Asphalt Rubber Asphalt Concrete Friction Course Overlay as a Pavement Preservation Strategy 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 SIXTH MEXICAN ASPHALT CONGRESS Cancun, Mexico, August 24th to 28th, 2009

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

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.

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 reacted in the hot asphalt cement sufficiently to cause swelling of the rubber particles.

Existing or new HMA Base Mix AR Bitumen % Air Voids % AR Bitumen Content % Air Voids % Typical HMA Cross Section ARFC 13 mm ARAC 50 mm ARAC Open Gap / SMA Dense

Base Asphalts for AR Use Type 1: Hot ClimatePG (Pen 60/70) Type 2: Moderate Climate PG (Pen 80/100) Type 3: Cold ClimatePG (Pen 200/300)

Is AR a Good Pavement Preservation Strategy? 1.Performance / Durability 2.Highway Noise 3.Thermal Gradient / Urban Climate Interaction 4.Friction / Safety 5.Ride Quality / Comfort 6.Tire Wear Emissions / Air Quality 7.Cost and Energy Consideration

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

Viscosity-Temperature Relationships Temperature Rankine (R)

Dynamic Complex Modulus E* AASHTO TP 62-03

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

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

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

Courtesy AZ511.com Thermal Gradient Test Site

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%)

Urban Heat Island

4- Friction / Safety

5- Ride Quality / Roughness

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

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

ProcesskJ/kg Tire Shedding-1744 Shred Transportation-1744 Granulation-3586 CRM Transportation-1744 Steel Recovery1900 Asphalt Saved209,325 to 465,168 Aggregate Saved107,860 Gain / Loss310,267 to 566,109 ½ Thickness Design Criteria 7- Energy Consideration Positive Impact on CO2 Emissions

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

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 √

Arizona - USA Thank You