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!

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 Sensitivity

Test

Moisture Sensitivity

Test

Dynamic Modulus

Test

Dynamic Modulus

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 Environment

Happier Workers

Better Performance

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