1. Evaluating the Effect of Coarse Rubber Particles on Asphalt Concrete Mixtures James K. Laicovsky Laura C. Miller Amanda R. Zimmerman The 18 th International Conference on Solid Waste Technology and Management Philadelphia, PA March 25, 2003

2. Outline of Presentation  The Tire Problem  Superpave  Project Scope  Results

3. Waste Tires Total ~ 300 Million Tires ~2.5 Million Tons

4. Solid Waste in the U.S. Scrap Tires = 1.5% Commercial & Industrial Residential

6. Solution

7. Recent Projects 85% of scrap tires are located in -- Connecticut, New York, Pennsylvania, Ohio, Michigan, Colorado, Virginia, Texas, and Alabama.

8. Superpave SUperior PERforming Asphalt PAVEments Strategic Highway Research Program New techniques to specify, test, and design

9. Project Scope §Rubber Analysis §Gradation Manipulation §Rubber Substitution §Specimen Fabrication §Specimen Testing §Fine-Tune Rubber Substitution

10. Gradation Manipulation Desired Superpave Gradation Curve Sieve Size.45 Percent Passing Bad Mix Good Mix Bad Mix

11. Rubber Analysis ¾” Rubber Particles #4 Rubber Particles #12 Rubber Particles

12. Rubber Substitution §Substituted Rubber into Original Superpave Gradation §0.5% - 5.0% Rubber Particles

13. Specimen Fabrication

14.  Gyratory Compactor 1.25°

15. GC Data Compaction Height, cm Gyration, N

16. 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 gyrations Lower the number, softer mix

17. GC Data Plot Log (Number of gyrations), N Compaction Height, cm

18. Results Area Under “k” Curve vs. Rubber Substitution Area Under “k” Curve Rubber Substitution, %

19. Analysis  4% rubber substitution uses:  60 tons of GTR ~ 7,600 tires/lane mile  Rubber cost ~ $10,000/lane mile

20. Analysis  4% rubber substitution reduces:  780 tons of aggregates ~ $156,000 savings/lane mile Savings of $146,000/lane mile

21. Conclusions  Improved rutting performance.  Potentially useful with NJ aggregates.  Continued investigation to determine optimal substitution percentage.

22. Web Site http://engineering.rowan.edu/~mill2633/rowan_rubber.htm

23. QUESTIONS?