Evaluating the Effect of Coarse Rubber Particles on Asphalt Concrete Mixtures

James K. LaicovskyLaura C. Miller

Amanda R. Zimmerman

The 18The 18thth International Conference on Solid Waste International Conference on Solid Waste Technology and Management Technology and Management

Philadelphia, PA Philadelphia, PA March 25, 2003 March 25, 2003

Outline of Presentation

The Tire Problem

Superpave

Project Scope

Results

Waste Tires

Total ~ 300 Million Tires

~2.5 Million Tons

Solid Waste in the U.S.

Scrap Tires = 1.5%

Commercial

&

IndustrialResidential

Solution

Recent Projects

85% of scrap tires are located in --

Connecticut, New York, Pennsylvania ,

Ohio, Michigan, Colorado, Virginia,

Texas, and Alabama.

Superpave

•SUperior PERforming Asphalt PAVEments

•Strategic Highway Research Program

•New techniques to specify, test, and design

Project Scope

Rubber AnalysisGradation ManipulationRubber SubstitutionSpecimen FabricationSpecimen TestingFine-Tune Rubber Substitution

Gradation Manipulation

Desired Superpave Gradation Curve

Sieve Size.45

Perc

en

t Pass

ing

Bad Mix

Good Mix

Good Mix Bad Mix

Rubber Analysis

¾” Rubber Particles

#4 Rubber Particles

#12 Rubber Particles

Rubber Substitution

Substituted Rubber into Original Superpave Gradation

0.5% - 5.0%

Rubber Particles

Specimen Fabrication

Specimen Fabrication Gyratory Compactor

1.25°

GC Data

112

117

122

127

132

137

142

0 10 20 30 40 50 60 70 80 90 100 110

0%

0.50%

1.00%

1.50%

2.00%

5.00%

Com

pacti

on

Heig

ht,

cm

Gyration, N

GC Data Analysis

Log (Number of Gyrations)

0 100

H1

H2

Area = ½(H1-H2)(log100-log1)

k

1

Slope = k

Air voids at 100 gyrationsLower the number, softer mix

GC Data Plot

110

115

120

125

130

135

140

145

0 0.5 1 1.5 2 2.5

Linear (0%)

Linear (0.50%)

Linear (1.00%)

Linear (1.50%)

Linear (2.00%)

Linear (5.00%)

Log (Number of gyrations), N

Com

pacti

on

Heig

ht,

cm

Results

245

250

255

260

265

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5

Area Under “k” Curve vs. Rubber Substitution

Are

a U

nd

er

“k” C

urv

e

Rubber Substitution, %

Analysis

4% rubber substitution uses:

60 tons of GTR ~ 7,600 tires/lane mile

Rubber cost ~ $10,000/lane mile

Analysis

4% rubber substitution reduces:

780 tons of aggregates

~ $156,000 savings/lane mile

Savings of $146,000/lane mile

Conclusions

Improved rutting performance.

Potentially useful with NJ aggregates.

Continued investigation to determine optimal substitution percentage.

Web Site

http://engineering.rowan.edu/~mill2633/http://engineering.rowan.edu/~mill2633/rowan_rubber.htmrowan_rubber.htm

QUESTIONS?