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)
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.
University of Iowa in Iowa City
Global Warming
Grinnell Glacier, Glacier National Park, Montana
1911
2000
Since 1979,
more than 20% of the polar icecap has melted!
Climate
Change is Real!
First Modern Asphalt Facility
Built in 1901 by Warren Brothers in
East Cambridge, Massachusetts
Current Asphalt Plants in United States
 About 4,000 asphalt mixing
plants
 Mostly drum mix plants
 Produces 500 million tons of
HMA
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
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.
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.
Exposure of Workers to Emissions Working
at HMA and WMA Job Sites
12
10
HMA
8
Exposure
in mg/m3
6
4
WMA
2
0
Pavor Operator
Screedman
Which Picture Represent WMA
Construction Sites in Iowa?
WMA Plants Reduce Greenhouse Gas
 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%.
EAP (2006); Newcomb (2007); Ruhl (2004); D’Angelo (2008)
WMA Saves Energy Cost Compared with HMA
Iceland
Honolulu, HI
Joliet, IL
No. 2 Fuel oil
Diesel
Natural gas
2-3 gallons
2-3 gallons
2.5-3.5 therms
$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
Fuel source
Fuel to make 1 ton
of HMA
Fuel Cost
Ólöf Kristjánsdóttir (2007)
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
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
Evaluation of WMA Products in Laboratory
Six WMA Mixtures:
CECABASE RT®, Sasobit®, Asphalt-min®, Advera
WMA, Evotherm J1, and RedisetTM WMX.
Control WMA Mixture
and HMA Mixture
Indirect
Tensile
Strength
Test
Temperature
Maximum Specific
Gravity
Bulk Specific Gravity
Air Void
Moisture
Sensitivity
Test
Dynamic
Modulus
Test
Repeated
Load
Test
Mixing Method and Dosage Rate of WMA Additive
Additive
CECABASE RT®
Process
Wet
Dosage Rate
0.40% of binder weight
Dry
Sasobit®
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
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 125°C for WMA
Temp.
135°C for HMA
Asphalt Heating
Temp.
149°C for both WMA and HMA
Mixing and Compaction Temperatures of
WMA Mixtures
170
Average of Aggregate Temperature
Average of Mixing Temperature
Temperature (˚ C)
160
Low Compaction Temperature
High Compaction Temperature
150
140
130
120
110
CECABASE
RT®
Sasobit®
(Wet
Process)
Sasobit®
(Dry
Process)
Aspha-min® Aspha-min®
(Powder)
(Granular)
Advera
WMA
Type of Mixture
Evotherm J1
Rediset
WMX
Control
WMA
Control HMA
Density of WMA Mixtures
Air Voids of WMA Mixtures
Moisture Sensitivity of WMA Mixtures
800
Dry Condition
Indirect Tensile Strenght (psi)
600
TSR=
48.6%
TSR=
41.4%
TSR=
50.5%
TSR=
35.4%
TSR=
31.9%
TSR=
57.6%
Wet Condition
TSR=
38.2%
TSR=
68.0%
TSR=
37.8%
TSR=
61.5%
400
200
0
CECABASE
RT®
Sasobit®
(Wet
Process)
Sasobit®
(Dry
Process)
Aspha-min® Aspha-min®
(Powder)
(Granular)
Advera
WMA
Type of Mixture
Evotherm J1
Rediset
WMX
Control
WMA
Control HMA
Asphalt Material Performance Testing (AMPT)
Equipment was used to Measure
Dynamic Modulus and Flow Number
Dynamic Modulus @ 4.4° C
Dynamic Modulus (Mpa) at 4.4˚C
20,000
CECABASE RT®
Sasobit® (Wet Process)
Sasobit® (Dry Process)
Aspha-min® (Granular)
Advera WMA
Evotherm J1
Rediset WMX
Control WMA
15,000
Control HMA
10,000
5,000
0
0.1
1
10
Loading Frequency (Hz)
100
Dynamic Modulus @ 21.1° C
Dynamic Modulus (Mpa) at 21.1 ˚C
8,000
CECABASE RT®
Sasobit® (Wet Process)
Sasobit® (Dry Process)
Aspha-min® (Granular)
Advera WMA
Evotherm J1
Rediset WMX
Control WMA
6,000
Control HMA
4,000
2,000
0
0.1
1
10
Loading Frequency (Hz)
100
Dynamic Modulus @ 37.8° C
Master Curves of WMA Mixtures
Dynamic Modulus, KPa
1.0.E+08
1.0.E+07
CECABASE RT®
Sasobit® (Wet Proess)
1.0.E+06
Sasobit® (Dry Proess)
Aspha-min® (Granular)
Advera WMA
Evotherm J1
Rediset WMX
Control WMA
Control HMA
1.0.E+05
1.E-05
1.E-03
1.E-01
1.E+01
Frequency, Hz
1.E+03
1.E+05
1.E+07
Flow Number of WMA Mixtures
at 45° C 138 kPa
Ranking of ITS, TSR, Dynamic Modulus, and Flow
Number of WMA Mixtures
Ranking
Indirect
Tensile
Strength
Tensile
Strength
Ratio
Dynamic
Modulus
Flow Number
Average
Ranking
Score
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
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
Type of Mix
Aspha-min® (powder)
Summary and Conclusions
 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.
 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.
 In the future, the majority of asphalt mixtures will be
produced at a lower temperature than today.
Better
Performance
WMA
Better
Environment
Happier
Workers
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.
Cool-Mix Asphalt:
A Door to a Better Road
Phase 2
CREDITS
Dr. Yongjoo Kim, Anand Sampath
Nishant Sheth, Jeremy Purvis, David Blanco
Korea Institute of Construction Technology (KICT)
Kumho Petrochemical Ltd.
Slide design © 2009, Mid-America Transportation Center. All rights reserved.