Asphalt Rubber Asphalt Concrete Friction Course Overlay as a Pavement Preservation Strategy

1. Asphalt Rubber Asphalt Concrete Friction Course Overlay as a Pavement Preservation Strategy SIXTH MEXICAN ASPHALT CONGRESSCancun, Mexico, August 24th to 28th, 2009 K. Kaloush, K. Biligiri, M. Rodezno, M. Belshe Arizona State University, G. Way and D. Carlson, Rubber Pavement Association, Arizona, USA. J. Sousa, Consulpav International, Inc. USA - Portugal

2. Presentation Outline • Objectives of Study • Background on Asphalt Rubber • AR Pavement Preservation Strategy - Performance / Durability - Highway Noise - Thermal Gradient / Urban Climate Interaction - Friction / Safety and Ride Quality / Comfort - Tire Wear Emissions / Air Quality - Cost and Energy Consideration • Summary and Conclusions

3. Objective Evaluation of AR-ACFC benefits as a pavement preservation strategy in terms of laboratory material characterization tests and field performance evaluation including: highway noise reduction, mitigation of daily thermal variances in PCC pavements, improved skid resistance, reduced roughness, and reduction of emission rates of tire wear.

4. ASTM D8 Standard Definitions of Terms Relating to Materials for Roads and Pavements Asphalt Rubber–a blend of asphalt cement, reclaimed tire rubber and certain additives in which the rubber component is at least 15% by weight of the total blend and has reactedin the hot asphalt cement sufficiently to cause swelling of the rubber particles.

5. 13 mm ARFC ARAC 50 mmARAC Dense Open Gap / SMA Typical HMA Cross Section AR Bitumen Content 8.8 - 10% Air Voids 18 - 20% AR Bitumen 6.8- 8% Air Voids 7 - 10% Existing or new HMA Base Mix

6. Base Asphalts for AR Use Type 1: Hot Climate PG 64-16 (Pen 60/70) Type 2: Moderate Climate PG 58-22 (Pen 80/100) Type 3: Cold Climate PG 52-28 (Pen 200/300)

7. Is AR a Good Pavement Preservation Strategy? • Performance / Durability • Highway Noise • Thermal Gradient / Urban Climate Interaction • Friction / Safety • Ride Quality / Comfort • Tire Wear Emissions / Air Quality • Cost and Energy Consideration

8. 1- Performance / Durability • Binder Tests • Triaxial Shear Strength • Dynamic Modulus E* • Permanent Deformation FN / FT • Fatigue • IDT Creep and Strength

9. Temperature Rankine (R) Viscosity-Temperature Relationships

10. Dynamic Complex Modulus E* AASHTO TP 62-03

11. 2- Tire / Pavement Noise (dB) for Arizona I-10 Test Sections Field Noise Validation Studies

12. I-10 TEST SECTIONS AR-ACFC ¾” SMA ¾” P-ACFC ¾” Field Noise Validation Studies ACFC ¾” PEM 1 ¼”

13. 3- Field Investigation of PCC Thermal Behavior • Temperature Gradients induce damaging Curling Stresses

14. Thermal Gradient Test Site Courtesy AZ511.com

15. Thermal Gradients Effect • Observed benefits of porosity and lower thermal mass of the ARFC layer. • Thermal Blanket Effect of ARFC reduces PCC Curling Stresses (8-25%)

16. Urban Heat Island

17. 4- Friction / Safety

18. 5- Ride Quality / Roughness

19. 6- Air Quality • Rare opportunity to sample tire wear emissions at the tunnel before and after the AR-ACFC overlay. Deck Park Tunnel, I-10 Phoenix, AZ

20. Tire Wear Emission Rates Based on Tire Wear Tracers May 2004 and June 2005 Emission rates calculated per kilometer driven (mg/km).

21. 7- Energy Consideration ½ Thickness Design Criteria Positive Impact on CO2 Emissions

22. Cost Benefits • Longer Service Life • Reduced cracking and maintenance. • Reduced thickness.

23. Conclusions • AR-ACFC is a System Preservation Design Strategy: • Performance / Durability √ • Safety √ • Ride Quality √ • Quality of Life Issues √ • Highway Noise • Air Quality • Urban Heat Island • Energy Savings and Cost Effective √

24. Thank You Arizona - USA