High Reclaimed Asphalt Pavement Use in Asphalt Mixtures

1. High Reclaimed Asphalt Pavement Use in Asphalt Mixtures Canadian User/Producer Group for Asphalt Moncton, Canada November 15, 2009 Audrey Copeland and Gerry Huber FHWA and Heritage Research

2. Defining High RAP • Reclaimed Asphalt Pavement • Removed and/or reprocessed pavement materials containing: ~ binder (5%) ~ aggregates (95%) High RAP is defined as more than 25% RAP by weight of mix.

3. RAP Efforts • State of the Practice • Primary Barriers and Remaining Challenges for Increased RAP Use • National Efforts to Overcome Challenges

4. States that Permit more than 25% RAP

5. AK WA VT ME MT ND OR MN NH WI MA NY ID SD RI WY MI PA CT NJ DE MD DC NE IA NV OH IL IN UT WV CO KS MO VA CA KY NC TN OK AZ AR NM SC GA MS AL TX LA HI FL PR States that Use More than 20% RAP in HMA Layers All layers (20% or more) Base and Intermediate layers only Base layer only Do not use more than 20% RAP

6. So, why does < half of the nation use < 20% RAP? • Blended virgin and RAP binder qualities especially for high RAP mixes and polymer modified binders • Stiffening of the mix from high RAP quantities and resulting cracking performance.

7. Other “Roadblocks” • Presence of dust • Consistency/variability of RAP • Lack of Quality Control (QC) by contractor • Durability, especially in the surface layers • Raveling

8. Things are improving… Since 2007: 21 States have increased amount of RAP permitted 23 States now have experience with high RAP mixes 11 States have experience with high RAP and Warm Mix Asphalt mixes

9. Website: www.moreRAP.us

10. Current Guidelines AASHTO M 323 Standard Specification for SuperpaveTM Volumetric Mix Design Based on significant blending between virgin and RAP binder Effects of plant production unknown Calls for virgin binders that may be more expensive, hard to get Blending chart analysis is time-consuming! 10

11. Issues to Consider when Increasing RAP • Additional Processing & Quality Control (QC) • Characterizing RAP • Changing Binder Grade • Mix Design • Blending/Co-mingling of Virgin and RAP Binder • Performance

12. Processing and Quality Control • Mill Intelligently • Processing RAP • Stockpile Management

13. Characterizing RAP for High RAP Use • Asphalt Content • RAP binder contribution, reduce virgin binder required • Ignition oven or solvent extraction • Performance Grade of RAP binder • Estimate blended binder properties • Evaluate stiffness of RAP • Recovered Binder is unaged • RAP Aggregate Gradation • Ensure quality material • Determining Gsb, Gse of RAP aggregate – significant effect on VMA and asphalt content • Combined aggregate properties must meet consensus requirements

14. Investigation of Properties of Plant Produced RAP Mixtures Assess current guidelines for RAP usage by determining low and high temperature properties of plant-produced HMA with varying RAP contents and virgin binder grades Investigate virgin and RAP binder blending during plant production 14 14

15. Experimental Design

16. Phase I, PG64-22, 40% RAP

17. Phase I, PG58-28, 40% RAP

18. Phase I Conclusions • RAP has less impact than expected. • Higher RAP contents not significantly stiffer than virgin mix. • Binder did not stiffen linearly with increasing RAP content. • Dropping grade to PG58-28 not necessary.

19. Phase II – Mixture Test Methods • Dynamic Modulus, E* • Master Curves • Indirect Tensile Test (IDT) Creep & Compliance • Critical Cracking Temperature • IDT at high temperatures • Relaxation Modulus • Complex Modulus, G* and d, of Recovered Binder

20. Phase 2 Contractor A, PG 64-22 Mixes

21. Contractor A, 64-22 vs 58-28

22. Contractor B, PG64-22 Mixes

23. Contractor B, PG64-22 vs 58-28

24. Contractor C, PG64-22 Mixes

25. Contractor C, PG64-22 vs 58-28

26. Contractor D, PG64-22 Mixes

27. Contractor D, PG64-22 vs 58-28

28. Indirect Tensile Test Low temperature creep compliance test 0, -10, -20C Low temperature strength test -10°C Determine stiffness, strength, and critical cracking temperature, Tc

29. Contractor A - IDT Strength 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

30. Contractor A - IDT Stiffness 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

31. Contractor B - IDT Strength 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

32. Contractor B - IDT Stiffness 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

33. Contractor C - IDT Stiffness 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

34. Contractor D - IDT Strength 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

35. Contractor D - IDT Stiffness 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

36. Phase II Summary • Dynamic Modulus results seem to agree with Phase I results • RAP has less impact than expected. • Higher RAP contents not significantly stiffer than virgin mix. • Dropping grade to PG58-28 may not be necessary. • Critical cracking temperatures are mixed bag, but also indicate that binder grade changes may not be necessary.

37. NCHRP 9-46 Mix Design and Evaluation Procedure for High Reclaimed Asphalt Pavement Content in Hot Mix Asphalt High RAP Mix Design • Objective: Develop mix design method and specification for HMA containing up to50% RAP. 37 37

38. Evaluating RAP Performance at Auburn University • Long Term Pavement Performance SPS-5 sections • Virgin • 30% RAP • Milled and non-milled surface • 50 and 125 mm thick • Oldest is over 17 years

39. SPS-5 Project Locations at Auburn University

40. at Auburn University 40

41. at Auburn University 41

42. at Auburn University 42

43. at Auburn University 43

44. Experience and data supports the proper use of high RAP can provide similar or better performance than virgin mixes, but available plant and field data is sporadic. On-going research results indicate high RAP use is possible without adversely affecting performance. More studies are needed with emphasis on plant mixtures and field performance. So….What’s The Take-away?

45. Thank you!