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Warm-Mix Asphalt: A Window to a Better Road
Phase 1
Hosin “David” Lee, P.E. Ph.D., ProfessorPublic Policy Center,
Department of Civil and Environmental Engineering,University of Iowa
President of Korean-American Scientists and Engineers Association (KSEA)
DisclaimerThe 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
GradeHMA 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
0
2
4
6
8
10
12
Exposure
in mg/m3
Pavor Operator Screedman
HMA
WMA
Which Picture Represent WMA Construction Sites in Iowa?
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%.
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 make1 ton of HMA
$5.00-$7.50 $4.40-$9.00 $1.75-$2.80
Electricity to make1 ton of HMA
8-14 kWh 8-14 kWh 8-14 kWh
Electricity Cost $0.02/kWh $0.1805/kWh $0.0445/kWh
Average energycost 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)
WMA Technology
Category WMA Additive Company U.S. Project
Organic
Sasobit®Asphaltan®Licomont BS-100Cecabase RT®LeadCap
SasobitRomontaClariantCecaKumho
YesN/AN/AYesYes
Foaming
Advera®Aspha-Min®Low Energy Asphalt Double-Barrel®GreenUltrafoam GXTerex®WMA SystemAquablack Warm Mix Asphalt WAM-Foam
EuroviaPQ CorporationMcConnaughay Tech.AstecGencorTerexMaxam Equipment IncKolo Veidekke, Shall
YesYesYesYesYesYesYesN/A
ChemicalEvotherm J1RedisetTM WMA
MeadWestVaco/MathyAkzo Nobel
YesYes
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
Indirect Tensile
Strength Test
Indirect Tensile
Strength Test
Moisture Sensi-tivity Test
Moisture Sensi-tivity Test
Dynamic Modu-lus Test
Dynamic Modu-lus Test
Repeated Load Test
Repeated Load Test
TemperatureTemperature Maximum Specific Gravity
Maximum Specific Gravity
Bulk Specific Gravity Bulk Specific Gravity Air Void Air Void
Six WMA Mixtures:
CECABASE RT®, Sasobit®, Asphalt-min®, Advera WMA, Evotherm J1, and RedisetTM WMX.
Six WMA Mixtures:
CECABASE RT®, Sasobit®, Asphalt-min®, Advera WMA, Evotherm J1, and RedisetTM WMX.
Control WMA Mixture and HMA Mixture
Control WMA Mixture and HMA Mixture
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 weightWet
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
AggregatesNominal 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 WMA135°C for HMA
Asphalt Heating Temp. 149°C for both WMA and HMA
Mixing and Compaction Temperatures of WMA Mixtures
110
120
130
140
150
160
170
CECABASERT®
Sasobit®(Wet
Process)
Sasobit®(Dry
Process)
Aspha-min®(Powder)
Aspha-min®(Granular)
AdveraWMA
Evotherm J 1 RedisetWMX
ControlWMA
Control HMA
Type of Mixture
Tem
pera
ture
(C̊
)
Average of Aggregate Temperature
Average of Mixing Temperature
Low Compaction Temperature
High Compaction Temperature
Density of WMA Mixtures
Air Voids of WMA Mixtures
Moisture Sensitivity of WMA Mixtures
0
200
400
600
800
CECABASERT®
Sasobit®(Wet
Process)
Sasobit®(Dry
Process)
Aspha-min®(Powder)
Aspha-min®(Granular)
AdveraWMA
Evotherm J 1 RedisetWMX
ControlWMA
Control HMA
Type of Mixture
Indir
ect
Ten
sil
e S
tren
gh
t (p
si)
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%
Asphalt Material Performance Testing (AMPT) Equipment was used to Measure
Dynamic Modulus and Flow Number
Dynamic Modulus @ 4.4° C
0
5,000
10,000
15,000
20,000
0.1 1 10 100
Loading Frequency (Hz)
Dyn
am
ic M
od
ulu
s (M
pa)
at
4.4̊
C
CECABASE RT®Sasobit® (Wet Process)
Sasobit® (Dry Process)Aspha-min® (Granular)
Advera WMAEvotherm J 1
Rediset WMXControl WMA
Control HMA
Dynamic Modulus @ 21.1° C
0
2,000
4,000
6,000
8,000
0.1 1 10 100
Loading Frequency (Hz)
Dyn
am
ic M
od
ulu
s (
Mp
a)
at
21
.1̊C
CECABASE RT®Sasobit® (Wet Process)
Sasobit® (Dry Process)Aspha-min® (Granular)
Advera WMAEvotherm J 1
Rediset WMXControl WMA
Control HMA
Dynamic Modulus @ 37.8° C
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
Dyn
am
ic M
od
ulu
s,
KP
a
CECABASE RT®
Sasobit® (Wet Proess)
Sasobit® (Dry Proess)
Aspha-min® (Granular)
Advera WMA
Evotherm J 1
Rediset WMX
Control WMA
Control HMA
Flow Number of WMA Mixtures at 45° C 138 kPa
Ranking of ITS, TSR, Dynamic Modulus, and Flow Number of WMA Mixtures
Type of Mix
RankingAverage Ranking
Score
Indirect Tensile
Strength
Tensile Strength
Ratio
Dynamic Modulus
Flow Number
CECABASE RT® 9 5 9 8 7.75Sasobit®(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
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.
Better Envi-ronment
Happier Workers
Better Per-formance
WMA
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
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