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EPA-450/2-78-004
Air Quality and Energy Conservation Benefits
From Using Emulsions to Replace Asphalt Cutbacks in
Certain Paving Operations
Prepared By
Francis M. Kirwan
Environmental Protection Specialist
and
Clarence Maday
Consultant
U. S. Environmental Protection Agency
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Strategies and Air Standards Division
Research Triangle Park, North Carolina 27711
January 1978
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This report has been reviewed by the Strategies and Air Standards
Division, Office of Air Quality Planning and Standards, Office of
Air and Waste Management, Environmental Protection Agency, and
approved for publication. Mention of company or product names does
not constitute endorsement by EPA. Copies are available free of
charge to Federal employees, current contractors and grantees, and
non-profit organizations - as supplies permit - from the Library
Services Office (MD/35), Environmental Protection Agency, Research
Triangle Park, North Carolina, or may be obtained, for a nominal
cost, from the National Technical Information Service, 5285 Port
Royal Road, Springfield, Virginia 22161.
Publication No. EPA-450/2-78-004
11
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TABLE OF CONTENTS
Page
Executive Summary iv
I. Purpose of Study 1
II. Asphalt Paving-General 1
III. Previous Efforts to Encourage Emulsified 4
Asphalt Use
IV. Air Quality Considerations 5
V. Energy Conservation Considerations 9
VI. Eight-State Survey of Paving Practices 9
and Economic Considerations
VII. Summary and Conclusions 10
References 12
Appendix A - Commonly Used Terms Associated with A-l
Asphalt Paving Operations
Appendix B - Pros and Cons - Emulsified Asphalts B-l
Appendix C - Liquified Asphalt Data: Sales, C-l
Hydrocarbon Emissions Estimates - National
and State Summaries
Appendix D - Energy Conservation Considerations D-l
Appendix E - Eight-State Survey of Paving E-l
Practices and Economic Considerations
iii
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Executive Summary
This paper examines the air quality and energy conservation aspects
of asphalt paving practices using liquefied asphalt. There are two
basic types of liquefied asphalt: (1) asphalts liquefied with petroleum
distillates such as kerosene or heavy naphtha, called cutback asphalts,
and (2) asphalts liquefied using water and an emulsifying agent, called
emulsified asphalts. One type of emulsified asphalt (cationic) is cured
through an electrochemical process. All other types of liquefied asphalt
are cured through the evaporation of the liquefying constituent. Cutbacks
emit reactive hydrocarbons during the curing process; emulsions emit
almost no air pollutants.
In 1975 cutbacks accounted for 2.3% of estimated national hydrocarbon
emissions. In some states the cutbacks accounted for more than 15% of
the state's estimated total hydrocarbon emissions. Some states, e.g.,
Wisconsin, Indiana, Illinois, Ohio, Pennsylvania, Virginia, and West
Virginia, have significant air stagnation problems and require regulatory
control of hydrocarbon emissions to attain and maintain oxidant air
quality standards. These states also have had significant hydrocarbon
emissions attributable to paving with cutbacks. Since asphalt paving
operations occur predominantly during warm-weather months, when formation
of oxidants from photochemical synthesis of hydrocarbon emissions is
most prevalent, the decreased use of cutback asphalt could provide major
assistance in oxidant attainment and maintenance strategies.
iv
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It is estimated that in 1975 more than 10 million barrels of
petroleum distillates were used nationally to liquefy asphalt for paving
purposes. These distillates represent fuels which were evaporated to
the atmosphere or were retained in the pavement. The total energy
associated with laying one gallon of cutback asphalt as pavement is about
50,200 Btu, while the total energy associated with a gallon of emulsified
asphalt is about 2,830 Btu. For these reasons, the use of emulsified
asphalt as a replacement for asphalt cutback has energy benefits.
Some paving operators claim three instances when emulsions cannot be
substituted for cutbacks: (1) when long-life stockpiles are required,
(2) for some emulsions when ambient temperatures fall below about 50°F,
and (3) possibly when used as a penetrating prime coat. Others claim
that these are not deterrents and that they have had success in using
emulsions to replace cutbacks in all applications.
The price difference between the two types of liquefied asphalt was
found to be not significant at this time.
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Air Quality and Energy Conservation Benefits
From Using Emulsions to Replace Asphalt Cutbacks in
Certain Paving Operations
I. Purpose of Study
The purpose of this paper is to examine potential reductions in
hydrocarbon emissions which may be achieved through substituting one
kind of liquefied asphalt for another in certain paving operations. The
paper reviews (1) the differences in asphalts liquefied with petroleum
distillates (cutback asphalts), and (2) asphalts liquefied using water
and an emulsifying agent (emulsified asphalts). Amounts of reactive
hydrocarbons emitted when using cutback asphalts are discussed, as well
as the substitutability of emulsified asphalts in place of cutback
asphalts. Energy conservation considerations are presented, and the
results of an eight-state telephone survey of highway paving practices
are summarized.
II. Asphalt Paving - General
Asphalt is a by-product of petroleum distillation (natural or man-
made) which man has put to use in many different ways. In ancient times
he used it in its natural form to caulk boats and ships, as mortar in
masonry construction, and as a cement for mending stone tools. Now we
use it for roofing, weatherproofing, floor tile, insulating materials,
1
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molded electrical equipment, papers, shingles, coatings, and many other
applications. One of its better known uses is for pavements. Because
of its durability and weather resistant qualities we use it in many
different paving applications. These pavement uses can range from a
thin layer sprayed on a dirt road to keep down dust, to a heavy duty
pavement of thick layers of asphalt mixed with aggregate (crushed rock,
gravel, slag or sand) placed on a well prepared base and designed to
carry heavy traffic. In between these two extremes, asphalt pavement
may be of a wide variety of thicknesses and strengths, depending on
the traffic it will have to carry.
Asphalt surfaces and pavements are composed of compacted aggregate
and asphalt. Aggregate materials are produced from rock quarries as
manufactured stone or obtained from natural gravel or soil deposits.
Metal ore refining processes produce artificial aggregates as a by-
product. The aggregate performs three functions. It transmits the
load from the surface to the base course, takes the abrasive wear of
.traffic, and provides a nonskid surface. The asphalt binder holds the
aggregate together, preventing displacement and loss of aggregate, and
provides a waterproof cover for the base. Asphalts take the form of
asphalt cement (the residue of the distillation of crude oils), and
liquefied asphalts. Liquefied asphalts are: (1) asphalt cutbacks (asphalt
cement thinned, or "cut back" with volatile petroleum distillates such
as naphtha, kerosene etc.), and (2) asphalt emulsions (nonflammable liquid,
produced by combining asphalt and water with an emulsifying agent such as
soap). Asphalt cement, which is semi-solid, must be heated to convert it
to a useable liquid. Asphalt cutbacks and asphalt emulsions are produced
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in a wide variety of types and grades related to intended use, curing
time and structural design requirements. Some of the uses are defined in
Appendix A.
Emulsified asphalts are used widely in the construction and
maintenance of pavements ranging from high-traffic-volume highways and
airports to low-volume rural roads and city streets. Although emulsions
have been available since 1903 and used extensively since the 1930s, recent
energy and environmental problems have focused attention on increased
use of these materials. The use of emulsions can reduce energy
requirements by reducing or eliminating petroleum distillates that
are used in liquefied asphalts and by lowering heating requirements,
especially in heating aggregates to dry them. The elimination of petroleum
distillates also reduces air pollution by eliminating emissions of
hydrocarbons evaporated during the curing process.
Asphalt paving is a seasonal operation, with cold temperatures
and rainy weather severely limiting construction and maintenance
operations. Winter-time paving is usually limited to emergency repairs,
although some states have claimed good results even during periods of low
air temperature. Some emulsified asphalts (nonionic and anionic) usually
are not used when rain is anticipated or when air temperatures fall below
50°F. With cationic emulsions these deterrents are not critical since
curing depends on the electrochemical action of the positively charged
emulsion bonding with the negatively charged aggregate surface. Generally
speaking, emulsified asphalt can substitute for cutbacks in almost any
application. Some believe that emulsions are not good for priming purposes,
others believe that proper soil preparation is the answer, and still
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others question the very need for priming. Some states have had no
success with long-term stockpiling (more than 3-4 weeks) while others,
using heated tanks or using mixes with a relatively small amount of fuel oil
included, have had excellent results in stockpiling for a year or more.
The same construction equipment used for cutbacks can be used for emulsions.
A moderate amount of training (one or two days) is recommended before first
using emulsions. This training is readily available from members of the
Asphalt Emulsion Manufacturers Association. Local policies which encourage
the use of cutbacks are the only known institutional constraints that
inhibit the use of emulsified asphalt. Appendix B presents more detail
on the advantages and limitations of emulsified asphalts.
III. Previous Efforts to Encourage Emulsified Asphalt Use
Some of the organizations concerned with energy problems affecting
the supply and use of asphalt road paving materials are: Department of
Transportation (DOT), Federal Highway Administration (FHWA), Federal
Energy Administration (FEA), U. S. Department of Agriculture (USDA)
Forest Service, Environmental Protection Agency (EPA), Transportation
Research Board (TRB), National Asphalt Pavement Association (NAPA), The
Asphalt Institute (AI), Asphalt Emulsion Manufacturers Association
(AEMA), American Society for Testing and Materials (ASTM), American Road
Builders Association (ARBA), American Association of State Highway and
Transportation Officials (AASHTO), and state and local highway agencies.
In December 1973 and again in January 1974, FHWA issued notices
concerning fuel conservation in federally funded highway construction
programs. (Appendix B & D contain copies of these two notices.)
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These notices encouraged state officials to minimize the use of cutback
asphalts by substituting emulsions and to reduce mixing temperatures.
They also provided guidelines on conserving fuel and presented analyses
which demonstrated the large quantity of petroleum distillates which could
be saved by substituting emulsified asphalts for cutbacks. FEA and EPA
studies resulted in the conclusion that increasing fuel prices had already
established a trend of increased use of emulsions. To accelerate this
trend, FEA contracted with the National Research Council's Transportation
2
Research Board to produce a synthesis report on the use of asphalt
emulsions for pavements. This report was widely publicized by DOT and
various trade associations. FEA alone distributed 4,700 copies to city
and county engineers in December 1975. In October 1975, EPA informed
its regional offices by letter of the advantages of emulsified asphalts
over cutbacks and advised the regional offices to encourage the use of
emulsions to save energy and reduce emissions of hydrocarbons.
Other agencies and organizations have been at work on the problem.
3
For example, NAPA has published a paper on energy conservation
in highway paving, AEMA has been making extensive efforts throughout its
membership to encourage the use of asphalt emulsions, and USDA Forest
Service has published a report on its experience in using asphalt
emulsions, as has the Navajo Area Bureau of Indian Affairs. However, only
very recently has there been any indication of a trend toward switching
from cutbacks to emulsions.
IV. Air Quality Considerations
The volatiles in cutback asphalts release hydrocarbons into the
atmosphere in amounts that vary according to the type of cutback.
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Cutback asphalts fall into three broad categories: Slow Cure (SC)
(sometimes referred to as Road Oil), Medium Cure (MC) and Rapid Cure (RC).
o
Cutback content averages 35% diluents (hydrocarbons). SCs are a fairly
heavy residual oil in the Bunker C range. MCs are diluted with a
kerosene-type solvent. RCs are diluted with a heavy naphtha or a gasoline-
type solvent. For the purposes of calculating hydrocarbon emissions
estimates in this document the average value of 35% hydrocarbons is used
to demonstrate order of magnitude.
Table 1 is a summary of estimated hydrocarbon emissions resulting
from the use of cutback asphalts for paving purposes. The emission
calculations are based on the 35% volatiles contained in the cutbacks and
on the following estimated evaporation amounts: SC - 20%-30% evaporated
(average: 25%), MC - 60%-80% evaporated (average 70%), and RC -
70%-90% evaporated (average: 80%). Results of evaporation rate testing
now being done for EPA by Midwest Research Institute form the basis for
these estimated evaporation amounts. Most of the loss is believed to take
place early during paving operations. Continuing amounts are lost to the
atmosphere as time goes by but at an ever decreasing rate.
Table 1. SUMMARY OF NATIONAL HYDROCARBON EMISSION
ESTIMATES FROM THE USE OF CUTBACK ASPHALT
PAVING PRODUCTS
Volatiles, HC emissions,
tons/year tons/year
1971 1,916,857 1,146,915
1972 1,830,724 1,112,932
1973 1,975,451 1,210,233
1974 1,613,454 973,516
1975 1,434,895 886,348
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It is important to remember that paving operations are seasonal
and that the paving season occurs during the warm weather months when
formation of oxidants from photochemical synthesis of hydrocarbon emissions
is most prevalent. Attempting to arrive at specific answers to questions
about photochemical reactivity of the hydrocarbons emitted by cutbacks
is complicated by the fact that there are so many cutbacks of varying
chemical compositions. The situation is further complicated by the
variables of solar radiation, cloud cover, air mass stagnation, hydrocarbon
concentrations, and oxidant formation. However, cutbacks can be classified
as moderately to highly reactive as far as oxidant formation is concerned.
Emulsified asphalts, on the other hand, consist of asphalt liquefied
with water containing an emulsifier. Emulsions are relatively pollution-free
with few volatiles to evaporate into the atmosphere. FHWA has pointed out
that there may be some distillates in some formulations of emulsified asphalt.
Table 2 indicates the relationship of hydrocarbon emissions from
cutback asphalts used in paving, to national hydrocarbon emissions.
(Asphalt paving operations are not now included as a source of HC emissions
in the national summary).
Table 2. HYDROCARBON EMISSIONS FROM CUTBACK ASPHALT
AS A PERCENTAGE OF NATIONAL HC EMISSIONS
Summary of Relationship of
national HC cutback asphalt
emissions, HC emissions to
106 tons/year national HC emissions %
3.4
3.2
3.5
2.9
2.8
1971
1972
1973
1974
1975
33.3
34.1
34.0
32.9
30.9
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Table 3 shows a breakdown of national hydrocarbon emissions for
mobile and stationary sources and displays the emissions from cutbacks
in context with the two other sources.
Table 3. U.S. HYDROCARBON EMISSIONS BY CATEGORY7
(106 tons/year)
1971
1972
1973
1974
1975
Mobile
sources
13.7
14.0
13.7
12.5
11.7
Stationary
sources
19.6
20.1
20.3
20.4
19.2
Cutback
sources
1.1
1.1
1.2
1.0
0.9
Appendix C contains additional detailed information: Table C-l
summarizes annual national sales of cutback asphalts for paving purposes
from 1971 through 1975; Table C-2 displays by EPA Region and by State,
sales of cutback asphalts and sales of emulsified asphalts in 1975; and
Table C-3 displays by EPA Region and by State the statewide hydrocarbon
emissions from the use of cutback asphalts, State total hydrocarbon
emissions, and the percentage of State total emissions accounted for by
the cutback asphalts.
It is further noted that some states experience frequent air mass
stagnation and have oxidant air quality problems. Some of these states,
e.g., Wisconsin, Indiana, Illinois, Ohio, Pennsylvania, Virginia and West
Virginia, require regulatory control of HC emissions for attainment and
maintenance of oxidant ambient air quality standards. Most of these states
also have significant quantities of hydrocarbon emissions attributable to
paving with cutback asphalts.
8
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V. Energy Conservation Considerations
In 1975, 10,249,250 barrels of petroleum diluents were used to liquefy
asphalt for road paving operations. This amount of cutback is equivalent
to 464,906,000 gallons of gasoline, enough to fuel almost 558,000
automobiles for a single year in the United States. Rather than powering
automobiles, airplanes, or industry, however, energy in the form of
diluents was poured onto road surfaces, where some evaporated and some
remains. The energy impact of using cutback asphalts is just as striking
when viewed in terms of the energy expended per gallon of paving material.
The total energy associated with manufacturing, processing, and laying
one gallon of cutback asphalt is about 50,200 Btu. On the other hand,
analysis of emulsified asphalts shows that about 98% of the petroleum
diluents is replaced with water with the result that only about 2,830 Btu
is associated with each gallon of paving material. The components of
these energy costs are described in Appendix D.
VI. Eight-State Survey of Paving Practices and Economic Considerations
State highway maintenance divisions in eight states were contacted
for information, opinions, and experiences regarding the use of emulsified
asphalt paving materials. The states selected for this survey were the
larger users of asphalt. Since each state is responsible for some
fraction (which may differ for each state) of the roads within its
boundaries, this survey addresses only those asphalt paving operations
for which the state is directly responsible.
In general, the survey showed that there has been an increased use
of emulsified asphalts. This increased use, which varies with each
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state contacted, has been brought about primarily through fuel con-
servation measures and economic considerations. Relatively little
consideration is given to HC emission from paving operations. For example,
in Allegheny County, Pa., the Pennsylvania DOT uses emulsified asphalts
almost exclusively for county road paving operations because of conservation
and economics. In areas where such considerations do not exist, the
choice of emulsified asphalt or cutback asphalt depends largely upon
user preference as well as experience in specific materials and suppliers.
Individual responses ranged from general acceptance of emulsified
asphalts for paving to indifference and skepticism about emulsions.
Pennsylvania has changed from 30% emulsions/70% cutbacks in 1973 to
70% emulsions/30% cutbacks today. New York State uses 97% emulsions/
3% cutbacks.
New York and Pennsylvania have initiated training programs
to instruct their personnel and contractor personnel in the correct
use of emulsions.
Appendix E further describes the eight-state survey.
VII. Summary and Conclusions.
The air quality and energy conservation aspects of the use of
liquefied asphalt for paving operations have been analyzed to determine
the potentials for energy savings and reduced emissions. Cutback asphalts
are liquefied with hydrocarbon distillates such as kerosene or naphtha;
these reactive hydrocarbons are emitted during the curing process.
Emulsified asphalts use water and an emulsifying agent for liquefaction;
virtually no pollutants are emitted during the curing of emulsions. Some
10
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suppliers of emulsified asphalt include small amounts of distillates in
their emulsions. In such cases the amount of hydrocarbons emitted would
be a function of the amount of distillates used.
Overall, more than 10,000,000 barrels of distillates are used annually
for paving purposes. Most of this is evaporated into the atmosphere; the
remainder is retained in the pavement. Use of emulsions would save much
of those 10,000,000 barrels of distillates for use as or conversion to fuels.
In some states the curing of cutback asphalts accounted for a signi-
ficant amount of the state's total annual hydrocarbon emissions. This
problem is made more serious by the fact that asphalt paving operations
take place primarily during warm weather when oxidant formation from the
photochemical synthesis of hydrocarbon emissions is most likely. Reduced
use of cutback asphalts could decrease materially the oxidant problem in
these states.
It is anticipated that a minimal amount of cutback asphalt will
continue to be used at air temperatures lower than 50°F and for dusty
surfaces. Also, some cutbacks will be used where portable plants are
not available, because the stockpile life of emulsions is a problem
for some operators. Other concerns (discussed in Appendix B), can usually
be met through good management.
Significant energy savings and air quality improvements can be
realized from the increased use of emulsified asphalts.
11
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REFERENCES
1. "Magic Carpet, The Story of Asphalt", The Asphalt Institute,
1975, College Park, Maryland 20740
2. National Cooperative Highway Research Program Synthesis of Highway
Practice 30, "Bituminous Emulsions for Highway Pavements", Trans-
portation Research Board, National Research Council, 1975.
3. "Fuel Conservation", Charles R. Foster and Fred Kloiber, Washington,
D. C. National Asphalt Pavement Association, Riverdale, Md. 20840.
4. "Asphalt Emulsion Construction on the Navajo Reservation", W. R. Meier,
Bureau of Indian Affairs, Gallup, N.M., April, 1976.
5. "Sales of Asphalt in 1975", U.S. Department of the Interior, Bureau
of Mines, Mineral Industry Surveys, July 19, 1976.
6. "Lets Get Acquainted with Asphalt Emulsions", Prithvi S. Kandhal,
Commonwealth of Pennsylvania, Department of Transportation, Bureau
of Materials, Testing and Research, April 1974.
7. "National Air Pollution Emission Estimates, 1970-1975", undated
working paper, MDAD, OAQPS, EPA.
12
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APPENDIX A
COMMONLY USED TERMS ASSOCIATED WITH
ASPHALT PAVING OPERATIONS
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Appendix A
Commonly Used Terms Associated with
Asphalt Paving Operations
1. Crack Filler - Asphalt used to fill and seal cracks in existing
pavements.
2. Dust Palliative - A light application of liquefied asphalt (cutback
or emulsified asphalt) for the express purpose of controlling
loose dust.
3. Maintenance Mix - A mixture of asphalt and mineral aggregate for
patching holes, depressions, and distressed areas in existing
pavements. These mixes are suitable for relatively small spot
application, hot or at ambient temperature, using hand-laying
and compaction techniques. This includes mixes for immediate use
or for stockpiling for future use.
4. Penetration Macadam - Pavement construction using essentially
one-size coarse aggregate that is penetrated in place by an
application of asphalt binder. The asphalt application may be
followed by an application of finer aggregate to'reduce the void
space.
5. Plant Mix, Cold Laid - A mixture of liquefied asphalt (cutback or
emulsified asphalt) and mineral aggregate prepared in a central
bituminous mixing plant and spread and compacted at the job site
when the mixture is at or near ambient temperature.
6- Plant Mix, Hot Mix - Hot Laid - A mixture of oaving asphalt and mineral
K
aggregate usually prepared in a conventions, hot-mix plant or dryer-
drum mixer at a temperature of about 250°F ana spread and compacted
at the job site at a temperature above 200°-.
A-l
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7. Prime Coat - An application of asphalt to an absorptive surface
to penetrate and bind the aggregate surface and promote adhesion
between it and the new superimposed construction.
8. Road Mix (Mix-in-Place) and Travel Plant Mix - A procedure by
which the asphalt and mineral aggregate are mixed on the job
site by means of travel mixers, motor graders, or other special
road-mixing equipment.
9. Surface Treatment - An asphalt surface that results from one
or more successive alternate applications of asphalt binder
and cover aggregate to a prepared consolidated gravel, crushed
stone, waterbound macadam, earth, stabilized soil, or similar
base. Multiple application of asphalt and mineral aggregates
may be used.
10. Seal Coat - An asphalt surface that results from one or more
successive alternate applications of asphalt binder and cover
aggregate to an existing paved surface.
11. Slurry Seal - A uniform application of a mixture of emulsified
asphalt, fine aggregate, mineral filler, and water to an existing
pavement. Single or multiple applications may be used.
12. Tack Coat - An application of asphalt applied to an existing surface
to provide a bond between new surfacing and existing surface and
to eliminate slippage planes where the new and existing surfaces
meet.
A-2
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APPENDIX B
PROS AND CONS - EMULSIFIED ASPHALTS
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Appendix B
Pros and Cons - Emulsified Asphalts
In any comparison of alternate methods for accomplishing a given
job there is usually a concern for the advantages and disadvantages of
one method relative to another. In the evaluation of emulsified asphalts
versus cutback asphalts, such concerns were raised and have been considered.
Reduced hydrocarbon emissions and fuel conservation have been cited as
advantages to be expected from the use of emulsified asphalts instead
of cutback asphalts. The reduction in emissions and the fuel savings
are significant. Cost comparisons are generally favorable to emulsified
asphalts but there are specific instances where the cost differential
is negligibly small. While the foregoing suggests that the large-scale
use of emulsified asphalts should be encouraged, there are a number
of reasons given by some users which prevent a complete switchover to
emulsified asphalts. These include: (1) Varying experiences with stockpile
life. Use of portable mixing plants, heated tanks, and inclusion of a
small amount of fuel oil should overcome this objection. (2) Possible
washout in a heavy rain. Cutbacks are also susceptible to washout. (3)
"It's not like buying an 'off-the-shelf item." Cooperation between the
contractor, aggregate supplier, and emulsion supplier should result in
the proper selection of an emulsified asphalt. (4) Miscellaneous reasons
which can be met through the implementation of a training program to
instruct contractors and operators in the proper use of emulsified
asphalts. Some comments by FHWA follow:
B-l
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"In some States, maintenance materials may be purchased on annual
contracts. This may create ideal conditions for the use of emulsions
since the available expertise of the emulsion manufacturer can be
utilized to insure a satisfactory product by adjusting the emulsion
formulation to suit the aggregates, designing the mixture and training
personnel. In the competitive bidding situation for construction projects
this may not be the case. Traditionally, State's material sections
have either designed the bituminous mixtures or verified the contractor's
submitted mix design for adequacy to the intended purpose. A number of
the States have had little or no experience in the design of asphalt
emulsion mixtures and currently there are no nationally recognized
standard procedures for the laboratory design of these mixtures as
there is for hot asphaltic concrete or cutback asphalt mixes. A large
research effort is necessary in this area."
"It can be safely said that all of the State highway agencies are
aware of and concerned with the needs for energy conservation and protection
of the environment. The slower than desired trend by some of these
agencies toward total substitution of emulsions for cutbacks can in part
be attributed to the following factors.
1. Lack of nationally accepted standard laboratory design procedures
for asphalt emulsion mixtures.* A number of design methods have been
developed, mostly by members of the emulsion manufacturing industry.
*Authors' Note: Similarly, there are only regionally accepted prodecures
for cutbacks. There are no nationally accepted precision statements
available on any design procedure for hot mixes and cutbacks.
B-2
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None of these have been endorsed by the standardizing associations AASHTO
or ASTM. The availability of a recognized objective reproducible
laboratory design procedure for use by the highway agencies is considered
a necessity in the effort to foster greater usage of asphalt emulsions.
2. Lack of reliable data on the structural worth of the asphalt
emulsion mix. The pavement designer needs this information in the
development of the structural section for a project. The general use of
emulsions in the past has not been conducive to obtaining this type of
data.
3. The tight money conditions that most State highway agencies
have experienced in the past 3 years. This has not enhanced the climate
for highway agencies to more or less experiment with a new product
particularly when there is no price advantage. In response to item 1
above, the FHWA's Office of Research and Development has underway an in-
house effort to develop a laboratory method of asphalt emulsion mix
design. However, the allocation of necessary manpower and financial
resources has been somewhat limited because of competing research
requirements. That is not to say that we believe the effort to be
unwarranted, just that strictly from a highway point of view there are
other, more urgent, research needs."
An FHWA Notice (January 1974) is attached.
B-3
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U. S. DEPARTMENT OF TRANSPORTATION
F FEDERAL HIGHWAY ADMINISTRATION
SUBJECT Use of Emulsified Asphalts in Lieu
of Cutback Asphalts in Highway
Construction.and Maintenance
Operations January 17,1974
FHWA NOTICE
•N 5080.5 •
1. PURPOSE. To direct the attention of the Federal Highway
Administration field offices, States, and local
governments to overall fuel savings possible using
emulsion asphalts in lieu of cutback asphalts for
highway construction and maintenance operations.
2. BACKGROUND.
a. The national energy crisis relative to fuel and
petroleum distillate shortages, as well as
ecological problems with atmospheric contamination,
necessitates consideration of an alternative for
cutback asphalt use in highway construction and
maintenance work.
Cutback asphalts require heating before application
and incorporate petroleum products in short supply
that almost entirely evaporate into the atmosphere.
The fuel and cutback solvents could be used for
higher priority items and, at the same time, would
lessen the pollution problems associated with
bituminous work.
b. A U.S. Bureau of Mines tabulation for petroleum
asphalts consumed in the United States in 1972
relative to highway construction and maintenance
is as follows:
Asphalt Cement and Fluxes 24,725,001 tons
Emulsified Asphalts 2,535,833 tons
Cutback Asphalts 3,860,094 tons
Assume 1-ton of cutback asphalt = 240 gallons
3,860,094 tons x 240 gallons/T = 926,400,OOO gallons
of cutback asphalt used.
The average cutback asphalt is composed of
one-third solvent and two-thirds asphalt,
therefore, one-third solvents (kerosene or naptha)
of 926,4OO,OOO gallons = 309,OOO,000 gallons of
O.STR,BUT,ON: Headquarters OP,: HHO-31
Regions
Divisions 3.4
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FHWA NOTICE
petroleum products in the critical supply
category which can possibly be saved by use
of emulsified asphalts in lieu of cutback
asphalts.
c. Emulsified asphalts are mixtures in which minute
globules of asphalt are dispersed in water or
aqueous solutions by means of an emulsifier to
assure coating of aggregates. Emulsifiers
include soap of fatty or resinous acids, glue,
and gelatin. Use of emulsified asphalts is not
a new concept since they have been used in
varying degrees by State and local construction
and maintenance agencies for a number of years.
The magazine titled "Rural and Urban Roads"
published three reports on how the States were
using emulsions. Part I of the report was
published in February 1972, Part II in April 1972,
and Part III in June 1972. Over 20 States
detailed the scope of their use of emulsions.
An overall State summary was included in Part I
and showed that emulsions were used as follows:
Subbases = 8 States
Base Mixes = 15 States
Cold Mix Surfacing = 10 States
Shoulders = 20 States
Primes = 30 States
Sealcoats for Surface Treatments = 38 States
Surface Treatments = 38 States
Slurry Treatments = 24 States
Cold or Hot Patching = 15 States
A recent Federal Highway Administration survey
has revealed that most of the States are presently
using emulsified asphalts in maintenance operations
where in many cases cutback asphalts had formerly
been used.
d. Some advantages in using emulsion asphalts rather
than cutback asphalts are:
1. Reduced atmospheric pollution problems.
2. Emulsions penetrate and seal rr cks in existing
surfaces during chip seal procadures prior to
"breaking." The term "breaking" as applied to
emulsified asphalts, refers to the condition
where separation of water and asphalt occurs.
B-5
-------
FHWA NOTICE
3. Emulsions can be applied at lower temperatures
since little or no external heat is required.
This presents a greater safety factor since jione_
or_a mini mum pf. _pe t roleum. .djlst i 11 at e is pre sent.
4. Setting characteristics of emulsions can be
varied over a wider range than cutbacks.
Setting is not dependent on the solvent and
this gives desirable properties for tack coats,
slurry seals, and surface treatments.
5. Emulsions have the ability to coat wet surfaces of
aggregates.
6. Potential cost savings whenever emulsions are
used.
Reference specifications for use of emulsion
asphalts are:
Standard Specification for Emulsified Asphalt -
AASHO Ml40 (ASTM D977) (Anionic)
Standard Specifications for Cationic Emulsion Asphalt -
AASHO M2O8 (AST?! D2397)
3. ACTION.
Since the situation regarding fuel shortages
appears likely to become more acute as time
goes on, it is directed that the Federal Highway
Administration field offices strongly urge the
States and local governments to use emulsified
asphalts in lieu of cutback asphalts whenever
feasible. This is especially important since
serious delays in highway construction may be
encountered where cutback asphalts having
petroleum products in short supply are specified.
Areas in which emulsions have been used are:
1. Soil Stabilization.
2. Tack Coats.
3. Prime Coats (Except where special penetration
is needed).
4. Sub-Bases.
5. Bases.
6. Intermediate Pavement Layers.
7. Surface Treatments.
8. Slurry Seals.
9. Shoulder Treatments.
1O. Curing Seals for Cement-Treated Bases.
11. Cold-Patching.
12. Mulching Tiedown.
13. Penetration Macadam.
14. Dust Palliatives.
B-6
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FHWA NOTICE
There will be a need to evaluate and adjust current
specifications in order to provide types and grades of
emulsions as direct substitutes for existing cutback
materials. Modification of existing contracts, to
substitute emulsified asphalts for cutback asphalts
is encouraged where feasible.
Emulsified asphalts have been used to some degree in lieu
of conventional heated plant mixtures, principally in
base courses. In some western States, experimental
special open graded emulsified asphalt mixtures have been
used successfully to construct full depth flexible
pavements. Experimental project construction utilizing
asphalt emulsion pavement mixtures are encouraged in
order to learn more about thickness equivalencies and
service performance of such mixtures. Where full depth
open graded mixtures are used experimentally, special
attention should be given to the quality of the subgrade
and the provision of durable skid resistant surfaces.
Aside from obvious advantages of reduced heating
requirements and attendant pollution problems, there are
indications of significant cost savings with the
open graded asphalt emulsion pavement mixtures.
Although emulsified asphalts can be substituted for
cutback asphalts in many situations as pointed out in
this Notice, there will continue to be instances where
cutback asphalts will be required for one reason or
another. Even though emulsions can be used with aggregates
which are not entirely dry, excessive moisture from rain
or showers can result in complete loss of the work if the
emulsified asphalt has not broken completely. The
emulsified asphalts are more susceptible to problems
during colder weather where stripping can occur because
of the slower break. Proper mixing procedures are
important because excessive mixing can cause stripping.
Stockpiling of emulsified asphalt mixes for long periods
should be avoided, as this has led to problems due to
premature or partial breaking.
Attachment "A" contains a bibliography of some reports,
papers, and articles regarding the use of emulsions in
bases, surfaces, etc., in highway work. These publications
contain data of a technical nature as well as sample
specifications. ,
.-*.-. •'/•"••
H. A. Lindberg '
Associate Administrator for
Engineering and Traffic Operations
Attachment "A"
B-7
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FHWA NOTICE
ATTACHMENT "A"
EMULSIONS
How the States Use Emulsions - Rural and Urban Roads,
February, April, and June 1972 publications.
Bitumuls Base Treatment Manual - Chevron Asphalt Company -
555 Market Street, San Francisco, California 94120.
Design and Construction of Emulsified Asphalt Open-Graded
Mixes and Overlays (March 17, 1972) - L. P. Coyne,
Research Engineer, Chevron Asphalt Company.
Emulsified Asphalt Hot Mixes (November 197O) - J. Ferguson,
Pounder Emulsions - 1474 Wall Street, Winnipeg 3, Manitoba.
Emulsified Asphalt for Better Paving - K. E. McConnaughay,
Asphalt Plants and Processes - 426 Columbia Street,
Lafayette, Indiana.
Thickness Equivalencies - Charles R. Foster, National
Asphalt Pavement Association, 6715 Kenilworth Avenue,
Riverdale, Maryland.
B-8
-------
APPENDIX C
LIQUEFIED ASPHALT DATA: SALES, HYDROCARBON EMISSIONS ESTIMATES -
NATIONAL AND STATE SUMMARIES
-------
Appendix C
Liquefied Asphalt Data: Sales, Hydrocarbon Emissions Estimates -
National and State Summaries
Table C-l displays a summary of national sales of cutback asphalt
for paving purposes. It is based on Bureau of Mines annual reports of
asphalt sales for the years shown. The Bureau of Mines data are further
broken down into the three categories of cutbacks based on an estimated
usage ratio of 65% Medium Cure (MC) and 35% Rapid Cure (RC).
Table C-l SUMMARY OF NATIONAL SALES OF CUTBACK ASPHALTS
FOR PAVING (TONS/YEAR)
Year
1971
1972
1973
1974
1975
Slow cure
(Road Oils)
1,543,091
1,370,546
1,424,000
1,251,091
991 ,455
Medium
cure
2,557,868
2,509,061
2,743,095
2,183,205
2,020,359
Rapid
cure
1,375,775
1,351,033
1,477,051
1,175,572
1,087,886
Total
5,476,734
5,230,640
5,644,146
4,609,868
4,099,700
C-l
-------
Tablea-2 Sales of Cutback Asphalt and Emulsified Asphalt in 1975,
by EPA Region and State
Cutback Asphalt Sales Emulsified Asphalt
EPA Region (Includes Road Oils) Sales
and State (tons) (tons)
Region I
Connecticut 20,355 2,340
Maine 23,702 16,742
Massachusetts 18,510 4,855
New Hampshire 22,982 12,994
Rhode Island 927 677
Vermont 321 299
Region II
New Jersey 26,528 55,357
New York 103,435 156,755
Region III
Delaware 1,168 1,746
Maryland + D.C. 42,411 62,122
Pennsylvania 143,096 57,369
Virginia 58,222 58,270
West Virginia 11,707 31,238
Region IV
Alabama 45,138 51,829
Florida 46,387 26,753
Georgia 50,003 56,318
Mississippi 2,989 27,658
Kentucky 37,241 71,455
North Carolina 31,966 80,631
South Carolina 16,993 47,514
Tennessee 25,651 112,447
Region V
Illinois 312,041 31,042
Minnesota 129,783 17,815
Michigan 39,305 24,441
Ohio 297,417 182,896
Indiana 80,805 162,636
Wisconsin 125,093 16,853
C-2
-------
Region VI
Arkansas 68,829 40,454
Louisiana 19,867 35,631
New Mexico 70,848 40,228
Oklahoma 390,836 7,372
Texas 189,648 131,079
Region VII
Iowa 98,242 17,496
Kansas 121,111 38,427
Missouri 470,686 13,102
Nebraska 21,928 8,519
Region VIII
Colorado 73,736 1,255
Montana 50,692 6,099
North Dakota 49,373 22,140
South Dakota 41,152 5,771
Utah 27,397 17,006
Wyoming 15,705 1,931
Region IX
Arizona 152,121 100,987
California 236,685 136,802
Hawaii 5,220
Nevada 47,183 6,828
Region X
Alaska 7,416 5,370
Idaho 60,426 21,008
Oregon 25,417 58,074
Washington 141.066 57.246
Total 4,099^700 2,143,877
C-3
-------
Table C-3
Cutback Asphalt Hydrocarbon Emissions Contribution
to State Total Hydrocarbon Emissions
EPA Region
and State
Region I
Connecticut
Maine
Massachusetts
New Hampshire
Rhode Island
Vermont
Region II
New Jersey
New York
Region III
Delaware
Maryland & D.C.
Pennsylvania
Virginia
West Virginia
Region IV
Alabama
Florida
Georgia
Mississippi
Kentucky
North Carolina
South Carolina
Tennessee
Region V
Illinois
Minnesota
Michigan
Ohio
Indiana
Wisconsin
Cutback Asphalt HC
Emissions Total* and %
of State HC Emissions
(tons)
State Total HC
Emissions
**
(tons)
5,227
6,087
4,747
5,902
238
82
6,812
26,223
300
10,891
36,718
14,951
2,985
9,997
11,894
12,841
662
8,104
8,209
4,363
5,582
67,984
28,244
8,554
66,090
17,585
21,710
2.3%
4.6%
<1 %
6.3%
<1 %
<1 %
1.1%
2.3%
<1 %
2.5%
4.3%
3.0%
2.6%
1.4%
1.0%
2.7%
<1 %
2.2%
1.5%
1.2%
1.4%
3.6%
6.9%
1.0%
5.6%
2.8%
3.6%
221,736
125,390
520,930
88,366
85,283
41,372
639,325
1,116,330
64,813
427,337
811,992
483,501
113,711
729,076
,140,776
467,461
224,298
352,382
548,584
360,971
391,719
,831,465
381,938
824,898
,117,174
603,771
574,454
C-4
-------
Region VI
Arkansas 15,245 7.4% 189,896
Louisiana 4,400 <1 % 1,228,769
New Mexico 15,525 9.8% 143,116
Oklahoma 86,850 18.1% 391,672
Texas 42,305 1.9% 2,211,509
Region VII
Iowa 21,380 5.7% 353,844
Kansas 26,356 7.3% 336,756
Missouri 104,593 18.9% 448,299
Nebraska 4,772 1.3% 378,922
i
Region VIII
Colorado 15,275 6.4% 224,797
Montana 10,494 5.0% 197,518
North Dakota 10,934 13.3% 71,522
South Dakota 8,956 9.5% 85,161
Utah 5,672 5.2% 103,047
Wyoming 3,251 4.6% 67,654
Region IX
Arizona 27,436 10.2% 241,985
California 38,719 1.8% 2,115,039
Hawaii 889 <1 % 94,405
Nevada 8,088 13.1% 53,429
Region X
Alaska 1,263 1.1% 109,370
Idaho 12,214 9.3% 118,532
Oregon 4,328 1.5% 290,495
Washington 24,011 6.7% 336,944
*Weighted average by state. See Table 1 narrative (Sect IV, p. 5)
**State total hydrocarbon emissions estimates are based upon latest
available data on emission sources as presented in EPA-450/2-76-007,
May 1976, "1973 National Emissions Report," National Emissions Data
System (NEDS) of the Aerometric and Emissions Reporting System (AEROS),
Asphalt paving operations were not included as a source.
C-5
-------
APPENDIX D
ENERGY CONSERVATION CONSIDERATIONS
-------
Appendix D
Energy Conservation Considerations
The energy associated with cutback asphalt can be compared with
that associated with emulsified asphalt by considering their respective
compositions, the attendant process energy, and the energy required
for asphalt spray applications using an asphalt distributor. Since the
petroleum distillates content of cutback asphalt varies from 20% to 50%
of the total mixture, the energy associated with these asphalts spans a
wide range. In order to strike one kind of comparison, consider cutback
asphalt and emulsified asphalt, each with 65% asphalt. This is reasonable
because this percentage is generally recommended for emulsified asphalts
and the eight-state survey (Section VI and Appendix E) revealed that
the amount of cutback asphalt (typically containing 60% - 70% asphalt)
required for paving operations was about the same as for emulsified asphalts.
About 2500 Btu is required to process a gallon of asphalt for paving*
and to this is added the energy content of the cutback which, for a medium
cure is about 135,000 Btu/gal. Thus, for one gallon of cutback asphalt
with 65% asphalt and 35% cutback the energy represented therein is 2500
+ .35 x 135,000 = 49,750 Btu. About 2050 Btu is required to obtain one
gallon of emulsified asphalt, independent of emulsifier energy content.*
According to ARMAK (leading manufacturer of emulsifiers) there is about
7500 Btu/lb associated with the production of emulsifiers. At about
0.084 Ib emulsifier/gal (1%) an additional 630 Btu should be added to
* "Energy Requirements for Roadway Pavements," The Asphalt
Institute (MISC-75-3) April 1975.
D-l
-------
the 2050 Btu for each gallon of emulsified asphalt giving an intermediate
total of 2680 Btu/gal.
Finally, the energy requirements for asphalt spray applications
using an asphalt distributor amount to 444 Btu/gal for cutbacks and
144 Btu/gal for emulsions.* (An additional 300 Btu/gal is required to
heat the cutback asphalt). Hence, the total energy associated with
laying one gallon of cutback asphalt is about 50,200 Btu while the total
energy associated with a gallon of emulsified asphalt is about 2830 Btu.
Each ton of petroleum diluent used in cutbacks is equivalent to
about 300 gallons. The tons of volatile diluents displayed in Table C-l
convert to barrels (42 gals/bbl) as follows:
Table D-l PETROLEUM DILUENTS USED TO LIQUEFY ASPHALT
(ESTIMATED BBLS/YEAR)
1971 13,691,836
1972 13,076,600
1973 14,110,364
1974 11,524,671
1975 10,249,250
These petroleum diluents (fuels) were evaporated to the atmosphere '
or were retained in the asphalt pavement. In terms of energy content, the
amount of gasoline equivalent to the 10,249,250 barrels of petroleum
diluents used in 1975 for cutback asphalts is:
Mn 9/10 9cn KK-M v fAO «=i/Kki\ ~ 135,000 Btu/gal diluent
(10,249,250 bbl) x (42 gal/bbl) x ^OOO Btu/gal gasoline =
464,906,000 gal gasoline
* "Asphalt Surface Treatments and Asphalt Penetration Macadam," The
Asphalt Institute, Second Edition, November 1969, Manual Series No. 13
(MS-13)
D-2
-------
For an annual mileage of 10,000 at 12 mpg this gasoline equivalent
would fuel almost 558,000 automobiles for one year.
An FHWA Notice (December 1973) is attached.
D-3
-------
U. S. DEPARTMENT OF TRANSPORTATION
? FEDERAL HIGHWAY ADMINISTRATION
SUBJECT
Conservation of Fuel
Federal-Aid Highway Construction Program
Direct Federal Highway Construction Program
FHWA NOTICE
• N 5080.2
December 6, 1973
1. PURPOSE
The purpose of this Notice is to set forth the Federal Highway
Administration's position relative to the taking of immediate
measures to conserve fuel on Federal-aid and direct Federal
highway construction.
2. BACKGROUND
In view of the seriousness of the current fuel shortage and the
likelihood of it worsening, it is imperative that all feasible
steps be taken quickly to improve the efficiency of highway
construction operations from the standpoint of fuel usage.
3. ACTION
Accordingly, FHWA field office personnel should meet with
appropriate State officials to review and identify actions that
could feasibly be taken under prevailing conditions to effect
reduction in fuel usage on ongoing and future Federal-aid
highway construction projects. FHWA direct Federal construction
personnel should undertake a similar review of direct Federal
highway projects. This review and action program should be
initiated immediately. The Federal Highway Administration
encourages and will accept design proposals and change orders
that will effect fuel savings without undue sacrifice in the
timeliness, quality, or cost of such construction.
Some, suggested actions to consider are listed below:
a. Minimize the use of cut-back asphalts and road oils by
substituting emulsions, and other bituminous products.
The FHWA is presently preparing a detailed statement on
this subject, which should be issued in the very near
future. Present information indicates over 300,000,000
gallons per year of naphtha and kerosene could be saved
by this substitution on construction and maintenance
operations.
-more-
DISTRIBUTION: Headquarters OPi: HHO-32
Regions
Divisions D-4
-------
FHWA NOTICE
b. Reduce mixing temperatures for plant-mixed bituminous
mixtures. Mixtures should be produced at the lowest
temperature that will permit proper mixing, laydown, and
compaction. Mixing temperatures should be based on the
temperature-viscosity relationship at the particular type
of grade of bituminous material being used. Data on this
relationship should be required in chart form for each
source. More detailed information can be found in "The
Asphalt Handbook, Manual Series No. 4 (MS-4)" published by
the Asphalt Institute. Utilization of mixtures produced
at lower temperatures might require the use of insulated
truck bodies and covers to retain adequate heat for laydown
and compaction.
c. Use insulated forms instead of heated enclosures for cold
weather concreting operations. Defer cold weather concret-
ing except for critical items affecting the efficiency
of other major operations or to avoid major delays in
project completion.
d. Encourage carpooling by State, FHWA, and contractor personnel.
e. Use fewer but thicker lifts in bituminous pavements. Lifts
in the 6-inch to 8-inch range have been successfully used
in many areas, particularly in black base construction.
However, consideration of thicker lifts should not be
confined to bases but should also be considered for surface
course layers.
f. Prohibit use of petroleum products to facilitate the
burning of brush.
g. Assure that construction equipment is operated within
manufacturer's recommended ranges.
h. Avoid the necessity to redo-grading by protecting it with
adequate erosion control measures applied on a timely
basis. Encourage the proper scheduling and performance of
erosion control measures by relieving the contractor of
responsibility for maintaining satisfactorily completed
work.
i. Require the use of borrow and waste sites selected by the
State to minimize fuel consumption. FHWA will find
-more-
D-5
-------
FHWA NOTICE
mandatory use of such sites to be in the public interest
if fuel savings would result.
j. Use mobile communication equipment to minimize'project
related travel.
k. Increase use of engineering studies to identify project
conditions that would permit fuel saving construction
features. For example, study the soils that will be used
in embankment construction to determine the maximum
permissible lift thickness(es). Where feasible, we would
encourage the use of end result density specifications
combined with test strip control to achieve thicker
embankment lift construction.
Additional information relative to such highway program activities
as design, selection of projects and possibly others, as they relate
to conservation of fuel, is being developed and will be forthcoming.
BarTTelsrrfey'ef'
Deputy Administrator
D-6
-------
APPENDIX E
EIGHT-STATE SURVEY OF PAVING PRACTICES AND ECONOMIC CONSIDERATIONS
-------
Appendix E
Eight-State Survey of Paving Practices
and Economic Considerations
Eight state highway maintenance divisions were contacted for their
opinions, facts, and experiences regarding the use of emulsified asphalt
paving materials. The states selected were the larger users of asphalt.
An initial contact with each state was made in order to establish an
overview of their operations. A second contact was made to obtain more
detailed information.
In discussions with the eight states it was found that there was an
insignificant difference (overall) in the costs of the two types of
asphalts at this time. Until three.years ago the cutback asphalts were
less expensive but the increase in oil prices has changed this picture.
The local picture may be influenced by varying economic considerations.
However, the availability of light diluents from a nearby (and older)
refinery could make cutbacks very attractive. Newer refineries are able to
recycle naphtha and similar light stock to turn out a more profitable
product. When a nearby source of these light diluents is not available,
the additional freight costs to deliver the material usually tips the
scales in favor of emulsions.
A specific example is found in Waukesha County, Wisconsin.* The
switch to emulsions was made to conserve energy in 1973. In 1976 the
county used emulsions for resurfacing and realized about a 10% cost
saving in materials: 36.92
-------
The following is an account of discussions with each highway
maintenance division.
Illinois
Primary roads are usually paved with portland cement concrete. Main-
tenance operations and paving of secondary roads are under local (city or
county) jurisdiction. The local agencies are being encouraged ("jawboned")
to use emulsified asphalts. The state "Specification Book" now lists
emulsions as a viable option. Cationic and High Float Emulsions (HFE) are
preferred (for definitions see reference 2). Stockpile life is no
problem. There is almost no cost differential. Most user problems are
expected to be resolved as more plants come into operation. Also, the
expanded use of "porta-pugs" (portable on-site mixing equipment) should
benefit pre-mix emulsions.
Paving with emulsions is not done after September 30. Under favorable
conditions (3 consecutive preceding days with maximum temperatures over
60°F in the shade and a night time minimum of 40°F or higher) emulsified
asphalts can be used until October 31. Use of emulsions is resumed in
the spring when these temperature ranges are obtained.
Missouri
Until 3 or 4 years ago cutback asphalt was used exclusively. Today,
emulsions are satisfactory for tack coats. Emulsions are generally
unsatisfactory for road surfaces. The emulsified asphalt industry in
Missouri is in its infancy and has not been able to live up to its claims.
Problems include emulsions break-up and non-adherence to aggregate
resulting in rough surface. Procurement of emulsion asphalt is not like
buying an off-the-shelf item. The emulsifying agent and proportions must
E-2
-------
be tailored to the available aggregate the particular job. Their most
successful emulsions use 4-10% cutback.
Most of the paving work is done under contract.
Pennsylvania
The Department of Transportation has its own environmental section
which maintains liaison with the state Department of Environmental Resources.
The expanded use of emulsified asphalts was initiated as a fuel and
cost conservation measure about three years ago. DOT has continued to use
emulsions because they expect the cost of petroleum diluents to increase
further. Pennsylvania is directly responsible for and controls much of its
highway system (as do Virginia, North Carolina, and Texas), i.e., 44,000
miles of the 104,000 miles of roads in the state. The Pennsylvania DOT is
under annual contracts with asphalt suppliers and hence control the type
of asphalt to used on a given job.
About ten years ago emulsified asphalts were used for the first
time. Three years ago usage was 30% emulsions. Today, it is 70%
emulsions. No further increase is expected. The state is committed to
emulsions and has directed its districts accordingly. One-day training
programs have been set up for administrators as well as operators.
Hot-mix will be used for primary roads for some time because
suppliers have considerable investment in plants and equipment.
A design procedure for Seal Coats (Surface Treatments) is available.
Special mixes such as cold patch material requires stockpiling. All
operations require strict quality control. Furthermore, mixes cannot be
stockpiled in excess of a depth of 4 feet. Pennsylvania also uses travel-
mix plants to prepare the emulsion on the job site.
E-3
-------
Emulsions are used for recycling pavements. Cutbacks are still used
for dust control.
Ohio
The increased use of emulsions is being encouraged. The state cannot,
however, mandate to the local governments. At present there is an
insignificant price differential but the cost of cutback asphalt is expected
to increase.
Oklahoma
Emulsified asphalts are used for seal coats and slurry seals - about
10-15% more emulsified asphalt is required than cutback asphalt for a
given surfacing requirement. Emulsions are not used for surface paving.
There is an insignificant price differential today. Emulsion costs are
expected to decrease but a trend to increased use of emulsions is not
foreseen.
Texas
The state is trying to increase use of emulsions as a result of
energy conservation efforts and financial conditions. Overall they find
an economic advantage in the use of emulsions. Emulsions are not used
for heavy traffic applications or where roads must be opened immediately
after re-surfacing. Stockpile life for emulsions is about one month.
There are 25 Districts in Texas and each District Engineer is
responsible for maintenance. Attitudes are important - some users have
been using emulsions with success for years while others are unalterably
opposed to it.
E-4
-------
New York
In 1976, 97% of liquid asphalts used were emulsions; 3% were cutbacks.
New York state has an educational program to instruct its personnel in
the correct use of emulsions and recommends and stresses the advantages
of emulsions over cutbacks. In 1977 the use of cutbacks will be restricted
to pavement repairs only. The State knows that emulsions are actually
being used in paving operations by inspecting and testing material for
acceptance and adherence to specifications. They have experienced no
stockpile problems. They feel that four weeks is a good average for stock-
pile life and generally use the material within a four week period. Some
material has been stockpiled for longer periods with no problems. The
foregoing information pertains only to the use of emulsions by the New
York State Department of Transportation and does not include counties
and municipalities within the state.
California
California State Department of Transportation uses cutbacks as the
primary liquid asphalt. The emulsion that is used is mainly for seal
coats. They have no prejudice against emulsions per se, but they stockpile
for the whole winter, particularly for the remote areas in the northern
part of the state, and emulsified asphalt stockpiles will not last
more than a few weeks before they set up and become unusable. The cost
differential between emulsions and cutbacks is negligible. Paving
operations are in compliance with environmental requirements.
Although not a part of the eight-state survey, a discussion with
the Southern California Air Pollution Control District, Metropolitan
Zone (formerly L.A. District) is believed pertinent. Cutbacks are
E-5
-------
forbidden to be used in that District under the Volatiles Rules, Rule 442
(Usage of Solvents) and Rule 443 (Labeling of Solvents). These rules
are formerly known as Rule 66.
E-6
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/2-78-004
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Air Quality and Energy Conservation Benefits From
Using Emulsions to Replace Asphalt Cutbacks in Certain
Paving Operations
5. REPORT DATF
January, 1978
6. PERFORMING ORGANIZATION CODE
7-j^UTHO/KSL. ... . -, ...
Francis M. Kirwan and Clarence Maday
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
US
OAWM
OAQPS
RTP, North Carolina 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This paper reviews practices found in the use of liquified
asphalts for paving purposes. It examines (1) the solvent content
difference in asphalts liquified with petroleum distillates (cutback
asphalts) and asphalts liquified using water and an emulsifying agent,
and (2) the amounts of hydrocarbons emitted when using cutback asphalts in
relation to national and state hydrocarbon emissions. The substitut-
ability of cutbacks and emulsions are discussed. Energy conservation
considerations are treated. The results of an eight-state telephone
survey of highway paving practices are presented.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Cutback Asphalt
Hydrocarbon Emissions
Fugitive Emissions
Emulsified Asphalt
Energy Conservation
Air Pollution
Air Pollution Control
Energy Conservation
8. DISTRIBUTION STATEMENT
19. SECURITY CLASS (This Report)
Unclassified
Unlimited
21. NO. OF PAGES
50
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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