This document summarizes research on warm-mix asphalt (WMA) conducted by the University of Iowa. The research evaluated several WMA additives in the laboratory and found that Sasobit, Evotherm J1, and Rediset WMX were effective at producing WMA mixtures with comparable performance to hot-mix asphalt. WMA was shown to reduce worker exposure to fumes, lower construction costs through reduced energy usage, and decrease environmental impacts versus hot-mix asphalt. Future research opportunities were identified to further study WMA mixtures and their field performance.

1. Warm-Mix Asphalt: A Window to a Better Road
Phase 1
Hosin “David” Lee, P.E. Ph.D., Professor
Public Policy Center,
Department of Civil and Environmental Engineering,
University of Iowa
President of Korean-American Scientists and Engineers
Association (KSEA)

2. Disclaimer
The contents of this report reflect the views of
the authors, who are responsible for the facts
and the accuracy of the information presented
herein. This document is disseminated under the
sponsorship of the Department of Transportation
University Transportation Centers Program, in
the interest of information exchange. The U.S.
Government assumes no liability for the contents
or use thereof.

3. University of Iowa in Iowa City

4. Global Warming
Grinnell Glacier, Glacier National Park, Montana
1911 2000

5. Since 1979,
more than 20% of the polar icecap has melted!

6. Climate
Change is Real!

7. First Modern Asphalt Facility
Built in 1901 by Warren Brothers in
East Cambridge, Massachusetts

8. Current Asphalt Plants in United States
 About 4,000 asphalt mixing
plants
 Mostly drum mix plants
 Produces 500 million tons of
HMA

9. Mixing Temperatures of HMA
Grade
HMA Plant Mixing Temperature, °C
Range Midpoint
PG 58-28 127 ~ 154 140
PG 64-22 129 ~ 160 144
PG 70-22 138 ~ 165 152
PG 76-22 140 ~ 168 154

10. Too High Temperature of Asphalt Mix
 During the past century, the asphalt industry
has been concerned about keeping the
temperature of asphalt mix high enough for
adequate coating, placement, and compaction.
 An answer to the problems in coating and
compaction has been to raise the temperature
of asphalt mix.
 Now, for better performance and the
environment, a new approach is to lower the
temperature of asphalt mix: Warm-Mix
Asphalt (WMA), a window to the future.

11. Worker’s Exposure to Asphalt Fumes
 About 4,000 asphalt plants and 7,000 paving contractors
employ nearly 300,000 workers in the United States.
 In 1977, the National Institute for Occupational Safety
and Health (NIOSH) recommended that workers should
not be exposed to airborne particulates at a concentration
greater than 5mg/m3 during any 15-minute period.
 NIOSH concluded that the collective data currently
available from studies on paving asphalt provided
insufficient evidence for an association between lung
cancer and exposure to asphalt fumes during paving.
 Asphalt fumes and PAHs at the HMA job site were below
the current acceptable exposure limits.

12. Exposure of Workers to Emissions Working
at HMA and WMA Job Sites
0
2
4
6
8
10
12
Exposure
in mg/m3
Pavor Operator Screedman
HMA
WMA

13. Which Picture Represent WMA
Construction Sites in Iowa?

14. WMA Plants Reduce Greenhouse Gas
EAP (2006); Newcomb (2007); Ruhl (2004); D’Angelo (2008)
 The U.S. Environmental Protection Agency (EPA) issued a
rule that was designed to reduce SO2 by 70% and NOx
emissions by 60% by 2015.
 Some state and local governments require that HMA
plants in some ozone sensitive areas limit asphalt
production to a certain number of hours per week.
 WMA plants would reduce CO2 and SO2 by 30% to 40%,
volatile organic compounds (VOC) by 50 percent, CO by
10% to 30%, NOx by 60% to 70% and dust by 20% to
25%.

15. WMA Saves Energy Cost Compared with HMA
Iceland Honolulu, HI Joliet, IL
Fuel source No. 2 Fuel oil Diesel Natural gas
Fuel to make 1 ton
of HMA
2-3 gallons 2-3 gallons 2.5-3.5 therms
Fuel Cost $2.50/gal $2.20-3.20/gal $0.70-0.80/therm
Fuel Cost to make
1 ton of HMA
$5.00-$7.50 $4.40-$9.00 $1.75-$2.80
Electricity to make
1 ton of HMA
8-14 kWh 8-14 kWh 8-14 kWh
Electricity Cost $0.02/kWh $0.1805/kWh $0.0445/kWh
Average energy
cost for 1 ton of HMA
$5.15-$7.78 $5.84-$11.53 $2.11-$3.44
20% savings with
WMA
$1.00-$1.50 $0.88-$1.80 $0.35-$0.56
50% savings with
WMA
$2.50-$3.75 $2.20-$4.50 $0.88-$1.40
Ólöf Kristjánsdóttir (2007)

16. WMA Technology
Category WMA Additive Company U.S. Project
Organic
Sasobit®
Asphaltan®
Licomont BS-100
Cecabase RT®
LeadCap
Sasobit
Romonta
Clariant
Ceca
Kumho
Yes
N/A
N/A
Yes
Yes
Foaming
Advera®
Aspha-Min®
Low Energy Asphalt
Double-Barrel®Green
Ultrafoam GX
Terex®WMA System
Aquablack Warm Mix Asphalt
WAM-Foam
Eurovia
PQ Corporation
McConnaughay Tech.
Astec
Gencor
Terex
Maxam Equipment Inc
Kolo Veidekke, Shall
Yes
Yes
Yes
Yes
Yes
Yes
Yes
N/A
Chemical
Evotherm J1
RedisetTM WMA
MeadWestVaco/Mathy
Akzo Nobel
Yes
Yes

17. WMA Additives Selected for Laboratory
Evaluation at the University of Iowa
Organic
Additives:
CECABASE RT®,
Sasobit®
Foaming
Additives:
Asphalt-min®,
Advera WMA
Chemical
Additives:
Evotherm J1,
RedisetTM WMX

18. Evaluation of WMA Products in Laboratory
Indirect
Tensile
Strength
Test
Moisture
Sensitivity
Test
Dynamic
Modulus
Test
Repeated
Load
Test
Temperature
Maximum Specific
Gravity
Bulk Specific Gravity Air Void
Six WMA Mixtures:
CECABASE RT®, Sasobit®, Asphalt-min®, Advera
WMA, Evotherm J1, and RedisetTM WMX.
Control WMA Mixture
and HMA Mixture

19. Mixing Method and Dosage Rate of WMA Additive
Additive Process Dosage Rate
CECABASE RT® Wet 0.40% of binder weight
Sasobit®
Dry
1.50% of binder weight
Wet
Asphalt-min® Dry 0.30% of mixture weight
Advera WMA® Dry 0.25% of mixture weight
Evotherm J1® Wet 0.50% of binder weight
RedisetTM WMX Wet 2.00% of binder weight

20. Mix Design Parameters
Aggregates
Nominal Maximum Aggregate Size of
19.0 mm
Ndesign 86 gyrations (for 3 million ESAL)
Asphalt Content 5.5% using PG 64-34
Aggregate Heating
Temp.
125°C for WMA
135°C for HMA
Asphalt Heating
Temp.
149°C for both WMA and HMA

21. Mixing and Compaction Temperatures of
WMA Mixtures
110
120
130
140
150
160
170
CECABASE
RT®
Sasobit®
(Wet
Process)
Sasobit®
(Dry
Process)
Aspha-min®
(Powder)
Aspha-min®
(Granular)
Advera
WMA
Evotherm J1 Rediset
WMX
Control
WMA
Control HMA
Type of Mixture
Temperature(˚C)
Average of Aggregate Temperature
Average of Mixing Temperature
Low Compaction Temperature
High Compaction Temperature

22. Density of WMA Mixtures

23. Air Voids of WMA Mixtures

24. Moisture Sensitivity of WMA Mixtures
0
200
400
600
800
CECABASE
RT®
Sasobit®
(Wet
Process)
Sasobit®
(Dry
Process)
Aspha-min®
(Powder)
Aspha-min®
(Granular)
Advera
WMA
Evotherm J1 Rediset
WMX
Control
WMA
Control HMA
Type of Mixture
IndirectTensileStrenght(psi)
Dry Condition Wet Condition
TSR=
48.6%
TSR=
41.4%
TSR=
50.5%
TSR=
35.4%
TSR=
37.8%
TSR=
31.9%
TSR=
61.5%
TSR=
57.6%
TSR=
38.2%
TSR=
68.0%

25. Asphalt Material Performance Testing (AMPT)
Equipment was used to Measure
Dynamic Modulus and Flow Number

26. Dynamic Modulus @ 4.4° C
0
5,000
10,000
15,000
20,000
0.1 1 10 100
Loading Frequency (Hz)
DynamicModulus(Mpa)at4.4˚C
CECABASE RT®
Sasobit® (Wet Process)
Sasobit® (Dry Process)
Aspha-min® (Granular)
Advera WMA
Evotherm J1
Rediset WMX
Control WMA
Control HMA

27. Dynamic Modulus @ 21.1° C
0
2,000
4,000
6,000
8,000
0.1 1 10 100
Loading Frequency (Hz)
DynamicModulus(Mpa)at21.1˚C
CECABASE RT®
Sasobit® (Wet Process)
Sasobit® (Dry Process)
Aspha-min® (Granular)
Advera WMA
Evotherm J1
Rediset WMX
Control WMA
Control HMA

28. Dynamic Modulus @ 37.8° C

29. Master Curves of WMA Mixtures
1.0.E+05
1.0.E+06
1.0.E+07
1.0.E+08
1.E-05 1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 1.E+07
Frequency, Hz
DynamicModulus,KPa
CECABASE RT®
Sasobit® (Wet Proess)
Sasobit® (Dry Proess)
Aspha-min® (Granular)
Advera WMA
Evotherm J1
Rediset WMX
Control WMA
Control HMA

30. Flow Number of WMA Mixtures
at 45° C 138 kPa

31. Ranking of ITS, TSR, Dynamic Modulus, and Flow
Number of WMA Mixtures
Type of Mix
Ranking
Average
Ranking
Score
Indirect
Tensile
Strength
Tensile
Strength
Ratio
Dynamic
Modulus
Flow Number
CECABASE RT® 9 5 9 8 7.75
Sasobit®
(wet process) 3 6 1 2 3
Sasobit®
(dry process) 4 4 2 1 2.75
Aspha-min® (powder) 10 9 - - 9.5
Aspha-min®
(granular) 7 8 7 7 7.25
Advera WMA 8 10 5 9 8
Evotherm J1 1 2 6 6 3.75
RedisetTM WMX 2 3 3 5 3.25
Control WMA 5 7 8 4 6
Control HMA 6 1 4 3 3.5

32. Summary and Conclusions
 Based on the limited test results, Sasobit®, Evotherm J1,
and RedisetTM WMX additives are effective in producing
WMA mixtures in the laboratory that are comparable to
HMA mixtures.
 Pavement is expected to perform better because the
asphalt is not aged.
 Working environment will be better for construction
workers with a lower amount of asphalt fumes.
 In the future, the majority of asphalt mixtures will be
produced at a lower temperature than today.

33. Better
Environment
Happier
Workers
Better
Performance
WMA

34. Future Research
 Lime and Anti-stripping Additives should be
considered for WMA to improve the moisture
susceptibility.
 To predict the rutting
performance under
moisture, Hamburg
Wheel Tracking test
should be performed.
 More test sections using WMA should be constructed
adjacent to HMA.

35. Cool-Mix Asphalt:
A Door to a Better Road
Phase 2

36. Slide design © 2009, Mid-America Transportation Center. All rights reserved.
Dr. Yongjoo Kim, Anand Sampath
Nishant Sheth, Jeremy Purvis, David Blanco
Korea Institute of Construction Technology (KICT)
Kumho Petrochemical Ltd.
CREDITS