WARM MIX ASPHALT PAVING THE GREEN WAY

Shu Wei GohZhanping You

Meor Othman Hamzah

Presentation Outline

• Warm Mix Asphalt Introduction• WMA Field Trial• Laboratory Evaluation• Summary and Conclusion

Hot Mix Asphalt• What is Warm Mix Asphalt (WMA)?

– A technology that allowed the producers of Hot-Mix Asphalt (HMA) pavement material to lower the temperatures at which the material is mixed and placed on the road.

• Available Technologies:– RH-WMA®, Aspha-min®, Advera WMA, Sasobit®,

Evotherm®,etc.

Warm

The wave of Future?

Why Warm Mix Asphalt?

• Reduce Production and Laydown Temperature• Reduce Emissions• Reduce Fuel Costs• Reduce Aging of Binder• Decrease Wear and Tear of Equipment• Increase Production Rates• Better Compaction• Maximization of Asphalt Recycling Rate

While achieving the same or better density

WMA Field Trial

Project Information

• Project Location: Spread Eagle, Wisconsin, USA• Asphalt Binder used: PG58-34• Design Traffic level: 3 millions ESALs• HMA

– Compaction Temp: 150˚C• WMA made with 1.5% Sasobit® (5E3)

– Compaction Temp: 127˚C

Project Location

Description Value

Ambient Air Temperature (ºC)

7.66

Surface Temp. (ºC)

11.61

Average Wind Speed (km/h)

8.05

Latitude (Deg. North)

88.08

Travel Distance: ~8-10km

Mixture Cooling time

0 5 10 15 20 25 30 35 40 45120

130

140

150

160

170

180

Time (minute)

Tem

per

atu

re (

Cel

siu

s) HMA, approximate 7 minutes traveling time

WMA, approximate 7 minutes traveling time

Calculated using MultiCool Program

WMA Construction at Iron Mountain, MI

Warm Mix Asphalt Hot Mix Asphalt

Reference: Goh, S. W., and You, Z. (2008). "Warm Mix Asphalt using Sasobit®: A Brief Field and Laboratory Experience." Mid-Continent Transportation Research Forum 2008, Wisconsin, Madison.

Stack Emission Results

NOX VOC CO2 Fuel Usage-40%

-30%

-20%

-10%

0%

10%

20%

Per

cen

t In

crea

se/ R

edu

ctio

n (

%)

Reference: Graham C. Hurley, Brian D. Prowell and Andrea N. Kvasnak (2009), Michigan Field Trial of Warm Mix Asphalt Technology: Construction Summary. NCAT Report No. 09-10, Auburn University

WMA Construction at Iron Mountain, MI

WMA Laboratory Testing

Laboratory Evaluation

• Volumetric Properties• APA Rutting• Dynamic Modulus Testing• Tensile Strength Ratio (TSR)

Material Preparation:Asphalt Mixture Performance Testing

• Testing Sample (Collected from Asphalt Plant at Iron Mt., MI):– Asphalt Binder used: PG58-34– SuperpaveTM Gyratory Compactor: 86 gyrations– HMA (5E3) – Compacted at 150◦C– WMA made with 1.5% Sasobit® (5E3) - Compacted at

127◦C

Sieve Size (mm) 12.5 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075

Percent Pass, % 100 99.1 75 55.9 41.3 27.5 14.5 7.5 5.5

AC, % 5.5

Volumetric Properties

Description HMA WMA

Maximum Specific Gravity, Gmm 2.573 2.569

Bulk Specific Gravity (Gmb) at the

end of Compaction2.441 2.455

Air Void Level 5.13% 4.45%

Asphalt Binder Content 5.52% 5.52%

APA Rutting Test

• Asphalt Pavement Analyzer:– The purpose of this test is to

evaluate the rut resistance of the asphalt mixture and the rut depth was measured using the Asphalt Pavement Analyzer machine.

• Testing Parameters:– 8000 Cycles– 58C (136 ˚F)– 100 lbs

APA Rutting Results

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

2

4

6

8

10

12

14

HMAWMA

Cycle Number

Per

man

ent

Def

orm

atio

n (m

m)

Dynamic Modulus Test

• Determined by applying sinusoidal vertical loads to cylindrical samples while measuring the deformation

• Tested ranged from 0.1 to 25 HZ

• Temperature tested: – -5C – 4C– 13C– 21.3C– 39.2C

Dynamic Modulus Test Results

0.00000001 0.000001 0.0001 0.01 1 1000

5000

10000

15000

20000

25000

Reduced Frequency

Dyn

amic

Mod

ulu

s (M

Pa) WMA

HMA

-10 0 10 20 30 40 50-6

-5

-4

-3

-2

-1

0

1HMA Shift Fac-tor

Temperature (Celsius)

Sh

ift

Fac

tor

Tensile Strength Ratio (TSR)

16.4 21.4 26.4 31.4 36.4 41.4 46.4 51.4 56.40

100

200

300

400

500

600

Time (Sec)

Ten

sile

Str

ess

(KP

a)

Tensile Strength Ratio

1.5% Sasobit (WMA) Control (HMA)0

100

200

300

400

500

600

700

520

609

442

532

Dry Moist

Ten

sile

Str

engt

h (K

Pa)

Ratio: 0.85±0.05

Ratio: 0.87±0.05

HMA vs WMAAfter 2 years of Serviceability

Sasobit® and Control Test Sections after Two Years of Traffic

Reference: Graham C. Hurley, Brian D. Prowell and Andrea N. Kvasnak (2009), Michigan Field Trial of Warm Mix Asphalt Technology: Construction Summary. NCAT Report No. 09-10, Auburn University

Description HMA Sasobit®

Rut Depth (mm) 1.4 0

Total Length of Crack (ft.) 3 46

Density (% Gmm) 97.3 95.7

Conclusions

• Emissions from WMA were significantly reduced compared to HMA production.

• Early performance indicates that Sasobit® WMA can be successfully used in cold weather climates.

• Based on emission stack testing, a decrease in asphalt stack emissions and fuel usage was determined during the production of WMA. An increase in CO and VOCs for the WMA indicates the need for additional burner tuning to fully combust the burner fuel

Conclusions

• WMA has a higher E* throughout all the temperatures and frequencies. Mixtures with higher E* generally have a lower rutting potential and this concluded that WMA has more resistance to rutting.

• Based on the tensile strength ratio result, it was found the moisture susceptibility of WMA was compatible with HMA. However, it was found that the tensile strength of WMA is lower than HMA.

Conclusions

• Based on the APA testing, the field produced WMA made with 1.5% Sasobit® (compact at 23 ˚C lower than HMA) has similar rutting potential compared to control HMA.

• Based on the field evaluation (after 2 years of serviceability), it was found that WMA made with Sasobit® has better rutting resistant. However, it was found the additional Sasobit® decreased the crack resistance of pavement.

Acknowledgements

The research work was partially sponsored by the Federal Highway Administration (FHWA) through Michigan Department of Transportation (MDOT).

The authors also acknowledge the funding support from the United States Department of Transportation through the University Transportation Center for Materials in Sustainable Transportation Infrastructure at Michigan Technological University.

Question?Shu Wei Goh, PhD.

(gsw@universalpave.com)

Asphalt Research Laboratory Testing

Dynamic Modulus Four Point Beam Fatigue

APA Rutting Indirect Tension

Flow Number

Gyratory Compactor

Direct Tension TestModified Asphalt BBR

Rotational Viscometer

Dynamic Shear Rheometer

Rutting, fatigue cracking, and low temperature cracking; moisture damage and reflective cracking; binder’s creep stiffness and rheological properties