Asphalt Rubber Usage Guides in California

1. Asphalt Rubber Usage Guides in California R. Gary Hicks, Ph.D., P.E. Technical Director California Pavement Preservation Center Prepared for Brazilian Delegation September 26, 2007

2. DESIGN PRODUCTION & EQUIPMENT CONSTRUCTION SAMPLING & TESTING Asphalt Rubber Usage Guides RAC USAGE GUIDELINES A B C D

3. Design Guide-Contents RAC USAGE GUIDELINES Rubberized Asphalt Concrete Technology Center (RACTC) • www.rubberizedasphalt.com • Introduction • Asphalt Rubber • AR Design Considerations • AR Materials Issues • AR Construction Issues-HMA & Chip Seals • Pre-construction meeting • Environmental considerations • Current/Future Developments • References

4. Caltrans Design Guide RAC USAGE GUIDELINES • Introduction • Asphalt rubber product design, selection and use • Production of AR binders and mixtures • Construction and inspection guides • References www.dot.ca.gov/

5. Where and Why Used? RAC USAGE GUIDELINES • Replaces conventional mixes where paving temperatures and haul distances are favorable • More resistant to cracking and fatigue Particularly Reflection Cracking

6. AR Design Considerations RAC USAGE GUIDELINES 1 BINDER DESIGN 2 STRUCTURAL DESIGN

7. Asphalt Rubber Blend Profile RAC USAGE GUIDELINES • Developed to evaluate compatibility between materials used • Checks for stability of the blend over time • Should be required for each project

8. Binder Design RAC USAGE GUIDELINES ASPHALT RUBBER

9. Asphalt Rubber Tests RAC USAGE GUIDELINES • CONE PENETRATION • RESILIENCE • R&B SOFTENING POINT • FIELD VISCOSITY

10. AR Binder Production RAC USAGE GUIDELINES • Overview of process • Hold over and reheating issues • Documentation • Sampling & Testing requirements

11. AR Blending Schematic RAC USAGE GUIDELINES ASPHALT STORAGE TANK GROUND RUBBER HEAT TANK BLENDER Reaction Vessel

12. Holdover and Preheating Issues Documentation RAC USAGE GUIDELINES Production Set Up • Heating must be discontinued 4 hrs after 45 minute reaction period • Two reheat cycles are allowed • Specification compliance • Restoring viscosity Caltrans Specs Certificate of compliance AR binder design AR binder production log

13. Uses for High Viscosity Binders- Hot mixes • Most effective in gap-graded and open-graded mixes • Most effective in relatively thin surface lifts (max 60 mm) • Gap-graded is used as structural layer, equivalent to DG • Open-graded is used as surface friction course • Increased resistance to rutting, fatigue and reflective cracking a function of binder content • Not suitable for DGAC INCREASES COST SO USE WHERE MOST EFFECTIVE

14. AR Hot Mixes RAC USAGE GUIDELINES RAC - G • Similarities to conventional DGAC • Mix production • Importance of temperature • Sampling and testing requirements • Construction

15. AR Good Construction Practices RAC USAGE GUIDELINES • Same as DGAC • Quality Control • Inspection Troubleshooting Good Practices • Segregation • Smoke • Appearance • Production • Delivery • Placement • Compaction

16. AR Delivery Equipment RAC USAGE GUIDELINES • ITEMS TO WATCH FOR • Release agents • Plant production • Mix delivery • Placement • Compaction • Balanced production

17. AR Placement RAC USAGE GUIDELINES Minimum Handwork and Racking

18. Hot Mix Compaction RAC USAGE GUIDELINES • Good practices • Temperature requirements • Factors affecting compaction • Test strips and rolling patterns • Finishing

19. SAMPLING AND TESTING RAC USAGE GUIDELINES • QC TESTING REQUIREMENTS • Tests • Frequency • QA TESTING REQUIREMENTS • Tests • Frequency • Field GO NO-GO Test STANDARD PRACTICES AS PER HMA VISCOSITY OF BINDER CONTENT

20. AR Benefits RAC USAGE GUIDELINES • Improved durability as surface layer • Resistance to fatigue cracking • Resistance to reflection cracking • Resistance to aging • Can be used in reduced thickness • Reduced noise • Lower life cycle costs • Environmental

21. RAC Limitations RAC USAGE GUIDELINES • Increased initial costs must be offset by improved performance • Not amenable to raking • Higher temperatures for placement and compaction • Environmental issues - air quality and odor concerns • Knowledge of users and good HMA practices

22. Environmental Concerns 4 RAC USAGE GUIDELINES • ENVIRONMENTAL - AIR QUALITY • Smoke issue in parts of CA • Can be controlled • HEALTH & SAFETY • No increased risk per numerous studies • RECYCLING OF AR MIXES • Stockpile uniformity – per conventional HMA • No indication of problems with Air Quality

23. Frequently Asked Questions ? RAC USAGE GUIDELINES • Is the use of AR technically sound and cost effective? • AR be used in cold weather climates? • Can AR be rehabilitated and/or recycled? • Why isn’t AR more widely used by other agencies? YES YES YES Education

24. Implementation RAC USAGE GUIDELINES • Educating users • Benefits of AR • Identifying best places to use AR • Understanding the Limitations

25. Conclusions RAC USAGE GUIDELINES • AR has been used since the 1960’s in chip seals and thin hot mix overlays • AR design and construction guides are now available • AR has proven to be a cost effective treatment for pavement maintenance and rehabilitation • Despite the many successes, its use is still limited to a few states

26. Conclusions RAC USAGE GUIDELINES • Good standard practices and understanding of the materials are required for design, production, and construction of AC and RAC pavements. • AR is a cost effective treatment for pavement maintenance and rehabilitation

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