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Office of Infrastructure R&D U.S. Department of Transportation Federal Highway Administration High Reclaimed Asphalt Pavement Use in Asphalt Mixtures Canadian.

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Presentation on theme: "Office of Infrastructure R&D U.S. Department of Transportation Federal Highway Administration High Reclaimed Asphalt Pavement Use in Asphalt Mixtures Canadian."— Presentation transcript:

1 Office of Infrastructure R&D U.S. Department of Transportation Federal Highway Administration 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 U.S. Department of Transportation Federal Highway Administration 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 U.S. Department of Transportation Federal Highway Administration RAP Efforts State of the Practice Primary Barriers and Remaining Challenges for Increased RAP Use National Efforts to Overcome Challenges

4 U.S. Department of Transportation Federal Highway Administration 4 States that Permit more than 25% RAP

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

6 U.S. Department of Transportation Federal Highway Administration So, why does < half of the nation use < 20% RAP? Blended virgin and RAP binder qualities especially for high RAP mixes and polymer modified bindersBlended 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.Stiffening of the mix from high RAP quantities and resulting cracking performance. 6

7 U.S. Department of Transportation Federal Highway Administration Other “Roadblocks” Presence of dustPresence of dust Consistency/variabilityConsistency/variability of RAP Lack of Quality Control (QC) by contractorLack of Quality Control (QC) by contractor Durability, especially in the surface layersDurability, especially in the surface layers –Raveling 7

8 U.S. Department of Transportation Federal Highway Administration 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 U.S. Department of Transportation Federal Highway Administration 9 HMA Asphalt Pavement Recycling Expert Task Group Advance the use of RAP in asphalt paving applications by providing highway agencies with critical information regarding the use of RAP, technical guidance on high-RAP projects, and direction on research activities. The members consist of representatives from highway agencies, industry, and academia. Website:

10 U.S. Department of Transportation Federal Highway Administration 10 Current Guidelines AASHTO M 323 Standard SpecificationAASHTO M 323 Standard Specification for Superpave TM 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! Recommended Virgin Asphalt Binder Grade Percent (%) RAP No change in binder selection < 15 Select virgin binder grade one grade softer than normal 15 – 25 Follow recommendations from blending charts > 25

11 U.S. Department of Transportation Federal Highway Administration 11 Issues to Consider when Increasing RAP Additional Processing & Quality Control (QC)Additional Processing & Quality Control (QC) Characterizing RAPCharacterizing RAP Changing Binder GradeChanging Binder Grade Mix DesignMix Design Blending/Co-mingling of Virgin and RAP BinderBlending/Co-mingling of Virgin and RAP Binder PerformancePerformance

12 U.S. Department of Transportation Federal Highway Administration Mill Intelligently Processing RAP Stockpile Management Processing and Quality Control

13 U.S. Department of Transportation Federal Highway Administration 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 U.S. Department of Transportation Federal Highway Administration 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 gradesAssess 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 productionInvestigate virgin and RAP binder blending during plant production

15 U.S. Department of Transportation Federal Highway Administration Reclaimed Asphalt Pavement Binder Grade0%15%25%40% PG 58-28XX PG 64-22XXXX

16 U.S. Department of Transportation Federal Highway Administration Phase I, PG64-22, 40% RAP

17 U.S. Department of Transportation Federal Highway Administration Phase I, PG58-28, 40% RAP

18 U.S. Department of Transportation Federal Highway Administration 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 U.S. Department of Transportation Federal Highway Administration 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 , of Recovered Binder

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28 U.S. Department of Transportation Federal Highway Administration   Low temperature creep compliance test   0, -10, -20  C   Low temperature strength test -10°C   Determine stiffness, strength, and critical cracking temperature, T c

29 U.S. Department of Transportation Federal Highway Administration Contractor A - IDT Strength 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

30 U.S. Department of Transportation Federal Highway Administration Contractor A - IDT Stiffness 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

31 U.S. Department of Transportation Federal Highway Administration Contractor B - IDT Strength 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

32 U.S. Department of Transportation Federal Highway Administration Contractor B - IDT Stiffness 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

33 U.S. Department of Transportation Federal Highway Administration Contractor C - IDT Stiffness 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

34 U.S. Department of Transportation Federal Highway Administration Contractor D - IDT Strength 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

35 U.S. Department of Transportation Federal Highway Administration Contractor D - IDT Stiffness 0% 15% 25% 40% 25% 40% PG64-22 PG58-28

36 U.S. Department of Transportation Federal Highway Administration 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 U.S. Department of Transportation Federal Highway Administration 37 High RAP Mix Design NCHRP 9-46 Mix Design and Evaluation Procedure for High Reclaimed Asphalt Pavement Content in Hot Mix AsphaltNCHRP 9-46 Mix Design and Evaluation Procedure for High Reclaimed Asphalt Pavement Content in Hot Mix Asphalt Objective: Develop mix design method and specification for HMA containing up to 50% RAP.

38 U.S. Department of Transportation Federal Highway Administration Evaluating RAP Performance 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 at Auburn University

39 U.S. Department of Transportation Federal Highway Administration SPS-5 Project Locations at Auburn University

40 U.S. Department of Transportation Federal Highway Administration 40 at Auburn University

41 U.S. Department of Transportation Federal Highway Administration 41 at Auburn University

42 U.S. Department of Transportation Federal Highway Administration 42 at Auburn University

43 U.S. Department of Transportation Federal Highway Administration 43 at Auburn University

44 U.S. Department of Transportation Federal Highway Administration So….What’s The Take-away? 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.

45 U.S. Department of Transportation Federal Highway Administration Thank you!


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