pulverized form, the finenes s
should be the same as the fly ash. The inability to consistently produce
ash of the proper fineness, at the adjacent power plant, has limited the
aggregate operation. Pellets of various sizes are formed on each
pelletizing dish; however, the portion of the total production suitable
4-37
-------
for use in concrete block is insufficient and sometimes structurally weak.
(A grinding operation is not used in any phase of this operation other than
to break up the cake after sintering.) Despite the problems, the operators
are optimistic and the development of this operation is continuing.
4. 2. 2. 3
Inhibitions For Use of Fly Ash in Lightweight
Aggregate
Several technical factors have been identified in the production of
lightweight aggregate from fly ash which have inhibited the development
and growth of the fly ash industry. The most significant factor has been
the restrictive limitations of the technology to accept the variability in
quality of fly ash that is normally obtained from power plants. Laboratory
and pilot plant operations do not reveal these problems because of their
relatively limited capabilities. The Enercon, Ltd., process design is
one solution to the major problem of carbon control; other solutions that
are being used or planned include blending of fly ashes having different
levels of carbon and blending fly ash with pulverized coal.
Another inhibiting factor has been the scale-up of pilot plant design to
production machinery. The use, or abuse, of production equipment is far
more severe than that encountered in a pilot plant. The production
equipment for lightweight aggregate manufacture from fly ash has suffered
from major deficiencies in mechanical design (see Appendix D). Excessive
maintenance, repair and replacement of this equipment has further
aggravated the growth of this industry. While not being the primary factor,
these two manufacturing difficulties have been major contributors to the
closing of at least one plant.
These factors have certainly inhibited the rate of growth of an industry
which manufactures lightweight aggregate from fly ash; however, such
factors are not unusual in an infant industry. Solutions to these problems
are being actively sought and incorporated in the process operation, and
it has been shown that a quality product can be manufactured.
4-38
-------
1-
To date, the two commercially producing fly ash lightweight aggregate
plants in the United States have not been able to market their product
competitively for a profit. Whether the manufacturing process and market
can be sufficiently developed to economically compete with other lightweight
aggregates remains to be seen.
Indications are that to successfully compete in the lightweight aggregate
market, the aggregate plant would be most effective located adjacent to
the power plant so as to minimize the handling of fly ash. Additionally,
definite commitments by, or involvement of, the power company would be
necessary to guarantee a dependable supply of the required quality of
fly ash.
A significant increase in the utilization of fly ash in the manufacture of
lightweight aggregate appears possible, but cannot be expected in the near
futur e.
4.2.3
Portland Cement Manufacture
Another potential market for fly ash is utilization as a raw material in the
manufacture of cement. Fly ash can be combined with cement in two ways:
as an additive, or as a component in the raw cement batch.
As an additive in the cement manufacturing process, fly ash can be mixed
with the finished cement or inter ground with cement clinker. Fly ash
added at either of these two points in the manufacturing process remains as
fly ash and although thoroughly blended into the portland cement, the
resulting material will perform about the same functions subject to the
same limitations as those obtained by adding fly ash to concrete mix.
Cement with fly ash additive must be marketed as a separate product (which
is done in some instances), and as such, separate handling, storage, stock-
ing, etc., are involved. Also, the ble~ding of the two materials requires
special techniques to ensure uniformity of the cement. The economics of
handling and transportation do not allow for the mass utilization of fly ash
in this manner without the combined cooperation of power plants and portland
cement producers.
4-39
-------
Used as a raw material in the manufacture of portland cement before firing,
fly ash possesses chemical elements which are found in portland cement,
but in different proportions. In the manufacture of the various types of
portland cement, two or mOre raw materials must be blended to achieve
proper chemical composition in the kiln feed. The most important sources
for lime are cement rock, limestone, marl, shell, marble and chalk; for
silica: sand, quartz, and quartzite; for alumina: clay, shale, and slag; for
iron oxide: iron ore, pyrite cinders, blast furnace flue dust, and mill scale.
The four major chemical components in the kiln feed are lime (CaO), silica
(SiOZ)' alumina (AlZ03)' and iron oxide (FeZ03)' Although minor differences
exist between the various types of portland cement, the raw material blend
is generally 73 to 78 percent CaC03' lZ to 17 percent SiOZ' Z to 5 percent
AIZ03' 1 to 3 percent FeZ03' 1 to 5 percent MgC03' and less than 1 percent
alkalies (C-ll). The potential raw material that fly ash can substitute for
in portland cement is essentially the aluminous, ferrous and siliceous content
of clay, shale, schist, and blast-furnace slag. In comparison to these,
fly ash compares very favorably as a sour ce of mater ials for blending with
limestone in cement manufacture. An important chemical requirement of
fly ash in the manufacture of cement is that it be uniform without appreciable
var iation in the compos ition as it is delivered to the cement plant. A uni-
form quality fly ash is necessary in order to avoid frequent costly and time
consuming checks and adjustments of the raw mixture to maintain proper
kiln feed compos ition.
The use of fly ash as a raw mater ial eliminates the mining, crushing, and
pulverizing process that is required for use of clay and shale. An additional
advantage of fly ash results from the presence of carbon which can supply
fuel for firing in the kiln. Also, it contains no water of crystallization, as
do clay and shale, which must be driven off at the expense of heating.
In order to use fly ash economically, it would be necessary for the cement
plant to be located near a coal-burning utility. Also., if a cement operation
is stripping clay or shale to obtain underlying limestone, it will probably
4-40
-------
use that clay or shale in the raw batch whether or not fly ash is available
nearby. As previously mentioned, the finenes s and flow character istics of
fly ash require special handling, transportation, and dust collection equip-
ment. Finally, and not of least importance if fly ash is to be used, is the
fact that cons iderable capital investment in cement plant des ign and equip-
ment must be committed to a fly ash raw mater ial source which ordinar ily
does not make guarantees as to quantity and quality that will be available
for future use.
Of the approximately 180 portland cement producing plants in the United
States only three currently use fly ash as a raw mater ial in their manufac-
tur ing process. Two of these three plants use fly ash merely for the purpose
of making up for the alumina and' iron deficiencies in the local clay. In
each of these two operations, fly ash represents only about 4 percent of
the raw mix. Neither of these operations is dependent upon the use of
fly ash. If the availability or quality of fly ash were to become unacceptable,
these plants could eas ily convert to comparable alternative mater ials, such
as mill scale, and kaolin clay which are readily available.
The third plant, which is discussed in detail in the following paragraphs,
represents the only cement manufacturing plant in the United States that
exploits the use of fly ash to its fullest extent.
In Joppa, Illinois, the Mis sour i Portland Cement Company is located adja-
cent to the Electric Energy Incorporated power plant close to the Ohio River
(C-116, C-1l7). This cement plant has a capacity of 5 million barrels
annually and uses approximately one-half of the fly ash produced by the
1000 megawatt electr ic power plant.
The decision to locate this plant adjacent to the utility, approximately 70
miles from the quarry for limestone and sandstone, was based on several
factors. Once the general area had been chosen because of accessability to
major markets, the limestone quarry location was determined based upon
the availability of limestone in the general area. The plant was, however,
not located at the quarry site because of limited flat land above poss ible
4-41
-------
flood areas of the somewhat unpredictable Ohio River.
After the determina-
tion that it was impractical to locate the plant at the limestone quarry site,
a decision was made to locate adjacent to the utility and to use fly ash in
place of shale, which normally makes up approximately 5 to 12 percent of
the total raw mix. In this manner, it was possible to eliminate the quarrying
of the shale, and reduce the operational cost considerably.
The operating proce~s used at the Joppa plant is described in Appendix E.
Wet and dry processing are shown; however, the Joppa plant uses the dry
process only. An interesting aspect of the wet process is that it would
technically lend itself to the utilization of limestone-modified fly ash; how-
ever, the related economics are generally unfavorable.
With respect to the economics of cement production, it can be noted that
there are several special situations that exist in the case of the Joppa plant.
The limestone which makes up the majority of the raw material is quarried
at a site which is unsuitable for a cement manufactur ing plant. Secondly,
a river is available to transport the bulk of the raw material by barge from
the quarry to the location of the manufactur ing plant adjacent to the utility.
It has been estimated that the cost of transporting by barge costs approxi-
mately 0.4 cents per ton/mile, not including the depreciation cost of the
barges which are both designed and owned by the Missouri Portland Cement
Company. In contrast, transportation by rail under the same conditions
would cost approximately 2 cents per ton/mile, or roughly five times the
bar ge cos t. A major advantage of us ing fly ash is that a relatively small
operating cost is required once the capital investment of the pneumatic
conveying system from the utility is paid for as compared to the operational
cost involved in quarrying shale.
It is estimated that the total cost of cement production is approximately one-
third to one-fourth for raw materials and tpe remainder for operations and
payment of capital investment. The capital cost of a cement plant is esti-
mated at $10 to $15 per barrel annual capacity, 80 that a five million barrel
annual capacity plant would cos t from $50 to $75 million. The operational
4-42
-------
costs are divided evenly between fuel, electrical and labor costs. It is
concluded that fly ash lends itself to the production of portland cement
under certain special situations where the manufacturing plant cannot be
located adjacent to the major raw material source or where possibly the
limestone, sandstone deposits are located close to a utiJity. However, in
most cases such special situations do not exist. This, coupled with the fact
that there is no demand for new cement plants since the present market
requires less than about 70 percent capacity, the potential for utilizing fly
ash for the manufacture of portland cement is relatively low. '
4.2.4
Br icks
The manufacture of brick from fly ash has been the object of several investi-
gations, yet, no brick plant in the United States is currently using fly ash
as a constituent even though its feasibility was demonstrated more than 20
years ago (Refs. C-99, C-53). The construction of such a plant in Western
Canada has recently been reported, and will be the first of its kind.
4.2.4.1
Fly Ash Br ick Technology
Because clay minerals are the most prevalent foreign material found in bi-
tuminous coals, fly ash is very similar in chemical compos ition to the clay
and shale raw mater ials normally used in br ick manufacture. However,
fly ash exists as small glass spheres rather than as a clay mineral and
physically behaves more like fine sand or silt and does not provide the
plasticity associated with the clay minerals. As a consequence, while
chemically similar, fly ash does not provide the properties required for
forming processes (extruding) used conventionally for brick manufacture.
An advantage can be gained by us ing fly ash as an ingredient in br ick,
especially with very plastic clays having a high clay mineral content, because
the mixture could be formed by an easier extrusion operation. A series of
clay-fly ash br icks were made at varying fly ash compos itions up to 75 per-
cent by weight in conventional brick making equipment. The results demon-
strated that satisfactory products could be made with respect to strength,
structure, absorption, and other phys ical properties (Ref. C-128).
4-43
-------
An evaluation of br icks composed of fly ash and boiler slag fabr icated in a
conventional manner was made and the results indicated that the bricks
were satisfactory with respect to strength, absorption, and durability
(Ref. C -128). Br icks made of fly ash and sand were investigated in which
the bricks were unfired and dependent upon pozzolanic reaction of the res i-
dual lime in the fly ash for strength development. This work demonstrated
that selected cementitious fly ashes can be used with sand to make construc-
tion br icks or blocks.
The Coal Research Bureau of West Virginia University (WVU) has for some
time been conducting rather extens ive investigations of potential uses for
fly ash. This research has resulted in the development of a process for
\
producing brick from coal ash (Refs. B-lS, C-17, C-53, C-98, and C-99).
To establish the validity of their development theories through actual full-
scale operation, a fly ash brick pilot plant was designed and built. From
1000 to 1200 bricks per day have been produced by this pilot plant which is
limited by the capacity of the firing kilns. This process uses 74-percent
fly ash, 23 -per cent bottom ash or slag and 3 -percent sodium silicate binder.
A description of this process is given in Appendix F. This process requires
no raw material preparation other than sizing of the boiler slag, and, has
resulted in a brick product that meets the requirements recommen9.ed by
the ASTM. Another advantage of this process is the reported lighter-weight
bricks that result and the proximity of fly ash raw material to the high
dens ity br ick mar keto
As in most products that use fly ash, a uniform quality fly ash is important.
In this process the final br ick color, a function of the chemical content of
the ash materials, can vary considerably. Excessive carbon content in the
fly ash tends to retard oxidation of the iron and leaves voids that make the
brick too absorptive.
As noted previously, fly ash bricks are not formed in the conventional extru-
sion manner. A dry press forming process is used which is usually a more
expensive operation than an extruding process. However, the additional
4-44
-------
costs of this process would be offset by the elimination of the pulverization
process normally used for clays and shale.
In summary, it is evident that discrete technological inhibitions to the use
of fly ash in the manufacture of building brick do not exist. However, inhi-
bitions do exist which interact with technology. Probably the greatest advan-
tage of us ing fly ash is the oppor tunity to extend the life of a depleting supply
of clay or shale used as a raw material in the manufacture of brick. Using
fly ash as an additive to the clay or shale, satisfactory brick could be pro-
duced with the only cost being that necessary to handle and blend raw mater-
ials. However, in the last 10 years, four operators have exhausted their
local source of raw material and have chosen to truck clay or shale from as
far as 50 miles in order to continue operation.
4.2.4.2
Economics
In addition to the problem that present brick production exceeds the demand,
the capital investment for constructing a new plant to manufacture bricks
from fly ash would incur the risk of availability, quality, and cost of the
necessary raw material. Moreover, the pollution problem presented by
brick plants located near the source of fly ash in high density areas will be
the object of increas ing pres sure and will result in costly equipment to meet
the more stringent environmental requirements.
The work accomplished by the Coal Researc h Bureau of WVU has included
not only the successful development of a fly ash brick process, but also
included a detailed economic analysis. This method has been developed and
programmed on an IBM 7040 computer to determine the potential economics
of a proposed fly ash br ick plant under widely varying conditions for any
given marketing area.
Although over 1000 inquiries have been received by WVU since the announce-
ment of the success of this development and numerous parties have seriously
considered construction of a commercial brick plant utilizing this process,
not a single plant has been constructed in the United States using this pro-
cess, nor is there one currently known to be under consideration.
Although
4-45
-------
all the factors that may have discouraged prospective entrepreneurs from
constructing a fly ash br ick plant are not known, it can only be reasonably
assumed that their inhibitions, whether valid or not, were based on a com:-
bination of factors involving questionable quality and availability of fly ash.
Information was obtained on the investigation of fly ash brick in two major
metropolitan areas located in different sections of the country. In the first
case, a major electr ic generating utility obtained the interest of an investor
for manufactur ing fly ash br icks adjacent to one of the ir lar ge coal burning
plants. To assure the investor that fly ash from the specified power plant
would be of adequate uniform quality, the utility in conjunction with WVU
developed limits for fly ash phys ical properties and chemical compos ition
necessary in the satisfactory production of bricks. Also, during the nego-
tiation, the investor requested that the utility provide a stockpile of fly ash
of sufficient quality and quantity to supply raw mater ial for operation of the
brick plant during the succeeding 10 to 15 years. Although the utility con-
sidered agreement to such a provision as a considerable gamble, the pre-
liminary negotiation proceeded into an economic evaluation phase. Cost
values encountered in the particular area were applied to the WVU economic
analys is program. The results indicated that it would cos t $40 per thousand
\
for a plant to manufacture fly ash brick in this area. Upon relating these
production costs for fly ash brick to the current market price of $38 to $55
per thousand for fired clay brick, the investor lost interest in the venture.
In the other case, the manufacture of brick was considered in an area where
the availability of fly ash is particularly plentiful. This utilization of fly ash
was considered by a major manufacturer that has accepted the use of fly ash
in the manufacture of other products. He confirmed the comparative eco-
nomic results reported in the fir st area and, in addition, concluded that fly
ash would present more technical problems than clay and shale.
4.2.4.3
Potential Utilization
Geography plays an important role in the use of fly ash for brick manufacture.
The principal sources of fly ash, in the North, Central and Eastern portions
4-46
-------
,-
of the United States, are all close to ample sources of natural raw materials
for brick manufacturing. Whether the coincidence of a depleting source of
natural raw materials, a dependable local source of high quality fly ash, and
a knowledgeable investor will soon exist may determine whether fly ash will
eventually find an application as an ingredient in br ick. This is not expected
on a wide scale.
If there is no fear of early depletion of the locally available sources, the
additional costs of handling and storage facilities will deter an operation
from using fly ash in brick manufacture. Furthermore, since the industry
f
is presently operating at over capacity, no new plants are planned for the
immediate future. However, in the Western United States where clay and
shale depos its suitable for br ick manufacture are not as plentiful, the poss i-
bility for building new plants would be more likely except for the fact that
fly ash is not readily available. (The new plant previously mentioned for fly
ash br ick manufacture is located in Western Canada where raw mater ials
are not readily available, but fly ash is. )
From the foregoing discussion and the fact that present United States brick
production capacity exceeds demands, it is not expected that this fly ash
utilization potential will mater ialize to any appreciable extent.
4.2.5
Filler in Bituminous Products
4.2.5.1
Utilization Potential
The benefits of adding mineral filler to asphaltic paving mixtures has been
fairly well established (Refs. A-9, B-15, C-49). Although mineral filler is
not normally applied to asphaltic mixes for secondary type roads, its presence
in mixes for primary surfaces is considered to provide increased stability
and durability. For asphaltic surfaces that utilize mineral filler, only a
small proportion (approximately four percent) of the mix is represented by
,
this ingredient. Many different materials are accepted as filler types.
Thes e include limestone dust, rock flour, volcanic ash, hydrated lime,
powdered shale, diatomaceous earth, portland cement, mineral sludges,
bentonite clay, and fly ash.
4-47
-------
Although from a technical standpoint, fly ash is not one of the better fillers
in consideration of traction, its use does provide adequate pavement
characteristics. Since filler requirements permit a maximum of 12 per-
cent carbon content and a fineness of 70 to 100 percent passing a 200-mesh
sieve, a low quality fly ash can be tolerated. Since low quality fly ash can
normally be purchased at $1. 00 to $2.00 per ton F. O. B. at the utility,
fly ash becomes an attractive
filler types are not available.
in Sections 4. 3 and 4.4.
filler mater ial for areas where other low cost
Further discus s ion of the subject is presented
A major disadvantage of us ing fly ash as a filler in asphalt mixes is the
difficulty associated with transporting, handling, and stor ing of the mater ial.
In addition, the use of fly ash would require special facilities to store fly
ash as well as installation of dust collection systems to collect the fly ash
that escapes in the plant dur ing conveying and batching.
The flow of mater ial through all asphalt plants is quite similar and is
briefly descr ibed in the following paragraph.
Aggregates which include sand, gravel, crushed stone, slag, and mineral
filler are fed from storage to the dryer where the moisture is removed and
the aggregate heated. The heated, dr ied aggregate is continuously fed to
vibrating screens which divide it into the specified separations. Each
separation flows into its respective hot bin. The next steps are measuring
and mixing where the proper amounts of aggregate from each hot bin and
the correct percentage of asphalt are released and mixed to conform to the
mix de sign.
Fly ash has been used successfully in bituminous products made in industrial
plants such as roofing, filled mastics, plank, and similar commodities
(Ref. A-9). Although this use can only account for relatively small quantities
of fly ash, it is normally a year -round market, unlike the seasonal market
of the construction field.
4-48
-------
The use of fly ash as a mineral filler in asphaltic road surface mixes appears
to offer an attractive utilization for fly ash from a technical and economic
viewpoint. However, mineral filler is not used in all asphalt road applica-
tions and when used represents only a small portion of the mix. In addition
to this market being a seasonal one, fly ash is not geographically and there-
fore not economically available to at least one-half of the United States. On
this basis the full exploitation of fly ash in the bituminous products industry
would not be expected to exceed one million tons per year.
4.2.6
Remote Filling of Mine Cavities
In the coal mining areas, mine subsidence damage to homes, bridges, and
roads is an increasing problem. The increase is due only partially to addi-
tional mining. It can also be attr ibuted to the growing need for urban and
suburban land which has extended building over 014 mines, where slow
deter ioration of supporting conditions results in surface subs idence many
year s after mining has occurred. In addition to the subs idence, abandoned-
mine fires have also become a serious problem in coal mining areas. The
Bureau of Mines has developed a method for using fly ash to prevent and
control the mine subsidence and fire problem (Refs. C-5l and C-133). This
method remotely fills underground cavities by pneumatically injecting dry
fly ash down boreholes dr illed from the surface to inter sect the mine voids.
Normally, fly ash is injected directly into the borehole from the trucks. The
fly ash, which compacts during transportation, is refluidized by forcing
compressed air through a perforated plate in the bottom of the sealed com-
partment. This operation, which takes two to five minutes, also pressurizes
the compar tment to between 12 and 15 ps ig. The valve at the bottom of the
compartment is then opened and fly ash is drawn into a 25-ft long, 4-in.
diameter feed line by the airflow. The air pressure in the compartment is
not critical since the fluidized material,would flow by gravity. When
injected pneumatically through a borehole, fly ash exhibits good flow charac-
teristics, flows readily, and has a very low angle of repose. Fly ash can be
4-49
-------
injected economically at a high rate of flow (0.5 ton per minute) without
special nozzles or elaborate equipment in all kinds of weather. It fills
voids and will harden without shrinking in the presence of moisture. The
Bureau of Mines experimental work has indicated that from 200 to 1000 tons
of fly ash per hole would be required to fill mine voids depending on their
size.
The current experience of the Bureau of Mines in the Pittsburgh area indi-
cates that the cost of this operation is $2. 00 to $4. 00 per ton of fly ash
deployed in a mine cavity located within a 30-mile radius of the source of
fly ash. This expense is also based on obtaining fly ash from the power
plant at no charge. The cost for drilling a hole is about $2. OO/ft with the
casing and adapter costing about $20.00 to $30.00.
Since many large coal burning power plants are located near the coal mining
areas, the filling of abandoned mines appear s to be an excellent means for
utilizing/disposing of the entire amount of fly ash produced by these utilities
(Ref. C-llO). Since the utilities are currently incurring costs of up to
$2. OO/ton to dump fly ash, the economics of this utilization may be justified,
particularly when cons ider ing the potential increased value of the land above
the mines.
4. 2. 7
Miscellaneous Uses
Other uses of fly ash in which large quantities can be potentially accommo-
dated include agriculture and land reclamation, oil well cementing, grouting,
mineral recovery, and ceramics. However-, except for mineral recovery
and ceramics, both of which require development programs, these uses
were considered to have a low potential for the consumption of large quan-
tities of fly ash in actual practice. Characteristics of some of the more
significant of these are described in the following paragraph. Additionally,
road base course applications offer a large' utilization potential technically.
This is discussed separately in Section 4.4.2.2.
4-50
-------
4.2.7.1
Agr iculture
From a technical standpoint, agr iculture has the potential of utilizing the
total annual production of fly ash. Some of the phys ical and chemical
proper ties of fly ash that are cons idered advantageous for agr icultural
purposes include the ability to neutralize soils, the ability to retain more
available moisture than many natural soils, and a loosening effect when
mixed with tight and heavy textured soils. Fly ash can contribute to the
neutralization of soil from either an acidic or basic condition, however,
most fly ashes have a high pH, making them amenable to the neutralization
of acidic soils. The proportionate amounts of fly ash to limestone required
to achieve an equivalent soil condition or crop yield is sufficiently high as
to be beyond consideration. For example, Ref. C-l9 indicates that 600 tons
per acre of fly ash is required for an equivalent growth of fescue attained
by the application of limestone at the rate of 8 tons per acre. This investi-
gation also reported that 200 tons of fly ash per acre could be used in
the growing of corn, with larger applications creating toxic effects which
lowered the yield. In addition, research results reported in Refs. C -19
and B-l5 indicate that the plants which can tolerate all the chemical ele-
ments occurr ing in fly ash ar e quite limited.
Although this application appears to be a method for utilizing large amounts
of fly ash, it does not seem to be economically attractive when compared to
the use of lime or other additives to adjust soil pH. The transportation and
handling costs for the large amounts of fly ash that would be required appears
to be prohibitive. Moreover, the presence of certain trace elements often
found in the fly ash would be detrimental to the growth behavior of many
common types of vegetation.
4.2.7.2
Land Fill
The largest use of fly ash is as a land fill material -- whether the fill is
required or not. When fill is not required, it is an expensive means of
disposal of the fly ash; the cost normally varies from $0.50 to $2.00 per
ton and is borne by the power company. However,' if fill is required and
4-51
-------
hauling distances are short, fly ash can often be used more economically
than other fill mater ials, and can provide technical advantages (Ref. C-73).
Among these advantages are ease of handling and spreading, low compaction
density, and shear strength that continues to increase with time (a conse-
que.nce of pozzolanic reaction with res idual lime content in the ash).
when covered with soil, provides excellent drainage for vegetation.
Fly ash,
Optimum compaction occurs at approximately 20 percent moisture content
and when fully compacted will exhibit shear strengths that double in 28 days
and triple in 90 days. Early strength development is significantly lower
for lower compaction dens ities but with time strength will approach the
values of higher compaction densities.
The use of fly ash for land fill (excluding fly ash disposal) is not widely
applied in the United States. It has demonstrated its usefulness in embank-
ments and abutment backing in highway construction, but it is not widely
used for these purposes because of the availability of natural fill mater ials.
An example of the use of fly ash in massive amounts as a roadway struc-
tural fill in England is given in Section 4.2.9. A special set of circum-
stances requiring a particularly high fill placed on deep alluvial soil
favored fly ash structurally over locally available rock and soil. Except
for special circumstances such as that, little use of fly ash as a land
fill is expected except for disposal purposes.
4.2.8
Gas Concrete
Gas concrete is a lightweight cellular concrete widely used in Europe as a
building construction material but not in the United States. It is also known
as porous concrete, foamed concrete or cellular concrete.
In its formulation
and preparation, several European countries permit the liberal uses of
fly ash as a pozzolan and as the s iliceo,us filler (instead of, or together with,
sand). For this reason, gas concrete manufacture appeared to offer a
4-52
-------
potentially large outlet for the consumption of fly ash in this country,
and an investigation of its technology and applications was undertaken
with the planning and assistance of the National Ash Association. As part
of this effort, visits were made to facilities and sites in selected areas
of Europe where gas concrete is produced and utilized. Organizations
visited were the Robert Hildebrand Company, Stuttgart, Germany;
Hand H Industri, Copenhagen, Denmark; and Celcon, London, England.
There is an abundance of available literature pertaining to the history,
proper ties, production, and utilization of gas concrete (see Appendix A,
Refs. E-ll, E-l2, E-13, and E-l6 through E-20). The following discus-
s ion deals pr incipally with gas concrete as a utilization potential for fly
ash. Published information is repeated only as necessary for clar ity,
and in most cases technical and economic data not available in the literature
are included.
4.2.8.1
Material Requirements and Gas Concrete Properties
Each manufacturer of gas concrete has his own formula and procedure and
there are no universally established materials requirements. However, the
requirements are similar in that manufacture entails the use of powdered
aluminum as the aera'ting' constituent for a mixture of cement and/or lime,
water, and a siliceous filler, and autoclave treatment of precast sections.
Where fly ash is used, it appears that the fineness and silica content are
the pr imary areas of concern, and that the requirements are lenient enough
that most fly ash produced in the United States would be suitable. In this
connection, it is interesting to note that at one European plant, fly ash from
12 different sources was used in a single day.
The following are ranges of fly ash properties requirements as used by
several European producers, with notations on actual practice:
4-53
-------
r
a.
Fineness -
Blaine - 2500 to 3000 cm2 /gm minimum (2000 cm2/gm
. has been used successfully)
Sieve - 10 percent retained on a 90-micron sieve; 35 per-
cent retained on a 60-micron sieve
b.
Loss on Ignition - 15 percent maximum, or 25 percent maximum
of fly ash when combined with another aggregate, but total not to
exceed 15 percent. (LOr is usually ignored unless a particular
color is des ired. )
Unreacted Lime - 2 to 4 percent maximum (up to 6 percent has
been used successfully).
Sulphates - 2.5 to 3 percent maximum (up to 9 percent has been
used succes sfully).
Silica - 50 percent minimum (as low as 40 percent has been used
s ucce s s fully).
Magnesia - 2 percent maximum (up to 3.5 percent has been used
succe ss fully).
c.
d.
e.
f.
When sand is used, the desired properties are:
a.
Fineness - Same as for fly ash (see above).
Silica - 80 to 85 per cent.
Magnesia and Mica - 2 percent maximum,
Feldspar - 10 per cent maximum.
Clay - 6 percent maximum, by volume.
each.
b.
c.
d.
e.
The lime and/or cement and aluminum powder should have a fineness equi-
valent to the siliceous filler. For lime, the slaking curve should be low
with a temperature increase from 75 to l450F occurr ing after about 15
minutes.
Fly ash concrete consists of 75 percent air and 25 percent solids; two-thirds
of the air is trapped in closed spher ical cells. The formulation most used
in European building construction has a density of about 45 Ib/n3 and a
compressive strength of about 650 psi mini~um. Strength modifications
can be had through variations in material density, amount of cement used,
3
autoclave conditions, and fly ash quality; however, the 45 lb/n material
4-54
-------
has proved to be adequate for both structural and nonstructural applications.
The modulus of elasticity corresponding to this dens ity is approximately
500,000 psi.
Fly ash gas concrete is a particularly good insulator. It has a thermal
conductivity of 1. 30 Btu in./ftZ-hr-oF when the density is 45 Ib/ft3, which is
equivalent to that of wood and about one -s ixth that of br ick. When sand is
used, instead of fly ash, the thermal res istance is reduced by a factor of
about Z. 5.
The acoustical insulating quality of gas concrete is not as good as that of
ordinary brick or concrete, principally because of its low density. However,
in areas where sound insulation is a problem, it has been shown that us ing a
gas concrete 4-in. outer wall and a 3-in. inner wall separated by 3/4-in.
rock wool will provide a 56 db reduction compared to a single 4- in. wall.
4.Z.8.Z
Manufacturing Processes
The only practical proces s of importance today for producing gas concrete
consists of autodaving precast units. This is accomplished by thoroughly mix-
ing cement - and/or lime with a slurry of siliceous material and adding an
aerating agent such as aluminum powder. This mixture is poured into molds,
filling them about half way. (For panels which require structural stabiliza-
tion, reinforcing steel rods previously dipped in bitumen are provided in
the mold; vinyl coatings are not adequate. Also, large nonstructural panels
are provided with small-gauge, unprotected steel rods to provide structural
stability during handling.) There the aluminum reacts with the calcium
hydroxide to produce hydrogen according to the formula
ZAI + 3Ca(OH)Z + 6HZO-3CaO . AIZ03 . 6HZO + 3HZ
The released hydrogen causes an expans ion of the mas s, approximately
doubling its size. This occurs in 10 to ZO minutes, depending on the formu-
lation used.
4-55
-------
The material is then allowed to set for about 1-1/2 hours at 150 to 165°F.
Setting must begin within 5 minutes of aeration completion to prevent the
expanded slurry from falling. Setting before completion of aeration causes
fissures which reduces strength. The mold walls are swung down, the rounded
top of the set material is cut off, vacuum lifted and slurried to the original
production slurry vat. The cutting ope ration is pe rformed by automatic
machinery resembling an egg slicer which divides the semirigid material into
predetermined block or panel sizes. The piano wires of the cutting machine
can be smooth or beaded to give the cut faces a particular surface texture.
After cutting, the mold sides are returned to an upright position and the mold /
material unit is moved with numerous others into an autoclave where they are
subjected to a pressure of about 10 atmospheres at a temperature of about
360°F in the presence of saturated steam. This condition is maintained for
6 to 7 hours for blocks, and for 11 to 12 hours for panels. The blocks or panels
are then available for immediate use. Panels are occasionally provided with a
decorative finish, in the factory, such as an aggregate surface or an acrylic
containing fine marble chips.
Although the gas concrete can be used immediately after autoclaving, a drying
out process occurs naturally which is not detrimental to the material. In this
proces s, a 50 1:b /ft3 finished block, which contains approximately 20 percent
water, drops in density to 47 Ib/ft3 in 2 months, and stabilizes at 44 Ib/ft3 in
12 to 18 months.
A current production formulation for gas concrete utilizing large amounts of
fly ash consists of 80 percent fly ash, 20 percent portland cement, 0.05 percent
aluminum, and water sufficient to form approximately 38 percent the weight
of the dry materials. Numerous variations exist depending on the availability
and quality of materials, and the research that has been performed by a producer.
Some processes employed today use sand a'nd no fly ash, with a lime/cement mix,
and some use 8 percent fly ash and 78 percent sand, with the remainder a mix
of lime and cement. All use a siliceous slurry and add O. 05 to O. 06 percent
4-56
-------
aluminum powder. According to the literature, small quantities of setting
accelerators or hydration retarders also may be used~
It should be noted that when sand is used, a grinding operation is required to
obtain the necessary fineness of the sand; this operation is not necessary when
the total siliceous material is fly ash. Other factors that favor the use of fly
ash instead of sand are that the fly ash improves strength and can improve
shrinkage resistance. Moreover, it can be transported to the production
facility containing as much as 40 percent water which negates the need for
sealed shipping containers and sophisticated handling equipment.
4.2.8.3
Applications
Gas concrete is normally cast into blocks or panels and used as structural or
nonstructural walls, partitions, floors, ceilings, or roofing. It can also be
prefabricated into complete wall or room sections. Applications are for single
family dwellings, multistory apartment or commercial buildings, and factories.
In addition to its excellent thermal insulation properties and reasonably high
compressive strength combined with light weight, gas concrete offers other
advantages such as fire and frost resistance, freedom from termites and
decay, and negligible shrinkage and expansion factors. Its lightness (about
1/3 to 1/4 that of ordinary concrete), of course, simplifies construction costs
and, for multistory buildings, can also mean great savings in foundations and
structural framework. It is easily workable: it can be sawed, plained, drilled,
nailed, and routed with ordinary hand tools.
Structural gas concrete buildings (without framework) are limited to three
stories. Only a poured concrete shear ring is used at the periphery of the
building between floors. In this form of construction, steel rods are inserted
in the grooves between the steel-reinforced panels which can be 2 to 4 feet
wide and approximately 10 feet tall and'4 to 10 inches thick depending upon
the structural usage (ceiling slabs can be 20 feet long if necessary). The rods
placed between the panels are connected to adjacent panels such that the entire
4-57
-------
structure is an integral unit, i. e., it is a monocoque form of a construction
making it res istant to tornado and earthquake loadings. The slabs ar e glued
together to prevent air passage, and grouting is only used to retain the
stabilizing rods and, if des ired, to provide a smooth finish at the joints. In
most cases, the chamfered edges are not filled in with grouting thereby giving
a distinct panel appearance. The surfaces are smooth enough to allow the
inner surfaces to be lightly sanded to form a final finish, or they can be painted
or papered. Usually the surfaces of outer walls are painted with a silicone,
primarily to prevent sweating of the inner wall. Vapors which exist inside a
house can escape through the wall; however, moisture droplets formed by rain
or condensation are lar ge enough to not penetrate the wall and, therefore, the
inner walls stay dry. In addition, moisture held by the panel tends to alleviate
problems of low humidity dur ing dry per iods by releas ing moist air into the
building.
Some typical construction applications are shown in Fig. 4-9.
4.2.8.4
Economics
The most attractive quality of fly ash gas concrete is the economic advantage
it offers over other forms of building construction. In West Germany it has
been noted that the cost of building construction, less land, can be reduced
by 20 to 30 percent for conventional brick, block, or concrete homes, and
large buildings or developments" respectively. More explicitly, erected gas
concrete panels cost approximately half that of poured- in-place concrete, with
an appreciable portion of that saving due to a 25- to 30-percent labor cost
reduction. Further studies of the economics of building construction in the
United States are neces sary to accurately as ses s cost savings. However,
indications are that the savings would be appreciable since a significant factor
in gas concrete economics is labor reduction.
4-58
-------
Fig. 4- 9a.
Structural Panels
Fig. 4-9c.
Load-bearing Blocks
Fig. 4-9.
'" II
...
"I
....
Fig. 4-9b.
Multistory Building,
Nonstructural Panels
Ref. E- 11
Fig. 4- 9d.
Gas Concrete,
Hand Work Features
Typical Construction Applications
4-59
-------
Some miscellaneous installed-panel selling prices of German panel construction,
six inches thick, are as follows:
Non-load-bearing
Load - bearing
$ O. 56/ft2
$ o. 65/ft2
German masons are paid approximately $2.25 per hour, and cement sells for
about $16 per ton.
Varying estimates of constructing a minimum-size gas concrete plant in the
United States, producing 65,000 to 100,000 yd3/yr, are put at $2 to $3 million,
excluding land. The use of fly ash instead of sand would delete the cost of
grinding equipment, which represents 10 to 12 percent of capital costs (about
$90,000), and eliminate 15 to 18 percent of the production cost. It is also
estimated that a small plant producing about one-third as much as the above
on a two-shift basis, with direct casting instead of cutting and by using fly ash
instead.of sand, would cost about $800,000.
4.2.8.5
Usage Potential for Fly Ash and Limestone -Modified Fly Ash
in Gas Concrete
European utilization of gas concrete has proven it to be a highly desirable form
of building material from the standpoint of construction economy and structural
qualities. It is used in at least 20 countries; in West Germany, for example,
gas concrete is used in the constr~ction of 80 percent of all new factory
buildings while in Sweden such use approaches 100 percent. Additionally, in
the Philippine Islands it is now being used for the construction of low-cost
housing projects.
Much of the gas concrete produced incorporates large amounts of fly ash. For
example, in England in 1971 it is expected that 1 million tons of fly ash will be
consumed. Since fly ash improv,es the quality of gas concrete, reduces capital
and production costs, and is available in ab~dance in urban areas, it could
conceivably find a large market throughout the United States as a constituent
of gas concrete.
4-60
-------
The future of gas concrete in this country is not readily assessable. As a
new industry, it would have to compete with numerous well-established
building techniques using conventional materials. To establish fly ash con-
crete as a building cons truction mater ial on a wide scale would require
substantial technical and economic surveys, coupled with the dis semination
of the technology. Its acceptance, of course, could be accelerated through
the construction and operation of at least one plant in the United States. For
a bare-minimum plant or a plant the size of the largest available engineered
plant by European standards, estimates of fly ash utilization are 7,000 and
45,000 annual tons, respectively.
Wet-collected limestone-modified fly ash also has an apparent potential for
utilization as an ingredient of gas concrete. Theoretically, the amount of
free lime in the ash would be less than 5 percent (see Table 5-1), and there
would not be any unreacted sulfur. However, the silica content may be
inadequate (15 to 30 percent versus 40 to 50 percent required) and a sand
additive may be required. Because of the necessity for sand grinding, gas
concrete incorporating modified fly ash would be more expensive than if
regular ash were used. Its manufacture would be further complicated by
the fact that the content of silica and other cons tituents would vary con-
s iderably, depending on the sulfur content of the coal and the effic iency of
the boiler. Nevertheless, these apparent disadvantages do not rule out the
possible utilization of wet-collected, limestone-modified fly ash. A program
of chemical and phys ical character ization and utilization research is neces-
sary to evaluate its true potential.
4.2.9
Foreign Utilization
Information on the utilization of fly ash by Japan, and by West Germany,
England, and Denmark was gathered during the study. Data were also
reviewed for the production and utilization of combined bituminous ashes
in 1967 by the three above-named European countries and seven others
4-61
-------
-'-
(as shown in Table 4-7) -~. In Europe, the indications are that the utilization
of fly ash continues to increase and exceeds that of the United States in
total fly ash used and in percentage used of the total produced.
The current annual bituminous coal fly ash production in West Germany is
estimated to be 1. 1 million tons, with an additional 5 million tons of bottom
ash. This ash is produced in wet-bottom cyclone furnaces, and has a high
carbon content after the fir st burn. Since this type of boiler allows reinjec-
tion of the fly ash (which is 40 percent of the original total ash) until the
carbon content is reduced to 6 percent or less, the fly ash is approximately
16 percent of the total ash produced. Large quantities of lignite are also
burned in Germany in dry-bottom furnaces, producing about 6 million tons
of fly ash annually.
However, none of this ash is utilized.
The German government controls the use of fly ash as a cement replacement
in concrete. Presently, only one unit of one powerplant is certified to sell
fly ash for this purpose, and one other is expecting certification soon. A
one-year per iod of government inspection of the power plant on a random,
unannounced schedule is required prior to certification.
In England, the predicted 1971 production of fly ash is approximately 9
million tons. Six million tons (70 percent) of this will be utilized: over
2-1/2 million for load-bearing fill in highway construction, and one million
as an ingredient in gas concrete blocks for internal wall linings and partition
walls. The major portion of the remainder is used as a cement replace-
ment in concrete.
In Japan, approximately 5 million tons of fly ash were produced in 1969 and
26 percent of this was utilized. More than 70 percent of this usage was
for the manufactur ing of cement or for the replacement .of cement in con-
crete.
-'-
-"Further information is available in a report prepared by the Economic
Commission for Europe, Committee on Electric Power (Ref. E-21).
4-62
-------
In some cases in these countr ies, the utilization of fly ash is enhanced
through government issuance of standards, e. g., for the use of fly ash in
concrete. The eventual utilization of fly ash, however, generally evolves
from research, resultant technology, and most importantly, economics.
As mentioned, Table 4-7 shows the European bituminous ash production
and utilization for 1967. Except for the data on German ashes, these data
apply to combined values for fly ash, bottom ash, and boiler slag. As
noted in the table, 48 percent of the total European ash is utilized for roads,
dams, and fill, while 46 percent is used for construction materials and
cement binder. (Utilization of ash in the United States is in comparable
proportions, however. in lesser total tonnages.) Of the 12,501,000 tons
of total ash utilized in the ten countries identified on the chart, 82 percent
was used in England, France, and Germany. In England, it is known that
fly ash is used in lar ge quantities as noted above; in France it is used
pr incipally as a cement additive and as a road fill or base material. Over
60 percent of all coal ash produced in France is utilized. Government
ownership of mines, power companies and roads, plus an under produced
cement industry and a lack of borrow pits, aids this situation, but exact
fly ash data are not published. Total coal ash produced in France in 1970
is estimated at 4.5 million tons; and in Germany it is exported in nominal
amounts to neighboring countries for fill material in asphalt road building
as well as being used locally.for secondary roads and concrete block manu-
facture.
Preliminary estimates identify English and French usage of fly ash as that
which causes the total European fly ash usage to rate well above Americals.
This is due pr incipally to the control of the coal burning utilities by the
government, coupled with the desire of the government to use flya.sh, and
the existence of an economical market for fly ash utilization.
4-63
-------
Table 4-7.
Fore ign Production and Utilization of
Bituminous Ashe s - 1 967
(Fly Ash, Bottom Ash and Boiler Slag)
~
I
0"-
~
Con- Roads
Production Cement struction Dams
1 000 Tons Utilization Binde r Materials Fill Misc.
Country (Metric) 1000 Tons Percent 1000 Tons 1 000 Tons 1000 Tons 1000 Tons
Belgium 1,300 557 42 54 254 224 25
West Germany
Fly Ash 900 680 70 300 200 110
Bottom Ash 4,500 3.000 - 1.700 1 . 1 00 200
Slag 800 600 - - 400 200
-
6,200 4,280 69
Denmark 340 321 96 34 34 181 72
England 9.500 3,993 42 57 1,295 2,504 137
France 3.700 2,026 55 887 III 999 29
Poland 3.300 1.025 31 - 785 230 10
-
Romania 240 24 10 - - - 24
Spain 860 1 , 000 12 23 "1 76 -
Czechoslovakia 1 . 1 00 175 16 10 125 40 -
Turkey 170 - - - - -
Total (1 000 Tons) 26.710 12, 501 47 1,135 4,605 5,954 807
0/0 of Ash Utilization 100 9 37 48 6
-------
As for technological advancements, the European use of fly ash in gas
concrete (see Section 4.2.8) is the outstanding application noted that was
super ior to, or nonexis tent in, Amer ican utilization. However, effor ts to
introduce gas concrete in American building construction are being made,
and the American Concrete Institute has established a committee to study
and recommend spec ifications for gas concrete.
Other applications of a less sophisticated nature, but still using fly ash
somewhat differently or mor e abundantly than in the United States, include:
c.
Asphalt Filler in Paving - A West Germany utilization called
IIGans Pavingll for secondary roads, 28 percent fly ash versus
4 percent in the United States (see Section 4.5.4).
Highway Structural Fill - An English procedure us ing 100
per cent fly ash for high embankments placed on alluvial
soils, in the cons truction of pr imary roads (see Section 4. 5.4 '.
Base Course Materials for Parking Lots - An English usage,
88 to 90 percent fly ash, plus cement and water (see Section 4.5.4).
Abandoned Sewer Fill - An English application us ing mix
approximately the same as in item c. The slurry is pumped
into abandoned sewers.
a.
b.
d.
Individual dis cuss ions of these fly ash utilizations are included in separate
sections as noted by the reference paragraphs.
4-65
-------
4.3
4. 3. 1
FLY ASH SPECIFICATIONS AND PROPERTIES
Introduction
The objective of this portion of the study was to examine the existing
specification literature pertaining to fly ash, and to form an assessment
of the extent to which present specifications enhance or inhibit the
utilization of fly ash.
The most significant group of specifications pertains to fly ash for use as
a pozzolanic admixture in portland cement concrete. Summaries of fly
ash analyses and physical property data were compared with the require-
ments of several of these specifications. It was possible to identify the
portion of fly ash which did not meet the requirements. ASTM C-6l8- 68T
was the most lenient of the specifications, but only 61 percent of the
sampling met its provisions. The most severe were TVA Construction
Specification G-30, Class I ash, and certain Bureau of Reclamation
specifications; only 30 percent of the samples conformed to these. There
were numerous instance 5, however, of the succes sful use of nonspecifica tion
ash in concrete mixes.
The following conclusions can be made:
a.
Specifications as currently written contribute to the
inhibition of the widespread use of fly ash in portland
cement concrete.
Nonspecification ash can be employed successfully, but
technological development is required.
Certain provisions of the fly ash specifications bear little
relevance to the performance of fly ash in a concrete mix.
Specification modifications are indicated.
b.
c.
d.
Specifications on fly ash for use in products othe r than
portland cement concrete are few in number but are in
no way inhibitory.
Specifications for fly ash do not exist for numerous
products in which it is used. However, in these case s
specifications do exist for the products themselves.
These specifications inhibit the use of fly ash only when
the existing technology limits the selection of materials
for reasons of incompatibility with the production technique,
e. g., certain grades of fly ash in s intered aggregate
production.
e.
4-67
-------
4. 3. 2
Specifications Applicability
Specifications pertaining to fly ash generally are of two types: (l) raw
material specifications, and (2) product specifications. Raw material
specifications provide for the use of fly ash as a batch ingredient for a
specific product or class of products. They specify the chemical and
physical requirements for the ash in various levels of detail, depending on
the level of technology required in the manufacture of the product. Typical
of the raw material specifications are:
a.
ASTM C-6l8, Fly Ash and Raw or Calcined Natural
Pozzolans for Use in Portland Cement Concrete
ASTM C-593, Fly Ash and Other Pozzolans for Use with
Lime
b.
c.
ASTM D-242, Mineral Filler for Bituminous Paving
Mixtur e s
Product specifications deal only with the requirements or properties of
the product, and mention peripherally or not at all the properties of the
ingredients. They typically state that fly ash may be a constituent of, say,
a blended hydraulic cement, a lightweight aggregate, or certain masonry
units. The product specification is of limited pertinence to the present
study because it does not constitute a direct inhibition to fly ash use.
Fly ash specifications have been published by advisory bodies such as the
ASTM and the American Petroleum Institute, a regulatory body such as the
General Services Administration, and by various users of fly ash. These
specifications differ in certain significant, and not-so-significant,
particulars as will be detailed later. Probably the most prestigious of
the specifying bodies is ASTM. For example, ASTM C-6l8 and its
evolutionary precursors have set the tone for several specifications on
fly ash for use in portland cement concrete. Its acceptance is such that
many users of fly ash simply stipulate that the ash conform to the
appropriate ASTM specification per se, or with specific modifications.
Fly Ash for Use in Portland Cement Concrete
4. 3. 3
4.3. 3. 1
Development of Specifications
Probably the most technically demanding application for fly ash, and
4-68
-------
certainly the one that has received the most attention in the technical and
specification literature, is as an admixture in portland cement concrete.
Initial investigations of this application date from the early 1930's, and
the report which served as the foundation for the specifications, methods
of testing, and use of fly ash in cement was published in 1937 (Ref. C-122).
During the late 1940's, representatives of firms marketing fly ash began
to urge ASTM to prepare standards under which fly ash could be marketed
in the cement and concrete industry. The matter was assigned for
committee action. After numerous iterations, ASTM C- 350 was evolved,
approved, and issued in 1954. It was then modified in 1957, 1960, 1963,
1964, and 1965 to accommodate new information. Finally, in 1968 it was
combined with ASTM C-402 (Natural Pozzolans) to form the current
ASTM C-6l8. Additionally, the Bureau of Reclamation, U. S. Army Corps
of Engineers, and other agencies developed and published their own
specifications.
4. 3. 3. 2
Provisions of Specifications
As stated, the specifications published by various agencies differ in a
few important provisions. These differences can be seen in Table 4- 8
which details the chemical and physical requirements for fly ash provided
by a number of specifications.
With reference to ASTM C- 618, a major difference between it and all
of the others shown is the allowable loss on ignition (LOI). ASTM permits
up to 12 weight percent, while all other specifications require maxima of
5 to 6 percent. The LOI, in weight percent, corresponds very closely to
the residual unburned carbon remaining in the ash. Exces sive carbon is
undesirable onat least two counts. One is that the carbon, which is
generally coarse, decreases the pozzola:qic activity of the ash and also
the desirable workability which the ash imparts to concrete. Possibly
more importantly, carbon interferes with the normal action of air-entrain-
ment in concrete, which is required to impart weathering resistance to
4-69
-------
concrete. For example, an ash with an excessive carbon content may
necessitate that the concrete batch contain upwards of 20 times the normal
dosage of air-entraining agent for a satisfactory level of air-entrainment.
Furthermore, high carbon content makes air-entrainment difficult to control.
A further objection to carbon is that it may impart an undesirable color to
concrete and thereby create adverse consumer reaction.
Two federal agencies, the Bureau of Reclamation and TVA (for Class I ash),
impose maxima of 10 to 12 weight percent on the amount of residue retained
on a 325-mesh sieve. Neither A8TM, the U. 8. Army Corps of Engineers,
nor the Federal specifications provide for a 325-mesh-sieve residue
limitation. TVA mitigates their specification by providing additional
specifications: Class II ash and Class III ash may contain up to 22 percent
and 32 percent 325-mesh residue, respectively.
The justification for a sieve fineness specification is similar in some
respects to that for a carbon limitation. The pozzo1anic activity of fly ash
is usually directly related to its fineness, and the residue on a 325-mesh
sieve is usually regarded as just inert particulate material. Moreover, it
may be highly carbonaceous, with its concomitant inconveniences. The
exception provided by TVA in specifying ashes of different finenesses reflects
their concept that a coarse ash may be a useful raw material, but it will
require different concrete mix designs.
There are other differences in certain allowable chemical and physical
properties called out by the specifications in Table 4- 8. These
differences are generally minor, and are not felt to be highly significant
to the performance of fly ash in a concrete mix. Only experts having a
particular bias are apt to contend strongly that the difference between,
for example, 3.0 and 3. 5 percent 803' or 1.5 and 2. 0 percent alkalies
will affect substantially the utility of a fly ash. No scientific data
supporting such contentions were found.
As the foregoing shows, there presently is no standard or specification
which is univer sally accepted. In effect, each user agency has written
its own specification. A movement is afoot to establish Federal
4-70
-------
Specification SS-P-00570b (Ref. F -41) as a uniform standard which would
be acceptable to all government agencies. This document is nearly identical
to Corps of Engineers Specification CRD-C-262-63 (Ref. F-50), but
requires only half as much qualification testing of fly ash. However,
SS-P-00570b's lack of provision of a maximum 325-mesh-sieve residue is
likely to cause objections by some agencies. And so the difficulties of
standardization remain unresolved.
4. 3. 3. 3
Specifications Versus Fly Ash Properties
It is instructive at this point to examine the specification requirements in
light of how they compare with chemical analyses and physical properties
actually measured on typical samples of fly ash. Two fairly large and
reasonably complete bodies of data (Refs. C-9 and C-34) on fly ash were
consulted. The reported properties of 59 fly ashes are tabulated and
compared with the pertinent properties called out by several specifications.
Chemical specifications and sample analyses are shown in Tables 4- 9
and 4-10. The key physical specifications and the fly ash properties, as
available, are presented in Tables 4-11 and 4-12.
The most frequent chemical delinquency of the ashes in these samplings is
their LOI. Only. a few other instances of chemical nonconformity are noted
and some of these are for ashes that are clearly atypical. Also apparent
is that virtually all of the ashes shown in Tables 4-9 and 4-10 meet the
ASTM LOI requirement, but many of them do not conform to the LOI
requirement of the other specifications.
Physical property data on fly ashes generally are quite limited. For
example, available survey data seldom report compressive strength of
mortar cubes, pozzolanic activity index, and many.of the other physical
requirements detailed in Table 4- 8. The most frequently reported
properties are the Blaine fineness (or specific surface area) and the
325-mesh-sieve residue. The data presented in Tables 4-11 and 4-12
are limited to these latter properties. Clearly, a large portion of these
samplings is deficient by one or both criteria.
Tables 4-9
through 4-12 show that the key criteria provided by these
4-71
-------
Table 4- 8.
Specifications for Fly Ash as an
Admixture in Concrete
*'"
I
-J
N
Property ASTM CE Federal Bu Rec 317Z; TVA G-30 TVA G-30
C-618-68T CRD-C-Z6Z-63 SS-P-570b Bu Rec DC-3413 (Class I) (Class II)
SiOz + AIZ03 + FeZ03' min, wt % 70 70 75 SiO 40, AIZ03 15 75 75
MgO, max, wt % - - 5.0 5.0 3.0 5.0 5.0
503' max, wt % 5.0 4.0 4.0 3.5 4.0 4.0
Moisture, max, wt % 3.0 3.0 3.0 3.0 3.0 3.0
LOI, max, wt 0;0 IZ.O 6.0 6.0 5.0 6.0 6.0
Available alkalies, as NaZO, max, wt % 1.5 1.5 Z.O 1.5 Z.O Z.O
Finene s s, surface area, min, crnZ/cm3 6500 6500 6500 3000 cmZ/g 6500 5000
Amount retained, 3Z5M, max, wt % -- - - -- lZ IZ ZZ
Compressive strength of mortar cubes:
Percent of control, 7 day, min 100 -- - - -- -- --
Z8 day, min 100 -- -- 85 -- --
Pozzolanic activity index:
Portland cement, Z8 day, min, percent of control 85 75 75 -- 85 70
Lime, 7 day, min, psi 800 900 900 -- 1000 800
Water requirement, max, percent of control 105 103 103 103 -- --
Increas.. of drying shrinkage, mortar bars, 0.03 -- -- -- -- --
Z8 day, max, percent
Soundness, autoclave expansion or 0.05 0.50 0.50 -- -- --
contraction, max, percent
Specific surface, Max variation from 15 ZO Z5 -- -- --
average, percent
Specific gravity, max variation from 5 5 6 - - -- --
average, percent
Air-entrainment agent requirement, ZO -- -- -- -- n
Max variation from average
Reactivity with cement alkalies:
Mortar expansion, 14 day, Max percent O.OZO - - - - -- - - --
Reduction of mortar expansion, Z8 day, - - 75 60 60 -- --
min percent
- - Dashes indicate either no specification or not available
ASTM C-618-68T:
CRD-C-Z6z-63:
SS-P-570b:
Fly Ash and Raw or Calcined Natural Pozzolans for Use in
Portland Cement
Pozzolan for Use in Portland Cement Concrete
Pozzolan for Use in Portland Cement Concrete
TVA G-30:
Fly Ash for Use as an Admixture in
Concrete
Cachuma Dam, 1950
Davis Dam Spillway, 1951
Bu Rec 317Z:
Bu Rec DC- 3413:
-------
ASTM C-618-68T
Specification
Corps of Engineers
CRD-C- Z6Z-63
FederaISS-P-570b, and
TV A G-30 (C1aases 18<11)
Sa Ree 317Z. DC-3413
(Caehuma. Davio)
~
I
-.J
W
:
N
'"
'"
~
.2
iii
~
:5
.c
.. .
<~
...'"
~-:
-it
00
.~~
~o
a....
.!i,:.
~'"
~ .
~o
~z
bi,D
go:
~rJ
~~
~Z6
..
~
o
.J>
E
"
z
...
~
..
'"
E
o
o
-50
Table 4- 9.
AIZ03
+
SiOZ
+
FeZ03
70 min
70 min
75 min
5Z
87.4
94.0
89.0
89.0
90.0
38
17
87.7
83.0
83.0
34
91. Z
84.8
93.4
39
Z8
89.3
91. 5
89.4
88.8
87.7
86.Z
14
36
94. I
85.3
4Z.3
35
87.5
31
88.8
86.3
87.0
9
90.5
n.4
83.3
8Z.0
8Z.4
85. I
II
96.4
Comparisons of EEl Fly Ash Sample Data with
Chemical Specifications
--
40 min
5Z. I
50.1
45.0
43.0
4Z.0
3Z.0
39.6
4Z.6
49.4
37.0
45.7
40.3
41. 4
43.1
38.0
45.0
4Z.3
58.0
44.4
30.7
39.7
44. 7
49.Z
4Z.0
44.6
36.6
36.6
45.Z
4Z.3
51. Z
Analysis (Weight Percent)
SiOZ
AIZ03
--
.-
--
15 min
n.o
B.Z
31. 0
Z6.0
Z4.0
ZO.8
Z3.9
Z3.8
ZZ. I
Z4.4
Z9.8
ZI. 5
19.8
Z3.9
14.6
Z.14
ZO.7
n.o
Z6.0
0.5
17.4
ZI. 9
Z5.5
ZO.8
35.4
Z6.3
Z3.3
Z7.9
Z5.7
Z9.8
.-
--
--
MgO
--
5max
5max
4max
5 max
4max
3 max
3. 5 max
0.4
0.5
0.6
0.4
0.6
0.8
0.7
1.0
0.9
0.9
1.4
Z.I
I.Z
I. I
1.5
1.9
Z.O
0.6
0.7
0.8
0.8
0.9
0.5
1.1
0.8
0.9
O. 7
0.8
0.7
0.6
1.5
O. I
0.5
0.5
1.0
tr
0.6
O. I
tr
5.7
O.Z
0.8
O.Z
0.6
0.8
Z.5
Z.O
1.8
0.3
0.6
1.5
1.4
1.6
1.5
0.9
1.1
1.4
I.Z
1.3
3.6
503
IZ max
Z. I
1.9
5.3
5.3
4.5
Z.Z
5.9
6.0
Z.4
10.7
8.0
Z.6
3.8
3.5
--
6.0
7. I
0.6
6.4
O.Z
6.4
6.4
6.0
3.3
5. I
8.0
8.6
6.9
3.9
1.3
LOI
6 max
6max
5 max
Mois-
ture
3max
3max
3max
3max
0.3
0.3
O.OZ
0.04
0.00
o
--
0.3
--
0.1
0.1
--
O.Z
0.1
0.1
0.1
0.1
0.5
1.1
4.0
1.1
0.6
--
--
I.Z
o
o
o
--
--
0.6
0.1
0.1
0.07
0.07
Avail.
Alk. as
NaZO
ASTM
C-618-
68T
Fly Ash not Conforming to Specifications
Federal
55-P- 570b;
TV A G-30.
Classes
18< II
BuRee 31n.
DC-3413
0.8
0.9
Z.O
I.Z
1.1
Alk.
1.5max\I\\\
1.5max
Zmax
1.5max
Z.O
Alk.
--
0.3
0.9
0.7
0.6
--
Alk.
0.3
--
--
1.3
I.Z
1.3
Z.I
Alk.
--
u
--
--
u
--
CE
CRD-C.
Z6Z-63
Alk.
Alk.
LOI
LOI
Alk.
LOI
LOI
LOI
LOI
Alk.
LOI
LOI
LOI
LOI
LOI
Alk.
LOI
LOI
LOI
LOI
Alk.
LOI
LOI
LOI
LOI. Alk.
LOI
SiOZ' Alk.
~r LOI
SiO, LOI
LOI
Alk.
~f' AI Z03
LOI
LOI
LOI
SiOZ. LOI
LOI
LOI
Alk.
LOI
SiOZ' LOI
~f' LOI
5°3
-------
Table 4-10.
Comparison of OHIO Fly Ash Sample Data with
Chemical Spec ifications
*'"
I
-J
*'"
Analysis (Weight Percent) Fly Ash not Conforming to Specifications
AI203 Federal
Specification + Mois- Avail. ASTM CE 55-P-570b; Bu Rec 3172,
5i02 5i02 AI203 MgO 503 LOI AIk. as C-618- CRD-C- TVA G-30,
+ ture Na20 68T 262-63 Classes DC-HI3
Fe203 I &. II
ASTM C-618-68T 70 min -- -- - - 5 rnax 12 max 3 max 1.5 rnax \ \ \ \
Corps of Engineers 70 min -- -- 5 max 4 max 6 max 3 max 1.5 max
CRD-C-262-63
Federal 55-P-570b, and 75 min -- -- 5 rnax 4 max 6 max 3 max 2 max
TVA G-30 (Classes I &. II)
Bu Rec 3172, DC-3413 -- 40 min 15 min 3 max 3. 5 max 5 max 3 max 1.5 max
(Cachuma. Davis)
-I 89. 77 43.25 21. 93 O. 76 I. 21 3. 23 0.25 0.71
2 92. 76 49. 70 22.85 I. 34 0.49 O. 24 0.17 0.53
" 3 -- -- - - -- -- -- -- --
.c 4 90.81 42.74 23.15 0.54 0.49 4.83 0.16 0.59
[-0>-
- ~ = - 5 87. 37 44.13 24.67 0.77 I. 28 6.61 0.49 0.66 LOI LOI LOI
O"tl ~ 6 91. 85 44.77 22. 54 I. 04 0.44 2.29 0.25 0.52
"'''~ 7 -- -- -- -- -- -- -- --
NU~
, ~ u 8 90.24 44.61 21. 49 0.93 I. 15 3.62 0.18 0.81
13"" ~ 9 94.54 38.61 18.39 0.81 0.25 0.13 0.10 0.61 5i02
00
~~u 10 91. 70 49.08 33.43 0.70 0.35 4.63 0.17 O. 75
v >- C 91. 60 46.91 24.33 0.68 I. 22 2.95 0.52
"-,, II I. 03
'cO;< S 12 90.83 45.61 26.13 0.84 0.16 5.09 O. II 0.82 LOI
~ u" ..
o..ju ~ 13 93.61 46.93 27.00 0.69 0.19 0.89 0.09 0.62
" 14 86.62 48.12 25.47 0.98 I. 70 5.55 O. 35 I. 05 LOI
--"" .0
-> 0 ; S 15 84.50 41. 21 19.63 O. 77 0.51 9.03 0.25 0.63 LOI LOr Lor
.... 111- ~ 16 80.87 47.50 22.36 0.85 0.54 6.27 0.21 0.87 LOI LOI LOI
:5~~ z
,, 17 92.19 43.03 19.15 0.67 I. 16 3.54 0.44 0.77
.:J 0.. a. 18 92.33 35.78 19.30 0.52 0.90 3.12 0.16 0.41 5i02
U5 -;;.s S 19 67.69 30.33 22.07 0.82 I. 19 6.46 0.57 0.92 * * * 5i02' LOr
o~ '" 20 77.36 40.99 20.45 0.98 I. 14 16.82 0.79 0.73 LOI LOr LOr LOI
.... c II) I/)
.c,,~
O~~ 21. 16 0.80 0.84 I. 74 0.16 0.67
o~ 21 92.90 44.93
-o...~
..;"" S 22 76.47 37.71 18.03 0.92 I. 00 13.12 14.23 I. 00 LOI, LOI, LOI, LOI
~~"" Mois. Mois. Mois. 5i02. Mois.
1/)",< 23 80.95 39.63 16.96 I. 00 0.74 9.79 0.16 0.86 LOI LOI 5i02' LOI
->- M
~~ ~# 24 90.28 43.85 19.83 0.13 0.29 5.40 0.16 0.54 LOI
bJ.... II) - 25 88.14 44.81 23.33 I. 12 0.39 5.09 0.16 0.69 LOI
.0 '" 26 84.24 41. 71 21. 64 I. 03 0.59 8.25 0.16 0.51 LOI LOI LOI
. '" .
co-.c u 27 89.30 51.43 21.67 0.88 O. 76 5.35 0.43 0.80 LOr
~~
-------
Table 4-11.
Comparisons of EEl Fly Ash Sample Data with
Phys ical Specifications
of::>.
I
--.J
U1
Physical Property Requirement8 Fly A8h not Conforming to Specification8
Specification Specific % Retained Fineness-Surface ASTM CE Federal Bu Rec TVA Q-30 TVA Q-30
on 3Z5M Area Minimum C-618- CRD-C- 317Z,
Gravity Sieve cmZ/cm 3 cmZ/g 68T Z6Z-63 SS-P-570b DC-HI3 (Cia.. I) (Cla.. II)
ASTM C-618-68T - - - - 6500 -- \ \ \
Corps of Engineer. -- -- 6500 --
CRD-C-Z6Z-63
Federal SS-P-570b - - -- 6500 --
Bu Rec 311Z, DC-3413 - - IZ -- 3000
TVA Q-30 (Cla.. I) -- IZ 6500
TVA Q-30 (Cla.. II) -- ZZ 5000 --
,..46 Z.5 -- 83Z0 HZ6
Z.5 h 11,550 4603
..; Z.5 -- 6810 Z764
'" Z.5 h IZ,700 5007
'"
- Z.4 -- 7800 3Z43
a. Z.4 - - 5700 Z31Z SA SA SA SA SA
" Z.4 h 8Z30 HZ7
UI
<> Z6 Z.O ZO 5700 Z850 SA SA SA SA,3Z5 SA, 3Z5
... Z. Z 17 6600 3000 3Z5 3Z5
.
'"
'" 5Z Z.3 14. Z 8830 3840 3Z5 3Z5
,; Z.5 10.Z 8850 3540
Z Z.5 13.8 6800 Z710 3Z5 3Z5
~ 17 Z.4 15.6 8680 36Z0 3Z5 3Z5
0. .
i;i .. 8880
" 34 e.5 4.4 3545
101 J>
= ~ 39 Z.5 14.3 8480 3390 3Z5 3Z5
..; Z Z.4 18.1 10,ZOO 4310
'"
~ >-
c
~ It Z8 Z.4 11. 4 6160 Z571 SA SA SA SA,3Z5 SA, 3Z5
.2 g 14 Z.5 Z4.1 4040 1616 SA SA SA SA,3Z5 SA,3Z5 SA,3Z5
:0
~ U Z.5 10 7550 30Z0
Z. 3 51 3390 141Z SA SA SA SA,3Z5 SA,3Z5 SA, 3Z5
:S Z.3 18 6680 Z904 3Z5, SA 3Z5
.c Z.3 38.6 41Z0 Z05Z SA SA SA SA, 3Z5 SA, 3Z5 SA,3Z5
.
< 36 Z.3 18 5750 Z500 SA SA SA SA, 3Z5 SA, 3Z5
>-
~ 35 Z. Z Z1. 3 4690 ZlZ7 SA SA SA SA,3Z5 SA, 3Z5 SA
.; Z.O 6Z.8 3Z80 1639 SA SA SA SA, 3Z5 SA, 3Z5 SA,3Z5
.~ 51 Z.4 4Z.1 4800 ZOOO SA SA SA SA, 3Z5 SA,3Z5 SA, 3Z5
.
.s 31 Z.5 13. Z 5Z70 Z105 SA SA SA SA, 3Z5 SA, 3Z5
.~ Z.3 IZ.8 4790 Z516 SA SA SA SA, 3Z5 SA,3Z5 SA
!: Z.Z 19.4 4950 ZZ54 SA SA SA SA, 3Z5 SA,3Z5 SA
u
" 9 Z.4 36.4 3360 139Z SA SA SA SA,3Z5 SA, 3Z5 SA, 3Z5
iJ Z. I 19 8080 3850 3Z5 3Z5
c
0
. -II Z.5 Z7.4 -- - - 3Z5 3Z5 3Z5
:; Z.5 38. I -- - - 3Z5 3Z5 3Z5
101
Z.4 11. 4 -- - - 3Z5 3Z5
Z. 5 7.4 48Z0 nZ6 SA SA SA SA SA SA
- - Dashes indicate either no specification or not available
SA - Surface Area
-------
Table 4-12.
Compar isons of OHIO Fly Ash Sample Data with
Phys ical Specifications
Physical Property Requirements Fly Ash not Conforming to Specifications
Specification Specific % Retained Fineness-Surface ASTM CE Federal Bu Rec TVA G-30 TVA G-30
on 325M Area, Minimum C-618- CRD-C- 3172,
Gravity Sieve crnZ/cm3 em 2{ g 68T 262-63 SS-P-570b DC-3413 (Class I) (Class II)
ASTM C-618-68T 6500
Corps of Engineers 6500
CRD-C-262-63
FederaISS-P-570b 6500
Bu Ree 3172, DC-3413 12 3000
TVA G-30 (Class I) 12 6500
TVA G-30 (Class II) 22 5000
1 2.803 5400 1922 X X X X X
" 2 2.632 3920 1489 X X X X X X
-",., 3
1-<-. 4 2.568 5790 2251 X X X X X
= I<. - -
-" " 5 2.556 8700 3404
~ ~~u 6 2.653 5540 2048 X X X X X
I N:j~ 7 2.438 5800 2380 X X X X X
--J ' " " 8 2.698 7120 2636
"'00
0' ~&:~ 9 2.656 3520 1325 X X X X X X
~ ,.,,, 10 2.193 6640 3025
u- "
.2, -;;; E 11 2.493 8380 3361
0 u " ~ 2.346
Itju .. 12 9300 3955
" 13 2.345 5160 2201 X X X X X
~" .0
- 0 " E 14 2.543 14,500 5692
. ..
::>~- ~ 15 2.511 7740 3082
"'i: Z
~~~ 16 2.463 6410 2604 X X X X X
0- C ~ 17 2.648 4740 1784 X X X X X X
O'~'~ E 18 2.860 5490 1918 X X X X X
.... c «I) .. 19 2.517 14,100 5612
-",," "' 20 2.310 14,200 6149
O~~
o~
-11..~ 21 2.637 5480 2493
.." E
~"" 22 2.388 8860 3712
cnnS«~ 23 2.437 7110 2925
~~~~ 24 2.524 6750 2664
t;a;J.... CD 25 2.474 7080 2863
.0.. - 26 2.580 4600 1781 X X X X X X
... .
~.~.; ~ 27 2.429 10,000 4128
r.:I~
-------
Table 4-13.
Summary, Fly Ash Samples Conforming to Key
Provis ion of Var ious Specifications for Use in
Portland Cement Concrete
Fly Ash Samples, Percent Conforming to Key Provisions
Pertinent Specifications Blaine Fineness, cm21 LOI, % max, Retained on 325M Sieve, (% + 325M) x All Criteria,
cm3 min, 144 Samples 165 Samples % max, 151 Samples (% LOI)", 150, 0/.
and
6500 5000 12 6 12 20 149 Samples (No. of Samples)
ASTM C-618-68T, Fly 67.1 - 92.1 - N.R. N.R. - 60.8
Ash and Raw or Calcined (128)
Natural Pozzolans for
Use in Portland Cement
Concrete
Proposed Amendment - - 92.1 - - 78.0 87.2 78.5
to ASTM C-618-68T (149)
Federal Specification 67.1 - - 71. 1 N.R. N.R. - 46.1
~ SS-P-570b; Corps of (128)
Engineers Specification
I CRD-C-Z62-63;
....... American Petroleum
....... Institute Standard 1 OA
Bureau of Reclamation 67.1 - - 71. 0*" 39.7 - - 30.1
Specifications 3172 (113)
and DC-3413; TV A
Construction Specifica-
tion G-30 (for Class I
Ash)
TV A Construction - 90.9 - 71. 0 83.3* 62.8
Specification G-30 (113)
(for Class II Ash)
Note:
Data on 168 fly ash samples were taken from:
(a) "Laboratory Investigation of 81 Fly Ashes," Concrete
Laboratory Report No. C-680, Bureau of Reclamation,
Denver, Colorado, 11 Sept. 1953.
(b) "Fly Ash Utilization - 1962," EEl Pub. No. 62-70,
Fuel and Ash Handling Subcommittee of the Prime
Movers Committee, Edison Electric Institute, N. Y. ,
Sept. 1963.
(c) "Suitability of Ohio Fly Ashes in Portland Cement
Concrete," EES-230, Arrand et aI., Ohio State
University Engineering Experiment Station, March 1968.
*This number based on specification requirement that less
than 22 percent be retained on 325M.
** Assumes a 6% LOI requirement for Bu Rec. A 5% re-
quirement would reduce this percentage from 71. 0 to 56.4.
N.R.
Not required.
-
Not applicable.
-------
specifications ..:- which is to say, those most often not met -- are LOI,
Blaine fineness, and 325-mesh residue.
Chemical and physical property data for additional fly ash samples were
compiled in the interest of increasing the statistical validity of the sampling.
The data reported in Reference C-9 have been augmented by a later
publication (Ref. C-123). A large, but rather old, compilation by the
Bureau of Reclamation (Ref. B-7) was included, bringing the total number
of fly ash analyse s to 168. This entire body of sampling data is an~lyzed
but not totally reproduced here. This sampling is believed to be
representative of fly ash production between 1950 and 1962, and according
to contacts made with numerous fly ash producers, brokers and the National
Ash Association, no reason exists for believing that it differs significantly
from current production.
Table 4-13 summarizes the manner in which the fly ashes of this sampling
conforms to the key provisions of the specifications. ~:~ Clearly, ASTM C-6l8
is the least stringent of the specifications examined. Virtually the entire
sampling met its 12 percent LOI requirement, and about 61 percent met both
of its key provisions, LOI and fineness. (The proposed amendment to C-6l8
is discussed later in the text.) When the permissible LOI is decreased to
6 percent, only 71 percent of the sampling pas s. Federal Specification
SS-P-00570b and Corps of Engineers CRD-C-262-63 require 6 percent LOI,
while retaining the same Blaine fineness as the ASTM requirement.
Only 46 percent of the samples met both key criteria of these specifications.
With the added provision that maximum retained on a 325-mesh sieve not
oJ.
'.' A minor liberty was taken with the data. Bureau of Reclamation
Specifications 3172 and DC-34l3, which are now historical documents,
provide 5 percent maximum LOI. These have been combined in the table
with TVf:,.. G-30 (Class I), which specifies 6 percent LOI. This was done
to simplify the table, because their other key provisions are identical,
and because the Bureau now honors the 6 percent LOI criterion. If the
5 percent criterion were invoked, the percent conforming, in the LOI
column, would become 56.4.
4-78
-------
exceed 12 percent, as in TVA G-30 (Class I), only 30 percent of the
samples meet specifications. When TVA Class II ash (22 percent
retained on a 325-mesh sieve) is considered, then 63 percent of the
sampling comply with the specification. If the Blaine fineness require-
ment were deleted, as proposed by some users, the TVA Class I passing
becomes 36 percent and the Class II would not be appreciably affected.
Any of these specifications, if rigidly invoked and adhered to, would
disqualify a substantial portion of production ash. The prima facie
conclusion must be that current specifications inhibit the use of fly ash
as a pozzolan in concrete if the potential concrete dealer or consumer is not
motivated to use the ash. Methods by which the specifications are applied
generally by those who want to use fly ash are discussed in the following
paragraphs, and recommendations for specification changes are given in
4. 3.3. 6.
4. 3.3..4
Specifications Versus Fly Ash Utilization
An assessment of the impact of existing specifications on the extent of
fly ash utilization involves some vague parameters, and credible and
meaningful information is not always available. User attitude is a
consideration. Seldom will a user of a technically and economically useful
raw material regard a specification for that material as rigid and inflexible,
unless, of course, it suits some purpose to do so. Usually if sufficiently
motivated, a user can circumvent a provision in a specification, either by
allowing an exception, or by writing his own specification, or by altering
a specification. These maneuvers, however, come after the raw material
has been shown in plant or field trials to indeed meet his requirements.
This suggests a basic inadequacy in the specifications.
A few notable examples of the attitudes of successful fly ash users toward
specifications have appeared in the technical press and/or were developed
in this study.
Robert W. Cannon (Ref. C-55) of TVA has stated:
"Pre sent TV A policy is to use the sour ce of fly ash
which offers the greatest economy in the concrete
for each particular construction project regardless
of whether the fly ash meets Federal and ASTM
specifications. "
4-79
-------
A similar view was stated in an interview with a producer of concrete
-'c
block:-'
"Requirements such as LOI limits, fineness, or anything
else, are not specified to the fly ash suppliers. The fly
ash delivered must be good for concrete block, and it is
up to the supplier to provide the required fly ash. So far,
there have been no problems with this procedure. "
"'-
A prominent concrete technologist stated:-'-
"For some years it has been demonstrated that fly ashes
which will not meet standard specifications, when properly
proportioned with cement, aggregate and water, can produce
concrete of equal strengths to concrete without fly ash.
In effect, any given concrete requirement can be met with
most fly ashes as long as the ash characteristics are known. "
-,-
Finally, the views of a researcher, -.- as stated in a personal interview:
"Specifications are not an inhibition of fly ash utilization in
any way. Existing specifications are irrelevant but not
inhibiting. Some people use specifications as an excuse;
if the specifications were changed, they would find another
excuse. Specifications never prevented anyone from using
fly ash if they truly wanted to do so. "
Thus it is seen that fly ashes which do not conform to specifications can
and are being used successfully. However, this is not always easy to do,
for as the properties of an ash deviate from a norm, adjustments in concrete
batching must be made. This, of course, requires research and
development. The successful use of nonspecification fly ash seemS to
hinge on the motivation of the user. Those users who are not motivated
to improvise can contend with some' justice that a nonspecification ash is
unusable. If this is the interpretation, then the specifications are in fact
inhibitory. If a user wants to be inhibited in his use of fly ash by
specification, it can easily be arranged. Conversely, if a user really
wants to use fly ash, then, for most fly ash produced, the existing
specifications become meaningles s.
* .
Pe r sonal communications, 1 971.
4-80
-------
Adequacy of Existing Specifications
4.3. 3. 5
Some doubt was cast in the previous section on the adequacy of the existing
fly ash specifications. The fact that certain nonspecification ashes can
be made to perform satisfactorily in concrete mixes suggests that the
specifications indeed may not be all that they could be. As shown, fly ash
specifications are based on chemical analyses and a few physical
properties. To date there has been no particularly convincing demonstration
that these particular qualities of an ash correlate very strongly with its
performance in a concrete mix. In fact, there is evidence that a once
highly regarded property, the Blaine fineness of an ash, correlates poorly.
The questionable adequacy of the specifications has received and is
receiving the attention of numerous scientists and technologists in the field.
The views of Snyder (Ref. F-40) are deemed worthy of quotation at
some length:
"In Some cases, the specifications apparently have been
derived from continued satisfactory pe rformance of the
fly ash from a single producer, or a few producers, and
are es sentially a description of those fly ashe s. In
either case, because the specifications are primarily
based on experience with a limited number of fly ashes,
it is possible on the one hand, to find fly ashes which
meet a given specification but do not re sult in acceptable
products, and on the other hand, to find fly ashes which
do not meet the specification but do result in acceptable
products.
"Although it is pos sible for producers and consumers
of fly ash to reach agreement concerning the suitability
of a given fly ash for a given use on the basis of present
specifications, neither party's interests are fully served
by present specifications. From the viewpont of the
purchaser, there is an unknown degree of risk that a fly
ash which meets specifications may not prove to be
satisfactory in service. From the viewpoint of the
producer, the specifications may well be more restrictive
than is warranted, leading to the rejection of fly ash that
would have performed satisfactorily in service. From
the viewpoint of a person involved in research on the
characterization of fly ash, the specifications are
unsatisfactory because there is considerable question
about whether some of the characteristics being measured
and specified really have any significance with respect to,
the characteristics of the final product. "
4-81
-------
A different viewpoint is provided by Morrison (Ref. F -76) of American
Electric Power Service Corporation, a producer of quality ash:
"There are not too many technical problems connected
with using fly ash in Portland cement concrete structure s.
There is, however, the problem of getting state highway
departments, federal agencies, contractors, and some
large companies to adopt existing fly ash specifications.
Most of uS who have spent several years promoting fly ash
believe that resistance to change, or complacency, is the
largest stumbling block in ash promotion. Very few
individuals find fault with the merits of using fly ash or
adopting ash specifications."
Other investigators have advocated dual specifications, based both on
measured properties of fly ash and on its performance in concrete batches.
This approach would be the logical outgrowth of the empirical procedures
of some users who simply "try it and see if it works." Presumably, the
propertie s of a satisfactory fly ash concrete would form the basis of the
performance specification. This rather cumber some system would be
superior in terms of relevance of testing to the present system.
A developing body of opinion has corne to believe that the proper use of a
combination of properties currently covered by specifications could add
relevance to the specifications. Under ASTM committee scrutiny at the
present is a concept wherein the product relationship between LO! and
325-mesh-sieve residue, both in weight percent, should not exceed 150,
with the added provisions that LO! and the 325 residue individually not
exceed 12 and 20 weight percent, respectively (see Table 4-13 ). An
excerpt from ASTM committee correspondence, provided by one if its
.~
members" and based on lengthy statistical analyses, lends considerable
credence to the validity of the concept:
"The present existence of irrelevant specifications,
specifically the Blaine fineness requirement, is the
major deterrent to fly ash use in concrete. Significant
correlation coefficients are generally developed between
the sieve finenes s or the product of LO! times 325 sieve
fineness and performance of concrete containing fly ash
(including water requirement, strength of mortar, strength
of concrete, and air-entraining agent demand). The fact
..-
"'Personal Communication, 1971
4-82
-------
that the 325 sieve fineness and the LOI times 325 sieve
fineness often gives the highest correlation coefficient is
indicative of a relatively high, close correlation between
these factors and the performance of concrete containing
fly ash. No correlation is evident between the Blaine
finenes s and the overall performance value. In all of the
areas where there is some evidence of correlation between
the performance test and the Blaine fineness, the correlations
obtained by the use of other variables are more significant. II
It appear s that the committee is moving to abolish the Blaine finenes s
requirement of ASTM C-6l8 altogether. According to numerous sources,
the move is developing considerable support throughout the industry. If
indeed the product parameter is accepted as a sens itive indicator of fly ash
performance in concrete, the industry would have achieved a valuable gain
in relevance as well as simplifying the acceptance testing required for
fly ash. The Blaine test is relatively complex compared to LOI and
325-residue tests.
It is shown in Table 4-13 that the conformance of well over one hundred
samples to ASTM C-168 is increased from 61 to 79 percent by deleting the
Blaine finenes s requirement while invoking the LOI-finenes s product limit.
This may not be indicative of potential usage, however (See 4.3.3.6).
As to the future of fly ash spec ifications, a quotation by Edward J. Hyland
(Ref. C-13) of the Chicago Fly Ash Company seems appropr iate:
"Organizations such as The Amer ican Society for Testing and
Materials, The American Concrete Institute, and The Highway
Research Board wr ite specifications and recommended prac-
tices under which all of us are able to sell fly ash in the
ready-mixed concrete market. Up to now, those or ganiza-
tions have respected the legitimate rights of all fly ash
suppliers and recognize the advantages fly ash imparts to
concrete because some fly ash suppliers were willing to
invest their time and money in representing an industry.
However, all of us who are interested in further ing the
use of fly ash in ready-mixed concrete must join in the
effort to insure that proper documents are wr itten which
will permit the proper use of fly ash. Our objective in all
our activities including our technical society undertakings
should be that fly ash sould be fairly treated -- not afforded
an unfair advantage over anyone but also not legislated out
of its legitimate market by groups hostile to us. II
4-83
-------
4. 3. 3. 6
Proposed Specification Modifications
The arguments for specification changes are well founded (see Section 4.3).
The proposed modifications by ASTM and the federal specifications attest
to the industrial awarenes sand dis satisfaction with existing specifications.
Crucial to the entire argument for such changes is not only the irrelevance
of existing specifications, but also the relevance of the new specifications.
For example, the ASTM data accumulated to correlate fly ash parameters
to concrete properties have demonstrated the statistical relevance of the
multiple factor of percent LOI times percent retained on a 325-mesh sieve.
(Ref. C-129) Furthermore, these data have demonstrated the tremendous
superiority of this multiple factor to existing specification parameters.
The basis for this new parameter, however, is solely empirical and the
very limited number of fly ash samples studied cannot be considered
statistically repre sentative of "fly ashes".
The proposed ASTM modification would help solve part of the problems
generated by the existing specification, i. e., include fly ash which does not
now meet specifications but can produce an acceptable product (see Table
4-13). However, by so doing, it does not alleviate the problem of fly ash
that is acceptable according to specification but which does not produce an
acceptable product, nor does it neces sarily include all fly ashe s which can
produce an acceptable product. A1t~ough these proposed modifications
provide a distinct advantage over existing specifications, it is apparent
by their deficiencies that the multiple factor is still not the sole nor the
correct parameter by which fly ash should be judged. The basic work
which would unequivocally define such a parameter has not yet been
conducted.
A recent research study conducted at Iowa State University (Ref. B-2l) on
,
the pozzolanic reaction of synthetic fly ash most closely satisfie s the type
of study required to define the relevance of various physical and chemical
parameters of fly ash. This study found that the parameter which had the
4-84
-------
most influence on pozzolanic activity of fly ash was the extent of strain in
the glass particles which make up the finer fractions of the fly ash. The
finer fly ash was a more effective pozzolan than the coarser fly ash but
this behavior was explained by the increased quantity of glass particles
appearing in the finer fraction. (The chemical make-up of the fly ash also
had an effect on pozzolanic property but this effect was small relative to
the quantity and quality of glass particles.) The strain in the glass was
correlated with the thermal history in the snythesis of the fly ash and may
explain why the multiple factor is a more relevant parameter than others
since both fineness and residual carbon are functions of thermal history.
Nevertheles s, the Iowa State study has indicated that neither fly ash
fineness (which could be a function of coal type or pulverizer equipment as
well as thermal history of the fly ash) nor residual carbon (which could be
a function of pulverizer equipment and combustion oxygen ratio as well as
thermal history) are direct parameters, but, in fact, are secondary
parameters. In addition, there is no standard technique which could
directly test for the extent of strain in the glas s particles. Furthermore,
it is now premature to consider such a test until more extensive research
has been conducted to verify the observations of this study on power plant
fly ash.
The Iowa State University study suggests that the minimum requirements
on the oxides of silicon, aluminum and iron are meaningless and serve
only to exclude arbitrarily the lignite ashes. The acceptability of lignite
fly ash as a pozzolan has been more than adequately verified by studies
conducted at the University of North Dakota (Ref. A-I). Exceptions to
the irrelevance of limitations on chemical constituents are those on sulfur
dioxide, magnesium oxide and alkalies, which are unquestionably
detrimental in concrete and mortar.
Existing specifications are restr ictive pr imar ily with respect to res idual
4-85
-------
carbon and fineness (see Table 4-16).
While the proposed ASTM modifications
will be partially effective in relieving these restrictions and increasing the
relative amount of fly ash acceptable by specifications, it does not
neces sarily indicate that the amount of fly ash actually accepted for use in
concrete will be increased. By broadening the range of acceptable fly ash,
the specifications become les s effective in defining the ability of the fly ash
to be used in a standard manner to give predictable results. As an example,
users commonly impose a 6 percent LOI restriction on the ASTM specification
(ASTM C-618 limits LOI to 12 percent) because of the increasing difficulty
and expense in control of air entrainment as re sidual carbon increase s
beyond 6 percent. The requirement, then is for broad specifications which
classify fly ash in such a fashion that a standard technique for each class
can result in predictable performance.
The specifications on fly ash as defined by TVA provide a suitable example
for the type of classification that is required (Refs. F-80, F-81 and Appendix
H). In this case fly ash is class ified by finenes s, in which Clas s I represents that
ash in which les s than 12 percent is retained on a 325 mesh sieve. For
Classes I I and I I I, ashes up to 22 percent and 32 percent,. respectively,
may be retained on a 325-mesh sieve. In Class III, coarser fly ash is
accepted and is used successfully although not allowed by any other
specification. Furthermore, the use of coarse fly ash is done in a standard
manner and does produce predictable results. The TVA recognition of the
coarser fractions as a mineral filler allows suitable adjustment in sand and
cement so that virtually identical results can be obtained with each class
of fly ash.
It is conceived that this classification concept can be extended to other
relevant parameters such as residual carbon (LOI) and pozzolanic activity
index or any other parameter that is found to be truly relevant to the use
of fly ash as a pozzolan.
The consequence of this proposed change is immediately apparent.
Often,
4-86
-------
more than half the cost of fly ash is transportation. Many times heavy
transportation char ges are incurred because of the absence of a local
source of acceptable fly ash (by present specifications). With a class ifica-
tion system of specifications, such local fly ash may then be acceptable and
significant savings can be made and a total improvement in the economics
of using fly ash may result.
4.3.4
Fly Ash for Use in the Manufacture of Portland Cement
and Portland Cement Concrete Products
As mentioned earlier, there are specifications for concrete products and
cement in which fly ash is or may be used. Typical of these (Ref. F-6) are:
c.
ASTM C-90, Hollow Load-Bearing Concrete Masonry Units
ASTM C-129, Hollow Non-Load-Bearing Concrete Masonry
ASTM C -145, Solid Load-Bear ing Concrete Masonry Units
ASTM C-139, Concrete Masonry Units for Construction of
Catch Bas ins and Manholes
ASTM C-55, Concrete Building Brick
Units
a.
b.
d.
e.
These specifications simply state that if fly ash is used, it must conform
to the provisions of the current specification governing the use of fly ash
in concrete, which now is C-618.
Some product specifications are more informal.
For example, ASTM C-465,
"Processing Additions for Use in the Manufacture of Portland Cement, "
(Ref. F-18) is concerned with materials which may be inter ground with
cement clinker, of which fly ash may be one. It requires that the addition
"be classed as not harmful, II and details various tests of cemen~s containing
additions, the results to be compared with those of the same tests on control
speclmens.
ASTM C-595, "Blended Hydraulic Cements," (Ref. F-4) is slightly more
specific. It provides for portland-pozzblan cements, among others, and
imposes certain requirements on the pozzolans. Fly ash is identified as
a potentially useful pozzolan. According to C-595, the pozzolan must have
a pozzolanic strength with lime of 800 psi minimum, and a 325-mesh-sieve
4-87
-------
residue of lZ percent maximum.
Most fly ashes will meet the strength
requirement; the fineness requirement imposes restrictions on a substantial
portion of production ashes.
In addition to the requirements of specifications, good practice, developed
through experience, has led to certain informal requirements imposed by
individual producers. For example, Type II cement (moderate sulfate
res istance and moderate heat of hydration) has limitations imposed on the
AlZ03 and FeZ03 contents. These oxides in excessive amounts cause
the development of undesirable phases in the cement. A fly ash containing
large amounts of these oxides, used as kiln feed for the cement, .could
be classed as a harmful addition according to ASTM C-465.
Never theles s,
good practice dictates that a fly ash used in this manner not contain more
AIZ03 or FeZ03 than is allowed by ASTM C -150. Many fly ashes fail to
meet one or both of these criteria, and probably would be considered an
unsuitable raw material for kiln feed for Type II cement. Ashes interground
with cement are not under this constraint, since the undes irable phases are
generated only at high temperatures.
4.3.5
Fly Ash for Use in Products Other Than
Portland Cement Concrete
The specification literature on fly ash for use in products other than concrete
is meager. Only two such ASTM specifications were located. The more
pertinent is ASTM C-593-66T, IIFly Ash and Other Pozzolans for Use With
Lime, II (Ref. F-2). Compared to C-618, the requirements of C-593 are
not at all rigorous. It provides for a maximum water soluble fraction of
10 weight percent and a maximum residue on a ZOO-mesh sieve of 30 percent.
Also, the strength requirement for a lime-pozzolan mortar is less than that
required by C-618. Virtually all fly ashes (probably upwards of 90 percent)
will meet specification C-593.
The pertinence of C-593 lies chiefly in its applicability to the use of fly ash
in highway base course construction. This utilization is discussed further
in Section 4.4. Z. Z.
State highway departments who use lime-fly ash aggregate
4-88
-------
or lime-fly ash soil construction generally require that the fly ash conform
to C-593. Occasionally additional provisions are stated, such as limits on
fly ash content of the mix, e. g., 8 to 30 percent; 10 percent minimum; and
9 to 15 percent. These generally are dictated by local conditions and con-
struction practices, and do not seem to inhibit the use of fly ash. The only
limitations on fly ash that were stated for use in pozzolan base courses are
that its carbon content and 325-mesh sieve residue should not exceed 15
~~
and 50 weight percent, respectively.
ASTM specification D 242-64 (Ref. F-3) covers mineral filler for bituminous
paving mixtures. Filler generally constitutes 3 to 6 percent of these
mixtures. The only requirements of D 242 are that the filler be dry, free
of lumps, and that 70 to 100 percent pass a 200-mesh sieve. Any fly ash,
given reasonable handling, will meet this spec ification.,
Fly ash is used in certain processes based on sintering; for example, in
the manufacture of brick and lightweight aggregate (see Section 4.4.2.4 and
Section 4.4.2. 5). Ther e are no specifications on fly ash for use in these
applications. ASTM C-330 (Ref. F-7) and ASTM C-33l (Ref. F-5) mention
fly ash as a possible raw material for lightweight aggregates, but impose
no inhibiting requirements on the raw mater ials.
The manufacturers of sintered products have placed very specific require-
ments on raw materials properties. First, the material must be capable
of being formed into some useful shape. Then it must sinter in some
economic operation to develop the required strength and structure. In the
case of brick manufacture, a new raw material must be compatible with
other batch constituents. Also, it must not create soluble phases in the
finished brick, which would cause efflorescence. For lightweight aggregate,
the FeZ03 content of the fly ash should be moderate in the interest of light-
ness, and in order that iron in the aggregate not stain the concrete. Also,
common practice (largely developmental) requires that fly ash for lightweight
aggregate contain approximately 5 percent carbon a s a fuel in order to satis-
fy ASTM C-330 and 331.
)~
Per sonal Communication, 1971.
4-89
-------
4.4
FLY ASH CONCRETE - ADVANCED TECHNOLOGY
The technology related to the utilization of fly ash concrete is discussed
separately in consideration of the large potential market for this utilization,
the many inhibitions to its use, and the reasonable potential that exists to
remove the inhibitions through technological advancements >:'. These inhibi-
tions can be attr ibuted to the misunders tanding of the technology by fly ash
producers and potential users alike, and a lack of relevancy of existing
specifications to the true potential of the various grades of fly ash produced
today. It is recognized that this technology is well under stood by a few
individuals in the concrete industry, from whom much of these data were
obtained; however, it is believed that this technology has not reached the
thousands of individuals who are to be involved if large sums of fly ash are
to be consumed as an admixture in concrete.
The utilization of fly ash is pos sible only because suitable technology has
been developed. Representatives of the fly ash industry generally do not see
technology as an inhibiting factor to the use of fly ash; however, this study
has revealed that in its interactions with other factors, technology does
contr ibute to the inhibition of fly ash use. Inhibiting technical factors are
unique to the product and to the market in which it must compete. Besides
the factors associated with technologies that have not fully evolved, the
interactions of technology with economics, fly ash quality, specifications,
and user knowledge, acceptance and confidence have all had an inhibiting
effect on the use of fly ash. Moreover, technology has the potential capa-
bility to alleviate many of the inhibiting factors through continued develop-
mente However, in nearly every application of fly ash, the advancement of
the technology has not reached an optimum level of functional us e.
The earliest use of fly ash in the United States was made more than 30
years ago as a cement substitute in portland cement concrete. This use of
-'-
"'This section supplements 4.2. 1. 1 which pertains to the current
utilization of fly ash as a concrete admixture.
4-91
-------
fly ash has been the most important advancement during the development of
the fly ash industry and presently accounts for nearly one-third of the total
fly ash used for economic purposes. The early development of a fly ash
concrete technology is easily understood. It chemically and physically
resembles natural pozzolans and it is reasonable to expect that it would be
used for this purpose. However, as a pozzolanic material it is superior to
natural pozzolans; furthermore, it serves in a secondary role as a filler
material.
4. 4. I
Advantage,s and Disadvantages
Significant advantages can be realized in the properties of concrete containing
fly ash (Refs: A-9, B-IS, and B-19). With fly ash, concrete can be
designed for very high strengths which exhibit a smaller variability of
strength due to the pozzolanic reaction with the free lime in portland cement.
This reaction takes place over a long period of time and shows a continued
strengthening after portland cement concretes have fully matured. However,
when fly ash is improperly used in concrete, this slower reaction can produce
lower early strength and retarded setting may occur in the lean concrete
mixes.
As a mineral filler, fly ash replaces water, fine aggregate and cement. In
this role fly ash reduces the water requirement (e specially in conjunction
with a wetting agent) and improves workability; decrease s particle
segregation and bleeding; reduces water permeability which in turn improves
resistance to sulfate attack and improves surface wear resistance. The
slower reaction of fly ash especially in lean mixes, reduces the heat of
hydration and in conjunction with water replacement, reduces shrinkage.
Its reaction with lime reduces lime leaching and scumming and neutralizes
alkali-aggregate reactions. However, its small spherical particles which
improve workability also increase slump, and the retention of adequate air
entrainment for durability requires the use of suitable chemical admixtures.
Although the advantages of fly ash concrete far outweigh the disadvantages,
4-92
-------
adver se exper iences by concrete users have severely inhibited the use of
fly ash in concrete in certain regions. The technology required to circum-
vent these less desirable property characteristics has been developed but
is not be ing widely us ed.
4.4.2
Substitution Versus Ingredient
A distinctive point in the evolution of fly ash concrete was its recognition as
a technology apart from portland cement concrete technology. The early
uses of fly ash in concrete were made as a partial cement subs titute; fly ash
is still being used in this manner even by several large users of concrete.
Substitution is made on a 1:1 volume or weight basis. However, advance-
ments in the technology have recognized fly ash as a discrete ingredient in
concrete. Such concrete, although similar to portland cement concrete,
has distinctively different properties. Depending on the specific use of the
concrete, properties can usually be tailored to an advantage over those of
portland cement concrete.
In contrast, however, concrete in which fly ash
is used as a cement substitute cannot be tailored to compensate for those
less desirable properties given to the concrete by the fly ash. In some
specific applications, this is adequate since fly ash used in concrete within
certain limits (based on actual practice data) provides advantages without
developing significant structural des ign var iations from portland cement
concrete. This, however, is not taking advantage of the des ign efficiencies
that are possible through the use of fly ash.
The main pioneers of this advanced technology are the Chicago Fly Ash
Company and TVA (Refs. C-56 and C-55). In both cases, this newer
technology is described in terms of proportioning of the concrete mix.
An example of the fly ash technology established by Lovewell and Hyland of
the Chicago Fly Ash Company (and published in the Concrete Industr ies
Yearbook, 1970) is shown in Fig. 4-10 and demonstrates the structural ad-
vantages that can be gained by us ing fly ash as a concrete ingredient. This
figure, combined with other Yearbook data, provides suggested tr ial mixes
4-93
-------
6000
5000
In
Q.
::I:
~
~ 4000'
L.I.J
IX:
~
(J)
L.I.J
>
~ 3000
L.I.J
IX:
a..
~
o
u
2000
1000
o
. STRAIGHT PORTLAND CEMENT
o PORTLAND CEMENT + WATER REDUCER
~ PORTLAND CEMENT + FLY ASH
. PORTLAND CEMENT + WATER REDUCER +
FLY ASH
3.0
3.5 4.0 4.5 5.0
SACKS OF CEMENT PER CUBIC YARD.
5.5
Fig. 4-10.
Compressive Strength of Various Concrete Mixtures
Age at Test - 28 days
4-94
6.0
-------
which shows that comparable 28-day strengths can be attained by using less
cement and adding fly ash in a volume proportion of 2 fly ash added to 1
cement portion removed (suitable fine aggregate adjustments were also made).
An explicit example can be made at a compressive strength of 4000 psi where
a concrete containing 4 sacks of cement and 100 pounds of fly ash has com-
parable 28-day strength to a concrete containing 4. 75 sacks of cement (both
concretes contain water reducing agents).
The TVA has interest in concrete in a broad range of uses including both
structural and mass fill concrete. The proportioning schemes they have
developed use fly ash effectively in each of their applications. The variability
that is poss ible through appropr iate proportioning of concrete ingr edients
has permitted the des ign of concretes which maximize the advantages that
fly ash provides while minimizing the disadvantages. For example, by
replacing more fly ash than cement removed from the concrete mix allows
the fly ash to be used not only as a pozzolan to replace cementitious mater ials
but also to replace sand and water as mineral filler. With fly ash serving as
a mineral filler, non-air-entrained concrete has greater early strengths
(1-3 days) than comparable straight portland cement concrete, and air-
entrained has nearly the same strength as comparable straight portland
cement concrete, thereby eliminating the low early strengths often
as sociated with fly ash concrete by the substitution technology, and allows
form removal on the same schedule as with straight portland cement concrete.
The recognition of fly ash as a mineral filler has permitted TVA to use lower
quality fly ash than otherwise allowed because the coar se fraction replaces
fine aggregate (see 4.3.3.6).
The .example given in Fig. 4-11 illustrates the technology practiced by Cannon
of TVA. The two major factors affecting strength are simultaneously plotted:
the water-to-cementitious material ratio, and the fly ash-to-cement ratio.
The third var iable is the quantity of cement, plotted in dashed lines as sacks
of cement per yard of concrete. The solid lines represent the measured
compressive strength after 28 days for the given relationships.
A lateral
4-95
-------
FLY ASH TO CEMENT RATIO, MEASURED COMPRESSIVE
STRENGTH AFTER 28, 90 AND 180 DAYS AND SACKS OF
CEMENT (FROM TVA DATA)
28 day COMP STRENGTH
-- 90 day COMP STRENGTH
---180 day COMP STRENGTH
--- SACKS OF CEMENT
0.8
4000 (180)
4000 (90)
~
I
-..0
0'
en
en
<[
ID
I-
:J:
<.!)
UJ
3=
<[
u..
+
u
..........
3
0.3
o
0.5
1.0
FA/C WEIGHT BASIS
1.5
2.0
Fig- 4-11. Proportioning and Curing Time Effects on Compress ive Strength
-------
translation of cement quantity on the coordinates will cause a vertical
displacement on the strengths. The effect of the pozzolanic reaction is
shown for the 4000 psi strengths after 90 and 180 days, where the
importance of high concentrations of fly ash for high strength development
over long time periods can be readily seen. As an example, a concrete with
a W /(C+FA) ratio of O. 5 and a FA/C ratio of 1.0 has a 28-day design
strength of 2400 psi. This same concrete could be used for a 90 day
design strength of 4000 psi or a l80-day design strength of 4900 psi.
The curing conditions required for 90 and 180 day design concretes are
no different than those for standard 28-day design concretes.
As another example, a 4000-psi, 28-day compressive strength concrete
is taken at 4 sacks of cement. In this case the W / (C+F A) ratio is O. 5 and
the FA/C ratio is 0.38. If construction considerations allow, a 90-day
design strength permits a concrete mix with a W /(C+FA) ratio again of O. 5,
a FA/C ratio of 1. 0 and'only 2.25 sacks of cement are necessary. Further,
if l80-day design strengths can be permitted, 4000 psi can be obtained at
a W /(C+FA) ratio of O. 5, a FA/C ratio of 2.0 and only 1. 25 sacks of cement
are required.
The choice of concrete cure time should be based on the economics involved
with construction. Since the savings in materials from the use of fly ash
is often small relative to the cost of placing the concrete, the design
conditions should be dependent upon the requirements of construction.
However, the state-of-the-art in concrete construction requires design
compressive strengths of 28 days and does not include an optimal cure time
in the total economics. A cure time of 28 days represents that point at which
portland cement concrete will attain up to approximately 90 percent of its ulti-
mate strength and is considered representative of the true strength of the concrete.
However, in concrete containing fly ash, 28 day cure time s are arbitrary
and meaningless since the strength tested at that time does not represent
the ultimate strength of the concrete when fully cured. While the concept
4-97
-------
of 28-day design strengths largely dominate the concrete construction
industry, there are few examples that can be cited in which structures
under construction will experience their design loads in 28 days. Until
the concrete construction industry becomes aware of the increased latitude
in concrete mix design that is offered by a technology using fly ash in an
effective, economical manner, an inhibition to the use of fly ash in
concrete will per s is t.
The continued development and acceptance of properly proportioned fly ash
in concrete is likely to provide the bas is for renewed interes t in fly ash
as a concrete ingredient. When the users of concrete become more fully
aware of the range of properties that properly proportioned fly ash concrete
offers, their reluctance to use fly ash in concrete (based on the performance
of inadequate cement-substitution technology) will diminish and an increase
in the use of fly ash in concrete may be expected.
4.4.3
Quality-Specification Relationship
!,
Neither the quality of the fly ash nor the arbitrary restrictions of speci-
fications has seriously limited the use of fly ash in concrete, thus far;
however, further development of its potential will be inhibited by their
interrelationship. Elimination of this potential inhibition would require
either improvement in the quality of the fly ash being produced, changes
in specifications to increase the acceptability of fly ash, or both. It is
not the intent to discuss here the quality of the fly ash nor specifications
but to discus s the role of technology in the ir interrelationship. As previously
stated, virtually all fly ash can be used successfully in concrete. The role
of specifications is to allow fly ash to be used in a standard manner to
produce predictable properties. The role of technology then should be to
provide the basis on which a series of specifications may be established
which would permit all fly ashes to be used ip. one of a set of standard ways
to give a specific set of results. Unfortunately, the fundamental under-
standing of the pozzolanic reaction which would permit this to be done has
not been available. A significant insight into the understanding was recently
4-98
-------
acquired from work conducted at Iowa State University on synthetic fly ash
(see Section 4.3.3.6 and Ref. B-21). The various physical and chemical
parameters which are normally used to assess the quality of fly ash were
investigated relative to their pozzolanic reaction. The chemical content and
fineness are usually considered the most significant parameters for fly ash
quality and are the parameters found most res trictive in specifications.
However, the direct correlations between these parameter s and the perfor-
mance of the fly ash has never been adequately obtained. The data have
suggested that these parameters are not direct parameters and that the
pozzolanic activity of fly ash is dependent upon some yet unidentified variable.
The Iowa State study confirms this contention by identifying such a var iable.
Whereas the chemical constituents of the fly ash affected pozzolanic reaction
and the reactivity increased as expected with increased fineness, the most
sens itive parameter was the glas s content of the ash. Moreover, the
variable was seen not to be glass content per se, but the extent of strain
existing within the glass as a consequence of its thermal history. The most
reactive fly ash was that which was subjected to a rapid thermal quench;
slowly cooled fly ash was totally unreactive. From this study it may be
deduced that the major parameters affecting the quality of the fly ash are
the boiler conditions for producing the ash and the rate at which the ash is
cooled. This study indicates that the cr iteria presently used for qualifying
fly ash for concrete use is somewhat irrelevant. Furthermore, the present
technique for es tablishing specifications does not appear capable of defining
the suitability of fly ash for this purpose. The Iowa State study does not
provide sufficient bas is for establishing a new set of specifications, but it
does reveal an apparent impertinence of present specifications.
The technical inhibitions that contribute to the limited use of fly ash in
concrete as discussed in the previous paragraphs have been directed
pr imar ily toward on-s ite concrete. In contrast, in-plant production of
concrete products such as block and precast/prestressed concrete has not
4-99
-------
been affected by inhibiting factors towa.rd fly ash use. Manufacturers of
in-plant concrete products have an advantage of pre-testing their product
before sale, and further, they are subject to far fewer controls.
Concrete block are now being made by many manufacturers in which large
quantities of fly ash are being used. Technical limitations, if they exist,
are not apparent.
4-100
-------
4.5
FL Y ASH IN PAVING
Many components of modern roads have contained fly ash on an experimental
basis, and in a few instances fly ash is used routinely. It has been demon-
strated that with proper batching and placing, fly ash wear courses, base
courses, shoulders and structural fill possessing considerable technical
merit can be laid. In view of the vast tonnage of mater ials used in the paving
of roads, runways and parking surfaces, it is apparent that this type of
construction offers a large potential outlet for fly ash.
The following conclusions concerning the utilization of fly ash in this type of
construction can be made as a result of this survey:
4. 5. 1
1.
The widespread potential utilization of fly ash in wear cour se
portland cement concrete is low. Its potential as a constituent
of base courses is large, but may require government assist-
ance. As a fill material in bituminous concrete, its use is
good but will not consume large amounts. Its potential utiliza-
tion as a structural fill is small, although it can consume lar ge
sums in isolated cases only.
Most state highway departments are reticent about the reasons
for their limited use of fly ash.
Existing specifications do not seem to limit or inhibit the use
of fly ash in road building programs.
Most highway departments exhibit little interest in the applica-
tion of present or developing technologies leading to more
widespread use of fly ash.
Today's limited s'ucces s in local areas is due to the untir ing
effo:r:ts of only a few individuals.
Badly needed are programs of education and promotion to
demonstrate the technical and economic merits of effective
fly ash utilization in roadway programs.
Technical and marketing surveys of potential utilization of fly
ash as a base course material are recommended (see Section
1. 4. 1).
2.
3.
4.
5.
6.
7.
Pa vement De sign
The design of pavement to support a 700,000-pound airplane or withstand
4-101
-------
1,000,000 pas se s of a 20, OOO-pound axle load is a complex matter. Most
highway pavements have a few features in common. Starting with a prepared
subgrade, a base course generally, but not always, is laid. Its chief
function is to distribute the applied load over a large area of the subgrade.
The base course may consist of 6 to 12 inches of crushed stone or gravel; it
may consist of 4 to 8 inches of lime-fly ash-aggregate or lime-cement-fly
ash-aggregate; or it may consist of several inches of a bituminous concrete
composition or a low-grade portland cement concrete. Base courses are
not suited for highway wear and tear; therefore, they are covered by a wear
course designed to resist the friction and shear forces imposed by traffic.
This layer is usually 8 inches or so of portland cement concrete or 2 to 4
inches of asphalt.
Airport design presents different problems. Wheel loads may be upwards
of 1 00,000 pounds, but only 20,000 to 40,000 passes may be considered to
be the life of the pavement (Ref. H-l4). The major design difference
usually is that the airport section is thicker than a first-class highway
section.
However, materials and construction principles are generally
similar.
Several highway and recent airport designs are presented in Figs. 4-12 and
4-13 which show some typical pavement components which do or could
contain fly ash. Although fly ash is not a major constituent, it is seen
that significant quantities would be consumed were it widely employed.
Fly Ash Utilization in State Highway Programs
4.5.2
A short survey was conducted to estimate the extent of fly ash usage in
present highway construction. Contacts were made with numerous trade
associations and government agencies which included, among others, the
U. S. Corps of Engineers, the Bureau of Recl,amation, the Highway
Research Board, the National Ash Association, the American Concrete
Institute, the Portland Cement Association, and several paving associations.
4-102
-------
PORTLAND CEMENT CONCRETE
WEAR
COURSE
BASE
COURSE
SUB-BASE
~
I
-
o
w
ACTUAL OR POTENTIAL
FLY ASH UTILIZATION
FLY ASH r Ib/yd3
Ibl yd2
12 wt%IN
BASE COURSE
480
53
ASPHALT CONCRETE
4 wt%IN
WEAR COURSE
12wt% IN
BASE COURSE
640
93
4 wt %
160
53
12 Ibl BAG
OF PORTLAND
CEMENT
4wt% IN
WEAR COURSE
65
18
160
13
NOTE: SECTIONS SHOWN ARE TYPICAL AND ARE NOT INTENDED TO REPRESENT
COMPARABLE DESIGNS
Fig. 4-12.
Typical Highway Construction
-------
NEWARK,
END OF
RUNWAY
NEWARK,
CENTER OF
RUNWAY
AIRPORT
NEWARK,
TAXIWAY
LONDON
G.8 W.H. CORSON COMPARATIVE DESIGNS
28-in. LlME-
CEMENT-
FLY ASH-
AGGREGATE
6-in.
SUB-BASE
.p.
I
.....
0
.p.
FLY ASH ,lb/yd2 405 297 378 NONE NONE 432 244
PAVING COST ,ESTIMATED 12.30 24.80 18.40 12.80 13.80
$/ yd2
PAVING COST ,REPORTED 760 36.00 18.40
ACTUAL, $ lyd2
NOTE' (I ) DATA FROM o. DESIGN PROCEDURE FOR AIRPORT PAVING SYSTEMS, POZ - 0 -PAC INTERNATIONAL, AUGUST 1970, AND
b. NEWARK AIRPORT REDEVELOPMENT' THE PAVEMENT STORY. THE PORT OF NEW YORK AUTHORITY, MAY 1969.
(2) FLY ASH PROVIDED FREE, WITH A TRANSPORTATION COST OF $2.50 - $3.00 PER TON.
Fig. 4-13.
Fly Ash in Airport Construction
-------
Information and advice were provided and guidance for further inquiries
was offered.
Inquiries were then made to the highway departments of 30 states to
determine the following:
l.
2.
How and to what extent is fly ash employed?
Why is fly ash not used more extensively in existing
applications?
3.
Do existing specifications impose a significant inhibitory
effect on the use of fly ash?
What recent fly ash tonnage has been utilized?
4.
Twenty-five responses were received; a summary of these and two others
is given in Table 4-14. From this information it was determined that
fly ash is used by the states in the following manner and number:
1.
Wear Course
Alabama
West Virginia (R&D)
3.
Bituminous Filler
Pennsylvania
New Jersey
Michigan
Texas
North Carolina
New York
Kansas
2.
Base Course
Ohio
Illinoi s
Pennsylvania
West Virginia
Virginia (R&D)
Kentucky (R:&D)
4.
Shoulders or Soil
StabilIzation
Illinois
New Jersey
Most re sponse s were nonspecific as to the extent of fly ash used or the
reasons why it is not used more. For example, one state highway
department answered:
". . . we are knowledgeable regarding the various possible uses
of fly ash in highway construction and have access to several
sources of quality fly ash, but for several valid reasons, do not
currently provide for its use in any appreciable quantity. II
4-105
-------
Table 4-14.
Fly Ash Utilization in
Highway Programs
State
Called out by Highway Stated Factors Inhibiting Use
State Present Uses Department
Specification R&D Technical Economic
Alabama Concrete additive, required in Yes Yes -- Handling complexity t contractor
structures in or near salt water resistance
and in concrete pavement; per-
mitted in bridges
Colorado None No Yes -- Yes
Connecticut None Yes Yes Permitted only for noo- n
load bearing structures
Flo rida None No Yes h Shipping cost; no local sources
Georgia Concrete additive, though now -- Yes Low early strength Local filler materials cheaper
largely discontinued
Illinois Shoulders. base cour8es; 7455 Yes Yes -- n
tons fly ash in CY 69
Iowa Experimental base courSes Na Yes Local fly ash contains Shipping cost
excessive carbon
Kansa8 Bituminous filler Yes -- - - Contractor resistance
Kentucky Experimental lime-fly ash- - - Yes -- --
aggregate base courses
Maryland None No Yes - - Yes
Michigan Bituminous filler; unsuccessfully Yes Yes Base course frost- Baee course treatment more
in lime-fly ash-aggregate base susceptible expensive than conventional;
courses royalty requirement.
Minnesota Very limited No Yes -- --
Missouri None No Yes -- - -
New Jersey Filler bituminous concrete; Boil Yes -- -- --
B tabiliza tian
New Mexico None Na -- Specify 6-sack Portland --
cement concrete mix
New Yark Bituminous filler Modified C-618 Yes - - - -
North Carolina Bituminous filler No Yes Performance generally --
unsatisfactory in base
course and pipe and
block applications;
variable color
objectionable.
North Dakota Bituminous filler Yes u Lignite ash; Non- --
uniform quality
Ohio Fly ash-lime-aggregate base Yes -- -- Contractor resistance
Pennsylvania Extensive use &8 concrete addi- Yes - - -- --
tive. base courses. bituminous
fille r
Rhode Island None No - - -- --
South Carolina None -- -- - - - -
Texas Bituminous filler; one project, Yes Yes - - Lack of supply (implied)
Z08 tons fly ash
Virginia Experimental lime-fly ash- -- Yes - - --
aggregate base courses
West Virginia Bituminous filler, lime-fly ash- Yes Yes -- --
aggregate base courses
Wisconsin None No n -- --
WYOming None No Yes PCA Bulletin requires Shipping cast
low early strength and
wet curing
4-106
-------
Only Alabama cited the regular and obligatory use of fly ash as a batch
constituent in portland cement concrete roadways. Also, its use in bridges
is optional. Alabama presents a special case on several counts. First,
their local aggregate is known to enter into reaction with the alkalies
contained in cement; fly ash has been shown to retard these reactions.
Second, fly ash is available from various power plants within the state.
Third, in much of southern Alabama and, particularly, in the Mobile Bay
area, their structures are exposed to brackish, sulfate-containing waters
to which fly ash imparts a resistance in concrete. Nonetheless, their use
of fly ash is rather nominal (12 to 18 pounds per bag of cement), and they
have no plans to increase consumption for other reasons.
A few states reported that in some cases they employed lime-fly ash-
aggregate base courses (pozzolan base), and a number have used nominal
amounts of fly ash as a filler in bituminous pavements. And most states
indicated that research and development programs on fly ash had been or
are being pursued. A few stated that fly ash had been used one way or
another, but that its use was discontinued because of the substandard
performance of the structure.
Very little tonnage data were provided.
A number of states voiced technical objections to the use of available fly ash,
chiefly to its nonuniformity and nonreproducibility. These objections were
for fly ash collected from many different power plants including load-
following plants. Others objected to the relatively slow strength develop-
ment of fly ash concrete for use as a wear cour se. They believe this
could impede the progress of slip-form pavers, a.s well as prolong the
interval before highway equipment can use the new structures. The low-
early- strength inhibition is not valid since the application of
the proper technology can negate it. Other states cited poor performance
of fly ash-containing structures. It is probable, however, that imperfect
technology has resulted in imperfect performance. For example, one state
reported frost-heaving in lime-fly ash-aggregate base courses, while a
4-107
-------
contiguous state reported good success in the use of the same materials
system. Inadequate subgrade drainage or poor batching and laying
techniques could explain the apparent discrepancy in performance.
Despite these objections, little comment on the influence of specifications
was offered. State specifications on fly ash are few in number, and where
they exist seem to follow ASTM specifications closely.
Several states cited economic factors as inhibiting the use of fly ash, but
frequently they were not specific. Shipping cost is an obvious factor; a
readily available supply of acceptable local mater ials is another. A
significant and generally jus tifiable economic objection is the res istance
by the paving contractor s to the use of a new product such as fly ash
concrete for wear courses.
The contractors have to post performance
bonds and to warrant their work, and are reluctant to attempt to sell and
place a product with which they are not intimately familiar. Bes ides, to
produce fly ash concrete, for example, a contractor is required to buy,
store, inventory, and transport an additional ingredient which is difficult
to handle; to provide additional conveying equipment; and to run additional
risks of mistakes in batching.
His batching proportions are apt to be very
different from those employed in regular concrete preparation, and crews
must be sold on and educated to use new procedures.
Some potential users have objected to paying royalties on a patented lime-
fly ash-aggregate base course such as Poz-O-Pac; no factual economic data
which would bar fly ash from competing with other materials of equal
quality on this basis were located. Others. who pay royalties are perfectly
satisfied and have expressed an appreciation of the research and assistance
supplied by the parent company.
For urban paving, the price of pozzolan base course materials can be
twice that of, say, conventional crushed stone base courses on a dollar
per inch basis; however, only half the rock thickness is required for the
pozzolan base. Moreover, numerous studies have shown that the deflection
dish under a moving load on a pavement laid on a pozzolan base course is
4-108
-------
much more favorable for long life than the deflection of a similar pavement
laid on a crushed stone base course twice as thick as the pozzolan course.
Typical deflection patterns for pozzolan and crushed stone base courses
are shown in Fig. 4-14 (Ref. C-I08).
o
~ 0.02
.....
u
W
-I
l.L.
W
CI 0.03
8 - in. CRUSHED STONE BASE
0.01
.
c:
0.04
80
60
40
20 0 20
INCHES FROM CENTER OF AXLE
40
60
80
Fig. 4-14.
Typical Base Deflection Pattern Under a
Moving Load
-'-
.,.
According to one source, many cities permit the use of lime-fly ash-
aggregate base course in their local projects. However, little fly ash is
used. Certain municipalities tend to cheapen their construction through
the use of inadequate thicknesses of crushed stone base courses. The
predictable result is premature distress in the wear course, and frequent
maintenance. From an initial cost standpoint, pozzo1an base courses
cannot compete with that form of construction as long as city governments
are content with it.
*
Personal communication, 1971
4-109
-------
When a semirigid base course is required for urban use, lime-fly ash-
aggregate base course is a close technical and economic competitor for
bituminous base cour ses and lean portland cement concr ete base courses.
The pozzolan base generally contains from 10 to 14 percent fly ash. For
a given thickness, these materials have approximately equal strength
qualities and, generally, the cost of a pozzolan base is less than that of a
lean concrete or bituminous base within about 50 miles of the pozzolan
base source. The pozzolan, however, offers a water tight base that is not
prone to cracking or forming voids, is self-healing and continues to
strengthen with age, and is not subject to freeze-thaw cracking. Superiority
is claimed over the other two in that the lean portland cement concrete base
is not water tight, does not have good resistance to freeze-thaw cracking,
and cannot be dr iven on immediately after laying; ne ither the lean concrete
nor the bituminous bases are self-healing, and structurally degrade with
time.
Nevertheless, it is not unusual for a state to specify base course materials
without including pozzolan base as an alternate in highway contracts, whether
or not that state has a specification for pozzolan bases.
Certain observations on the presently limited use of fly ash road mater ials
by the states can be drawn from information other than that supplied by
highway department engineers. For example, some users and purveyors
do believe that the fly ash concrete 'and base course materials discussed
provide a valuable new, super ior mater ial of construction. They have
developed the technology successfully, but the economic aspects are some-
times marginal. One reason is that a high-volume, low-value bulk material
like fly ash can be shipped only so far. Because of this, plants that mix
lime-fly ash-aggregate base course compositions are generally located
close to the power plants, and can ship their products only 40 miles or so
I
on a competitive basis. Yet, in some states it is estimated that 50 percent
of the road construction is rural. Nevertheless, even though much of this
fraction is out of economic shipping radius, a vast amount of paving is
4-11 0
-------
within reach of potential pozzolan base course supplies. In addition,
portable mixing plants are finding some use; however, neither the technology
nor the use is widespread.
These new technologies seem to have had little, if any, effect on most high-
way engineers who seem content with safe, well-developed technology.
Technical risk and controversies are assiduously avoided. In some
instances, highway departments successfully provided that improved and
economic products be employed in their state highway programs. These
instances were the results of persuasive campaigns by senior
highway
engineer s appreciative of super ior, economic engineer ing mater ials.
Assistance was provided by individuals involved in fly ash research and
sale s.
Because of the difficulty of convincing state highway de par tments, some
purveyors of fly ash seem to think that opposing the obstacles involved is
not worth the effort. Additionally, overcoming the obstacles set by hostile
trade associations, var ious competing lobbies, and other special interes t
groups is a formidable problem. This difficulty is not helped by the fact
that there is no single jur is diction by which one may operate with highway
personnel. The American Association of State Highway Officials is an
advisory body much like ASTM, and provides no direct jurisdiction.
Several federal agencies such as the Highway Research Board, the Federal
Highway Administration>:<, and the Federal Aviation Agency are aware of
fly ash and its potential uses, but these three agencies do not write speci-
fications. It should be stressed that in the cases of the Federal Highway
Administration and the FAA, their approval of local specifications is
required in order that federal funds be allocated for highway and airport
cons truction.
>:,
Formerly the Bureau of Public Roads
4-111
-------
4.5.3
Fly Ash in Airport Construction
A brief survey of fly ash use in airport construction was made.
The
situation of airports is not particularly different from that of highways:
the mater ials of construction are the same and both are cons tructed with
public funds. An impor tant precedent for the use of fly ash in airpor t
construction was es tablished recently (Refs. C-124 and A-4). The Por t of
New Yor k author ity elected to use lime -cement-fly ash-aggregate base
courses in the redevelopment of the Newark airport. The only cost to
Newark for the fly ash was $2.50 to $3 per ton, for transportation. The
cost of laying the pozzolan base is $7 to $7.50 per square yard compared
to about $12 for an equivalent conventional asphaltic concrete and up to
$20 for a portland cement concrete pavement capable of sustaining equiva-
lent loads. This super ior ity in economics is due in part to the low delivered
cost of the fly ash and the use of in situ sand at the airport. Even under
less favorable conditions, the pozzolan base would still maintain an
economic advantage.
Although it is too early yet to as sess the quality of this construction,
preliminary indications seem favorable (Ref. C-124). Whether this
precedent will provide an impetus to similar constructions seems to
depend lar gely on local conditions and local agency attitude s.
4.5.4
Unique Fore ign Applications
Three unique applications of fly ash road technology, two in England and
one ill Germany,are worthy of note since they are being used successfully
and they offer additional outlets for fly ash in the United States.
In England, 2-1/2 million tons of fly ash will be used for highway structural
fill in 1971. An example of this is a portion of the Birmingham to Exeter
Motorway M5 (an expressway type road having 36-ft pavements on each
side of a 13-ft median, and 9-1/2 ft hard shoulders). Fly ash is being
used because of stability problems with alluvial soils (the alluvium being
up to 90 it deep in some places) and the height of the fill (26 ft). Other
4-112
-------
structural fill mater ials such as rock and soil cannot match those proper ties
of fly ash that enable it to provide a stable road base. In fact, rock fills
at depths greater than about 17 ft would: (a) overcome the compressible
base, and (b) require greater land acquis ition because the s ide slopes cannot
be as steep as with fly ash. Lower bulk density, superior compaction and
some pozzolanic reaction are dis tinct advantages of fly ash.
The fly ash is transported mostly by rail for this project, in a moist condi-
tion with the water content 40 percent maximum. The water simplifies
hauling and is necessary for compaction. A layer of crushed rock is
spread over the alluvial soil to allow water to move through the base, and
a layer of fine rock is spread over that to prevent choking by the fly ash.
On this, 100 percent fly ash that has been moistened is laid in 9-in.
thicknesses (lifts), and compacted. This procedure is continued until the
equivalent of 30 ft is laid. Compaction of the 9-in. lifts produces a
26-ft embankment (a total compaction of 4 ft). This will remain for a
year, settling at a rate of about 4 in. in 15 ft. That will be topped off
with a 6-in. sub-base of crushed rock, then 8 in. of dense asphalt put
in three lifts of 3, 3 and 2 in. Then it is surfaced with 4 in. of hot rolled
asphalt put in two lifts of 2-1/2 and 1-1/2 in. containing coarse aggregate
for skid res istance.
After the fly ash embankment is compacted, it is seeded with grass by a
system called hydro-seeding in which a mixture of seed and liquid fertilizer
is hosed onto the embankment. Hydro-seeding is applied only once.
After that, the grass is cut but not raked so that it will supply its own
organic nutrient thereafter. The small amount of boron in the fly ash
is poisonous to people and animals; therefore, it is fenced off. Clover,
which absorbs boron is included in the seeding. At the end of a growing
season, the grass is burned off and allowed to grow back.. After two years,
the boron is reduced to a negligible amount.
4-113
-------
A further use indicated in England is a parking lot and secondary road
base course material consisting of 88 to 90 percent fly ash plus cement
and water. This material is generally used in 6- or 7-in. thicknesses,
providing a compressive strength of 400- to SOO-psi. Data to verify the
adequacy of this mater ial have not been obtained.
In Germany, a unique method of paving, called "Gans Paving" is used
for secondary roads and for expressway ramps. This type of paving uses
a slurry consisting of 10- to 12-percent asphalt with aggregate up to
1-1/2 in., and 28 percent fly ash. Although used for secondary roads
only, this system incorporates cons iderably more fly ash than normally
allowed (about 4 percent) as a filler in bituminous paving in the United
States.
4. 5. 5
Potential Utilization
The use of fly ash in road building has a very high potential; however, this
use from a national standpoint is not encouraging based on present circum-
stances. Although its value in structural concrete and as base courses
and structural fill is understood, government agencies that originate road-
way contracts are not, on the whole, specifying fly ash. The risks and
problems of supply, quality and handling involved for concrete wear course
mater ials are a strong inhibitor for that usage. Road building is seasonal,
and demands large volumes of hig1?- quality fly ash for wear courses in a
short period of time, creating storage and stockpiling difficulties for which
utilities are not normally prepared. Little hope can be expres sed for fly
ash in wear courses; however, fly ash can be openly stored in the winter,
and with minimal processing, be used as an ingredient for base course
mater ials dur ing the construction per iod which may last from about 6 to 8
months, with some exceptions. This available, economical supply (the
quality does not have to be high), plus the normal supply, coupled with the
many advantages of pozzolan base cour ses, should make this alar ge outlet
for fly ash. If this is to be the case on a large scale, however, it may take
4-114
-------
government encouragement to break through the resistance of highway
departments and contractors to make a change from well-established habits
and methods.
The use of fly ash as a structural fill material for roads produces excellent
results, but it is a rare case when fly ash can compete with rock and soil
for the same purpose. Except for isolated cases where large sums would
be used, this use is considered small on a continuing national scale.
Fly ash as a mineral filler is a proven utilization employed in several
states. Its use in small percentages of thin layers of pavement, plus
competition from inexpens ive mater ials, prevent this from becoming a
large consumer of fly ash.
4-115
-------
4.6
DEVELOPMENT PROGRAMS
It is difficult to state with certainty that technically feas ible uses of fly ash
exist but have not yet been identified. There is presently a considerable
effort in determining new uses for fly ash, but a cons iderable amount of work
remains to be done both in research and development. The fundamental
research that provides the intrinsic characteristics and properties of this
material should rank among the highest priorities of tasks to be accomplished.
Much of the time and money being spent on product development might have
been obviated had an understanding of the behavior of fly ash pre-existed.
The establishment of a sound technical base would provide the foundation for
future product development and expedite the growth of the fly ash industry.
Even though the fly ash industry has expanded many fold through the last ten
years, the research on which new technology can be based is being conducted
by an extremely small group of individuals.
Fly ash as a raw mater ial has the potential for many undeveloped uses.
Examples of these uses must include the work conducted at the University of
Notre Dame on the utilization of regular fly ash in the treatment of polluted
water s. The potential for this use was demonstrated and should be investi-
gated further, especially in view of its synergisti,c relationship. The sug-
gestion that limestone-modified fly ash may be even more effective in treat-
ment of polluted waters should be investigated.
A grossly neglected area of research is in the production of ceramic products.
The development of bricks from fly ash has demonstrated the capability of
mater ial substitution in this product. The research to determine whether fly
ash could be a material substitute in other uses of ceramic raw mater ials
such as glasses, glazes, tile, whiteware, clay pipe and others has not been
conducted. The similar ity in the chemical content of fly ash and that of the
raw mater ials for most of these products is obvious. Yet, the only work
directed toward this ,potentially huge market has been done on a very limited
effort by Rutgers University (Ref. C-50). Their recent work on glass and
4-11 7
-------
glas s / ceramics has extremely high potential value, but the size of this
effort is inadequate for the research required in this area.
The role that fundamental research may play in developing a market for
fly ash is given by the following example. Although fundamental research
was not involved, it was, however, the understanding of physical charac-
terization that led to the recovery of the microscopic glass bubbles that
rise to the surface of disposal lagoons (Ref. C-112). These hollow glas s
spheres, called cenospheres, are finding many uses as a lightweight filler
components in spec ialty construction applications such as deep-diving
submersible vehicles.
An obvious use of fly ash for which there is no known work being conducted
in the United States is the development of gas concrete for the manufacture
of building materials. This use of fly ash is being successfully employed
in numerous foreign countries (see Section 4.2.8). In view of the possible
structural var iability and the existence of a potentially superb market in
this country, this application of fly ash deserves considerably more
attention than it has received.
There are numerous other research and development projects that have
been undertaken to utilize fly ash. An annotated list of references of such
work has recently been compiled by Cockrell, Shafer, and Leonard and
lists the following topic areas: adsorptive mater ial, br ick manufacture,
building mater ials, coagulant, metal and mineral ore recovery and
miscellaneous uses. A total of 146 such references is listed in Ref. B-4.
4-118
-------
4.7
FLY ASH USE-INHIBITIONS SUMMARY
The inhibitions to the use of regular fly ash are covered in the discussions of
each potential utilization category within Section 4. Many of those inhibitions
are applicable to numerous utilization schemes and would undoubtedly have an
impact on the development of new uses. The following listing of inhibitions
provides an overview of the total situation related to the problem of why the
utilization of fly ash is severely limited:
1.
Lack of understanding or appreciation of the applicable tech-
nologies by the general public (1. e., concrete, road base courses)
Lack of improvement of existing technologies or development of
new ones (i. e., structural concrete, lightweight aggregate, gas
concrete, ceramics, mineral recovery, etc.)
2.
3.
Irrelevance of existing specifications for fly ash as an admixture
in portland cement concrete
Lack of initiative on the part of power companies to treat the
production of fly ash as a profitable bus ines s, resulting in the
non-production or incons is tent production of good quality fly
ash to be marketed directly by the power companies or offered
for sale to fly ash broker s
4.
5.
Lack of sufficient adequate sales or ganizations to act as a catalys t
between power companies and fly ash users (i. e., power com-
panies not sure of market, users not sure of supply)
Reluctance of individuals to change (1. e., concrete, road base
courses)
Inability to economically compete with other materials for wide
scale usage (i. e.; cement manufacture, structural fill, bi-
tuminous filler, br icks)
Geographic limitations imposed by hauling costs (1. e., small
supply in Wes tern United States; too few Eastern United States
power companies producing, collecting, storing usable fly ash)
Difficulty in handling and transporting; additional equipment and
operational procedures required
Spread of misleading information (i. e., bad color, inadequate
early strength, waste mater ial); and adverse publicity resulting
from improper usage
6.
7.
8.
9.
IO.
4-119
-------
~
"'T1~
rm
-<-;-II
):>or
"" -
::2:==
",,~I
c--i
:::00
<2
IT! IT! I
-< '
==
o
S!
:::!J
m
c
-------
SECTION 5
WET-LIMES TONE-MODIFIED FLY ASH SURVEY
5. I
SCOPE OF SURVEY
This portion of the program consisted primarily of surveys of efforts being
made to determine potential uses for wet process limestone-modified fly
ash, and the determinations of efforts necessary to cause the utilization of
this material. Technically and economically feasible products utilizing
modified ash have not been determined. When they are, it is expected that
the marketing processes of the ash will be similar to those now used or
projected for the regular (unmodified) ash. Therefore, the major effort of
this total study, which relates to the utilization of regular ash, will be
applicable to the modified ash in many respects.
A brief review of research directed by EPA for the determination of potential
uses for limestone-modified fly ash is given in the following paragraph.
That work was performed at the Coal Research Bureau, West Virginia
Univer s ity.
5. 1. I
Limestone-Modified Fly Ash Research Performed at the
Coal Research Bureau
5.1.1.1
Dry-Collected Lim,estone-Modified Fly Ash
The objectives of this effort was to characterize the dry-collected limestone-
modified fly ash us ing mineral dres s ing techniques and to evaluate the
feasibility of utilizing the dry-collected limestone-modified fly ash to
manufacture saleable products. Among the products investigated were:
mineral wool, concrete, soil amendment, and mineral recovery. This
effort resulted in the classification of a number of possible uses for the
mater ial into technically potential categories as follows:
5-1
-------
a.
b.
c.
Low Potential
l.
2.
3.
4.
5.
mineral recovery
fluxing agent
lightweight aggregate
fired structural products
unreacted calcium recovery
Medium Potential
1.
2.
3.
4.
acid mine drainage neutralization
concrete admixtur e
cement kiln raw mater ial
soil stabilizer and amendment
High Potential
1.
2.
mineral wool
sulfur recovery
5.1.1.2
Wet-Collected Limestone-Modified Fly Ash
The objectives of this effort are to characterize the gross chemical and
physical properties of wet-collected limestone-modified fly ash in order
to get a preliminary indication as to the pos s ibility of substituting the
modified ash for regular fly ash in some of the more prominent fly ash
utilization schemes as well as in a'limited number of new applications.
Included in the list of applications to be investigated are: production of
802' soil amendment, brick manufacture, producing heat treated materials,
recovery of minerals, and manufacture of structural materials. For the
processes that have been investigated to date, their technical potential
has been broken down in two categories.
a.
Low Potential
1.
flotation as a means of recover ing separate fractions
5-2
-------
b.
Good Technical Potential
1.
2.
3.
sulfur recovery
sand-lime br ick
miner al wool
This wor k, which was begun recently, is continuing in the following areas:
5.2
a.
Soil amendment
Bas ic chemical and phys ical character ization of slurry and
sludge
b.
c.
Ceramic mater ials
d.
Recovery of S02 (thermal)
Calcium-silicate brick
Flotation
e.
£.
g.
Dewatering
1. settling
2. flocculants
3. filtration
4. centr ifugation
h.
Gas concrete
1.
High pressure alumina leaching
MODIFIED ASH PRODUCTION AND CONSIDERATIONS
The wet collection (adsorption) system is under going developments in
numerous localities in the United States. Units are in various phases of
installation, development, or operation in Kansas, Missouri, and Kentucky,
plus the installation of experimentation units at the TV A Shawnee plant
near Paducah, Kentucky. Additionally, similar units have been installed
in several foreign countries. At this time, none of these is operating
continuously at rated efficiencies; how~ver, corrections are being made
and improvements are being achieved.
5-3
-------
The problems that face the utilization of the modified ash are centered in
several areas: (a) the quality of the ash is affected appreciably by the sulfur
content of the coal burned, and by the efficiency of the combustion and
scrubbing process (see Table 5-1); (b) the ash is generally slurried to a pond
where the residue (sludge), being a pozzolan in the presence of lime and
water, is subject to "concreting;1I (c) the sludge contains sulfur which
creates additional problems of sulfur gas collection for many manufacturing
processes employing high temperatures; (d) the pozzolanic properties of
the ash are decreased; (e) if wet scrubbing is preceded by limestone injec-
tion into the furnace, the volume of ash produced will generally be between
1.5 and 3 times as much as without the modified process; and (f) water in
the settling pond is generally not conducive to the good health of fish or
humans. On the plus side, the modified ash contains: (a) possibly pozzo-
lanic proper ties, (b) nominal amounts of unreacted lime, and (c) apprec iable
amounts of gypsum.
Resear ch has shown that potential uses for the modified ash may exis t, but
the technical and economic feas ibility will have to be determined through
research and development programs.
5. 3
SUR VEY OF WET PROCESS SYSTEMS
Although the study of the mechanics of S02 removal systems was not an
element of this program, utilities in Kansas City and Lawrence, Kansas,
and St. Louis, Missouri, which have installed wet scrubber systems were
visited because (1) the combustion and collection processes appreciably
affect the quality and quantity of the modified fly ash, and (2) regular ash is
being marketed in some of those areas. Two of the three utilities visited
were engaged in the s'elling of fly ash (the third had burned coal infrequently
and did not have an ash collection system). Each of the two that do collect
fly ash, sell up to approximately 100,000 tons of fly ash per year. One had
investigated the pos s ibilities of utilizing the modified ash and had deter-
mined for his market area: (1) that the sulfur market was practically
saturated and therefore there was no interest in sulfur recovery; and (2) there
5-4
-------
Table 5-1.
..,
Wet-Adsorbed Limestone-modified Fly Ash - ...
Theoretical Var iations in Chemical and Phase
Compos ition with Var iations in Sulfur and Ash
Content of Coal Burned
10% Ash in Coal 20% Ash in Coal
Compos ition Typical Sulfur Content of Coal
(Weight Fly Ash
Per cent) (Unmodified) 1% 4% 1% 4%
Si02 45 30.6 16.2 36.8 23.9
A1203 23 15.7 8. 3 18. 8 12.2
Fe203 19 12.9 6. 8 15. 5 10. 1
Ti02 1 0.7 0.4 0.8 0.5
CaO 2 14.4 28.5 9.5 21. 5
MgO 1 O. 7 0.4 0.8 O. 5
S03 0.7 17.5 36.2 10.8 26.9
Alkalis 2.3 1.6 O. 8 1.9 1.2
LOr 6 4. 1 2.2 4.9 3.2
Relative 1. 00 1. 47 2.77 1. 22 1. 88
Ash
Quantity
Gypsum 0 28.3 60. 1 17.5 43.5
Free Lime 2.0 2.8 4.5 2.3 3. 7
Fly Ash 97.3 66.3 35. 1 79.5 51. 6
Notes:
2.
3.
.'-
"'Wet adsorption preceded by dry injection of limestone into furnace. Only
ash collection dev~ce is wet scrubber.
1. Values given for gypsum include both sulfates and sulfites, but exclude
combined water.
Sulfur collection system assumed 95 percent efficient.
Limestone added at 110 percent stoichiometric. Limestone assumed
to be 100 per cent CaC03'
5-5
-------
is little hope for selling fly ash mineral wool in competition with glass wool.
The other believes there is a very low potential for the utilization of the
modified ash and that it would eliminate his present fly ash market. It appears
certain that the modified ash is not going to be widely utilized without the
aid of further research.
The fact that coal containing varying degrees of sulfur, whether washed or
otherwise preconditioned (see Section 5.4), presents a vague picture as to
the amount and quality of modified fly ash that will be pr oduced. This indi-
cates that research performed for the determination of uses for the modified
ash must cons ider the wide var iations that may exist in the chemical and
phys ical qualities of the ash.
WET PROCESS LIMESTONE-MODIFIED FLY ASH
PROPER TIES AND QUANTITIES
5.4
A theoretical chemical analys is of the modified ash reveals the wide range of
values attached to the chemical constituents depending on the sulfur content
of the coal and the per cent of coal burned which becomes fly ash. Phys ical
phases vary widely in the same manner. An example of this is given in
Table 5-1. Values are shown for 10 and 20 percent fly ash content coal
and for a sulfur content of land 4 percent in each case. Although the pro-
duction of ash at 20 per cent of coal burned is higher than present data
would indicate, that column in the table provides other data points which
indicate trends. Not only are the variations in properties great, the dif-
ferences when compared to the unmodified ash are cons iderable, and the
modified ash is wet-collected. In addition, the amount of modified ash
produced per pound of coal burned may be as much as nearly three times
the amount produced without limestone injection.
5-6
-------
It is significant that certain actions or considerations are necessary if the
modified ash is to be used:
a.
Resear ch into the character ization of the ash, and its utilization,
must consider the wide variations in material properties. For
wide spread utilization, efforts should be expended to: (l) deter-
mine uses which are not particular ly sens itive to mater ial
properties var iations, and (2) determine uses based on par ticular
materials proper ties in the event that var iations are minimized
by way of specialized coal procurement, coal treatment, closely
supervised and maintained combustion and collection equipment,
or benefic iation of the ash.
b.
The stabilization of the quality of the modified ash at a given
utility, if necessary for utilization, is largely dependent upon
the utility's concern for and ability to do so.
c.
Most products made from the modified ash are not expected to
economically compete with the same products made from
unmodified ash. Since many utilities will not neces sar ily con-
vert to a limestone-injection wet-scrubbed system, or will have
provis ions to colle ct the ash dry or unmodified pr ior to gas
scrubbing, development programs for modified ash products
should include cons iderations of the effe ct of competition with
similar utilizations for unmodified ash. Additionally, develop-
ments for modified ash should include cons iderations for new
applications which are favorable to the use of this mater ial
over unmodified fly ash.
d.
A further consideration of the limestone-modified fly ash situa-
tion is a potential toxicity problem. Several analyses of dry
collected limestone-modified fly ash have been performed by
the Shell Development Co. and Oak Ridge Laborator ies to
determine trace metal constituents in the ash (see Appendix G).
These analyses are incomplete preliminary data and, although
they were performed on dry collected modified ash, they indi-
cate that appreciable amounts of toxic materials would also
exist in the wet-collected modified ash. If toxic mater ials in
the ash exist in soluble form, the leachability to ground water
supplies from mine fills, land fills, and road bases, would
have to be considered. There is the potential problem that bac-
teria could attack the material, giving off undesirable H2S gas.
Furthermore, to prevent harm to fish life in streams due to
overflow or seepage from ash ponds, it may be necessary to
aerate the pond waters to convert sulfites to sulfates to prevent
deoxidation of the stream water.
5-7
-------
5.5
WET-SCRUBBED LIMESTONE-MODIFIED ASH
RESEARCH
Research programs and investigations of a rather limited nature are
proceeding at var ious locations. Probably the most comprehens ive is the
research being performed at West Virginia University's Coal Research
Bureau and at the Combustion Engineering Company. Others are at Michigan
Ins titute of Technology, G. and W. H. Cor son Company, and several engi-
neering companies in the Philadelphia and Pittsburgh, Pennsylvania areas.
Uses being studied or considered include those for which the unmodified ash
is be ing or could be used, plus new developments. The following list
provides an overview of those considerations, and includes uses that may
be possible regardless of how slight their potential is.
a.
Uses Same as or Similar to Those for Actual or
Potential Unmodified Fly Ash Uses
1.
2.
3.
4.
5.
6.
7.
8.
9.
Concrete Admixture (Structure and Products)
Manufacture of Portland Cement
Fired Brick
Filler in Bituminous Concrete
Lightwe ight Aggregate
Road Base Cour se
Structural Fill
So il Amendment'
10.
11.
12.
Mine Void Fill
Sewage Plant Treatment
'"
Mineral Wool'"
13.
Neutralization of Acid Mine Drainage and Polluted Waters
Mineral Recovery
,',
"'Technology for this use, employing dry-collected modified ash, has been
developed at West Virginia University. Inhibitions, if they exist, are in the
comparative economics of manufacture and in the likelihood of overcapacity
in competition with mineral wool and fiberglass insulation materials. To
date, a market position for fly ash mineral wool has not been found.
5-8
-------
b.
Potential New Uses
1.
Asphalt Additive - sealant for lake and reservoir
linings, roofing
Waste Disposal/Sanitary Structural Land Fill
Autoclaved Products - gas concrete, br icks,
mineral aggregate
Hot Press Sintering - pipes, metal coatings
Wallboard, Plaster
Product Recovery - sulfur, lime, regular fly ash
Sulfur ic Ac id
2.
3.
4.
5.
6.
7.
There may be other uses or processes of a proprietary nature which have
not been identified.
5. 6
BASIC QUALITIES OF THE MODIFIED ASH AFFECTIN"G
UTILIZATION
The qualities of wet collected limestone-modified fly ash when compared to
those of unmodified ash are in general infer ior when cons ider ing most known
uses for fly ash. On the other hand, the modified ash apparently has
potential applications for several of the current uses for fly ash in addition
to some new uses. The most significant qualities or conditions affecting
its potential utilization are:
a.
b.
It is produced in a wet state and will have to be dewatered
for many uses to .prevent agglomeration due to the inter-
action of the pozzolan with self-contained lime in the
presence of water.
1.
2.
Dewater ing may alter the properties of the ash.
Agglomeration can require a gr inding operation
depending on fineness required.
Its use in the manufacture of sintered products has three
distinct disadvantages:
1. Sulfur is released and would have to be collected.
2. Decomposition of sulfates (or sulfites) takes place at
, temperatures below sinter ing and results in the
phys ical destruction of the" green formed" product.
5-9
-------
3.
The fusion temperature is lowered such that a short
range exists between sinter ing and melting, thereby
requir ing a sophisticated temperature control system
for the sintering process.
c.
Its pozzolanic properties are reduced because the sum of the
SiOZ' AlZ03' and FeZ03 content and consequently the glassy
phase is reduced (see Table 5-1). This may be somewhat
mitigated by the content of more unreacted lime, particularly
in uses where lime is normally added to the product mix.
d.
Sulfates may exaggerate set retardation in cementitious
products, and leaching may cause subsequent properties
degradation.
e.
Ash properties can be highly variable (see Section 5.4).
Blending may be required for many applications.
f.
An adequate character ization of the wet-collected modified
ash has not yet been performed.
g.
Wet-collected modified fly ash should be amenable to autoclave
processes, but verification of this potential has not been
demonstrated.
h.
It should be amenable to several ambient condition or low
temperature processes.
1.
The presence of gypsum (often as a major component) offers
the potential for new uses.
J.
The presence of sulfur, calcium, aluminum, iron, and other
constituents offers the potential for mineral extraction.
k.
There are the obvious economic problems of handling and
transporting the modified ash, either wet or dry.
Although this list of qualities of wet-collected modified fly ash is not necessarily
complete, it does represent the expected behavior as interpreted from the
small amount of data and information that currently exists. Until appro-
pr iate applications are explicitly defined, the var ious advantages or dis-
advantages of modified ash cannot be accurately assessed.
5-10
-------
5.7
EVALUATION OF UTILIZATION WITH SIGNIFICANT
USE PARAMETERS
An. assessment of potential uses of wet-collected limestone-modified fly ash
against the significant qualities or conditions associated with the ash was
made. To determine the applications worthy of development, deletions and
selections were made on the basis of the following factors in light of the
qualities and conditions listed in Section 5. 6:
a.
Potential technical feas ibility
Potential economic feas ibility
b.
c.
Potential large tonnage usability
Therefore, the following uses were eliminated: concrete admixture, manu-
facture of portland cement, fired brick, lightwe ight aggregate, mineral
wool, and soil amendment. As applicable, these deletions were based
pr imarily on the economic disadvantages associated with dewatering, sulfur
collection, low pozzolanic properties, and competition from les s costly
products. These disadvantages may not necessarily exist in every locality,
but they are considered to be generally applicable. If there were a potential
market for recovered sulfur, then the development of modified ash s intered
I
products coupled with sulfur collection would be advisable. However, an
analys is of the sulfur and sulfur ic acid mar kets, combined with potential
cons iderations of the unmodified ash s intered product markets should precede
technical developments of that sort. This conclus ion is based on the fact
that opinions have been given that, in general, new sulfur supplies are not
in great demand, and large scale marketing of unmodified ash sintered
products has not been established.
The following listing separates potential uses into generic classes and
provides comments on usability for each. The lack of specific technical
and economic data and potential toxicity effects precludes definitive detail
and therefore, best estimates are offered.
5-11
-------
e.
f.
g.
a.
Filler Mater ial
b.
1.
Structural fill, mine void fill, and land fill - Adequate
for many applications. Effects of soft gypsum phase
not understood. Toxicity of leaching to be studied.
Filler in bituminous concrete, asphalt additive, low-
grade concreting of wastes (including food wastes)
for sanitary structural land fill - Research and
development required. No apparent difficulties.
2.
Pozzolanic Products
1.
Road base course - Research and development required.
Impact of soft gypsum phase not known. Apparent
weakened pozzolan may restr ict this use.
c.
Autoclave Products
d.
1.
Mineral aggregate (Ref. Michigan Institute of Tech-
nology), gas concrete (Ref. 4.2.7), cast or formed
shapes - Research and development is required.
High potential both technically and economically.
Pressure Sintered Products
1.
Most sintered products - Research and development
required, questionable production economics.
Gypsum Products
1.
Wallboard, wall plaf?ter - Research and development
required. Apprppr iate use for many high sulfur ashes.
Miner al Re cover y
1.
Lime, aluminum, iron, pozzolan (glass particles),
titanium, silicon, rare elements - Research and
development required. Offers very high ultimate
potential.
Sulfur Extraction
1.
Sulfur and sulfur ic acid (by-product) - Not directly
economical, but may be a required by-product for
other uses of the ash.
5-12
-------
h.
Polluted Water Treatment
1.
Recovery of polluted streams, ponds, lakes - Research
and development required. Soluble lime is effective in
precipitating phosphates from polluted waters.
5.8
RESEARCH CONSIDERATIONS
The successful utilization of limestone-modified fly ash cannot be expected
without adequate research and development. It is only from such programs
that appropriate technology can evolve to provide the basis for economic
utilization. Some of the considerations for proposed research are discussed
in the following sections.
5. 8. I
Characterization
The most critical research required for expedient development of utiliza-
tion technology for lime stone -modified fly ash is the character ization of the
ash. Whereas the chemical analyses that have been used in the past serve
a valuable purpose, they are not adequate for defining or evolving new
technologies. Chemical and phys ical character ization of wet- collected fly
ash must include phase analys is, elemental compos iton (including trace
elements), states of oxidation, physical state, size distribution of particles,
and electrolyte levels. Techniques such as mineralogical and petrographic
analyses, spectroscopy, scanning electron microscopy, electron probe
microanalysis, and ion probe, mass analysis are valuable tools for adequate
character ization.
It is appropriate to reiterate the importance of adequate characterization of
the ash for the effective conduction of subsequent utilization research efforts.
The information gained from the analyses as suggested are critical to
schemes by which the ash can be either beneficiated for some types of mass
usage, or used as an ore material for mineral recovery.
5-13
-------
5. 8.2
Mass Usage of Limestone-Modified Fly Ash
Several potential mass uses of limestone-modified fly ash were suggested in
Section 5.7, but most required some research and development and at least
verification of its technical usability. Such verification is necessary for
structural fill and filler materials for bituminous concrete. A minimal
amount of research and development may be necessary for these uses, but
competing low cost alternate mater ials (including regular fly ash) prevent
extensive research or beneficiation as a means for promoting its use.
Resear ch in the area of road base cour se mater ials may depend heavily on
progress already made in private industry.
Limestone-modified fly ash for most potential utilizations is a new material
with unique characteristics. It cannot be thought of as just as modified fly
ash, and therefore, an extension of existing fly ash technology to limestone-
modified fly ash is not valid. Much of the research that has been conducted
on regular fly ash for the purpose of specific applications should be repeated
with the modified ash where utilization potential warrants investigation.
Other mass uses such as autoclave products, pres sure s intered products,
and gypsum products will each require extensive research and development
and, in many cases, the fly ash may require beneficiation to be usable.
Many of these applications may be competitive with alternative materials,
even with benefic iation. Resear ch to identify these applications and deter-
mine a suitable beneficiation scheme is required.
A particularly efficient system may be one of total utilization in which
various products emerge from a single installation. For example, such a
unit could produce mineral aggregate, lightweight aggregate, sulfur or
sulfur ic acid, recovered minerals, and filler for bituminous products. Any
unused ash from this operation would either be available for land fill or be
disposed of otherwise.
5-14
-------
5.8.3
Toxicology
It has long been recognized that fly ash, and for that matter almost any
earthy material, contains trace quantities of numerous heavy metals and
other toxic elements. These usually are in solution in silicate glasses or
immobilized as compounds or solid solutions, and thus are generally
innocuous to flora and fauna.
The situation with limestone-modified fly ash may not be so innocuous.
The process involves chemistry which is not yet perfectly understood.
Moreover, in the wet scrubber variation, soluble compounds, sulfites,
and sulfates are involved. Whether the dangerous species enter into these
reactions has not, to our knowledge, been clarified. For example, barium,
an alkaline earth whose chemistry is similar to that of c.alcium, could
conce ivably form BaS03; this compound has a measurable solubility in
water at 200C. Cadmium forms soluble sulfite and sulfate compounds;
and BeS04. 4H20 is quite soluble. The chemistry of vanadium is some-
what more complex. Vanadyl sulfate is known, and is reported to be very
soluble in water.
Recently received from EPA are spark source mass spectrographic analyses
of several size fractions of a TVA dry-collected limestone-modified fly ash
(see Appe.ndix G). These were provided by the Process Measurement Sec-
tion, Divis ion of Control Systems, Office of Air Programs. It should be
noted that these data resulted from a limited sampling only and that toxi-
cology problems have not definitely been determined. Several interesting
features were noted, however. The elements of concern showed little
tendency to be concentrated in any size fraction, five of which ranged from
average diameter s of 28. 7fJ. down to 1. 5fJ.. In all size fractions, however,
cer tain elements were reported at levels high enough to cause concern, e. g.,
As, 50 to 200 ppm; Ba, 200 ppm; Pb, 200 to 500 ppm; V, 200 ppm. These
levels should be ver.ified by several different analyses. Moreover, it should
be ascertained whether the dangerous species originated in the limestone,
the coal ash, or both. Any soluble constituents that can be leached from
5-15
-------
this ash deserve attention.
Solvents of interest are fresh water, sea water,
and saline solutions typical of body fluids. Further solvent variables might
be temperature, pH, and oxidation or reduction potential. Any positive
evidence of appreciable dissolution of toxic substances would then neces-
sitate reappraisal of utilization or disposal schemes, particularly those
in which the modified ash might be exposed to ground water s.
5. 8. 4
Mineral Recovery
The recovery of minerals from dry-collected limestone-modified fly ash
has been examined in a comprehens ive study by research scientists at the
Coal Research Bureau, West Virginia University (Ref. D-39). From this
work has developed a preliminary conceptual plan for an Emiss ion Control
Minerals Complex (ECMC) to utilize all parts of modified fly ash. The
ECMC process involves slurrying modified fly ash with water followed by
(a) carbonation of the slurry to convert unreacted lime and magnesia to
their carbonate form, (b) concentration of the lime from the carbonated
modified fly ash by agglomeration flotation for reinjection into the furnace,
(c) melting of the concentration rejects for the manufacture of such products
as mineral wool, and (d) recovery of the relatively clean and more con-
centrated sulfur gases evolved from the melt for the manufacture of such
products as sulfuric acid.
The technical potential and feasibility of the ECMC has been demonstrated
on a pilot plant scale. The economic viability of the process seems to
remain in doubt.
Numerous techniques available to the extractive metallurgist and chemical
engineer could prove appropriate for the extraction of minerals from modi-
fied (and unmodified) fly ash. Var ious aspects of hydrometallurgy could,
for example, be employed in the extraction of mineral values. Electrolysis
and electrophoresis, both aqueous and in a melt, may prove feasible for the
destruction of fly ash and the separation of its constituents. Pyrometallur-
gical schemes may be employed for oxidation, reduction, and separation of
5-16
-------
mineral values. Numerous physical processes involving density,
surface chemis try, and magnetic qualities could prove useful.
size,
The application of any of these potentially useful proces ses requires --
first and foremost -- a sound and detailed knowledge of the qualities of
the feed mater ial (see Section 5.8. I). Without such knowledge, which
must be gained in programs of detailed laboratory evaluation, rational
programs of mineral recovery will be very difficult, if not imposs ible,
to develop. Such evaluation s tudie s should be initiated and taken to a
fairly advanced state before serious attempts at mineral recovery are
undertaken.
5.9
UTILIZA TION INHIBITIONS
The inhibitions to the utilization of wet-scrubbed limestone-modified fly
ash are centered around the fact that it is a new material which is not
well understood, and for which applications have not been developed. It
is not applicable as a direct substitute for regular fly ash because its
chemical and physical properties are drastically different from the pro-
perties of regular ash. It does have a potential utilization for some
exis ting applications of the regular fly ash, but developments are required.
Also, its unique properties make it amenable to new uses for which the
regular ash is not usable, or which have not been developed. In any event,
programs of study, research and development are required before the
modified ash can be utilized.
Detailed discuss ions of these inhibitions are given in Sections 5.6 and 5. 7.
5-17
-------
> I
~I
~ I
o
c:;')
:::tI
>
"tI
:::z:
-< I
I
-------
A. I
B. I
C.I
D. I
E. I
F. I
G. I
H. I
APPENDIX A
INDEX
FLY ASH PRODUCTION.
. . . .
........
.......
FLY ASH PROPER TIES. .
.......
...........
FLY ASH UTILIZATION.
.........
..........
LIMESTONE-MODIFIED TECHNOLOGY.
.....
. . . . .
FOREIGN TECHNOLOGY. . . . . . . .
.....
......
SPECIFICATIONS' AND REGU LATIONS
...........
SULFUR DIOXIDE CONTROL
......
.......
. . . .
MlSCE LLANEOUS . . . . . . . .
.....
......
. . . .
ABBREVIATIONS USED IN BIBLIOGRAPHY. . . .
.........
A-I
A-3
A-S
A-7
A-17
A-20
A-22'
A-28
A-30
A-31
-------
APPENDIX A
BIB LIOGRAPHY
This bibliography includes both the documents specifically cited in the body
of the report and the documents surveyed during the literature search por-
tion of this study.
A.1
A-I
A-2
A-3
A-4
A-5
A-6
A-7
A-8
A-9
A-10
A-II
FLY ASH PRODUCTION
IIAsh from Lignite, II Oscar E. Manz, Second A. U. S. Bu. M. I. C. 8488
(March 1970).
II Availability, Quality, and Present Utilization of Fly Ash, 11
C. E. Brackett, Bu. M. I. C. 8348 (March 1967).
II Exper ience in Production and Utilization of Lightweight Aggregate
at Consolidated Edison, 11 A. S. Peatson, Bu. M. I. C. 8348
(March 1967).
IIA Look at the Fly Ash Picture, II J. H. Faber, ASME-IEEE Joint
Power Gener. Conf., Pittsburgh (September 27-0ctober 1970).
IIProduction and Utilization of Ash in the U. S., 11 C. E. Brackett,
2nd A. U. S. Bu. M. I. C. 8488 (March 1970).
IIAsh Collection and Utilization, II Ash at Work, Vol. 2, No.2 N. A. A.
(1970).
IIFly Ash Still Piling Up, II Chern. Eng. (April 1970).
IIOperating Character istics of a High- Temperature Electrostatic
Precipitator, II U. S. Dept. Int. R. 1. 7276 (July 1969).
II Fly Ash in Concrete: An Evaluation, II E. A. Abdun-Nur, Hwy
Resch. Bd. Bull. 284 (1961).
IIU. S. Navy Power Generation and Distribution, Chap. 1: Electric
Power Generation, II Dept. of the Navy Bureau of Yards and Docks,
Washington, D.C. (September 1954).
,
II Utility Directory, II 1970 Keystone Coal Industry Manual
A-3
-------
A-12
A-13
A-14
A-iS
A-16
A-17
A-18
A-l9
Extract from Vol. 2 Criteria for Waste Management, Bechtel Corp.,
San Francisco, (September 1969).
II Emissions from Coal-Fired Power Plant, II S. T. Cuffe &:
R. W. Gerstle, U.S. Dept. of H.E.W. (1967).
"8th Steam Station Design Survey, II L. M. Olmsted, Elec. World
(1964).
II 9th Steam Station Design Survey, 11 L. M. Olmsted, Elec. World
(1966) .
II 10th Steam Station Design Survey,'! L. M. Olmsted, Elec. World
(1968) .
"11th Survey on Steam Station Design, II L. M. Olmsted, Elec. World
(1970).
"7th Steam Station Design Survey, II Elec. World (October 1962).
"Data from Energy Resources Lecture, II Charles Stewart, Col.,
USAF, Industrial College of Armed Forces, Presented at National
Security Seminar, Manhattan, Kansas (23 Aprill97l).
A-4
-------
i----uu_-- -
!
i
B.1
B-1
B-2
B-3
B-4
B-5
B-6
B-7
B-8
B-9
B-10
B-11
B-12
B-13
FL Y ASH PROPER TIES
"Fly Ash, Properties and Beneficiation Methods," L. L. Lovell,
T. S. Spicer & R. L. Hornberger, Symposium on Coal Utilization,
American Institute of Mines (February 1964).
"A Critical Review of the Technical Information on the Utilization
of Fly Ash," M. J. Snyder & H. W. Nelson, Batt. Mem. Inst.
(July 1962).
"Prediction of Fly Ash Performance," L. J. Minnick, W. C. Webster,
& E. J. Purdy, Jr., 2nd A. U. S. Bu. M. I. C. 8488 (March 1970).
"New or Underdeveloped Methods for Producing and Utilizing
Coal Ash," C. J. Cockrell & H. E. Shafer, Jr., and J. W. Leonard,
2ndA.U.S. Bu. M.LC. 8488 (March 1970).
"Quality Control and Beneficiation of Fly Ash, 11 R. W. Styron,
2ndA.U.S. Bu. M.LC. 8488 (March 1970).
"Nuclear Measurement of Carbon in Fly Ash, II R. F. Stewart &
W. L. Farrior, Bu. M. I.C. 8348 (March 1967).
"Laboratory Investigations of' 81 Fly Ashes, Report No. C-680, II
Bureau of Reclamation, Concrete Laboratory, Denver, Colorado
(September 1953).
"Edison Electric Institute Bulletin," Edison Elec. Inst.
(February 1966).
"Investigations Relating to the Use of Fly Ash as a Pozzolanic
Material and as an Admixture in Portland Cement Concrete,"
L. J. Minnick, ASTM Proceedings, Vol. 54, (1954).
"Air Entrainment and Durability Aspects of Fly Ash Concrete, II
T. D. Larson, ASTM Proceedings, Vol. 64 (1964).
"Fly Ash as a Filter Aid," J. W. Gerlich, Pow. Eng., pp. 44-45
(January 1970).
"Edison Electric Institute Bulletin (pp. 420-424), II Edison Elec.
Inst. (Decembe r 1966).
"Expanding the Market for Fly Ash, II G. C. Gambs, Mech. Eng.,
pp. 26-28 (January 1970).
A-5
-------
B-14
B-15
B-16
B-17
B-18
B-19
B-20
B-21
IITVA Uses Non-Specification Fly Ash, II G. K. Leonard &
P. A. Schwab, Civ. Eng., Vol. 28, pp. 188-192 (1958).
IIFly Ash Utilization: A Summary of Applications and Technology, II
J. P. Capp & J. D. Spencer, Bu. M.1. C. 8483 (1970).
II Two-Day Symposium on the Physical Properties and Economic
Uses of Pulver ised Fuel Ash, II Royal College of Advanced Tech-
nology, Salford, England (May 1965).
IIPulverized Fuel Ash in Concrete Technology, Part I, II R. C. Jolly,
U.S.C.E.-W.E.S. (May 1965).
IISummary Report on Properties and Utilization of Fly Ash, II
M. J. Snyder, A. J. Roese, R.1. Hunter & P. Gluck, Batt. Mem.
Inst. (June 1966). .
IIPFA Data Book, Aerated Concrete, II Central Electricity Generating
Board, London, England (1967).
IlMajor Ash Constituents in U. S. Coal, II Bu. M.1. C. 7240 (1969).
IIPozzolanic Reactions in Synthetic Fly Ash, II E. A. Rosauer,
Iowa State University, ISU-ERI-AMES-84600 (August 1970).
A-6
-------
C. 1
C-l
C-2
C-3
C-4
C-s
C-6
C-7
C-8
C-9
C-lO
C-ll
C-12
C-13
C-14
FLY ASH UTILIZATION
"Final Report: Fly Ash Utilization Research Program, " M. J. Snyder,
A. J. Roese, R. I. Hunter & P. Gluck, Batt. Mem. Inst.
(December 1966).
"Beneficiation of Fly Ash, " H. T. Stirling, 2nd A. U. S. Bu. M. I. C.
8488 (March 1970).
flU. S. Ash Utilization and 167 Worldwide Figures, " Ash at Work,
Vol. 1, No.2, N. A. A. (1969).
"Highway Experts told of Fly Ash Advantages. France Keeps
Working to Expand Utilization. North Dakota Pushes Study of
Lignite Ash, " Ash at Work, Vol. 2, No.1, N. A. A. (1970).
"Problems in Fly Ash Marketing, " F. V. Zimmer, Bu. M. I. C.
8348 (March 1967).
"Fly Ash in the Future, " J. Pursglove, Jr., Bu. M. I. C. 8348
(March 1967).
"Utilization of Fly Ash," R. E. Morgan, U. S. Dept. Int. 1. C.
7635 (June 1952).
"Agr iculture Appear s Likely Fly Ash Outlet, " E. A. Rudulph,
Elec. World (June 1956).
"The Suitability and Potential Uses of Locally Produced Fly Ash as
an Admixture in Portland Cement Concrete, " R. W. Bletzacker,
Bldg. Resch. Lab., O. S. U. (December 1963).
"Lightweight Aggregates in the U. S., " G. R. Morris, 2nd A. U. S.
Bu. M. 1. C. 8488 (March 1970).
"Raw Mater ials for Manufacture of Cement, II W. R. Barton,
Bu. M.1. C. 8348 (March 1967).
IIFly Ash in Mass Concrete, II R. E. Philleo, Bu. M. I. C. 8348
(March 1967).
IIFly Ash in Ready-Mix Concrete, II E. J. Hyland, Bu. M.1. C.
8348 (March 1967).
II Fly Ash in Roadway Construction, II J. A. Hester, Bu. M. I. C.
8348 (March 1967).
A-7
-------
C-15
C-16
C-17
C-18
C-19
C-20
C-21
C-22
C-23
C-24
C-25
C-26
C-27
C-28
C-29
C-30
"Fly Ash in Concrete and Concrete Block Manufactur ing, n
J. R. Belot, Jr., Bu.M.I.C, 8348 (March 1967).
"Fly Ash in Concrete Manufacturing, " J. Seabright, Bu. M. I. C.
8348 (March 1967).
"Status Report on Bricks from Fly Ash," H. E. Shafer, et aI,
Bu. M. 1. C. 8348 (March 1967).
"Consumer Economics: Use of Fly Ash in Concrete," L. W. Hoy,
Bu. M.I.C. 8348 (March 1967).
"Fly Ash in Agriculture," J. P. Capp & C. F. Engle, Bu.M.l.C.
8348 (March 1967).
"Utilization of Fly Ash in the Cementing of Wells, " D. K. Smith,
Bu. M. 1. C. 8348 (March 1967).
"Use of Fly Ash in Specialized Concrete Work," G. O. Bergemann,
Bu. M. I. C. 8348 (March 1967).
"Future of Fly Ash Use, II G. L. Coryell, Bu. M. 1. C. 8348
(March 1967).
"New Applications for Fly Ash are Promising," Ash at Work,
Vol. 2, No.2, N.A.A. (1970).
"Fly Ash Brick, Concrete Block. Mineral Wool from Coal Ash
Slag," Ash at Work, Vol. 1, No.1, N.A.A. (1969).
"Ancient Concrete Mix Makes Jet Age Runway, II Eng. N. Rec.,
N. A. A. (Ma y 1 969) .
"Mix Design Hints for Fly Ash Concrete," Concrete Construction,
N. A. A. (July 1969).
"Fly Ash: What it Does for Concrete Block, Ready-Mix Concrete,
Concrete Pipe," Concrete Industries Year Book, Viall-Ohio Fly
Ash Co., Inc., Akron, Ohio (1964).
"Profit from Fly Ash," G. R. Morris, Pow. Eng. (October 1969).
"Fly Ash Utilization Climbing Steadily," Env. Sc. & Tech.; Vol. 4,
No.3 (March 1970).
"Fly Ash Goes Commercial," Coal Age, N.A.A. (April 1969).
A-8
-------
C-31
C-32
C-33
C-34
C-35
C-36
C-37
C-38
C-39
C-40
C-41
C-42
C-43
C-44
C-45
C-46
"The Lightweight Aggregate Boom, 11 R. A. Grancher, Rock
Products (December 1969).
II You Can Save Money with Fly Ash,'1 G. H. Roman, Coal Age, II
(August 1968).
"Fly Ash Aggregate-Lightweight Concrete, 11 D. W. Pfeifer, P. C.A.
(1969).
"Fly Ash Utilization - 1962,'1 Edison Elect. Inst. Pub. No. 63-70
(1963).
"Better Use of Wastes Spurs Comm.ercial Application of Hot
Briquetting, " Chem. Eng. (December 1967).
"Practical Use for a Pollutant, II The Halliburton Co., Report to
Stockholders, (5 August 1970).
TVA, Base for Roads, Parking Lots, Airport Runways, West
Virginia University Coliseum, Chicago Buildings," Ash at Work,
N.A.A. (1969).
"Ash in Road Building," Ash at Work, Vol. 2, No.3, N.A.A.
(1970) .
"Profits from Pollution," S. Klein, Machine Design (1970).
"Anti-Pollution Ideas Tucked Away, 11 W. J. Waugh, The Register
(May 1970). ,
"Method of Burning Oil Slicks, 11 Wall Street Journal,
(April 28, 1970).
"Air Pollutant Turn~d into Useful Product, 11 Machine Design
(June 1967).
"Fly Ash - North Dakota Roads, U.S. 60, Detroit, Czechoslovakia -
New Fly Ash Concrete Masonry Blocks Introduced," Ash at Work,
Vol. 1, No.3, N.A.A. (1969).
"Fly Ash as a Fertilizer," D. C. Martens, M. G. Schnappinger, Jr.,
J. W. Doran & F. R. Mulford, 2nd A. U. S. Bu. M. I. C. 8488 (Mar 1970).
"Study on the Utilization of Cinder Ash for Concrete Manufacturing,11
Tech. Lab., C.R.I.E.P.L, (February 1969).
"Report No. 17, Use of, Fluidised Combustion Ash (F.C.A.) In
Filters," N. Hodgkinson, National Coal Board Coal Research Estab-
lishment, Fluidised Combustion Section (February 1969).
A-9
-------
C-47
C-48
C-49
C-50
C-51
C-52
C-53
C-54
C-55
C-56
C-57
C-58
C-59
C-60
C-61
"Results of New Test in the Field of Ash Utilization," H. Schafer &
H. Knatz, VGB meeting IICoal Firing" in Ger 168 (February 1970).
"Fly Ash Concrete in Buildings in Chicago, " J. P. Roche, 2nd
A. U. S. Bu. M. 1. C. 8488 (March 1970).
"Fly Ash as a Bituminous Filler,r' F. V. Zimmer, 2nd A. U. S.
Bu. M. 1. C. 8488 (March 1970).
11 Technical Aspects of Fus ion Forming of Fly Ash Ceramic
Structures, 11 W.H. Bauer, 2ndA.U.S. Bu. M.1.C. 8488 (March 1970).
"Utilization of Fly Ash for Remote Filling of Mine Voids, "
M. O. Magnuson & W. T. Malenka, 2nd A. U. S. Bu. M. 1. C. 8488
(March 1970).
II Laboratory Evaluation of Fly Ash and Other Pozzolans for Use
in Concrete Products, II R. C. Valor, Jr., 2nd A. U.S. Bu. M. 1. C.
8488 (March 1970).
IIAn Industrial Evaluation of Fly Ash Bricks, " J. A. Reidelbach, Jr.,
2nd A. U. S. Bu. M. I. C. 8488 (Mar ch 1970).
"Fly Ash Utilization in the Treatment of Polluted Water, II
M. E. Tenney & W. F. Echelberger, Jr., 2nd A. U. S. Bu. M. I. C.
8488 (March 1970).
IIProportioning Fly Ash Concrete Mixes for Strength and Economy, 'I
R. W. Cannon, ACI Jour. Title No. 65 -75 (November 1968).
"Proportioning Concrete Mixtures Using Fly Ash," C. E. Lovewell
& G. W. Washa, ACI Jour., Pt. II, Title No. 54-64 (June 1958).
"Design and Control of Concrete Mixtures," Engineering Bulletin,
11th Ed., P. C. A. (July 1968).
"How Fly Ash Improves Concrete Block Ready-Mix Concrete,
Concrete Pipe, " Concrete Industries Year Book, N. A. A. (1970).
"Practical Use of Fly Ash in Concrete, " E. J. Hyland, Construction
Specifier (March 1970).
"Recycling Man-Made Ores for Industry, " S. L. Blum, Illinois Inst.
of Technology, Res ch. Ins t., Chicago (July 1970).
"Turf Soil Modification with Sintered Fly Ash, " J. C. Patterson &
J. P. Capp, U. S. Dept. Int. R.1. 7381 (May 1970).
A-lO
-------
C-62
C-63
C-64
C-65
C-66
C-67
C-68
C-69
C-70
C-71
C-72
C-73
C-74
"Experimental Concrete Pavement Containing Fly Ash Admixtures,"
R. D. Hughes, Hwy. Resch. Rec. No. 73, Hwy. Resch. Bd. (1964).
"Use of Fly Ash in Concrete by the Alabama Highway Department, "
J. A. Hester &0. F. Smith, Hwy. Resch. Rec. No. 73, Hwy.
Resch. Bd. (1964).
"Use of Fly Ash as Admixture in an Experimental Pavement in
Kansas," W. M. Stingley & R. L. Peyton, Hwy. Resch. Rec. No 73,
Hwy. Resch. Bd. (1964).
"Use of Fly Ash in Concrete Pavement Constructed in Nebraska,"
C. A. Sutton, Hwy. Resch. Rec. No. 73, Hwy. Resch. Bd. (1964).
"Experimental Fly Ash Concrete Pavement in Michigan,"
F. E. Legg, Jr., Hwy. Resch. Rec. No. 73, Hwy. Resch. Bd.
(1964) .
"Measuring Thermal Expansion of Lime-Fly Ash-Aggregate Composi-
tion Using SR-4 Strain Gages, II R. H. Miller & R. R. Couturier,
Hwy. Resch. Rec. No. 29, Hwy. Resch. Bd. (1963).
"Lime-Clay Mineral Reaction Products," G. R. Glenn &R. L. Handy,
Hwy. Resch, Rec. No. 29, Hwy. Resch. Bd. (1963).
II Characteristics of Lime Retention by Montmorillonitic Clays, "
C. Ho & R. L. Handy, Hwy. Resch. Rec. No. 29, Hwy. Resch. Bd.
(1963).
"Comparative Effects of Hydraulic, Calcitic and Dolomitic Limes
and Cement in Soil Stabilization," J. W. H. Wang, M. Mateos &
D. T. Davidson, Hwy. Resch. Rec. No. 29, Hwy. Resch. Bd.
(1963) .
"Compaction Characteristics of Soil-Lime-Fly Ash Mixtures, "
M. Mateos &D. T. Davidson, Hwy. Resch. Rec. No. 29, Hwy.
Resch. Bd. (1963).
"Curing Lime-Stabilized Soils," M. C. Anday, M. Mateos &
J. W. H. Wang, Hwy. Resch. Rec. No. 29, Hwy. Resch. Bd. (1963).
"Effect of Lime, Moisture ar" Compaction on a Clay Soil, "
M. Asharaf Jan & R. D. Walker, Hwy. Resch. Rec. No. 29, Hwy.
Resch. Bd. (1963).
"Bulletin 193, Lime and Lime-Fly Ash Soil Stabilization," Hwy.
Resch. Bd. (1958).
A-ll
-------
C-75
C-76
C-77
C-78
C-79
C-80
C-81
C-82
C-83
C-84
C-85
C-86
C-87
C-88
C-89
C-90
C-91
"Fly Ash Disposal," G. C. Halzel, Pow. Eng. (June 1969).
"Proposed Revision of ACI 613-54," ACI Jour. (August 1969).
"Fly Ash Utilization 1962," Edison Elec. Inst. Pub. No. 63-70
(September 1963).
"Use and Disposal of Fly Ash," J. H. Faber & P. H. Meikle, N. A. A.
(June 1970).
"Ash Utilization: a Liability to an Asset," R. E. Morrison,
American Electric Power Service Corporation, Charleston, West
Virginia (April 1970). .
"Ash Utilization Techniques Present and Future," J. H. Faber &
P. G. Meikle, N.A.A. (March 1970).
"Admixtures and Special Cements: Fly Ash and Fly Ash Cement,"
Masatane Kokubu, V -ISSC Paper, Tokyo (1968).
"Pulverised Fuel Ash in Highway Engineering and as Structural Fill, II
S. Raymona, U.S.C.E-W.E.S. (May 1965).
"Practical Aspects of Bulk Uses of Pulverised Fuel Ash,"
P. H. Smith, U.S.C.E.-W.E.S. (May 1965).
"P.F.A. In Concrete," M. H. Miles &S. W. Regin, U.S.C.E.-
W.E.S. (May 1965).
liThe Addition of P.F. Ash to Cement Grouts, Gypsum Plaster and
Certain Resins," A. Bannister, U.S.C.E.-W.E.S. (May 1965).
"Concrete and Concrete Making Materials, Significance of Tests
and Properties of, STP169A, II ASTM (1966).
"Expanding the Market for Fly Ash," G. C. Gambs, Mech. Eng.,
pp. 26- 28 (January 1970).
IITVA Uses Non-Specification Fly Ash," G. K. Leonard &
P. A. Schwab, Civ. Eng., Vol. 28, pp. 188-192 (1958).
"Asphalt Institute, The Role of Mineral Fillers in an Asphalt Mix,"
Asphalt Institute Quarterly (1961).
IIFly Ash and Bottom Ash," Mining Engineering (1970).
"Results of New Test in the Field of Ash Utilization, 11 H. Schafer &
H. Knatz, Combustion (February 1970).
A-12
-------
C-92
C-93
C-94
C-95
C-96
C-97
C-98
C-99
C-100
C-101
C-102
C-103
C-104
C10S
"Production and Value of Ready Mixed Concrete in 1969,"
N.R.M.C.A. (1970).
"Producing Mineral Wool from By-Products," K. K. Humphreys &
W. F. Lawrence, Mineral Processing (March 1970).
"Canadians Pioneer New Fly Ash Processing System, I' J. F. Boux,
Mineral Processing (March 1969).
"Fly Ash Lightweight Aggregate Masonry Receives Fire Rating, "
Ash at Work, Vol. 2, No.4, N.A.A. (1970).
I'Lightweight Concrete Aggregate From Sintered Fly Ash,"
L. J. Minnick, Hwy. Resch. Rec. No. 307, Hwy. Resch. Bd.
(1970) .
"Status of Fly-Ash Lightweight Aggregate, II D. J. Stefl, ASME-IEEE
Joint Power Generation Conference, ASCE Participating Society,
Pittsburgh, Pennsylvania (1970).
"Production of Structural Products from Fly Ash," K. K. Humphreys
& H. E. Shafer, Jr., ASME-IDDD Joint Power Generation Confer-
ence, ASCE Participating Society, Pittsburgh, Pennsylvania (1970).
I'Report No. 3-69, The Clay Brick Industry and the Fly Ash Brick
Potential," J. A. Reidelbach, Jr., N.A.A. (1969).
Report on 8-In. Concrete Masonry Units Made From Fly Ash
Aggregates and A Blend of Fly Ash and Sand Aggregates for Use
in Unreinforced Load Bearing Walls, N. A. A. (September 1970).
I'Fly Ash Concrete, Avon Lake Plant Unit No.9," The Cleveland
Electric Illuminating Co., Cleveland, Ohio (undated).
"Fly Ash Helps to Build A Fine New Condominium," American
Concrete Institute, Detroit, Michigan (August 1966).
l'Ash and Lime Subbase Used Under Concrete, I' Ohio Contractor
Magazine (1970).
I'Birth of an Industry - Lightweight Aggregate from Fly Ash, 11
Mining & Processing, Dwight-Lloyd Division, McDowell-Wellman,
Eng. Co., Cleveland, Ohio (June 1964).
A Newcomer in the Lightweight Divison, Fly Ash Lightweight
Aggregate Sintered at Consolidated Edison's Astoria Plant, "
D. H. Taeler, Dwight-Lloyd Division, McDowell-Wellman Eng. Co.,
Cleveland, Ohio (1964).
A-I3
-------
C -1 06
C -1 07
C -1 08
C -1 09
C-110
C-111
C-112
C-l13
C -114
C-115
C-116
C-1l7
C-118
C-119
"Experience in Production and Utilization of Lightweight Aggregate
at Consolidated Edison, II A. S. Pear son, Dwight- Lloyd Divis ion,
McDowell-Wellman Eng. Co., Cleveland, Ohio (1967).
:'Products and Processes, " S. W. Bryant & E. Heine, Fortune
(September 1965).
"Pozzolanic Pavements, " H. L. Ahlberg & E. J. Barenberg,
Bulletin 473, Eng. Exp. Sta., Univ. of Illinois, Champagne, Ill.
(1965 ).
"Fly Ash as a Pozzolan," R. F. Blanks, A. C. 1. Jour. (May 1950).
"Fly Ash Disposal, " G. C. Halzel, Pow. Eng. (June 1969).
"Edison Electr ic Institute Bulletin, Proces s Repor t: Fly Ash
Utilization Research Program~1 M. J. Snyder, A. J. Roese,
R. I. Hunter & P. Gluck, Edison Elec. Inst. (February 1966).
"Cheap Fly Ash Component Could Replace Microspheres, "
Mater ials.
"Fly Ash Pelletizing, " D. C. Violetta & C. J. Nelson, Dwight-
Lloyd Divis ion, McDowell-Wellman Eng. Co., Cleveland, Ohio
(February 1966).
"Recycling Man-Made Ores for Industry, II 1970 Engineering
Foundations Research Conference, Henniker, New Hampshire
(1970).
"Fly Ash Growth Chamber Studies," L. Murphy & D. Whitney,
Kansas State University.
"Innovations in Every Department, " J. H. Bergstrom, Missouri
Portland Cement Co., St. Louis, Mo. (April 1964).
"Missouri Portland Cement's New Joppa Plant, " B. C. Herod,
Pit and Quarry Publications, Chicago (April 1964).
"Lime-Fly Ash-Aggregate Mixtures, 11 E. J. Barenberg, Bu. M. 1. C.
8348 (March 1967).
"Chemical and Air Entraining Admixtures for Concrete, "
N. R. M. C. A. Pub. No. 132 (April 1970).
A-14
-------
C-120
C-121
C-122
C-123
C - 124
C-~25
C-126
C-127
C-128
C-129
C-130
C-13l
C -132
C-133
"Effects of Combining Two or More Admixtures in Concrete,"
C. E. Lovewell & E. J. Hyland, Chicago Fly Ash Co., Chicago
(J an uar y 1 9 7 1 ).
"Fly Ash Increases Res istance of Concrete to Sulfate Attack, "
J.T. Dikeou, U.S. Dept. Int. (1970).
"Properties of Cements and Concrete Containing Fly Ash, I.
R. E. Davis, et aI, Proc. A. C. 1., pp. 577-612 (1937). .
IISuitability of Ohio Fly Ashes in Portland Cement Concrete,
Project EES-230, " Arrand, et aI, Bldg. Resch. Lab., O. S. U.
(March 1968).
"The Pavement Story," Port of New York Authority (1 May 1969).
"Design Procedure for Airport Paving Systems, " P03-0-Pac
International, Plymouth Meeting, Pennsylvania (August 1970).
"Fly Ash Debut in Br ick Manufactur ing, " Paul Ramirez, Chem.
Eng., 74 (10), pp. 124-126 (1967).
"Fly Ash Br ick, " H. E. Shafer, C. F. Cockrell, and J. W. Leonard,
West Virginia University, Coal Resch. Bur., Morgantown, W. Va.,
Progress Report No. 26 (1966).
"Utilization of Waste Boiler Fly Jfsh and Slags in the Structural
Clay Industry," L. J. Minnick & W. H. Bauer, Am. Ceramic Soc.
Bull. , 2 9 (5), pp. 1 7 7 - 18 0 (1 9 5 0 ) .
"Predictions of the Effect of Fly Ash in Portland Cement Mortar
and Cement," L. J. Minnick, W. C. Webster, and E. J. Purdy, Jr.,
Journal of Materials, ~ (1), pp. 163-187 (1971).
"Te st Fir ing of Ash Br ick on a Short Time Cycle, " Paul L. Sieffer t,
2nd A. U. S., Bur. M. 1. C. 8488 (March 1970).
II The Fly Ash Counc il, " B. A. Thomas, 2nd A. U. S., Bur. M. 1. C.
8488 (Mar ch 1970).
II Effect of Cur ing Condition on Com pre ss ive Strength of Concrete
Test Specimens, " D. L. Bloem, Nat. Sand & Gravel Assoc.,
Circular No. 59 (1954).
"Use of Fly Ash for Remote Filling of Under ground Cavities and
Passageways, II E. M. Murphy, M. O. Magnuson, P. Suder,
J. Nagy, Bur. M. IC 7214 (1968).
A-IS
-------
C-134
II Manual of Instructions for the Structural Des ign of Bituminous
Pavements on Projects Involving MFT and FAS Funds, II State of
Ill., Dept. of Public Wk. & Bldgs., Bureau of Local Roads &
Streets (1969).
I
'The following citations listed in full elsewhere in this appendix (as indicated
by the letter prefix) also contain information that pertains to Fly Ash
Utilization: A-2, A-3, A-4, A-5, A-6, A-9, B-2, B-3, B-4, B-?, B-8,
B-9, B-IO, B-ll, B-12, B-13, B-14, B-15, B-16, B-1?, B-18, B-20,
D-35.
A-16
-------
D. 1
D-l
D-2
D-3
D-4
D-5
D-6
D-7
D-8
D-9
D-lO
D-ll
D-l2
LIMESTONE- MODIFIED TECHNOLOGY
II The New Fly Ash, II L. J. Minnick, 2nd A. U. S. Bu. M. I. C. 8488
(March 1970).
"Establishing a Market for Lime-Fly Ash Base, II F. M. Savage,
2nd A. U.S. Bu. M. 1. C. 8488 (March 1970).
II Character ization and Utilization Studies on Limestone Modified
Fly Ash, " J. W. Leonard & C. F. Cockrell, C. R. B. S. M. (June 1970).
II Pilot Scale -up of Proces s to Demonstrate Utilization of Pulver ized
Coal Fly Ash Modified by the Addition of Limestone-Dolomite Sulfur
Oxides Removal Additives (Progress Report 5/1/68 to 4/30/69), II
C. F. Cockrell, R. B. Muter, & J. W. Leonard, C. R. B. S. M.
(May 1969).
IIStudy of the Utilization of Fly Ash Modified by the Addition of
Limestone-Dolomite, II C. F. Cockrell, R. B. Muter, & J. W. Leonard,
C. R. B. S. M. (Apr il 1969).
IITest To Evaluate the Over burning of Carbonate Rocks, II D. C.
Drehmel, K. B. P. (June 1970).
II Petrographic and Miner alogical Character istics of Carbonate Rocks
Related to S02 Sorption in Flue Gases: Phase I Detailed Studies of
Certain Types of Rocks and Minerals, " R. D. Harvey, K. B. P.
(June 1970).
II Effects of Boiler Flue Gas. De sulfur ization Dry Additives on the
Design of Particulate Emission Control Systems, II A. B. Walker &
R. J. Brown, K. B. P.
IIStudy of Rate of S02 Absorption by an Agglomerated Single Sphere
of Ca02 Powder," M. Ishida, S. C. Wang & C. Y. Wen, K. B. P.
(June 1970).
"S02 Removal from a Pilot Moving Grate Furnace Stack Gas, "
C. M. Whitten & R. G. Hagstrom, K. B. P. (June 1970).
"S02 Capacity of Lime stones, " A. E. Potter, K. B. P. (June 1970).
"Research into the Effect on l1;1troducing Dolomite into Boilers on
the Dispos ition of Coals to Form Depos its on the Heating Surfaces, "
Dr. R. T. Chrusciel, K. B. P. (June 1970).
A-17
-------
D-13
D-14
D-15
D-16
D-17
D-18
D-19
D-20
D-21
D-22
D-23
D-24
D-25
D-26
"Physical Characteristics of Calcinated and Sulphated Limestones, "
G. H. McClellan, K.B.P (June 1970).
"Math Model of the Reaction Between S02 and Lime Particles,"
J. B. Howard, G. C. Williams &F.P.H. Ghazal, K.B.P.
(June 1970).
I'Limestone Addition as a Means of Reducing S02 Emission from
Power Plants," E. K. Kiehl, K.B.P. (May 1970).
"Laboratory Studies of Limestone - S02 Reaction," J. D. Hatfield,
K.B.P. (June 1970).
"Kinetics of the Reacti?ns of Calcium Compounds with S02'"
K. H. van Heek & H. Jungten, K.B.P. (June 1970).
"Kinetics of the Reaction of Calcined Limestone with S02 in
Combustion Gases," Y. Ishihara, K.B.P (June 1970).
l'Isothermal Reactivity of Selected Calcined Limestones with S02' 'I
R. H. Borgwardt, K.B.P. (June 1970).
"IR Studies of Solid State Side Reactions Involved in the Dry
Limestone Process," E. F. Rissman, K.B.P. (June 1970).
11 An IR Method for Rapid Analysis of the Sulfate Content of Reacted
Lime and Limestone Materials, liE. F. Rissman & R. L. Larkin,
K.B.P. (June 1970).
"An IR Kinetic Study of Mechanisms Involved in the Dry Limestone
S02 Removal Process," O. L. Ferguson &E. F. Rissman, K.B.P.
(June 1970).
"Investigation of the Kinetics of Reaction of Limestone with S02
in Flue Gas," R. W. Coutant, R. E. Barrett, R. Simon &
E. H. Lougher, K.B.P. (June 1970).
"Holographic Vizualization of Limestone Plumes Injected into an
Operating Steam Boiler, II B. J. Matthews, .K.B.P. (June 1970).
"Experimental Study of Limestone Injection and Dispersion, "
S. H. Schwarty & R. N. Salzman, K. B. P. (June 1970).
"Proceedings from Dry Limestone Injection Process Symposium, 11
K.B.P. (June 1970).
A-I8
-------
D-27
D-28
D-29
D-30
D-3l
D-32
D-33
D-34
D-35
D-36
D-37
D-38
II Environmental Engineering - A Guide to Industr ial Pollution Control, II
Chern. Eng. (27 April 1970).
liThe Dry Limestone Injection Process. Unit Full Scale Evaluation.
Part IV Solid Waste and Water Quality Cons iderations, II J. S. Morr is,
K. B. P. (June 1970).
"The Dry Limestone Injection Process. Unit Full Scale Evaluation.
Part III Test Program, II H. W. Elder, K. B. P. (June 1970).
liThe Dry Limestone Injection Process for S02 Control.
Scale Evaluation. Part II - Preliminary Test Results, "
T. D. Womble, Jr.,- & J. T. Reese, K. B. P. (June 1970).
Unit Full
liThe Dry Limestone Injection Process for S02 Control. Unit Full
Scale Evaluation. Part I - Equipment Description, Calibration
and Experience, II T. D. Womble, Jr., & J. T. Reese, K.B.P.
(June 1970).
"Dry Limestone Injection: Factors Affecting the Reaction of S02 with
Limestone Particles, II D. G. Thomas, K. B. P. (June 1970).
"Dry Limestone Process, NAPCA Program Review, II J. S. Bowen,
K. B. P. (June 1970).
"Reactions of Hydrated Lime with Pulverized Coal Fly Ash, II
L.J. Minnick, Bu. M.I.C. 8348 (March 1967).
"Sulfur Oxide Control and Fly Ash Utilization, II Progress Report,
N.A.A. 1-71 (1971).
IIStudy of the Pote.ntial for Recovering Unreacted Lime from Lime-
stone Modified Fly Ash by Agglomerate Flotation, II C. F. Cockrell,
R. B. Muter, J. W. Leonard & R. E. Anderson, C. R. B. S. M.
(May 1970). -
"Production of Mineral Wool Insulating Fibers from Coal Ash Slag
and Other Coal Derived Waste Materials, II K. K. Humphreys &
W. F. Lawrence, C. R. B. S. M. (March 1970).
IIExperience With Wet Scrubber for S02 Removal at the Lawrence
Station of the Kansas Power and Light Co., " D. M. Miller, Society
of Mining Engineer s of AlME (September 1969).
"Study of the Potential for Profitable Utilization of Pulverized Coal
Fly Ash Modified by the Addition of Limestone-Dolomite Sulfur
Dioxide Removal Additives, Final Report, 11 C. F. Cockrell, R. B.
Muter, & J. W. Leonard, C. R. B. S. M. (April 1969).
The following citations listed in full elsewhere in the appendix (as indicated by
the letter prefix) also contain information that pertains to Limestone-Modified
Technology: B-4, C-93.
D-39
A-19
-------
E.l
E-l
E-2
E-3
E-4
E-5
E-6
E-7
E-8
E-9
E-IO
E-ll
E-12
E-13
E-14
FOREIGN TECHNOLOGY
"Fly Ash in Cements and Concretes (USSR)," V. V. Stolnikov,
Bu. M. 1. C. 8348 (March 1967).
"U. N. Work-Ash Utilization, " Z. Falecki, Bu. M. 1. C. 8348
(Mar ch 1967).
"An Attempt to Explain the French Succes s in the Utilization of
Fly Ash, II A. Jarr ige, Bu. M. 1. C. 8348 (Mar ch 1967).
"Commer cial Utilization of Fly Ash - England, 11 H. W. G. Dedman,
But. M. I. C. 8348 (March 1967).
"Ash Production and Utilization in the German Federal Republic, "
H. Erythropel, Bu. M. 1. C. 8348 (March 1967).
"Production and Utilization of Fly Ash in Poland, 11 A. Paprocki,
Bu. M. 1. C. 8348 (March 1967).
"PFA Utilization in the United Kingdom," A. Wilson & E. G. Barber,
2nd A. U. S. Bu. M. I. C. 8488 (March 1970).
"Research in the Area of Fly Ash, "A. Tarrige, 2nd A. U. S.
Bu. M. 1. C. 8488 (March 1970).
"Properties of Lightweight Sintered Aggregate from some Yugoslav
Lignite Fly Ash, " P. N. Brzakovic, 2nd A. U. S. Bu. M.1. C. 8488
(Mar ch 1970).
"Study Tour of the United Kingdom Pulver ized Fuel Ash Industry, "
J. H. Faber, Civil Engineer ing and Public Works Review (Great
Br itain) (December 1969 )..
"PFA Data Book, " Central Electricity Generating Board, London,
England (September 1967).
"Information - Project: Lightweight Concrete Plant, " H+H INDUSTRI
A/S, Copenhagen, Denmark (June 1970).
"Celcon Building Blocks Technical Handbook, " Ce1con, London,
England (July 1970).
"PFA Technical Bulletin Nos. 1 through 33, " Central E1ectr icity
Generating Board, London (April 1965 - November 1970).
A-20
-------
------ -
I:
E-15
E-16
E-17
E-18
E-19
E-20
E-Zl
11 Visit to Motorway Construction in the South West, 10 and 11
September 1970. Notes on the Design and Construction of Embank-
ments on Alluvial Deposits, " The Institution of Civil Engineers
Society Western Association, London, England (September 1970).
"Porous Concrete Plant HD 501, " Robert Hildebrand, Maschinenbau
Gmbh, Nuertingen, West Germany (undated).
"Product- Mix and Phys ical Properties - Gas Concrete," H+H
INDUSTRI A/S, Copenhagen, Denmark (undated).
"Gas Concrete in Modern Architectural Design, II H+H INDUSTRI
A/S, Copenhagen, Denmark (December 1970).
IIHildebrand Plant HD 124 for the Production of Porous Concrete
PORONITI, " Robert Hildebrand, Maschinenbau Gmbh, Nuertingen,
West Germany (undated).
11 Lightweight Concrete Know-How, " H+H INDUSTRI A/S, Copen-
hagen, Denmark (September 1969).
"Symposium on the Use of Ash, in Particular in Production of
Concrete and Prefabricated Construction Elements," Economic
Commission for Europe Committee on Electric Power - Ankara
(November 1970), Distr ibuted N. A. A.
The following citations listed in full elsewhere in this appendix (as indicated
by the letter prefix) also contain information that pertains to Foreign
Technology: A-Z, A-3, C-3, C-4, C-94.
A-Zl
-------
F .1
F-1
F-2
F-3
F-4
F-5
F-6
F-7
F-8
F-9
F-10
F-11
F-12
F-13
F-14
SPECIFICATIONS AND REGULATIONS
"ASTM Designation C618-68T, Tentative Specifications for Fly Ash
and Raw or Calcinated Natural Pozzolans for Use in Portland
Cernent Concrete, II ASTM (1968).
II ASTM Designation C593 -66T, Tentative Specification for Fly Ash
and Other Pozzolans for Use with Lime, " ASTM.
"ASTM Designation D242-64, Standard Specifications for Mineral
Filler for Bituminous Paving Mixtures," ASTM.
"ASTM Designation C595-68, Standard Specification for Blended
Hydraulic Cements," ASTM.
"ASTM Designation C331-64T, Tentative Specifications for
Lightweight Aggregates for Concrete Masonry Units, " ASTM.
"ASTM Specifications C-55, C-90, C-129, C-139, C-145 for
Concrete Masonry Units, " ASTM.
"ASTM Designation C330-68T, Tentative Specifications for Light-
weight Aggregates for Structural Concrete," ASTM.
"ASTM Designation C311-68, Standard Methods of Sampling and
Testing Fly Ash for Use as an Admixture in Portland Cement
Concrete, II ASTM.
"ASTM De signation D692 -63, Standard Specifications for Coarse
Aggregate for Bituminous Paving Mixtures, 11 ASTM.
"ASTM Designation D1863-64, Standard Specifications for Mineral
Aggregate for Use on Built-Up Roofs, " ASTM.
"ASTM Designation C144-66T, Tentative Specifications for
Aggregate For Masonry Mortar, " ASTM.
"ASTM Designation D1865-3, Standard Method of Test for Hardness
of Mineral Aggregate for Use on Built-Up Roofs, " ASTM.
I'ASTM Designation D170-41, Standard Specifications for Bituminous
Grout for Use in Waterproofing Above Ground Level," ASTM
(reapproved 1965).
"ASTM Designation D1073-63, Standard Specifications for Fine
Aggregate For Bituminous Paving Mixtures," ASTM.
A-22
-------
F-15
F-16
F-17
F-18
F-19
F-20
F-21
F-22
F-23
F-24
F-25
F-26'
F-27
F-28
F-29
"ASTM Designation D 1139-68, Standard Specifications for Crushed
Stone, Crushed Slag, and Gravel for Single or Multiple Bituminous
Surface Treatments," ASTM.
"ASTM Designation C404-61, Standard Specifications for Aggregates
for Masonry Grout," ASTM.
"ASTM Designation D1864-63, Standard Method of Test for Moisture
in Mineral Aggregate for Use on Built- Up Roofs," ASTM.
"ASTM Designation C465-66T, Tentative Specifications for Processing
Additions for Use in the Manufacture of Portland Cement," ASTM.
"ASTM Designation D1241-68, Standard Specifications for Materials
for Soil-Aggregate Subbase, Base, and Surface Courses, II ASTM.
"ASTM Designation D1753-67, Standard Specifications for Hot-Mixed,
Hot-Laid Tar Paving Mixtures," ASTM.
"ASTM Designation C150-70, Standard Specification for Portland
Cement," ASTM.
"ASTM Designation C150 -68, Standard Specification for Portland
Cement, II ASTM.
"ASTM Designation D8-68, Standard Definitions of Terms Relating
to Materials for Roads and Pavements," ASTM.
"ASTM Designation D2487 -66T, Tentative Method for Classification
of Soils for Engineering Purposes," ASTM.
"ASTM Designation D653-57, Standard Definitions of Terms and
Symbols Relating to"Soil and Rock Mechanics," ASTM.
"ASTM Method C430, Test for Fineness of Hydraulic Cement by the
No. 325 Sieve," ASTM (1968).
"ASTM Method C204-55, Test for Fineness of Portland Cement,"
ASTM (1967).
"ASTM Method C185-59, Test for Air Content of Hydraulic Cement
Mortar," ASTM (1967).
"ASTM Method C109-64, Test "for Compressive Strength of Hydraulic
Cement Mortars," ASTM (1964).
A-23
-------
F-30
F-31
F-32
F-33
F-34
F-35
F-36
F-37
F-38
F-39
F-40
F-41
F-42
F-43
F-44
F-45
"ASTM Method C 114-67, Chemical Analysis of Hydraulic Cement,"
ASTM (1967).
"ASTM Method C311-68, Sampling and Testing Fly Ash for Use as
an Admixture in Portland Cement Concrete, " ASTM (1968).
"ASTM Method C331-67, Test for Effectiveness of Mineral
Admixtures in Preventing Excessive Expansion of Concrete due to
the Alkali-Aggregate Reaction," ASTM (1967).
"ASTM STP419, Test Methods for Compression Members, " ASTM
(1967).
"ASTM STP461, Rapid Test Methods for the Determination of
Bitumen Content in Bituminous Mixtures," ASTM (1969).
IIASTM STP441, Cement, Comparison of Standards and Significance
of Particular Tests," ASTM (1968).
"Cooperative Series of Tests on Fly Ash: Final Report of Test
Results," ASTM, Committee C-9, Subcommittee III-h, Sec. 2
(November 1967). .
"1970 Compilation of ASTM Standards in Building Codes," ASTM.
"ASTM Specifications on Fly Ash for Use in Concrete, " R. B. Mielenz,
Bu.M.I.C. 8348 (March 1967).
"Producing Specification Fly Ash," H. C. Skaggs & R. E. Morrison,
Bu. M. 1. C. 8348 (March 1967).
"Fly Ash: Specifications, Limitations, and Restrictions,"
M. J. Snyder, Bu.M.I.C. 8348 (March 1967).
"Federal Specification, Pozzolan (for Use in Portland Cement
Concrete), II Int. Fed. Spec. SS-P-00570b (GSA-FSS) (April 1969).
"Federal Specification, Aggregate (for Portland Cement Concrete), "
SS-A-281 b.
"Federal Specification, Cement, Portland," SS-C-192d.
"Federal Specification, Cement, Nat,ural (for Use as a Blend with
Portland Cement)," SS-C-185a.
"Federal Specification, Cement, Portland, Blast-Furnace Slag,"
SS-C-197b.
A-24
-------
F-46
F-47
F-48
F-49
F-50
F-51
F-52
F-53
F-54
F-55
F-56
F-57
F-58
F-59
F-60
F-61
F-62
"Federal Specification, Cement, Slag," SS-C-218d.
"Federal Specification, Cement, Portland-Pozzolan," SS-C-208c.
"Federal Specification, Road and Paving Materials; Methods of
Sampling and Testing," SS-R-406c.
"Federal Test Method Standard, Cements, Hydraulic; Sampling,
Inspection, and Testing," Fed. Test Method Std. No. 158a.
"Corps of Engineers Specifications for Pozzolan for Use in
Portland Cement Concrete, II CRD-C 262-63.
"Corps of Engineers Methods for Sampling and Testing Pozzolan
for Use in Portland Cement Concrete, II CRD-C 263-66.
IICorps of Engineers, Preplaced Aggregate Concrete, II CE 1401.03.
IICorps of Engineers, Standard Guide Specifications for Concrete, II
CE 1401.01.
"Corps of Engineers, Guide Specification for Military Construction
Concrete (for Building Construction), " CE -204.
"Corps of Engineers, Guide Specification for Military Construction
Concrete (for Building Construction), II CE-204. 02.
IICorps of Engineers, Civil Works Construction Abridged Guide
Specification for Concrete, II CE-140 1-02.
"Arne rican Petroleum Institute Specification fo r Oil-Well Cements
and Cement Additives, II API STD 10A.
IIStandard Concrete Specification;' National Steel Corporation.
Weirton Steel Company Division.
"Item P-305, Aggregate-Lime-Fly Ash Base Course, (Plant Mixed), II
Federal Aviation Agency.
"State of Alabama, Fly Ash Specifications From the Department of
Highways Handbook, II Section 806.
"State of Connecticut, Standard Specifications for Roads, Bridges
and Incidental Construction," (1969).
"State of Ohio, Department of Highways, Construction and Material
Specifications, II (January 1969).
A-25
-------
F-63
F-64
F-65
F-66
F-67
F-68
F-69
F-70
F-71
F-72
F-73
F-74
F-75
F-76
"State of Ohio, Departm.ent of Highways, Supplemental Specification
835, Aggregate-Lime-Fly Ash Base," (January 1969).
"State of Michigan, Department of State Highways, 8.02 Aggregates."
"Pennsylvania Department of Highways Specification, Form 408,
Paved Shoulders, Type 2."
"Pennsylvania Department of Highways Specification," Form 408,
Aggregate-Lime-Pozzolan Base Course."
"Pennsylvania Department of Highways, Section 332, Soil-Lime-
Pozzolan Base Course."
"Pennsylvania Departm.ent of Transportation, Section 322, Aggregate-
Lime -Pozzolan Base Cour se. "
"State of Illinois Department of Public Works and Buildings, Division
of Highways, Specification for Stabilized Shoulders and Sub-Base."
(effective October 1, 1970; revised NoveITber 2, 1970).
"State of Illinois Departm.ent of Public Works and Buildings, Division
of Highways, Special Provision for Pozzolanic Base Course, Type A."
(effective April 1, 1964; revised August 1, 1968).
"North Dakota State Highway Department, Special Provision,
Section 506, Hot Bituminous Pavement; Section 812, Aggregate
for Hot Mix Asphaltic Concrete Pavement and Mineral Filler, "
SP-42B.
"West Virginia Departm.ent of Highways, Special Provision for
Section 2. 21A, Lime-Fly Ash-Aggregate Base."
"Interim Specifications and Methods Adopted by the AASHO
Committee on Materials 1970," Arn.er. Assn. of State Hwy. Off. (1970).
"Standard Specifications for Highway Materials and Methods of
Sampling and Testing, Part I-Specifications," Amer. Assn. of
State Hwy. Off. (1966).
"Guide Specification for Highway Construction," Arner. Assn. of
State Hwy. Off. (1968).
"A Review of Ash Specifications," RI. E. Morrison, 2nd A. U. S.
Bu. M. 1. C. 8488 (March 1970).
A-26
-------
F-77
"Fineness of Cement, STP473, II ASTM (1970).
F-78
"Quality Assurance in Highway Construction, " U. S. Dept. of
Transportation, Federal Highway Administration, Bureau of
Public Roads, Washington, D. C.
F-79
"1968 Book of ASTM Standards, II ASTM.
F-80
IITVA General Construction Specification NO G-2, Plain and
Reinforced Concretell (February 1970).
F-81
IITVA General Construction Specification NO G-30, Fly Ash for
Use as an Admixture in Concrete" (March 1970).
The following citations listed in full elsewhere in this appendix (as indicated
by the letter prefix) also contain information that pertains to Specifications
and Regulations: A-9, B-3.
\
A-27
-------
G.1
G-1
G-2
G-3
G-4
G-S
G-6
G-7
G-8
G-9
G-10
G-11
G-12
G-13
SULFUR DIOXIDE CONTROL
"Process Control Engineering R&D for Air Pollution Control - A
Status Report," U.S. Dept. of H.E.W. (November 1969).
"Additive Injection for S02 Control - A Pilot Plant Study," R. C. Atig
& P. Sedor, Babcock & Wilcox Co., Research and Development,
Alliance, Ohio (June 1970).
"Air Pollution: The Control of S02 from Powe r Stacks. Part I- The
Removal of Sulfur from Fuels," A; M. Squires, Chem. Eng.
(November 1967).
"Air Pollution: The Control of S02 from Power Stacks. Part II-The
Removal of S02 from Stack Gases," A. M. Squires, Chem. Eng.
(November 1967).
"Air Pollution: The Control of S02 from Power Stac.Ks.
Part III-Process for Recovering S02'" A. V. Slack, Chem. Eng.
(December 1967).
"Air Pollution: The Control of S02 from Power Stacks.
Part IV -Power Generation with Clean Fuels," A. M. Squires,
Chem. Eng. (December 1967).
"S02 Removal from Power Plant Stack Gas. Conceptual Design
Cost Study. Sorption by Lirnestone or Lirne-Dry Process,"
TV A (Contract No. TV29233A for NAPCA) (1968).
"S02 Removal from Power Plant Stack Gas. Use of Lirnestone in
Wet-Scrubbing Process. Conceptual Design and Cost Study
Series, " TVA (Contract No. TV-29233A for NAPCA) (1968).
"Summary of Capabilities," U. S. C. E. -W. E. S (1969).
"Investigation of Cement-Replacement Materials, Report No. 13 -
Use of Water-Reducing and Water-Reducing Retarding Admixtures
in Mass Concrete," U.S.C.E. -W .E.S (Novernber 1966).
"Clean Power from Coal," A. M. Squires, Science, (August 1970).
"Biological Effects of Sulfur Dioxide and Fly Ash," J. W. Clayton, Jr.,
Edison Elec. Inst. R&D Panel for Environrnental Irnprovernent
(1970).
"Development of a Molten Carbonate Process for Removal of Sulfur
Dioxide from Power Plant Stack Gases. Part I, II No. Arner.
Rockwell, Corp., Canoga Park, Cali£. (April 1968).
A-28
-------
G-14
G-15
G-16
G-17
G-18
G-19
"Development of A Molten Carbonate Process for Removal of
Sulfur Dioxide from Power Plant Stack Gases. Part VII, "
No. Amer. Rockwell, Corp., Canoga Park, Calif., (April 1968).
"Development of a Molten Carbonate Process for Removal of
Sulfur Dioxide from Power Plant Stack Gases. Part VI, II
No. Amer. Rockwell, Corp., Canoga Park, Calif. (April 1968).
"Development of a Molten Carbonate Process for Removal of Sulfur
Dioxide from Power Plant Stack Gases. Part V," No. Amer.
Rockwell, Corp., Canoga Park, Calif. (April 1968).
"Development of a Molten Carbonate Process for Removal of Sulfur
Dioxide from Power Plant Stack Gases. Part III, II No. Amer.
Rockwell, Corp., Canoga Park, Calif. (April 1968).
"Development of a Molten Carbonate Process for Removal of Sulfur
Dioxide from Power Plant Stack Gases. Part IV," No. Amer.
Rockwell, Corp., Canoga Park, Calif. (April 1968).
"Development of a Molten Carbonate Process for Removal of Sulfur
Dioxide from Power Plant Stack Gases. Part II, " No. Amer.
Rockwell, Corp., Canoga Park, Calif. (April 1968).
A-Z9
-------
H.1
H-1
H-2
H-3
H-4
H-5
H-6
H-7
H-8
H-9
H-10
H-11
H-12
H-13
H-14
H-15
MISCELLANEOUS
"Public Concern for Environmental Improvement, II K. Holum,
Bu.M.1.C., 8348 (March 1967).
"Steam-Its Generation and Use: Fuel Ash Related to Boiler Design
and Operation, 11 Babcock & Wilcox Co., Alliance, Ohio, (1955).
"Magnetic Separator, CG Type," Haramaki Machinery Manufacturing
Co., Japan.
"Fuels for Steaming Purposes," Combustion Engineering.
"The Search for Low-Sulphur Coal," H. Perry & J. A. DeCarlo,
Mech. Eng. (April 1967).
"The Reaction Parameters of Lime, STP472,11 ASTM (1970).
"Section G, Industry Statistics of the Nonmetallic Industries, Pit
and Quarry Handbook, II Pit and Quarry Publications, Chicago, Ill.
(1970).
"Highway Statistics 1967,"A. S. Boyd, L. K. Bridwell &
F. C. Turner (October 1969).
"The Mineral Resources Task Group Presents: Mined-Land
Redevelopment," Mined-Land Redevelopment Office, Girard, Kansas
(September 1970).
"Statistics of Privately Owned Electric Utilities in the United States,"
Federal Power Commission (October 1969).
"Statistics of Publicly Owned Electric Utilities in the United States,"
Federal Power Commission (1968).
"Solid Waste Processing, " R. B. Eugdahl, Batt. Mem. Inst. (1969).
"Fly Ash and the Electric Utility Industry, " J. A. Tillinghast.
Bu. M. 1. C. 8348 (March 1967).
"Principles of Pavement Design, "E. J. Yoder, John Wiley and
Sons, Inc. (1959).
"Energy Sources of the Future for the United States," L.P. Gaucher,
Solar Energy Society, Vol. 9, No.3 (1965).
A-30
-------
ABBREVIA TIONS USED IN BIBLIOGRAPHY
Amer. Assn. of State Hwy. Off.
American Association of State Highway
Officials, Washington, D.C.
A. C. 1. Jour.
American Concrete Institute Journal
ASTM
American Society for Testing Materials,
Philadelphia
Batt. Mem. Inst.
Battelle Memorial Institute, Columbus,
Ohio
Bldg. Resch. Lab., O. S. U.
Building Research Laboratory, Ohio
State University, Columbus, Ohio
Bu. M.1. C.
Bureau of Mines Information Circular
Chem. Eng.
Chemical Enginee ring
Civ. Eng.
Civil Engineering
C. R. B. S. M.
Coal Research Bureau, School of Mines,
Morgantown, West Virginia
Edison Elec. Inst.
Edison Electrical Institute, New York,
New York
Elec. World
Electronic World
Eng. N. Rec.
Engineering News Record
Env. Sc. & Tech.
Environmental Science and Technology
Hwy. Resch. Bd.
Highway Research Board, National
Academy of Sciences, National Research
Council, Washington, D. C.
Hwy. Resch. Rec.
Highway Research Record
K.B.P.
Ken Bar Paper (NAPCA, Division of
Process Engineering, Dry Limestone
Injection Process Symposium,
Gilbertsville, Kentucky)
A-3I
-------
Mech. Eng.
Mechanical Engineering
Min. Eng.
Mining Engine e ring
NAPCA
National Air Pollution Control Adminis-
tration' Washington, D. C. (now APCO)
N.A.A.
National Ash Association,
Washington, D. C.
N.R.M.C.A.
National Ready Mixed Concrete
\
Association, Silver Springs,
Mary land
P.C.A.
Portland Cement Association, Skokie,
Illinois
Pow. Eng.
Power Engineering
2nd A. U.S.
Second Ash Utilization Sympo sium,
Pittsburgh, March 1970
Tech. Lab., C. R . 1. E . P . I.
Technical Laboratory, Centr'al Research
Institute of Electric Power Industry,
Tokyo, Japan
U.S.C.E-W.E.S.
u. S. Army Corps of Engineers,
Waterways Experiment Station,
Vicksburg, Mississippi
u.S. Dept. of H.E. W.
u. S. Department of Health, Education
and Welfare, Washington, D. C .
(now EP A)
u. S. Dept. Int. 1. C.
u.S. Department of the Interior Infor-
mation Circular
U. S. Dept. Int. R. 1.
u. S. Department of the Inte rio r Repo rt
Inve stigations
A-32
-------
~
:>
(")
='"
z
o
::e
I
,."
o
C)
,."
3:
,."
Z
-i
.."
-------
APPENDIX B
ACKNOWLEDGEMENTS TO SOURCES OF FLY ASH DATA
This appendix acknowledges the data of great value to this study that were
provided by individuals in industry, universities, trade associations, and
government agencies.
B.1
FLY ASH PRODUCTION, BENEFICIATION, AND
MARKETING
Data Source
American Electric Power
Service Corporation
Charleston, W. Virginia
American Electric Power
Service Company
New York, New York
Appalachian Power
Company
Charleston, W. Virginia
Central Electricity
Generating Board
London ECI, England
Chicago Fly Ash Company
Chicago, Illinois
Consolidated Edison
Company of New York,
Inc.
New York, New York
Dayton Fly Ash Company
Pittsburgh, Pennsylvania
Dayton Fly Ash Company
Smyrna, Georgia
Primary Contact
Data
Ronald E. Morrison
Fly ash production,
marketing
S. J. Marmaross
Fly ash production,
marketing
Henry Scaggs
Fly ash production,
collection
Alex Wilson
Fly ash production,
marketing
C. E. Lovewell
E. Hyland
Marketing
William Bannon
Fly ash production
Lou Marcuz
Marketing
Robert Styron
Marketing,
beneficiation
B-1
-------
Data Source
Duquesne Light & Power
Pittsburgh, Pennsylvania
Edison Electric Institute
New York, New York
Environmental Policy
Division
Legislative Reference
Se rvice
Library of Congress
Washington, D. C.
National Ash As sociation
Washington, D. C.
Southern Electric
Generating Company
Birmingham, Alabama
Southern Fly Ash
Company
Birmingham, Alabama
Steinkohlen Elektrizitat AG
Essen, W. Germany
Stirling Sintering Company
South Heights, Pennsylvania
Tennessee Valley Authority
Chattanooga, Tennes see
The Detroit Edison Company
Detroit, Michigan
The Detroit Edison Company
Detroit, Michigan
The Detroit Edison Company
Detroit, Michigan
Primary Contact
M. Jaworski
Dan Joseph
G. A. Olson
Harry Perry
John Faber
Phili p Me ikle
Charles Brackett
Mr. Hardison
Hermann Erythropel
Harold T. Stirling
Charles R. Barbison
Thomas Williams
William Arnold
D. Parker
F. V. Zimmer
B-2
Data
Fly ash production,
mar keting
Edison Electric
Institute survey
Fly ash production
Fly ash production,
marketing
Fly ash production
survey for 1970,
general utilization
Fly ash production,
marketing
Fly ash production
Beneficiation
Fly ash production
Fly ash production,
marketing
Operation and main-
tenance of coal
burning powe r plant
equipment
Fly ash production,
marketing
-------
Data Source
Tennessee Valley Authority
Knoxville, Tennessee
Viall-Ohio Fly Ash
Company
Akron, Ohio
Primary Contact
Ro be rt Cannon
Rupert Bullock
Alex Ridings
Robert Sneed
Paul Viall
Paul Viall, Jr.
Data
Fly ash production
Fly as h production,
marketing
B.2
FLY ASH UTILIZATION, SPECIFICATIONS, AND
TECHNOLOGY
Data Source
Alabama Highway
Department
Montgomery, Alabama
American Concrete Paving
Association
Oak Brook, Illinois
American Electric Power
Service Corporation
Charleston, W. Virginia
American Electric Power
Se rvice Company
New York, New York
American National
Standards Institute, Ine.
New York, New York
American Technology
Exchange, Inc.
Esslingen, W. Germany
Belden Brick Company
Canton, Ohio
Bergbau Forschung,
GmbH
Essen-Kray, W. Germany
Primary Contac"t
J. A. Hester
D. B. Flournoy
John Greesaman
Ronald E. Morrison
S. Marmaros s
C. H. Burns
W. W. Reichert
Burke Wentz
Dr. K. H. van Heek
B- 3
Data
Highways and
highway
specifications
Highways and
specifications
Product
development
General utilization
Specifications
gene ral utili70ation
Foreign technology
exchange, gas
concrete
Bricks
General utilization
-------
Data Source
California Highway
Department
Sacramento, California
Celcon
London, England
Central Electricity
Generating Board
London ECI, England
Central Research Institute
of Electric Power Industry
Tokyo, Japan
Chicago Fly Ash Company
Chicago, Illinois
Clawson Concrete Company
Detroit, Michigan
Collinwood Shale Brick
and Supply Company
Cleveland, Ohio
Colorado Department of
Highways
Denver, Colorado
Commonwealth Edison
Company
Chicago, Illinois
Connecticut Department
of Transportation
Wethersfield, Connecticut
Consolidated Edison
Company of New York, Inc
New York, New York
Consolidated Rock
Products Company
Los Angeles, California
Primary Contact
John Beaton
Mr. Smit-Hansen
Mr. Lucklin
Alex Wilson
Peter Smith
Yoshimi Ishihara
C. E. Lovewell
E. Hyland
Earl Colburn
Mr. Maxwell
C. E. Shumato
Jos;eph McCluskey
J. F.. Shugrue
William Bannon
Everett A. Jumper
B-4
Data
Highways and
highway
specifications
Gas concrete
Highway structural
fill
General utilization
Concrete
technology
Lightweight aggregate,
ready-mix
Ready-mix
Highway and
highway
specifications
Fly ash production
Highways and
highway
specifications
Lightweight aggregate
and road base course
Ready-mix
-------
Data Source
Cooke Contracting Company
Detroit, Michigan
Delta Concrete Company.
Arrow Block Company
Bellaire, Ohio
Dravo Corporation
Pittsburgh, Pennsylvania
Duquesne Light & Power
Elrama, Pennsylvania
Duquesne Light & Power
Pittsburgh, Pennsylvania
Edison Electric Institute
New York, New York
Environmental Policy
Division
Legislative Reference
Se rvice
Library of Congress
Washington, D. C.
Federal Aviation Agency
Washington, D. C.
Fisher Concrete Company
Memphis, Tennessee
Flood T e sting
Laboratories
Chicago, Illinois
Florida Department of
Transportation
Gainesville, Florida
Freeport Brick Company
Elrama, Pennsylvania
Freeport Brick Company
Freeport, Pennsylvania
Primary Contact
Bill James
John L. Seabright
Arthur Livingood
Larry Clark
J. Jaworski
Dan Jospeh
G. A. Olson
Harry Perry
P. E. Melville
R. W. F. Mosby
Walter H. Flood
J. D. Gammage
W. Kukuk
Ami! Proto
D. J. Stefl
B-5
Data
Asphalt filler
Ready-mix, concr.ete
block
Ready-mix
Lightweight aggregate
Lightweight aggregate
Edison Electric
Institute survey
Gene ral utilization
Airport runway
construction
Ready-mix
Concrete
spe cifications
Highways and
highway
specifications
Lightweight
aggregate
Lightweight
aggregate
-------
Data Source
G. and W. H. Corson
Company
Plymouth Meeting,
Pennsylvania
Georgia Highway
Department
Atlanta, Georgia
H + H Industri A/S
Copenhagen, Denmark
Highway Ready -Mix
Company
Dravosburg, Pennsylvania
Highway Research Board
Division of Engineering
National Research Council
Washington, D. C.
Illinois Department of
Public Works and
Buildings
Springfield, Illinois
Iowa Highway Commission
Ame s, Iowa
Iowa State University
Ames, Iowa
Kuhlman Builders Supply
and Brick Company
Toledo, Ohio
Marquette Cement
Company
Chicago, Illinois
Maryland State Roads
Commission
Baltimore, Maryland
Primary Contact
Dr. L. J. Minnick
Tom Atherton
T. D. Moreland
Erik Dam Hansen
Leo Blaabjerg
Srensen
J. Cutlip
J. W. Guinnee
W. E. Baumann
J. R. Coupal, Jr.
Dr. R. C. Joshi
William E. Brewer
Owen Brown
Nathan L. Smith, Jr.
B-6
Data
Sintered products,
road base materials,
concrete admixtures,
specifications
Highways and
highway
specifications
Gas concrete
Ready-mix, asphalt
filler
Highways and
highway
specifications
Highways and
highway
specifications
Highways and
highway
s pe c ifi cations
Synthetic fly ash
pozzolanic action
Ready-mix
Manufacture of
Portland cement
Highways and
highway
specifications
-------
Data Source
Material Service
Corporation
Chicago, Illinois
McDowell-Wellman
Dwight Lloyd Division
Cleveland, Ohio
Michigan Department of
State Highways
Lansing, Michigan
Michigan Institute of
Technology
Houghton, Michigan
Minnesota Department of
Highways
St. Paul, Minnesota
Missouri Highway
Commis sion
Jefferson City, Missouri
Missouri Portland
Cement Company
St. Louis, Missouri
National Ash As sociation
Washington, D. C.
National Asphalt
Pavement Association
Riverdale, Maryland
National Ready -Mix
Conc rete Association
Silver Springs, Maryland
Nello L. Terr Company
Flylite Division
Charlotte, No. Carolina
Primary Contact
Ronald Blick
Harold E. Rowen
R. L. Greenman
Professor Freiberger
F. C. Fredrickson
T. E. David
Bruce Kester
John Faber
Philip Meikle
. George A. Kladnik
Fred Kloiber
D. L. Bloem
Kenneth Nelson
\
B-7
Data
Ready-mix
Lightweight
aggregate
Highway and
highway
specifications
Lightweight aggregate
process without
sintering
Highways and
highway
specifications
Highways and
highway
specifications
Manufacture of
Portland cement
General utilization
Highways and
highways
specifications
Ready -mix
Lightweight
aggregate
-------
Data Source
New Jersey Department of
Transportation
. Trenton, New Jersey
New York Department of
Transportation
Albany, New York
Niagara Mohawk Power
Company
Syracuse, New York
North Carolina State
Highway Commis sion
Raleigh, No. Carolina
North Dakota Highway
Department
Bismarck, No. Dakota
Ohio Department of
Highways
Columbus, Ohio
Pennsylvania Department
of Transportation
Harrisburg, Pennsylvania
Penn Dixie Cement
Company
Pittsburgh, Pennsylvania
Pit and Quarry
Publications
Chicago, Illinois
Portland Cement
Association
Skokie, Illinois
Purdue University
Department of Engineering
Lafayette, Indiana
Ready-Mix Concrete
Company
Knoxville, Tennes see
Primary Contact
C. E. Kueker
M. Tedza
Arthur Stefanski
M. D. Barbour
R. W. Bradley
G. J. Thormeyer
L. D. Sandvig
Char Ie s Seamon
Paul Klieger
Dr. E. J. Yoder
F. H. Pittenger
B-8
Data
Highways and
highway
spe cifications
Highways and
highway
specifications
Lightweight
aggregate
Highways and
highway
specifications
Highways and
highway
specifications
Highways and
highway
specifications
Highways and
highway
specifications
Cement
manufacturing
Geographic locations-
cement and lightweight
aggregate plants
Fly ash concrete
Highways
Ready -mix
-------
Data Source
Rhode Island Department
of Transportation
Providence, Rhode Island
River Cement Company
St. Louis, Missouri
Robert Hildebrand
Maschinenbau GmbH
Nuertingen, W. Germany
Skidmore, Owings and
Merrill, Architects and
Enginee rs
Chicago, Illinois
South Carolina Highway
Department
Columbia, So. Carolina
Southwest Portland Cement
Company
Los Angeles, California
State Highway Commission
of Kansas
Topeka, Kansas
Steinkohlen Elektrizitat AG
Essen, Germany
Steinkohlen Elektrizitat AG
Essen, Germany
Stirling Sinte ring Company
South Heights, Pennsylvania
Structural Clay Products
Institute
McLean, Virginia
Tennessee Valley Authority
Knoxville, Tennessee
Primary Contact
M. Chorney
Arthur Hunter
Hansjurg Breinbauer
Harold Iyenger
J. D. McMahan, Jr.
J. L. Goetz
Carl F. Crumpton
H. Nteite
Hermann Erythropel
Harold T. Stirling
Charles R. Harbison
Richard Otterson
Robert Cannon
Rupe rt Bullock
B-9
Data
Highways and
highway
specifications
Cement manufacture
Gas concrete
Concrete
specifications
Highways and
highway
specifications
Fly ash in portland
cement manufacturing
Highways and
highway
specifications
Automatic brick
machinery, flyash
production
Fly ash production/
utilization
Lightweight
aggregate
Bricks
Concrete
technology
-------
Data Source
Tennessee Valley Authority
Sequoyah Nuclear Powe r
Plant
Knoxville, Tennessee
Texas Highway Department
Austin, Texas
The Asphalt Institute
College Park, Maryland
The Charles Svec
Company
Maple Heights, Ohio
The Detroit Edison
Company
Detroit, Michigan
The Master Builders
Company
Cleveland, Ohio
u. S. Army Corps of
Engineers
Los Angeles, California
U. S. Army Corps of
Engineers
Waterways Experiment
Station
Vicksburg, Mississippi
U. S. Bureau of Mines
Engineering Research
Center
Morgantown, W. Virginia
U. S. Bureau of Mines
Pittsburgh, Pennsylvania
Valore Research Associates
Ridgewood, New Jersey
Primary Contact
Stanley Carr
J. C. Dingwall
John M. Griffith
Charles Svec
F. V. Zimmer
Dr. Richard C.
Mielenz
Jack Short
Bryant Mather
John Capp
Malcolm Magnuson
Rudolph C. Valore,
Jr.
B-IO
Data
Concrete
construction
Highways and
highway .
specifications
Highways and
spe cifications
Concrete block
Lightweight aggregate,
concrete blocks,
ready -mix, bricks
ASTM specifications,
chemical admixtures
Highways and
highway
specifications
Spe c ifi ca tion,
concrete admixtures
Agriculture, land
reclamation
Disposal of fly ash in
abandoned coal mines
General utilization,
specifications, and
technology
-------
Data Source
VEBA Kraftwerke Ruhr
GmbH
Gelsenkirchen-Buer.
W. Germany
Viall-Ohio Fly Ash
Company. Inc.
Akron. Ohio
Waylite Corporation
River Rouge. Michigan
West Virginia Department
of Highways
Charleston, W. Virginia
West Virginia University
School of Mines. Coal
Research Bureau
Morgantown, W. Virginia
Williams Brothers
Concrete Company
Atlanta, Georgia
Wyoming Highway
Commission
Cheyenne, Wyoming
Primary Contact
Wilhelm Schmidt
Rudolf Feuser
Paul Viall
Paul Viall. Jr.
Allen Rowen
Joseph S. Jones
J. W. Leonard
C. E. Cockrell
Horace Williams
D. G. Miller
B.3
LIMESTONE -MODIFIED FLY ASH
Data Source
Combustion Engineering
Company
Windsor, Connecticut
Primary Contact
Dr. William C.
Taylor
B-ll
Data
Lightweight
aggregate
Ready-mix. concrete
block, and roadways
Lightweight
aggregate
Highways and
highway
specifications
Brick and mine ral
wool research
Ready-mix
Highways and
highway
specifications
Data
Lime stone - mod if ied
fly ash research
-------
Data Source
Environmental Policy
Division
Legislative Reference
Service
Library of Congress
Washington, D. C.
G. and W. H. Corson
Company
Plymouth Me eting,
Pennsylvania
Kansas City Power and
Light Company
Kansas City, Missouri
Kansas Geological Survey
Group
Mineral Resources Section
Kansas City, Missouri
Kansas Power and Light
Company
Lawrence, Kansas
Michigan Institute of
Technology
Houghton, Michigan
Mis souri Portland Cement
Company
St. Louis, Missouri
National Ash As sociation
Washington, D. C.
Union Electric Company
Merimec #2 Unit
St. Louis, Missouri
Valore Research Associates
Ridgewood, New Jersey
West Virginia University
School of Mines
Coal Research Bureau
Morgantown, W. Virginia
Primary Contact
Harry Perry
Tom Atherton
Pat Tansey
Mr. Davidson
Ronald D. Hardy
Lee Brunton
Professor Freiberger
Bruce Kester
John Faber
Mr. Harrington
Rudolph C. Valore,
Jr.
C. E. Cockrell
B-12
Data
Lime stone -modified
fly ash production,
research and
utilization
Limestone -modified
fly ash for road base
course
Limestone -modified
fly ash production
Lime s tone -modified
fly ash production
Limestone -modified
fly ash production
Lightweight
aggregate
Lime s tone -modified
fly ash
Limestone -modified
fly ash utilization
Limestone -modified
fly ash production
Lime s tone -modified
fly ash utilization
Limestone -modified
fly ash research and
utilization
-------
~
-1("')
1"'10
("')z
=t:("')
z::tl
01"'1
,-I
01"'1
~"'tI
::tI
o
"'tI
o
~I
01
z.
Z I
C)
-------
APPENDIX C
BASIC POR TLAND CEMENT CONCRETE PROPOR TIONING
TECHNOLOGY AND ECONOMICS OF FLY ASH CONCRETE
C. 1
GENERAL DISCUSSION
The two basic types of concrete in use today are classified as either non-
air-entrained concrete, which has a natural air content range from 0.3 to
3 percent, or air-entrained concrete, which has an air content ranging from
3.5 to 8 percent.
The greates t advance in concrete technology in recent
years has been the advent of air-entrainment, and today the use of entrained
air is recommended in concrete for nearly all industrial and commercial
structures (Ref. C-57). The principal reason for using intentionally entrained
air is to improve concrete's res istance to freezing and thawing exposure.
Non-air -entrained concrete is used mainly for relatively low strength res i-
dential structures where the problems related to exposure and other proper-
ties are not as severe as on commercial and industrial types of structures.
Figure C-l (Ref. C-57) indicates the relationship between the compressive
strength and curing age of concrete when a Type I portland cement is used.
In order for the concrete to develop to its full final strength, it is necessary
for moisture to remain in contact with the cement.
The s tr ength of the
concrete will then follow the. solid line indicated on Fig. C-1.
If the concre te
is not kept moist, and is exposed to air for the respective times indicated
on the figure, the full strength is not realized.
The early strength of concrete is of importance in using concrete in that it
determines the cur ing time to reach the required strength before loads can
be placed on the concrete. Table C-l indicates the strength that can be
expected from Type I cement after a given curing time. It should be noted
I
that in order to compare fly ash concrete with the conventional portland
cement concrete, it will be necessary to obtain approximately equal strength
at equal time per iods in the cur ing cycle in order to make a fair comparison
of their respective utilization when considering similar design conditions.
C-l
-------
:50
125
IN AIR AFTER 3 DAYS
---------
100
~
;= 75
<.:>
;z
w
Q:
>--
-
-------
The greatest influence in the strength of the concrete is exerted by the
water -to-cement ratio as indicated by Fig. C-2. It can be noted that a
considerable variation of strength can exist for a given water-to-cement
ratio at any time dur ing the cur ing cycle. The maximum and minimum
bands represent approximately 2 sigma standard deviations from the
average value (Ref. C-57).
The ease or difficulty of placing and consolidating freshly poured concrete
is called workability. With a given amount of water and cement paste, an
increase in the amount of aggregate causes a stiff mix which may require
cons iderable labor in placing and finishing. Concrete should be workable
but should not segregate into its or iginal components, nor should it bleed
excessively. Bleeding is the movement of water to the surface of freshly
cast concrete; and since excess ive bleeding may increase the water -cement
ratio at the surface, a weak surface layer of poor durability may result.
This is of particular importance if finishing operations take place while
this excess water is present. Generally, the most economical mix is one
that has the highest proportion of aggregate to cement, and yet is workable
at the water -cement ratio required for strength, durability, and other
properties. The test used to measure the consistency of concrete is called
a slump test. This is performed by forming a cone from the fresh concrete.
The form is then removed from the fresh concrete cone and is allowed to
settle.
The measurement of .the amount of settling in inches is defined as
the "slump" of the concrete.
The durability of concrete is mainly related to its res istance to freezing
and thawing, wetness, and temperature changes. As noted previously,
the freezing and thawing resistance depends on the amount of air entrained.
In addition to this, the water-to-cement ratio of the concrete is also of
importance in determining durability. Table C-2 indicates the recommended
maximum permissible water -cement ratios for different types of structures
and degrees of exposures.
C-3
-------
8
7
6
(J)
a..
,..,
I
X
-x- 5
~
(!)
z
w
a::
~
U)
w
> 4
U)
U)
w
a::
a....
::E
o
u
~ 3
w
a::
u
z
o
u
2
o
0.3
0.4
0.5 0.6 0.7
WATER / CEMENT WEIGHT RATIO, W / C
0.8
Fig. C-2. Water / Cement - Strength Relation of Concrete
C-4
0.9
-------
Table C-2.
ACI Recommended Maximum Permissible Water-Cement
Ratios fo~" Different Types of Structures and Degrees of
Exposure -,-
Exposure conditions..
Severe wide range in tempera-
ture, or frequent alternations Mild temperature rarely below
of freezing and thawing freezing, or rainy, or arid
(air-entrained concrete only)
Type of structures At water line or within At water line or within
In range of fluctuating range of fluctuating
water level or spray In water level or spray
air air
In In sea water In In sea water
fresh or in contact fresh or in contact
water with sulfatest water with sulfatest
A. Thin sections such as reinforced piles and pipe 0.49 0.44 0.40 0.53 0.49 0.40
B. Bridge decks 0.44 0.44 0.40 0.49 0.49 0.44
C. Thin sections such as railings, curbs, sills, ledges,
ornamental or architectural concrete, and all sec- 0.49 - - 0.53 0.49 -
tions with less than I-in. concrete cover over rein- ,
forcement
D. Moderate sections, such as retaining waIls, abut- 0.53 0.49 0.44 tt 0.53 0.44
ments, piers. girders, beams
. E. Exterior portions of heavy (mass) sections O.5S 0.49 0.44 tt 0.53 0.44
F. Concrete deposited by tremie under water - 0.44 0.44 - 0.44 0.44
G. Concrete slabs laid on the ground 0.53 - - tt - -
H. Pavements 0.49 ; - - 0.53 - -
I. Concrete protected from the weather, interiors of i
tt - - tt - -
buildings. concrete below ground I
]. Concrete which will later be protected by enclosure
or backfill but which may be exposed to freezing 0.53 - - tt - I -
and thawing for several years before such protection
is offered I
I - .
. Adapted from Recommended Practice for Selecting Proportions for Concrete (ACI 613-54).
.. Air~ntrained concrete should be used under all conditions involving severe exposure and may be used under mild exposure conditions to
improve workability of the mixture.
tSoil or groundwater containing sulfate concentrations of more than 0.2 per cent. For moderate sulfate resistance, the tricalcium aluminate
content of the cement should be limited to 8 per cent, and for high sulfate resistance to 5 per cent; CSA Sulfate-Resisting cement limits tri-
calcium aluminate to 4 per cent. At equal cement contents, air-entrained concrete is significantly more resistant to sulfate attack than non-air-
entrained concrete.
ttWater-cement ratio should be selected on basis of strength and workability requirements, but minimum cement content should not be less
than 470 lb. per cubic yard.
c-s
-------
A low water-to-cement ratio also improves the water tightness of the concrete,
and for this reason it is recommended for use in exposures where water
tightnes s or res istance to leakage is of importance.
The testing of the compressive strength of the finished concrete is per-
formed in accordance with a variety of ASTM and Crushed Stone Association
specifications. Basically, test specimens consisting of 6-in. diameter by
l2-in. high cylinders are made at a rate of two to three cylinders for every
150 yd3 of concrete produced. The total number of cylinders are then tested
for strength and their compressive strength is plotted on a probability plot
as indicated in Fig. C-3.
4.6
4.2
..
a.
..
o
>< 3.8
x
I-
C)
:z:
....
a:
l-
V'>
....
~ 3.4
V'>
....
a:
a.
:::E
o
u
3.0
2.6
0.1
V: 3~:~0 (100) : 11.3% I
3.450: X (APPROX)
2
10 50 80
% TESTS < TEST VALUE STRENGTHS
95
99
999
5
Fig. C-3.
Test Results Var iations
C-6
-------
From this plot the respective standard deviations of the strength of the
cylinders from the median strength can be determined, and a coefficient
of var iation, defined as the ratio of the standard deviation to the value of
the mean compressive strength in terms of percentage, is assigned as
follows:
L
V - - (100)
- X
The relationship between the required average strength of the concrete and
the specified strength of the concrete as related to the coefficient of varia-
tion can be expressed by the following formula:
f
cr
f'
- c
- 1 - tV
where
f
cr
=
required average strength
£'
c
=
specified strength
V
=
forecasted coefficient of variation expressed as a fraction
t
=
a cons tant depending upon the proportion of tests that may
fall below fl and the number of samples used to establish V
c
If V is established on the bas.is of a large number of samples (more than 30),
t = 0.842 for the requirement that not more than 20 percent of the tests may
be below fl and t = 1. 282 for the requirement that not more than 10 percent
c
of the tests may be below f'. Figure C-4 shows the ratio of required
c
average strength to specified strength for a wide range of values of the
coefficient of variation.
To illustrate, assume that specifications require that not more than one test
in ten shall be less than a specified design strength of 4000 psi. If the
forecasted coefficient of variation is 15 percent, the mix should be designed
for an average strength of about 1. 25 times 4000, which equals 5000 psi.
C-7
-------
Figure C-4 shows the relationship between the required average strength
of the concrete and the coefficient of var iation for a given allowable
number of specimens that are allowed to fall below the specified strength
value as determined by a statistical analysis.
1.5
1.4
5
10 15
COEFFICIENT OF VARIATION V , %
20
25
:I:
>-
'"
z
UJ
~ 1.3
U')
C>
UJ
U.
U
UJ
a-
U')
....
d
8 12
a:
1.1
1.0
o
Fig. C -4.
Design Requirements
Table C-3 collects the standards of concrete control as expressed in terms
of the expected coefficient of variation. Many users of concrete use coef-
ficients of variation in the area of 15 percent and allow from 10 to 20 percent
of the test specimens to fall below the specified strength value, thereby
utilizing ratios of required-to-specified strength of 1. 15 to 1. 25.
C-8
-------
Table C-3.
Standards of Concrete Control
. Coefficient of Variation - Percent
Excellent Good Fair Poor
Variation Within Large Number
Projects
Field Control of Tests 10 10-15 15-20 20
Laboratory Control of Tests 4 5-7 7-10 10
Var iation Within Single Project/
Single Class Concrete
Field Control of Tests 4 4-5 5-6 6
Laboratory Control of Tests 3 3-4 4-5 5
As noted previously, the strength of the ~oncrete is determined by the
water-to-cement ratio and is generally based on the minimum predicted
strength (as shown in Fig. C -2), if no tests are intended to be conducted.
In general, it would be expected that the actual strength of concrete pro-
duced by proportioning the water -to-cement ratio in this manner would be
considerably higher than the minimum. However, the water-to-cement
ratio can be increased only if tests are conducted in accordance with the
previously described procedure. These tests would be based on producing
a tr ial mix us ing test cylinder s. By evaluation of the data obtained from
this, the ratio of water to cement can be altered to arr ive at the required
water -to-cement ratio for the particular coefficient of variations obtained
as a result of the tests.
The proportioning of portland cement concrete mixes are generally based
on the specified strength, slump, and air content of the concrete. The
general procedure is specified in ACI 613-54 liRe commended Practice for
,
Selecting Proportions for Normal Weight Concrete. II The amount of water
to be used in the mix is determined from a table similar to Table C-4, and is
a function of the maximum aggregate size, slump, and whether the concrete
is non-air -entrained or air -entrained.
C-9
-------
Table C-4.
Amount of Water in Concrete Mixes
Aggregate Size (in. )
Non-Air -Entrained Concrete 3/8 1/2 3/4 CD 1-1/2 2 3
Slump 1 in. to 2 in. 350 335 315 300 275 260 240
Slump(3 in. to 4 in.) 385 365 340 @ 300 285 265
Air Content, Percent 3 2. 5 2 1.5 1 O. 5 0.3
Air -Entrained Concrete
Slump 1 in. to 2 in. 305 295 280 270 250 240 225
Slump 3 in. to 4 in. 340 325 305 295 275 265 250
Air Content, Per cent 8 7 6 5 4.5 4 3. 5
As an example for a maximum aggregate size of one inch, an allowable
slump of 3 to 4 in., and for non-air -entrainment, it would require 325 lb
3
of water per yd of concrete.
The amount of portland cement required to produce a given strength is com-
puted with the combination of the amount of water and water-to-cement ratio:
W
C = W /C
As an example, 3000-psi concrete requires a water-to-cement ratio of
approximately 0.69 (ACI 613.54) for non-air-entrained concrete. The amount
of cement for the previously referred to aggregate sizes, slump values, and
air contents are determined by dividing the required 325 lb/yd3 of water
by 0.69, resulting in approximately 470 lb/yd3 of portland cement.
The amount of coar se aggregate required per 'yd3 of concrete increases as
the maximum size of the aggregate increases and also increases with the
fineness of the fine aggregate. This requirement is mainly related to obtaining
a satisfactory workability of the concrete'. The range of amounts varies from
C-IO
-------
3 .
approximately 1300 Ib/yd for a maximum size of 3/8 in. of the coarse
aggregate to 2100 1b/yd3 for a maximum 1-1/2 in. size aggregate using a
medium size fine aggregate.
The amounts of fine aggregate are determined on the basis of the maximum
size of the coarse aggregate, and range from 1200 Ib/yd3 for 3/8 in. maxi-
mum size coarse aggregate to 900 Ib/yd3 for 1-1/2 in. maximum size coarse
aggregate.
Dur ing 1969, the total United States concrete ready-mix production was
186 million yd3 /yr. This was produced by approximately 5400 companies
and resulted in an average production per company of 35,000 yd3/yr.. It is
estimated that the median production company, i. e., company number 2700,
produced approximately 14,000 yd3 annually. Figure C-5 shows the distri-
bution of production in terms of percent of concrete produced by the ready-
mix concrete companies.
100
/
90
80
70
z
0
;:::
u
::> 60
o
o
Q:
0..
-'
'" 50
>-
~
...
0
>-
z 40
t!
Q:
'"
0..
30
20
10
/
/
/
/
/
./ V
L-- i-'"
- l--
10
20
30 40 50 60
PERCENT OF TOTAL COMPANIES
70
80
90
100
00
Fig. C-5.
Concrete Production Distr ibution
C-ll
-------
It can be seen that 90 percent of the 5400 companies produced approximately
40 percent of the total concrete and that the upper decile companies produced
60 percent of the concrete, amounting to approximately 110 million yd3.
Figure C-6 shows the percentage breakdown of the uses to which the ready-
mix was applied and also indicates the type of concrete that is used in
general for the particular types of uses shown. It can be noted that approxi-
mately 30 percent of the concrete is used for residential and farm construc-
tion which is usually lower strength, with lesser requirements on durability,
and can utilize non-air-entrained concrete. The remaining 70 percent are
mainly industr ial or commercial, and would in almost all cases use air-
entrained concrete. It can therefore be deduced that as a maximum, 30
percent of the total production of 186 million yd3, or approximately 55
million yd3 is non-air -entrained and is used mainly in the 2500 to 3500 ps i
range.
CONSUMER AREA PERCENT OF TOTAL PRODUCTION TYPE CONCRETE
HOME BUILDING 25.61 I NON - AIR
COMMERCIAL CONSTRUCTION 26.44 AIR
INDUSTRIAL CONSTRUCT JON 17.91 AIR
HIGHWAY CONSTRUCTION II. 20 AIR
NON - FEDERAL PUBL IC WORKS 8.16 AIR
FEDERAL PUBLIC WORKS 4.65 AIR
FARM CONSTRUCTION - 3.35 NON - AIR
OTHER ------ 2.69 ?
.
10
20
30
Fig. C - 6.
Ready-Mix Concrete Consumption
C-12
-------
C.2
ECONOMIC ANALYSIS OF FLY ASH NON -AIR-ENTRAINED
CONCRETE
An economic analys is of non-air -entrained fly ash concrete was conducted
us ing the ACI proportions for Mix C (See Table 4-5). The ground rules used
for this analys is are explained in the following dis cuss ion. At the end of the
example, the effects of varying the input parameters is given; that is then
followed by a discussion of the effects of air entrainment.
/
In this example, the value used for the cost of Type I cement was $22/ton,
equal to 1. 1 cent/lb as delivered to the ready-mix concrete producer. The
cost of the fly ash F. O. B. utility was expressed in parametric form at
2,4,5, and 6 dollars/ton, equivalent to 0.1, 1.2, 1.25, and 3.0 cents/lb,
respectively. The cost of transporting the fly ash from the utility to the
ready-mix concrete producer was obtained from a variety of fly ash sellers
and users and is shown in Fig. C-7. This is based on a $2.00 handling charge
plus variable transportation costs ranging from zero to $2.00 up to 65 miles.
After a dis tance of 65 miles from the utility to the ready-mix producer, the
cost was estimated at a straight $0.06 per ton/mile.
Since the use of fly ash by the ready-mix concrete producer requires addi-
tional equipment such as storage bins, handling equipment, and dust removal
equipment, a certain amount of capital investment and maintenance is
involved on his part to use fly. ash for the production of ready-mix concrete.
It was estimated that the ready-mix concrete producer would have a produc-
tion capacity of approximately 35,000 yd3, and that he would use in the area of
2000 tons of fly ash annually. Based on discussions with various ready-mix
concrete producers and fly ash brokers, it was concluded that this would
require an average investment of about $17,500. This was as sumed to be
amortized over a time period of approximately five years, resulting in a
capital investment cost of $3500 annually', Financing, if any, was ignored due
,
to the rough order of these approximations. To the $3500 would be added an
annual maintenance cost of approximately $2000, since fly ash has a variety of
damaging effects on equipment, requiring a considerable amount of maintenance.
C-13
-------
20
4
$ 2 LOADING AND UNLOADING FEE - 0 TO 65 mi
VARIABLE TRANSPORTATION COST - 0 TO 65 mi
STRAIGHT 6 ~ /Ion-mi - AFTER 65 mi
16
c
.£
......
~
~ 12
(f)
o
u
:z
o
i=
-------
Table C-5.
Economic Factors (Non-Air-Entrained Concrete,
I-in. Aggregate, 4-in. Slump, Type I Cement)
Convent.
Concrete Fly Ash Concrete
Fly Ash
Cement "C" Cement "Cm" $/ton-FOB Utility Transport Miles 1 + M
Concrete 28-Day 2 I 4 5 T 6 65 I 150 I 300
Strength, ps i Ib/yd3 $/yd3 Ib/yd3 $/yd3 Ib/yd3 $/yd3 $/yd3 $/yd3
2500 423 4.65 353 3.88 125 0.125 0.25 0.31 0.37 0.25 0.56 1. 12 0.17
3000 470 5.16 400 4.40 125 0.125 0,25 0.31 0.37 0.25 0.56 1. 12 0.17
3500 517 5.69 446 4.90 125 0.125 0.25 0.31 0.37 0.25 0.56 1. 12 0.17
3750 540 5.94 494 5.43 75 0.075 0.15 0.19 0.22 0.15 0.34 0.68 0.10
4000 564 6.20 517 5.68 75 0.075 0.15 0.19 0.22 0.15 0.34 0.68 0.10
5000 659 7.25 611 6.72 75 0.075 0.15 0.19 0.22 0.15 0.34 0.68 0.10
As an example, for the 3000-ps i non-air -entrained concrete, the pure port-
land cement concrete would require 470 lb of portland cement costing $5.16.
The fly ash concrete would require 400 lb of portland cement per yd3 at a
cost of $4.40 resulting in a savings for the cost of the portland cement of
$0.76. The savings as a result of using the fly ash would be diminished by
the cost incurred in buying, using, and transporting the fly ash. This is
shown in parametric fashion in Table C-5. Since 3000-psi concrete requires
3 3
125 lb/yd of fly ash, the cost of the fly ash/yd of concrete as bought at
$2. OO/ton from the utility, would be 12. 5 cents /yd3. If it were bought at
$6.00/ton, the cost per yd3 would be $0.37 /yd3, etc. To this would have to
be added the cost of transportation, which would be $0. 25/yd3 to transport
for a distance of 65 miles and $1. l2/yd3 to transport for a distance of 300
miles. Additionally, the previously discus sed capital inves tment and
maintenance cost would have to be added at $0. 17 /yd3.
C-15
-------
Figure C-8 shows the economics of the 2500 to 3500 psi fly ash concrete
relative to pure portland cement concrete for a variety of transportation
distances. Discussions with several contractors have shown that the $4.00/
ton F. O. B. utility cost is a typical value and will therefore be used as an
example to indicate the economics. It can be seen that if the ready-mix
producer is located extremely close to the utility, essentially no transpor-
tation costs, but only handling costs, are involved. A savings of approxi-
mately $0. 22/yd3 can be realized. At a distance of approximately 90 miles,
the fly ash concrete would break even with the portland cement concrete under
the conditions of this example.
The same data are shown for 3750 to 5000-psi concrete on Fig. C-9. It
can be seen that with the producer extremely close to the utility, the $4.00/
ton F. O. B. utility fly ash produces a savings of approximately $0.20 or
almost the same as the 2500 to 3500-psi concrete. The break-even distance
is somewhat further than for the lower strength concrete, namely at 120
miles, showing that at longer distances the higher strength fly ash concrete
can be more economical than the lower strength concrete. This can be
attributed to the fact that for the ACI proportions, the higher strength con-
crete requires less fly ash and therefore less mass would have to be trans-
ported. The greater savings for the higher strength are however almost
purely academic for non-air -entrained concrete, since this type of concrete
is used mainly in the 2500 to 3500:-psi range.
The forego ing analys is is parameter ized such that varying conditions can
be assumed to determine varying economic results. A further refinement
could include the parameterization of investment, maintenance, and portland
cement costs; however, it is a simple matter to vary these items using the
data given in Table C-5. In the basic example, to produce 28-day, 3000-psi
non-air-entrained fly ash concrete, it was determined from Table C-5 that,
f;r a ready-mix dealer selling 35,000 yd3 of concrete per year, 65 miles
from the utility, using fly ash at $4. OO/ton F. O. B. utility, portland cement
at $22/ton, paying hauling costs per Fig. C-7, and having an additional
C-16
-------
0.6
C/')
c.!)
2
~ 0.4
w
I-'Q
W >-
a:: .
<...> a ACI PROPORTIONS
2.....
8-<1)0
::I: 0.2
C/')
«
>-
...J
u..
0
C/')
C/')
o
...J
W
I-
w~
a:: .
U ::>
:z u
0"'"
<...>~
::I:
C/')
«
>-
...J
u..
0.4
PORTLAND CEMENT $ 22/ TON
FLY ASH EQUIPMENT AND
MAINTENANCE $ 2.80/TON
0.2
0.6
0.8
1.0
o
40
80
120 160
FLY ASH TRANSPORTATION I mi
200
240
280
Fig. C-8.
Fly Ash Concrete Economics, 2500-3500 psi
C-17
-------
0.4
w~
tJ>-
a::: ~
(.)0
z.......
80(1)-
:J: en 0.2
en~
«~
>->
-.J«
u..en
w
~ .
w ;:. 0.4
a::: .
(.) =>
ZO
0""'"
(.) -(f)-
:J:en
enw
«en
>- en 0.6
-.JO
u..-.J
o
ACI PROPORTION
0.2
PORTLAND CEME NT $ 22 / TON
FLY ASH EQUIPMENT AND
MAINTENANCE $ 2.80/TON
0.8
*FL Y ASH COST
1.0
o
120 160 200
FLY ASH TRANSPORTATION, mi
240
280
40
80
Fig. C -9. Fly Ash Concrete Economics, 3750-5000 ps i
C-l8
-------
- I
equipment and maintenance cost of $2. 80/ton, the cost reduction is 9 cents /
yd3. Varying some of the parameters, it can be shown that large savings
can be had if the ready-mix dealer is 10 miles from the utility, pays $26/
ton for portland cement and $2/ton fly ash F. o. B. utility plus hauling costs
per Fig. C -7, and reduces the additional equipment and maintenance cos t
by one-half to $1. 40/ton of fly ash (through less costly equipment investment)
the reduction in concrete cost is 53 cents /yd3. There are, of course,
numerous combinations of conditions because of the many significant para-
meter s involved.
The results of several examples, derived in the same manner as those
above, are given in Table C-6. The economics favorable to the use of fly
ash in this instance are apparent. Effects of variations in proportioning,
cure time and air entrainment are discus sed later.
Table C-6.
Example Cost Var iations of Fly Ash
Concrete Compared to Portland
Cement Concrete (28-Day, Non-Air-
Entrained, 3 OOO-ps i Concrete)
Fly Ash Concrete
(ACI Proportioned)
Example Cases A B C D E F
Cement Cost - $/ton 22 26 26 26 25 25
Fly Ash Cost - $/ton 4 4 2 4 4 4
F.O.B. Utility
Transportation Distance 65 100 10 150 150 65
Added Investment and 2.80 2.80 1. 40 1. 40 1. 40 2.80
Maintenance Cost -
$/ton Fly Ash
Cost Var iation - Cents /Yd3 -9 -11 -53 0 +3 -21
Compared to Portland
Cement Concrete Cost
Example: If dealer earns $1. 00lyd3 before taxes on portland cement concrete,
his profit impact for cases C and E is +53% and -3%, respectively.
If he earns $3.00 on portland cement concrete, the impact for
these two cases is +18% and -1%, etc.
C-19
-------
C.3
ECONOMIC ANALYSIS OF FLY ASH AIR-ENTRAINED
CONCRETE
The application of fly ash in concrete is recognized to have a depres s ive
effect on entrained air content and makes field control of air contents more
difficult. Fly ash carbon has been shown to have the capability for adsorbing
the organic substances of which most air-entraining agents (AEA) are
composed. Depending on the carbon content, some fly ashes in concrete
mixtures may require increasing the amount of air-entraining agent as
much as four times or more than needed with mixes not incorporating fly
ash (C-126). However, on the bas is of the chemical content of available
fly ash samples discussed in Section 4.3, an average carbon content of
four percent is assumed for purposes of the present economic analysis.
It is also conservatively estimated from data presented in Ref. C-126 that
ready-mix concrete containing four percent carbon fly ash will require
twice as much air -entraining agent as needed in conventional concrete
mixes. This information coupled with the detailed mix and strength data
presented in Ref. C -120 and the ACI proportions shown in Table 4- 5 was
used to formulate the economic factors that permit a compar ison of con-
ventional air -entrained concrete us ing portland cement with air -entrained
concrete using a mixture of fly ash and portland cement.
proportions for the two mixes are shown in Table C-7.
The resulting
Table C-7.
Air-Entrained Concrete
I-in. Aggregate, 34 Total Gallons Water,
4-in. Slump, 5 Percent Air-Entrainment
,'.
28- Day Cement +AEA Cement + Fly Ash ',' + AEA
Strength Concrete, psi lb fl oz lb lb fl oz
2500 423 4.5 353 125 9.0
3000 470 5. 0 400 125 10. 0
3500 541 5. 0 494 75 10.0
3750 588 5. 0 , 541 75 10.0
,,,"
"'4 Percent Carbon Fly Ash
C-20
-------
The costs for cement, fly ash, transportation, capital investment and
maintenance for additional facilities and equipment to utilize fly ash as
an additional ingredient in concrete mixes are as sumed to be the same as
those applied in the foregoing economic analys is for non-air -entrained
concrete. The only significant cost difference between these mixes and
those shown for non-air -entrained concrete in Section 4.2. 1. 1. 2 is the
cost of the air -entrainment agent. The cost of this agent is estimated at
4 cents/oz when used in proportions shown in Table C-7. This indicates
that air-entrainment agents for the mixes shown increased the cost of the
4 percent carbon-fly ash concrete by approximately 20 cents /yd3 when
compared to non-air-entrained concrete, and neglects minor effects of
water reducer agent requirements and sand proportioning. Referr ing to
Table C-6 it can be shown that the cost impact of air entrainment can be
determined by increas ing the cost of fly ash concrete in each case by
20 cents /yd3, which results in a net cost increase of as much as 20 cents /
yd3 in some cases, and a net cost decrease as much as 33 cents/yd3 in
another. This is not considered to be an inhibition to the use of fly ash
as des cr ibed, based on several contacts made in the industry.
It is to be emphasized that the foregoing results are based on the assumption
that the fly ash compos ition contains about four per cent carbon. Air-
entrained concrete with fly ash containing higher carbon contents will
become increasingly less economical in comparison to the conventional
portland cement concrete. And, air -entrained concrete containing fly ash
with less than four percent carbon content will become more economical
until finally fly ash with a carbon content of one percent or less generally
requires the same quantity of air-entraining agents as the pure portland
cement concrete mix for a given air content.
These estimations of 'fly ash concrete economics, although not performed
I
in extensive detail, are believed to be sufficient to highlight the more perti-
nent factors involved in costs. As noted, the economics vary considerably
depending on many parameters, but in any event, the superior qualities of
'fly ash concrete can be obtained in an economical manner, and in many
cases the cost of production is less than that for portland cement concrete.
C-21
-------
More importantly, in cons ideration of the utilization of II greater -than-28-
dayll design strengths, as described in Section 4.4.2. I, the production
costs of fly ash concrete (based on today's marketing) can be reduced rather
dramatically. Using this technology where applicable, cost reductions can
be had for any type of concrete,. and for some it can be well in excess of one
3
dollar per yd .
C-22
-------
!=1
-o!:: ,
~~ 'I
"'m
C')
::J:
-I
~
C')
C')
::tJ
I'TI
C')
~
-I
IT1
-------
APPENDIX D
DESCRIPTION OF TWO FLY ASH
LIGHTWEIGHT AGGREGATE PLANTS
There are only two operating lightweight fly ash aggregate plants in the
United States; a third is attempting to resume operations after having been
shut down. One significant inhibition to the use of fly ash is the difficulties
encountered in the manufacturing processes. The following description of
the two operating plants provide an insight into some of the critical
problems associated with the production of lightweight fly ash aggregate
that have been and are being faced.
The first plant dis cus sed obtains its fly ash from three power plants, one
of which is less than a mile away. At these power plants, the fly ash is
transported from collecting hoppers to storage silos, dampened (7 to
9 percent) and loaded out by truck. If, for any reason, the aggregate plant
cannot receive the ash from these storage silos, the trucks proceed to a
dumping site maintained by the utility. Normally, the dampened fly ash is
dumped at the lightweight aggregate plant into a below-grade hopper.
Figure D-l illustrates the flow for production fly ash aggregate by this
process. The process is initiated by elevating fly ash from the hopper
by conveyor and placing it into one of the five bins depending upon its power
plant origin.
Withdrawal from the bins is volumetrically controlled by a variable speed
belt feeder. There is considerable "rat-holing'" in these bins despite 700
sloping sides and relatively large bottom openings. This is overcome
through operation of autematic, sequentially programmed, expanding
rubber panels mounted on the bin walls and by use if air vibrators.
The fly ash is next conveyed to a mill where a blending of the different
D-l
-------
"
I. FLY ASH ARRIVAL
2. FEEDER
3. ARRIVAL OF CLAY
4. PUG MILL
5. DISENTEGRATOR
6. HOOD
7. SINTERING MACHINE
8. 4 TONS DELIVERING AIR
TO 4 SINTERING ZONES
9. AIR FOR BURNER
10. STORAGE PILES
II. SCREENING BUILDING
(WITH CRUSHER)
/2.GAS
13. WATER
14. PELLETIZING MACHINE
15. BINS AND FEEDERS
16. CONVEYOR
1~6
"'C7 u u
u 2 u CI1D5J
0"'""0 O""t> 0"'""0 0"'""0 O""t>
3 ---ou 13 u
~~I ~~4
4i1?~~~
u v 6
Figure D-l.
Fly Ash Lightweight Aggregate
Production Flow
types handled takes place. Two other ingredients, clay slip (slurry), and
dry fly ash, are added at this point and provide the key to this particular
process in compensating for variances in the fineness and carbon content
of the fly ash received from the various power plants. To compensate for
these variances, a small amount of high-carbon-content fly ash obtained
from a nearby industrial plant is added, and as much' clay slip as the
I
moisture content of other incoming raw materials will permit is used.
The amount of clay slip required at the mill is metered out of a trough by
a feeder. The speed of the feed is controlled by the shift operator, depending
D-2
-------
on the moisture needs. After the clay slip has been mixed with the fly ash
in the mill, the resulting material is conveyed through a lump disentegrator,
then to a pelletizer where 3/4 to 3/16 inch pellets are produced. Moisture
needs are determined by observing the ball size .and consistency in the
pelletizer. The practical limits of the pellet size is governed by the need
for proper firing of the pellets from shell to core. The pellets are spread
by a swinging conveyor onto an 8 by 102-foot-long sintering machine. They
contain about 25 percent moisture and must be dried slowly enough to avoid
exces sive condensation in the lower parts of the 8 to 1 O-inch deep sinter bed.
Approximately one-fourth of the sintering machine is used for drying.
After drying, the hardened pellets with a carbon content of about 5 percent
are ignited and burned, while a surface temperature of 1900 to 21 OOoF is
maintained on the pellet bed by overhead gas burners. After firing, the
pellets are air cooled, then lightly sprayed with water to lay the dust, then
discharged for immediate crushing and screening into the desired sizes.
This plant normally operates three shifts a day, 5 days a week. Fourteen
men normally are employed to operate the day shift, with two men employed
on both the afternoon and night shift. All maintenance, clean-up, clay slip
preparation, and loading-out of product take place on the day turn only.
The design capacity of the lightweight aggregate plant is 1000 tons / day.
Present yearly production averages about 500 tons/day, or 135,000 tons/yr.
During the planning of this particular operation, it was originally as sumed
that the anticipated variation in physical propertie s and carbon content of
the fly ash could be overcome through equipment design and operation alone.
However, it was found after a short period of operation that changes in the
fly ash, which could not be detected with equipment and personnel available
at the plant, were having such a radical effect on balling and firing that at
I
times a usable aggregate could not be manufactured. At this juncture,
the assistance of the utility was requested and obtained whereby the power
plants furnishing fly ash established a sampling program in which the
D-3
-------
analysis of ash samples during periods of good and bad operation was
provided. This program resulted in the determination that the sintering
plant failed to function satisfactorily whenever the combustible content of
the fly ash feed fell below 4 percent, or when the percentage of particles
below 5 microns in the feed was less than 15 percent.
During this period, a number of alternatives were considered to solve the
problem. Most were discarded due to excessive equipment or operating
costs for additional proces sing steps or additives. Grinding of the fly ash
was considered, but it was found that improvement obtained in particle
size was not significant from any reasonable amount of grinding. Also, it
was found that size separation, with disposal of the larger fractions, was
not feasible due to the large amount of material that would be lost. After
considerable deliberation and in-plant testing, it was decided to use local
surface clay and high-carbon fly ash as additives. While the initial cost
for handling equipment would be higher than for other additives, the purchase
and preparation costs for local clay and high carbon fly ash would be low
enough to pay for themselves. It was concluded that the added provisions
for accepting clay slip and high- carbon fly ash in this proce ss rendered
the operation les s sensitive to changes in the fly ash feed, and minimized
the danger of producing unusable material.
The second fly ash sintering plant was originally designed to accommodate
the entire fly ash output from a single power station. Initially only two
of the four sintering machines were installed. By eventually utilizing
four sintering machines, the output will be adjusted to meet demand.
Flexibility in the balance of the material handling equipment is achieved
through a complete system of conveyors, crushers, screens, and bins.
The material flow for this plant can be traced by referring to Figure D- 2 .
Beginning at the power plant fly ash silo, fly ash flows to the pre screening
building via a series of air slides. The screens remove particles larger
than mesh size (120), with the balance of fly ash pneumatically conveyed
D-4
-------
POWER PLANT
FLY ASH SILO
8000 ton
OUTDOOR
STORAGE
Figure D-2.
Fly Ash Lightweight Aggregate Production -
Ma te rial Flow
D-5
-------
to the 75-ton-capacity storage silos which have an automatic dust filter
system. Special mixers in the sintering building receive fly ash through
a screw conveyor from the storage silo. This particular portion of the
building is designed so that magnetic separators may be installed for iron
recovery if desired in the future.
Fly ash, water, return sinter fines and binder are mixed together and the
conditioned material is fed by screw conveyor and belt conveyor to the
extruder. Fly ash is forced through a die plate by an extruder auger.
Strands of varying diameters can be produced simply by changing dies,
although 1/4 to 1/2 inch is normal. Pellets are formed as the emerging
strands are cut to the desired length by rapidly rotating blades. The
pellets drop onto a special screening feeder which feeds onto the sintering
machine pallets. The pallets, which are 12 X 16 X 16 inches in size are
specially designed to permit uniform heat treatment and penetration of the
air into the bed. Fines which pass through the screening feeder are
returned to the mixing bin by conveyor belt.
A hydraulic piston type pusher is us ed to move the entire line of pallets at
the desired speed. After the piston reaches its limits of travel, it returns
to engage another pallet returning on the curved overhead track.
As the pallets are filled to the proper bed depth, they pass over the preheat
section where pellets are dried using waste heat from the cooling section of
the machine. The bed then pas se s over the enclosed burner section, where
the bottom 3 to 4 inches is ignited by a series of burners, then over a
series of wind boxes which control the rate with which the fire layer moves
up through the bed until firing is completed.
When the pallet reaches the end of the machine, the pallet is lifted up
and away from the machine, spilling the pellet clusters back onto a 30-inch
conveyor. The empty pallet is then deposited on the overhead return
track to begin the cycle over again. A dust collecting system is provided
for the pan conveyor area.
D-6
-------
The pan conveyor takes the pellet clusters to a spiked single-roll breaker
which separates the pellets that have become fused together. From here,
the pellets are moved via pan conveyor to a high-temperature screen where
minus ten mesh particles are removed and returned to the la-ton fines bin
where 5 to 10 percent of sintered fines is added to the raw fly ash at the
mlxer. This is controlled by bin indicators which activate the feeders
and conveyors automatically. The sinter not passing through the screen
is conveyed to the 8000-ton-capacity outdoor stockpile.
Sintered aggregate is reclaimed by an under-pile conveyor which is fed by
six vibrating feeder s. From the storage pile, material is fed by a bucket
elevator and conveyor to the primary crushing and screening station. The
primary crusher and screen is so arranged that part or all of the material
may be by-passed around the crusher directly to the final screening
stations and then the storage silos. Double-deck screens, 4 by 12 feet
in size, separate the material received from the crusher into five size
fractions and deposit them selectively into 100- ton blending bins. The
four coarse bins can be recycled should finer aggregate be required; thus,
it is possible to adjust each size fraction according to market conditions
without costly rehandling of excessive fines.
Provisions for blending any combination of the five sizes is accomplished
through feeders on each storage bin, which simultaneously and automatically
weigh out the correct amount of each size fraction onto the load-out belt
conveyor. Blended aggregate can be fed directly to a truck hopper with
the total weight of the shipment measured through a belt scale'.
Additional finished product storage is provided by three outdoor storage
piles fed by a system of conveyors from the silos. This material may be
loaded into trucks by a front-end loader for ,delivery to the customer.
In addition to the original capital investment, this plant ha's experienced
considerable additional expense s in the redesign, modification, development
D-7
-------
and fabrication of the various portions of the originally installed sintering
equipment. This additional investme~t and the plant downtime that resulted
has contributed greatly to exce ssive production costs.
As an indication of the technical problems and expense that have been
experienced with the sintering equipment, the grates represent a good
example. Each sintering machine contains 338 individual grates. The
original grates burned out at varying times, but only averaged approximately
500 hours of operation. The replacement cost of each original grate was
$30 in addition to the shutdown time required for replacement. A new grate
has been developed which will operate for about 2500 hours before replace-
ment is necessary at a cost of about $15 each.
This plant operates three shifts per day, 5 days a week, with a total of
22 employees. With two currently operational sintering machines, it has
a maximum capacity for producing 360 tons/day of lightweight fly ash
aggregate. This production can be doubled with the planned installation of
two additional sintering machines. The plant also includes a well-equipped
testing laboratory in which tests are conducted on the fly ash raw material,
green pellets, and final aggregate as well as on products manufactured
from the aggregate.
D-8
-------
ITI
('")
I'T1
==
I'T1
:z
-I
"
~
o
c
c=
('")
-I
0,
:z '
'"
'1
»
;z,
-j ,
-------
APPENDIX E
CEMENT PRODUCTION PLANT UTILIZING FLY ASH
The following figure, der ived from Refs. C-5 7, C -116, and C -117, shows
the general processing at the Missouri Portland Cement Company plant in
Joppa, Illinois. The limestone and sandstone are brought by 3000-ton
barges from the quarry site to the cement plant. Automatic unloading
systems unload the limestone and sandstone from the barge and mechanical
conveyors move this material to storage facilities. (See Fig. E-l.)
The fly ash presents some special handling problems. It is conveyed
pneumatically through a 7500-ft pipe from the utility to an 800-ton storage
tank. The tank is equipped with bottom aeration to prevent packing. To
minimize flushing, which is always a problem with fly ash, a rotary feeder
was ins taIled ahead of the we ightbelt feeder.
Gypsum, another portion of the raw mater ials, is delivered by rail as is
coal. All of the raw materials are stored in weather-proof enclosures and
are available for transfer to the raw milling operation. In order to avoid
the handling problems that are created by fly ash, a considerable amount of
ingenuity was utilized to prevent the dust and other types of handling prob-
lems that have been encountered in the past when using fly ash. Each of
the raw materials is stored separately as shown in the figure. The materials
are then proportioned and conveyed to the raw milling processing system.
In this process, the raw materials are ground to a fine powder and are
conveyed to the kiln. During this process, care is taken to keep the fly ash
covered at all times by conveying it with limestone on top of it so that the
dust problems frequently encountered with fly ash are minimized. Wet and
dry process ing are shown in the figure; however, the Joppa plant used the dry
I
processing only. In this case, the raw materials are ground, mixed with
water to form a slurry, and then blended.
E-l
-------
Since the fly ash is mixed with the other ingredients used in the manufacture
of portland cement following the processing of the raw materials, the
remainder of the production of cement is identical to the conventional
process where burning changes the raw mix chemically into cement clinker
and the clinker with gypsum added is ground into portland cement and
shipped. Shipping of the cement takes place in the same barges that brought
the raw mater ial.
E-2
-------
I
UTILITY Al/EA
M
I
W
STACK
DRY COUECTION
DR
WET SCRUBBING
.~,
LIMESTONE AND SANDSTONE
SECONDARY CRUSHER
I. STONE IS QUARRIED AND REDUCED IN SIZE
2b. RAW MATERIALS ARE GROUND, MIXED WITH WATER TO FORM SLURRY I AND BLENDED
RAW MIX IS KILN BURNED
TO PARTIAL fUSION AT 2700 'f
MATERIALS ARE
STORED SEPARATELY
CLINKER
..... .
PORTLAND
~CEMENT
TO
BARGE
TO
KILN
RCTATING KILN
3. BURNING CHANGES RAW MIX CHEMICALLY INTO CEMENT CLINKER
4. CLINKER WITH GYPSUM ADDED IS GROUND INTO PORTLAND CEMENT
Fig.
E-l.
Portland Cement Production
-------
=""
aJ
~
~
~
..
o
-t
."
..
»
z
~
-------
APPENDIX F
DESCRIPTION OF FLY ASH BRICK PILOT PLANT
The following figure shows a schematic diagram of the flow of raw materials
and equipment layout of the fly ash brick pilot plant at the Coal Research
Bureau of West Virginia University. Fly ash for the plant is stored in a 50-
ton hopper which is fed with a five - inch diameter pneumatic conveyor line.
Bottom ash is stored in a five-ton hopper after passing a four-ton per hour
scalping screen. Oversize rejects from the screens are discarded or
recycled through a secondary crusher and returned to the slag hopper.
Then, 74-percent fly ash and 23-percent bottom ash or slag is mixed with
3 -percent sodium silicate binder in a 13 -ton per hour continuous mix-muller
where the silicate bonds phys ically with the fly ash. The mixture is then
rapidly conveyed to a 750-ton toggle 'pres s that forms the des ired shape.
Green br icks from the press are then dr ied and fired us ing conventional
brick dryers and kilns. Two gas operated shuttle kilns are employed, each
having a acpacity of 500 br icks. The changes that take place dur ing the
firing are physical rather than chemical. As the temperature of the brick
increases, the sodium. silicate binder eventually becomes a viscous liquid
and at the end of the fir ing cycle the ash com.ponents under go vitr ifica tion.
Slag
receiving
hopper
(15 ton)
,1...."
1;/ ~,' ,
". ,
It, "
II "
:' ','"
I , ,
II ' , "
:1 "'<"
II "" "
II " "
II ..." r- -- 7
c--------~" I I
{) ,,,, I
"'\I i
, I
, I
, "
, -
"......'
/~
Fly ash
storage
hopper
(50 ton)
Metering pump
Fig. F-l.
Flow Diagram of Fly Ash-Brick Pilot Plant
F-I
-------
p
=:C
0;0
g-<
'"T1n
iTi~
cr
'"T11'T1
rn
-<-I
l;~
:J: r
~
I'T1
~
-I
o
:z
I'T1
-------
APPENDIX G
DR Y -COLLECTED LIMESTONE-MODIFIED FLY ASH
The trace analyses of TV A dry-collected limestone-modified fly ash per-
formed by Shell Development Company and by Oak Ridge Laboratories are
presented in Tables G-l, G-2, and G-3. These were provided by the
Environmental Protection Agency's Office of Air Programs, Division of
Control Systems, Process Measurements Section, and were not analyzed
in this study. However, they do indicate a need for cons ider ation of
potential toxic effects in the study of the modified ash.
Table G-1.
Spark Source Mass Spectrographic Analysis of TV A
Dry-Collected, Limestone-Modified Fly Ash by
Shell Development Company
Element C oncentr ation, % W in Tr iplicate
Fe~~ 7. 7 8.2 6.4
Al>:~ 6. 6 7.2 5. 9
Mg>:~ 2.0 2.0 1.7
Na>~ 0.55 0.57 0.43
B>~ O. 12 O. 12 0.09
Mn '0.06 0.06 0.05
Cu 0.006 0.006 0.005
Ti 0.2 0.2 0.2
Ni 0.02 0.02 O. 02
Cr 0.006 0.006 0.005
V 0.02 0.02 0.02
Si 20.0 20.0 16.0
,
Ca 10.0 11. 0 8.0
NOTE:
The general-purpose emiss ion method of Kroonen and Vader, (" Line
Interference in Emiss ion Spectrographic Analys is, " Elsevier, 1963)
was used for this analys is. The calibration constants supplied by
these authors were used directly to give an accuracy within a factor
of two of the amount present. The elements marked (>.'<) are believed
accurate to within :I: 20 percent.
G-l
-------
Deviations observed in triplicate analyses were observed in other fly ash
samples.
samples.
These deviations were largely due to the inhomogeneity of the
Table G-2.
Dry-Collected Limestone-Modified Fly Ash
Trace Analysis >:' by Shell Development
Company
Concentration
Element (ppm)
As 250
Br 12
Sm 27
Ba 7000
Zn 500
Cr 55
Lu 20
Co 10
Sc 7
Sb 4
Cs 3
Hf 2
Yb 1
Ta O. 5
,'-
"'Determined by neutron activation and atomic absorption
G-2
-------
Table G-3.
Oak Ridge Spark Source Mass Spectrometry
Analysis of TV A Dry-Collected Limestone-
Modified Fly Ash
Throttle Number *
E1ement
.- 0 4 12 16 18
As 100 200 100 100 200 50
B 300 300 500 500 500 500
Ba 200 200 200 200 200 200
Be 2 2 1 2 2 2
>,'(':C
Cd <5 <5 <5 <5 <5 100
Cr 130 130 130 130 300 300
Cu 130 150 150 200 200 200
Mn 190 200 240 290 390 500
Na 9400 9000 8000 9100 9600 8400
Ni 200 300 200 200 300 300
Pb 300 300 200 300 300 500
Sb <3 <3 <3 <3 <3 <3
Sr 200 250 250 250 250 300
T1 <5 <5 <5 <5 <5 5
Ti 3600 3500 3500 4100 4600 4200
V 200 200 200 200 200 200
S > 5000 >5000 >5000 >5000 > 5000 > 5000
Hg <5 <5 <5 <5 <5 <5
Se <10 <10 <10 <10 <10 <10
):(
"0" equals 28. 7 microns
"4" equals 25. 8 microns
"12" equals 12. 8 microns
"16" equals 4. 52 microns
"18" equals 1.5 microns
>,'<*
"5" is lower limit of detection
G-3
-------
::I:
V>
»
3:
-0
r
IT1
V>
-0
I'T1
C")
:!!
C")
»
-I
C5
:z
-------
APPENDIX H
SAMPLE SPECIFICATION AND USE DATA FOR FLY ASH
AS AN ADMIXTURE IN CONCRETE FURNISHED BY THE
TENNESSEE VALLEY AUTHORITY DIVISION OF
ENGINEERING DESIGN
H. 1
GENERAL DISCUSSION
The following documents, which are included in this appendix, provide a bas ic
indication of the approaches taken by the TVA for the development of speci-
fications and utilization of fly ash as an admixture in portland cement con-
cr e te:
1.
Excerpt from Construction Specification G-30. This provides a
description of the TVA method of classifying fly ash based on
proper ties data. Further information for testing, cur ing and
application is provided in the complete specification and in the
TV A Specification G-2, II General Construction Spec ification for
Plain and Re infor ced Concrete, II dated February 10, 1970.
2.
Some typical sample proportioning data are provided which
identify actual applications in the TV A sys tem. Many other
applications of different proportioning exist.
These data are pr ovided for information only, and no endor sement is intended.
However, this approach to the usage of fly ash in large quantities economi-
cally is cons idered significant since it provides appreciable detail pertaining
to one of the most advanced uses exhibited for fly ash in concrete. It is
interesting to note that according to the TVA Divis ion of Engineer ing Des ign
that
H-l
-------
II TV A does not differentiate in the curing requirements for different
classes of concrete nor do we require any unusual or extended curing
for fly ash concrete over what is normally considered acceptable
for regular portland cement concrete without fly ash. We require
all concrete to be protected from excessive loss of moisture for
a minimum per iod of 14 days.
II TV A has been us ing fly ash in all major construction projects since
1957. During this time we have not encountered a single service
problem which, in any way, could be attributed to the presence of
fly ash in the concrete. As a matter of fact, fly ash concrete has
significantly been free of service problems of any kind.
II The recent trend in usage of fly ash concrete in TV A is to specify
more 90 and 180 day strength requirements in order to utilize the
age-strength advantage of fly ash in concrete. II
This technology is applied not only to mass concrete but to building construc-
tion as well. This approach, therefore, should serve as a basis for the
development of a new set of spec ifications which could apply to the total
concrete industry, thereby eliminating the confusion which results from the
various existing specifications which conflict and do not recognize the
relevancy of the classification of fly ash to usage.
A comparison of existing specifications is given in Table 4-8, and a discus-
sion of proposed specification modifications which require further efforts
is given in Section 4. 3. 3. 6.
H-2
-------
EXCERPT 1
TVA SPECIFICATION
H-3
-------
TENNESSEE VALLEY AUTHORITY
DIVI:>ION 0' ENCINEERINC DESIGN
ALL PROJECTS
GENERAL
CONSTRUCTION SPECIFICATION
NO. G-30
FOR.
FLY ASH FOR USE AS AN ADMIXTURE IN CONCRETE
March 16, 1910
SPO~~OR ENGINEERS
;;f??Ih C~,
R. W. Cannon
~~~
; o. H. Raine
SPECIFICATIONS SECTION --4.;J{ '2:-,
~ W. Troy
SUllMl'l'rED te/,tt/. t;:;~
. Ward W{Jc.nr.le
f4!n4!/iJi
RECOMMENDED~ fi-;k~~
. F. P. ~
-------
,GENERAL CONSTRUCTION SPECIFICATION NO. G-30
FOR
FLY ASH FOR USE AS AN AJ1.1IXTURE IN CONCRETE
1.0 General
This specification has been coordinated with the Division of Construction
and the Office of Power. These specifications cover the use of fly ash as
on admixture in concrete. Fly'ash from TVA plants is separated into three
classes based on the fineness of the ash and the resultant contribution of
the fly ash-cement combination to the strength of concrete. All three
classes are acceptable for use; however, mix alterations may be required
in the concrete any time a change occurs in class of fly ash or source of
supply. (Collection from generating units with different type precipitators
also constitutes change in source.) Ash shall be collected onl~ fr~~its-
. opcrotin~ as base power units.
2.0
Class and General Use
Closs I - Fine Fly Ash - This provides the maximum strength contribution at
all ages for given proportions of fly ash to cement. When properly
proportioned, it is well suited for use in any class of concrete and is
particularly suited to requirements for high concrete strength and for early
concrete strength.
Class II - Medium Fly Ash - This class provides good strength contribution
at ages up to 28 days and very good strength contribution at 90 days or more
for given proportions of fly ash to cement. When properly proportioned, it
is well suited for use in any class of concrete.
Class III - Coarse Fly Ash - :This class provides low strength contribution
at ages up to 28 days and good strength contribution at 90 days or more for
given proportions of fly ash to cement. Delivered cost must be low for
economical use in 28-day strength concrete; however, when properly
proportioned, it is well suited for concrete having strength requirements
below 4000 psi at 90 days or more. Greater fluctuations in air content
can be expected, requiring more frequent testing of air content for control
with this class than required with the fine or medium fly ashes.
3.0
Recommended Mix Alterations
The amount of cement required and economic proportions of fly ash to cement
for each particular closs of concrete should be established by trial mixes.
When a chan~e in class of fly ash is anticipated, the following table gives
the relative adjustments in cement content for equal strength concrete.
These adjustments should be used until routine tests establish a more
accurate adjustment.
H-5
-------
RELATIVE ADJUS1MENTS IN ClMENT CONTENT
Concrete
Stren~th, PSI Age in Days
2000
3000
4000
5000
2000
3000
4000
28
28
28
28
90
90
90
4.0 Chemical Requirements
Class of Fly Ash
I II III
100 103 112
100 104 114
100 105 116
100 106
100 100 106
100 101 108
100 102 110
~he chemical requirements for all three classes of fly ash are:
Silicon dioxide (Si02); ~lus aluminum oxide (Al203);
plus iron oxide (Fe203)' minimum percent
Magnesium oxide (MgO), Maximum percent
Sulfur trioxide (S03)' maximum percent
Loss on ignition, maximum percent
Moisture content, maximum percent
Available alkalies as Na20, maximum percent
5.0 Physical Requirements
Fineness, surface area, cm2/cm3, minimum
Pozzolanic activity index:
With portland cement at 28 days,
minimum percent or control
With lime at 7 days, minimum psi
H-6
75.0
5.0
I
Class
II
-
6500
5000
85
70
800
1000
4.0
6.0
3.0
2.0
III
3500
55
600
-------
5.0 Physical Requirements (continued)
I
Class
ll.
III
-
Fineness index:
Amount passing when wet-sieved on
No. 325 (44 um) sieve, minimum percent
88
78
68
6.0 f-I:mpl:ina and Tcotina Requirements
Trial mix program
fly u-.;h from potentinl GO'.1rces of supply shall be sampled by the Singleton
HI). tcrials Lo.boratory and i;cstcd for -all specification requirements and
idcntjfied as to class prior to use by any project.
Project testing
Fly ash shall be sampled at the construction site at a minimum rate of one
sample for every three truckloads delivered. Each sample shall be tested in
the field for identification of class of fly ash by either the percent passing
No. 325 sieve or the sedimentation test. Since these two tests are only
indications of fineness, periodic samples must be sent to Singleton for
complete physical testing to assure correlation of fly ash identification.
For shipment and identification these samples shall be sealed in plastic
bags, dated, and numbered consecutively.
Any time individual field laboratory tests exceed the specified limits for
a given class or exceed the average of previous sedimentation tests by more
than 5 cc or the average percent passing the No. 325 sieve by more than
5 percent, concrete mixes shall be adjusted as needed for the next lower
class of fly ash.
Office of Power testing
The Office of Power shall be required to sample all units furnishing ash to
TVA projects at a minimum rate of one sample per month as long as shipments
are made. Complete physical tests are required from each sample for
identification of class. Complete chemical tests are required from every
twelfth sample or any time a change in class is indicated by the physical
tests. Six copies of all test results shall be supplied for distribution
to each project using the ash.
B-7
-------
EXCERPT 2
SAMPLE TVA FLY ASH CONCRETE USAGE DATA
H-9
-------
Project - Sequoyah Nuclear Plant
Construction Start - 1970
Construction Complete - 1974*
Class of Concrete 203BFW 201.5BFW 301. 5BFW 301.5AFW 401. 5AFW
Required Strength (psi) 2000 2000 3000 3000 4000
Age for Req. Str. (days) 90 90 90 28 28
Mix proportions
Cement (lbs) 135 160 220 310 441
Fly ash " 190 220 220 185 110
Hater " 155 190 201 210 230
Sand " 1127 1405 1270 1246 1214
3/8" coarse aggregate II 182 297 297 297 290
3/4" " " " 425 693 693 693 676
1-1/2"" " " 660 1076 1076 1076 1050
3" " " " 1273
WRA & AEA
** Air content cJ, 4.5 5.5 5.5 5.5 5.7
Slump Inches 2 1..5 2.5 2.5 3.5
(Average Compressive Strength in psi)
at 28 days 1600 1600 2700 3950 4900
at 90 days 3600 3350 4300 *5600 *6300
at 180 days *4100 *4100 *5200 *6400 *7000
Class of Fly Ash I I I I I
Where used (type o£ structure)
Reactor Building X X X X X
Auxiliary Building X X X X X
Control Building X X X X
Turbine Building X X X X
Service Building X X
Office Building X
*Estimated
**Portion passing & 1-1/2-inch screen
H-IO
-------
1___--_- .----
Project - Te11ico Dam
Construction Start - 1967
Construction Complete - 1968
Class of Concrete 203CFW 303BFW 301. 5BFW 301. 5Anl
Required Strength (psi) 2000 3000 3000 3000
Age for Req. Str. (d8¥s) 180 90 90 28
l-1ix proportions
Cement (lbs) 110 210 240 290
Fly ash II 208 126 192 174
Water " 150 160 190 205
Sand IV 1144 1100 1365 1360
3/8" coarse aggregate" 240 240 355 355
3/4" II " 10 480 480 658 658
1-1/2" " II " 795 795 1086 1086
3" II II IV 1140 1140
\VRA & AEA
** Air content 5.5 7.0 6.5 6.5
Slump 2.5 2.75 3.0 2.75
Average Compressive Strength in psi
at 28 days 1430 3620 3280 4100
at 90 days 3540 5520 5050 5900
at 180 days 4320
Class of Fly Ash I I I I
Where Used (type of structure)
Non-overflow (mass) X
Non-overflow (face) X X
Spillw8¥ (mass) X
Spillway (face) X X
**Port1on passing a 1-1/2" 8creeno
H-ll
-------
Project - Paradise Steam Plant - Unit 3
Construction Start - 1966
Construction Complete - 1968
Class of Concrete 301.5BFW 301. 5AFW 351.5AFW 400. 75AFW
Required Strength (psi) 3000 3000 3500 4000
Age for Req. Str. (d~s) 90 28 28 28
l-1ix proportions
Cement (lbs) 270 338 450 517
Fly ash " 108 152 135 130
\01 ater " 220 227 256 270
Sand " 1284 1284 1230 1195
3/8" coarse aggregate II 305 294 268 580
3/4"" " " 610 587 535 1180
1-1/2" " " " 1127 1080 990
\oJRA & AEA
Air content ~ 5 5 5 5.5
Slump Inches 2.5 2.5 4.0 4.0
Average Compressive Strength in psi
at 28 days 3030 3840 4860 5050
at 90 days 4110 5350 6150 6400
at 180 days *4800 *5900 *6800 *7000
Class of Fly Ash II II II II
Where Used (type of structure)
Powerhouse X X
Intake Tunnel X
Chimney X
Cooling Towers X
*Estimated
H-12
-------
Project - Wheeler Lock
Construction Start - 1960
Construction Complete - 1963
Class of Concrete 306AFw 301.5AFW 401.5AFW
Required Strength (psi) 3000 3000 4000
Age for Req. Str. (days) 28 28 28
l>1ix proportions
Cement (lbs) 245 415 590
Fly ash " 168 208 66
Water " 185 246 320
Sand " 720 950 1035
3/4" coarse aggregate" 310 1045 805
. 1-1/2"" " II 515 1075 1035
3" " " " 750
6" II " " 11.30
WRA & AEA
**Air content uJ, 6.5 6.0 6.5
Slump Inches 2.5 2.5 3.25
Average Compressive Strength in psi
at 28 days 3400 4240 4720
at 90 days 4600 5200
at 180 d8¥s *5300 *5900
Class of Fly Ash III III III
Where Used (type ot structure)
wck Wa.lls X X
Floating Approach Wall X
~:
Strengths listed are l~ less than actual test strengths to
compensate for air removeJ. in rodding cylinders based on comparative
strengths ot air entrained concrete rodded specimens vs drop table
specimens.
*Estimated
~ortion passing a 1-1/2 ineb screen
B-13
-------
|