EPA-450/2-77-037
December 1977
(OAQPS No. 1.2-090)
GUIDELINE SERIES
CONTROL OF VOLATILE
ORGANIC COMPOUNDS FROM
USE OF CUTBACK ASPHALT
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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EPA-4SO/2-77-037
(OAQPSNo. 1.2-090)
CONTROL OF VOLATILE ORGANIC
COMPOUNDS FROM USE OF
CUTBACK ASPHALT
Emission Standards and Engineering Division
Chemical and Petroleum Branch
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Watte Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
December 1977
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I OAQPS GUIDELINE SERIES
The guideline series of reports is being issued by the Office of Air Quality
Planning and Standards (OAQPS) to provide information to state and local
air pollution control agencies; for example, to provide guidance on the
acquisition and processing of air quality data and on the planning and
analysis requisite for the maintenance of air quality. Reports published in
this series will be available - as supplies permit - from the Library Services
Office (MD-35), U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711; or, for a nominal fee, from the National
Technical Information Service, 5285 Port Royal Road, Springfield, Virginia
22161.
Publication No. EPA-450/2-77-037
(OAQPS No. 1.2-090)
ii
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TABLE OF CONTENTS
Page
Chapter 1.0 Introduction 1-1
1.1 Need to Regulate Cutback Asphalts 1-1
1.2 Sources and Control of Volatile Organic Compounds
From Cutback Asphalts 1-2
Chapter 2.0 Source of Emissions and Approach to Emission
Reduction 2-1
2.1 Uncontrolled Emissions 2-3
2.2 References 2-3
Chapter 3.0 Costs of Applying the Technology 3-1
3.1 References 3-2
Chapter 4.0 Effects of Applying the Technology 4-1
4.1 Impacts of Atmospheric Emissions 4-1
4.2 Water and Solid Waste Impact 4-1
4.3 Energy Impact 4-2
4.4 References 4-2
ill
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ABBREVIATIONS AND CONVERSION FACTORS
EPA policy Is to express all measurements 1n agency documents
in metric units. Listed below are abbreviations and conversion factors
for British equivalents of metric units.
Abbreviations
1 - liters
kg - kilogram
m - cubic meter
2
m - square meter
m ton - metric ton
Mg - megagram
3 3
kg/10 m - kilograms per thousand
cubic meters
3
m /day - cubic meters per day
Conversion Factors
liters X .26 = gallons
kg X 2.2 = pound (lb)
1b X 0.45 = kg
m3 X 0.16 - barrel (bbl)
bbl X 6.29 = m3
m2 X 10.8 = square feet (ft2)
ft2 X 0.093 » m2
m ton X 1.1 - ton
ton X 0.91 = m ton
Mg = m ton
kg/103m3 X 0.35 = lb/103bbl
lb/103bbl X 2.86 = kg/103m3
m3/day X 0.16 = bbl/day
bbl/day X 6.29 = m3/day
iv
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1.0 INTRODUCTION
This document addresses the control of volatile organic compounds
(VOC) from paving asphalts liquefied with petroleum distillate. Such
liquefied asphalt 1s generally referred to as cutback asphalt. The sub-
stitution of emulsions for cutback asphalt nearly eliminates the release
of VOC air pollutants from paving operations. The VOC emitted from the
cutback asphalts are pta+ochemlcally reactive (precursors to oxldants).
Methodology described In this document represents the presumptive
norm or reasonably available control technology (RACT). RACT Is defined
as the lowest emission limit that a particular source 1s capable of
meeting by the application of control technology that 1s reasonably available
considering technological and economic feasibility. It may require technology
that has been applied to similar, but not necessarily Identical, source cate-
gories. It 1s not Intended that extensive research and development be conducted
before a given control technology can be applied to the source. This does not,
however, preclude requiring a short-term evaluation program to permit the
application of a given technology to a particular source. The latter effort
is an appropriate technology-forcing aspect of RACT.
1.1 NEED TO REGULATE CUTBACK ASPHALTS
Control techniques guidelines are being prepared for source categories
that emit significant quantities of air pollutants In areas of the country
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where National Ambient Air Quality Standards (NAAQS) are not being attained.
Cutback asphalts are a significant source of VOC and tend to be concentrated
In areas where the oxidant NAAQS are likely to be exceeded.
Nationwide VOC emissions from the use of cutback asphalts were
estimated to be 656,000 metric tons 1n 1975. This represents 3.8 percent
of total 1975 VOC emissions from stationary sources. In some States.
cutback asphalts accounted for more than 15 percent of 1975 emissions.
Since asphalt paving operations occur predominantly during warm
weather, when formation of oxidants 1s most prevalent, the decreased use of
cutback asphalts could provide major assistance In oxidant attainment and
maintenance strategies.
1.2 SOURCES AND CONTROL OF VOLATILE ORGANIC COMPOUNDS FROM CUTBACK
ASPHALTS
Liquefied asphalts are generally prepared by cutting back or blending
asphalt cement with petroleum distillate ar by emulsifying asphalt cement
with water and an emulsifying agency. Heated asphalt cement is generally
used to make asphalt pavements such as asphalt concrete. Cutback and
emulsified asphalt are used in nearly all paving applications. In most
applications cutback and emulsified asphalt are sprayed directly on the
road surface; the principal other mode is in cold mix applications normally
used for winter time patching.
1-2
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VOC evaporate to the atmosphere as the cutback asphalts cure.
The VOC In cutback asphalt will range from 20 to 50 percent by volume
averaging 35 percent. Emulsified asphalts, on the other hand, consist of
asphalt suspended in water containing an emuls1f1er. The petroleum distillate
(VOC) substitute Is approximately 98 percent water and 2 percent enulsifier.
The water In emulsified asphalt evaporates during curing while the emulslfier
1s retained in the asphalt. The emulslfier 1s composed of non-volatile organic
chemicals. The substitution of an emulsified asphalt for cutback asphalt
reduces VOC emissions by 0.078 tons per ton of slow cure asphalt, 0.209 tons
per ton of medium cure asphalt, and 0.204 tons per ton of rapid cure asphalt,
or about a 100 percent reduction.
1-3
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2.0 SOURCE OF EMISSIONS AND APPROACH TO EMISSION REDUCTION
Cutback asphalts are mixtures of solvent and a base asphalt of
selected hardness or viscosity. Solvent 1s of high, medium, or low
volatility depending on construction purposes. Of the liquid asphaltic
products Illustrated 1n Figure 1, the first three are cutbacks.
Figure 1. Liquid Asphaltic Products
6ASMME
or
mnmu
ASPHALT
coma
nosK
ASPMAIT
CEMENT
UNIT
WLATUft
MM-
VOUTftE
MS
ASPHALT
CEMENT
HMD
m
EMMFB
ASPHALT
CEMEKT
WATER
AND
EMUUfn
RCMCorSC
1HXHD ASPHALT
jura MEMHM sum ASPHALT mam
CUMNG OJIM6 OHUNG EMUSKMS EMULSfKD
OK) OM CO ASPHALT
•MB MS
1
^ 1
Upon exposure to atmospheric conditions, the highly volatile naphtha
solvent in rapid curing blends evaporates quickly and leaves a hard
viscous base asphalt. Less volatile kerosene evaporates more slowly
from medium curinq blends and leaves a base asohalt of medium hardness
or viscosity. Slow curing blends contain a low volatility fuel oil type
solvent hence they require the longest curing period; they leave a soft
low viscosity asphalt on the aggregate. Slow curing cutback alternately
2-1
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may be made directly by distillation. Both the curing rate and
characteristics of the residual asphalt are factors to be considered 1n the
selection of liquid asphalts for various uses.2 Cutback asphalts are
applied either 1n a spray directly to the road surface or 1n a cold nr*:-.
either prepared 1n advance of application, or at the job site.
Hydrocarbons evaporate from cutback asphalts at the job-site and
mixing plant. At the job-site, hydrocarbons are emitted from equipment
used for applying the asphaltlc product and from road surfaces. At the
mixing plant hydrocarbons are released during mixing and stockpiling.
The largest source of emissions, however, 1s the road surface Itself.
For any given asphalt/solvent mix, total emissions will remain the
same regardless of stockpiling, mixing, and application time. The control
technique requires the substitution of an emulsifying agent and water for the
petroleum distillate resulting 1n an emission reduction at all the sources.
Switching to an emulsion does not result In any equipment changes or
application procedure changes. The major consideration Is that the
emulsion mixes properly with the aggregate resulting 1n a pavement of
comparable durability. States with experience In applying asphalt report
that emulsions can be used 1n almost all applications where cutback has
heretofore been employed. In the past three to four years the State of New
York cites little or no difficulty 1n converting 100 percent from cutback to
emulsified asphalt. The State of Pennsylvania 1s presently using 70 percent
emulsified asphalt to 30 percent cutback asphalt; the State Is committed to
2-2
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emulsions and expects to substitute 1n greater quantity.4 The State of
Indiana Is a heavy user of emulsified asphalt, as well as a strong
supporter of Its use. Some State highway departments have expressed
concern over the use of emulsified asphalt during wet and cold weather
and In applications which require stockpiling. States which experience
wet and cold weather, however, have been able to switch from cutback
to emulsified asphalt.
2.1 UNCONTROLLED EMISSIONS
It is the petroleum distillate (diluent) in the cutback asphalt
that evaporates; the average diluent content in the cutback is 35
percent by volume. The percentage of diluent to evaporate is dependent
on the cure type. The emission factors are: Slow cure (SC) - 20 to
30 percent of diluent content, average 25 percent; Medium cure (MC) -
60 to 80 percent, average 70 percent; Rapid cure (RC) - 70 to 90 percent,
average 80 percent. These factors are independent of the percent of
diluent in the mix within the normal range of diluent ysage for cutback
asphalts.
2.2 REFERENCES
1. A Brief Introduction to Asphalt and Some of Its Uses, The
Asphalt Institute, Manual Series No. 5 (MS-5), Seventh Edition, September
1974, p. 3.
2. ASTM, Designation D2399, Draft 12-3-75, Revision 7-22-76, p. 6.
3. Letter from William P. Hofmann, P.E., Deputy Chief Engineer,
Department of Transportation, New York State to David W. Markwordt,
2-3
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Section Engineer, Office of Air Quality Planning and Standards, Environmental
Protection Agency, RTP, N.C. 27701, September 14, 1977.
4. Klrwan, Francis M. and Maday, Clarence, "Air Quality and Energy
Conservation Benefits From Using Emulsions to Replace Asphalt Cutbacks 1n
Certain Paving Operations," Draft, May 1977, Appendix E, p. E-3.
5. Letter from Roger Marsh, Executive Director, Indiana State
Highway Commission to Richard Rhoads, Director, Control Programs Development
Division, Office of A1r Quality Planning and Standards, Environmental
Protection Agency, RTP, N.C., 27701, June 28, 1977.
6. Memo from Francis Klrwan, Environmental Protection Agency, Office
of Air Quality Planning and Standards, Energy Strategies Branch to the files,
October 3, 1977.
2-4
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3.0 COSTS OF APPLYING THE TECHNOLOGY
To address the costs of replacement of asphalt cutbacks with asphalt
emulsions, this section focuses on the differences In unit operating costs
between cutbacks and emulsions on a cents per gallon basis. The user of
asphalt mixes does not .nave to.undergo..any capital expenditures In making
the substitution. Generally, the same mixing plant that formulates cutback
mixtures can prepare emulsion paving mixtures without any equipment changes.
In addition, the same highway equipment used for application of cutback can
be used to apply emulsions.
The comparison of asphalt cutbacks with emulsions Is best stated In
terms of a price per gallon for the total asphalt mix. State highway
departments In their procurement of construction projects with paving
contractors view costs in this manner. A typical example might be a
reported price comparison for Waukesha County, Wisconsin. The cost of
emulsified asphalt was 33.75 certs per gallon versus 36.92 cents per
gallon for cutback, a savings of approximately 10 percent for the emulsion
mix. According to Industry representatives each gallon of cutback In the
total asphalt mix 1s normally replaced with one gallon of emulsion. Based on
communications with 35 State highway departments, substitution of emulsions can
2
result in savings up to 20 percent, which is approximately 6 to 7 cents per
gallon. Conversely, one State reported a cost penalty of 1 cent per gallon
3
for the use of emulsions. A review of price quotations in the Engineering
3-1
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4
News Record for 11 metropolitan areas finds that price differences for
emulsions range from a 5 cent per gallon savings to a 1 cent per gallon
penalty. These price quotations were based on materials used for surface
treatment applications (Rapid cure cutback, for example). Based on the
responses from the States and the literature, the conclusion Is that overall
replacement of cutbacks with emulsions will generally result 1n savings on
the order of 3 cents per gallon.
It would appear that the most Important factors that affect pricing
of the two competing asphalts are the type of application (slow, medium,
rapid cure), customer reluctance toward emulsions in some areas, and
availability of distillates. However, the extent to which these factors
apply Is difficult to quantify. The size of the paving project 1s not a
factor.
In terms of cost-effectiveness, a 1 cent per gallon differential
represents a cost or a credit of 1.6 cents per kilogram of VOC emission
reduction. The basis for this derivation is the following assumptions:
(1) a nationwide emission rate of 655,000 metric tons per year of
VOC emissions from 3,"29,000 metric tons of asphalt cutback sold in 1975
(see page 4-1) and
(2) a weight density of 7.82 pounds per gallon for medium cure
cutback, which is the most common type cutback used.
3-2
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3.1 REFERENCES
1. Kirwan, Francis M. and Maday, Clarence, "Air Quality and Energy
Conservation Benefits From Using Emulsions to Replace Asphalt Cutbacks In
Certain Paving Operations." Draft May 1977, Appendix E, page E-l.
2. Personal Communication from William Hofmann, Deputy Chief
Engineer, Department of Transportation of New York, to David Markwordt,
Emission Standards and Engineering Division, Office of Air Quality Planning
and Standards, U.S. Environmental Protection Agency, September 14, 1977.
3. Personal Communication from Robert N. Hunter, Chief Engineer,
Missouri State Highway Commission to Roger Powell, Control Programs
Development Division, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, June 3, 1977.
4- Engineering News Record, a McGraw-Hill Weekly Publication,
October 6, 1977.
3-3
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4.0 EFFECTS OF APPLYING THE TECHNOLOGY
4.1 IMPACTS ON ATMOSPHERIC EMISSIONS
The estimated uncontrolled hydrocarbon emissions In 1975 from the
use of cutback asphalt were 655,000 metric tons per year. This represents
3.8 percent of the estimated 1975 total stationary source hydrocarbon
emissions of 18 million metric tons per year.
The 1975 national sales of cutback asphalts for paving are as
follows: Slow cure (SC) - 901,000 metric tons; Medium cure (MC) -
1,840,000 metric tons; and Rapid cure (RC) - 988,000 metric tons.1
Hydrocarbon emissions * cutback asphalt (metric tons/year)
X fraction diluent (assume 35% by volume.
therefore, by weight SC = 31.1%;
MC = 29.8%; RC = 25.5%)2
X fraction of diluent that evaporates
Total hydrocarbon emissions = (901,000) (.311) (.25) +
(1,840,000 (.298) (.70) +
(988,000) (.255) (.80) = 655,000
metric tons/year
The use of emulsified asphalt 1n place of cutback asphalts results in a
100 percent reduction of hydrocarbon emissions.
4.2 WATER AND SOLID WASTE IMPACT
There are no significant solid or liquid wastes associated with the
use of emulsified asphalt.
4-1
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4.3 ENERGY IMPACT
The total energy associated with manufacturing, processing, and
laying one gallon of cutback asphalt 1s approximately 50,200 Btu. On
the other hand, analysis of emulsified asphalts shows that about 98 percent
of the petroleum diluents are replaced with water with the result that only
2,830 Btu are associated with each gallon of emulsified asphalt.3 Based
on the 1975 usage, the substitution of emulsions for the petroleum distillate
would save approximately 1.6 bill1on liters of distillate for use as or
conversion to fuels.
4.4 REFERENCES
1. Kirwan, Francis M. and Maday, Clarence, "Air Quality and Energy
Conservation Benefits From Usir.g Emulsions to Replace Asphalt Cutbacks in
Certain Paving Operations," Draft May 1977, Appendix C, p. C-l.
2. Memo from David W. Markwordt, Environmental Protection Agency, Office
of Air Quality Planning and Standards, Chemical and Petroleum Branch to the
files, October 14, 1977.
3. Kirwan, Francis M. and Maday, Clarence, op.cit. p. D-2.
4-2
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(ITeae rtad IiutnictioM on the revene before compUOiif} _
1. REPORT NO.
EPA -450/2-77-037
4. TITLE AND SUBTITLE
Control of Volatile Orgar
Cutback Asphalt
7. AUTHOR(S)
David W. Markwordt, ESED
Frank Runyard, SASD
9. PERFORMING ORGANIZATION NAME AM
Environmental Protection
Office of Air and Waste *
Office of Air Quality PI a
Research Triangle Park, h
2. 3. RECII
B. REPO
i1c Compounds From Use of . ...
B* PERF
B. PERF
OAOf
D ADDRESS 10. PRO
Agency
lanagement n.cdN
nning and Standards
lorth Carolina 27711
12. SPONSORING AGENCY NAME AND ADDRESS 13. TYP
SAKE *« <&>*** . Q t
RT DATE
DRMING ORGANIZATION CODE
DRMING ORGANIZATION REPORT NO.
'S 1.2-090
GRAM ELEMENT NO.
TRACT/GRANT NO.
E OF REPORT AND PERIOD COVERED
NSORING AGENCY CODE
200/04
16. ABSTRACT
This document addresses the control of volatile organic compounds (VOC)
from paving asphalts liquefleld with petroleum distillate. The recommended control
technology consists of the substitution of emulsions for cutback asphalt.
17.
a. DESCRIPTORS
Air Pollution
Asphalt CuUack
Emulsified Asphalt
Regulatory Guidance
18. DISTRIBUTION STATEMENT
EPA Form 222O-1 («-73)
KEY WORDS AND DOCUMENT ANALYSIS
b. IDENTIFIERS/OPEN ENDE
A1r Pollution Co
Stationary Sourc
Organic Vapors
i». SECURITY"CLASS fnatl
Unclassified
20. SECURITY CLASS (TUi f
Unclassified
D TERMS c. COSATI Field/Group
ntrol
5S
leport) 21. NO. OF PAGES
18
*gt) 22. PRICE
f^Z A/?<2 - AM
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