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RAP, RAS and Durable Asphalt Pavements

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  1. 1. www.wrsc.unr.edu RAP, RAS and Durable Asphalt Pavements Adam Hand, PhD, PE Pavement Engineering and Science Program University of Nevada, Reno CalAPA Fall Conference Sacramento, CA October 27, 2016
  2. 2. www.wrsc.unr.edu Whats Up With Recycled Materials Use in and Durability of HMA? NAPA Nationally FHWA Binder ETG Mixture ETG TFHRC TRB Annual Meeting NAPA Annual Meeting AAPT Annual Meeting NCHRP Projects The Pendulum Swung Too Far and We Need to Get Durability Under Control
  3. 3. www.wrsc.unr.edu How is HMA Durability Improved? Raw Materials Aggregates - Contribute to Cracking Resistance? Asphalt Binder Stiffness + Ability to Relieve Stress + Aging Sensitivity HMA Design Binder Content Higher the Better, VMA, Gsb vs. Gse if using RAP/RAS Denser Mix Types Construction In-place Density 8%
  4. 4. www.wrsc.unr.edu Where is the Pendulum Headed? Mid 1990s Superpave without Performance Indicator Tests Early 2000s Rutting and Moisture Sensitivity Focus Hamburg Wheel Track Device Proliferation More Fine Graded Mixtures Late 2000s Economic Collapse and Escalating Binder Costs Increased Competition/Collapsing Margins Recycling Focus and Push Mid 2010s Mix Durability WITHOUT Forgetting Rutting Late 2010s BMD and Moderate Recycled Materials
  5. 5. www.wrsc.unr.edu Outline RAP & RAS Use Agency & Industry Responses AASHTO Standards & Related NCHRP Projects Performance Trends - Our Future?
  6. 6. www.wrsc.unr.edu 2014 NAPA Annual Survey 2015 Survey Soon 2014 Trends Continued?
  7. 7. www.wrsc.unr.edu RAP 2013 to 2014 Flattening/Reduction in Use
  8. 8. www.wrsc.unr.edu RAS Reduction in Public Agency Use
  9. 9. www.wrsc.unr.edu Count of State DOT Allowable RAP Percentages 2013 to 2014 Reduction in 10-20% & Increase in 20-30+% 4 DOTs > 30% RAP, 2 Since Reduced
  10. 10. www.wrsc.unr.edu FHWA Memo October 2014 Premature Cracking High Recycled Binder Content RAP & RAS RAS
  11. 11. www.wrsc.unr.edu Caltrans Memo June 2016 Premature Cracking Failures Caltrans NSSP >15% RAP Blending Charts
  12. 12. www.wrsc.unr.edu 2015 Caltrans SS & NSSP on %RAP & %ABR Type A HMA Location in Pavement Allowable ABR (%) 2015 Standard Specification (RSS 05-06-16) NSSP Upper 0.2 (Surface Courses) = 25% n/a Below 0.2 (Intermediate or Base Courses) = 40% n/a Reference and Levels PG Required 2015 Standard Specification (RSS 05-06-16) NSSP %RAP = 15% Specified PG n/a - silent >15% = 25% As specified or -1 PG by REQUEST Blending Charts & Meet Specified PG >25% = 40% Does not allow > 25% RAP n/a - silent %ABR >0% = 25% As specified or -1 PG by REQUEST n/a - silent >25% = 40% -1 PG REQUIRED n/a - silent
  13. 13. www.wrsc.unr.edu Current NCHRP Projects Many Related to High ABR Performance, RAP, RAS, Aging http://www.trb.org/NCHRP/NCHRPProjects.aspx
  14. 14. www.wrsc.unr.edu NCHRP Project Highlights 09-52 Short-term Laboratory Conditioning of Asphalt Mixtures Lab mix short-term aging underestimates field aging 09-54 Long-term Aging of Asphalt Mixtures for Performance Testing and Prediction AASHTO R30 Lab mix long-term aging (compacted mix at 85C for 5 days) significantly under estimates long-term field aging Preliminary - Loose mix oven aged at 95C for 5 to 25 days 09-58 Effect of Recycling Agents on Asphalt Mixtures with High RAS & RAP Binder Ratios RAs not Equal, Dose Rutting/Cracking, Aging Susceptibility Diminishes Effectiveness, Compatibility, Binder Availability 09-61 Short- and Long-term Binder Aging Methods Replace or Modify T240 and R28
  15. 15. www.wrsc.unr.edu Current AASHTO Standards AASHTO M320 PG Binder Grading AASHTO T240 Short-term Binder Aging (RTFO) AASHTO R28 Long-term Binder Aging (PAV) AASHTO M323 Superpave Mix Design AASHTO R30 Short-term Mixture Aging AASHTO R30 Long-term Mixture Aging AASHTO MP15 Recycled Asphalt Shingles AASHTO PP78 RAS in HMA NCHRP 9-61 NCHRP 9-61 NCHR 9-52 NCHRP 9-54 PP78 Revisions Significant Change is Coming Not Bad, but Different
  16. 16. www.wrsc.unr.edu AASHTO PP78 Changes before SOM Increase %AC over Optimum 0.1%AC per 2%RAS Tc -5C On Blended Virgin/RAS Binder What is Virgin Binder Tc? What is RAP/RAS/Virgin Binder Tc?
  17. 17. www.wrsc.unr.edu What is RAP Stiffness Range in California? Consider Climate Central and North Coast San Joaquin Valley Southern Deserts PG76-16 to PG100-4 4 PGs so 4x Stiffness and ?x Embrittlement Is Cracking Similar in the Different Environments?
  18. 18. www.wrsc.unr.edu High ABR HMA Performance Observations NCHRP Report 752 Illinois DOT FHWA ALF NCAT Nevada MinnRoad WiscDOT Mathey
  19. 19. www.wrsc.unr.edu Current Focus High ABR Mixes What is High Asphalt Binder Replacement? >25% Virgin Asphalt Binder Replacement with RAP, RAS, or RAP&RAS %ABR = %Asphalt Binder Replacement Specs Changing to %ABR from %RAP or %RAS Why? %AC in 25% Coarse RAP %AC in 25% Fine RAP RAP with 4% vs. 5.5%AC Tear-off RAS vs. Manufacture Waste RAS Why Does It Matter? %ABR = Binder Stiffness + Stress Relaxation High Stiffness/Low Stress Relaxation = Cracking and Durability Issues
  20. 20. www.wrsc.unr.edu IL DOT FHWA ALF High Binder Replacement Mixtures FHWA Memos High ABR, RAS and REOB Warning to DOTs FHWA lllinois DOT Memo http://www.youtube.com/watch?v=zJv2oZG2Mys Illinois DOT Reduced %ABR 40% to 25% Base Mix 40% to 15% Surface Mix 40% to 10% PMA Mix FHWA ABR RESEARCH RAP, High RAP, RAS, RAP+RAS Sections with and without PG Grade Drops
  21. 21. www.wrsc.unr.edu FHWA ALF Like HVS used in California Simulated Truck Loading and Pavement Temperature 35,000 Load Cycles per Week 7k to 19k Wheel Load
  22. 22. www.wrsc.unr.edu FHWA ALF Test Sections
  23. 23. www.wrsc.unr.edu FHWA TFHRC ALF
  24. 24. www.wrsc.unr.edu FHWA ALF Cycles to 200 of Cracking 0 50 100 150 200 250 300 350 400 450 L1: 0% ABR Control PG64- 22 L9: 20% ABR RAP PG64-22 Foamed WMA L4: 20% ABR RAP PG64-22 WMA Evotherm L6: 20% ABR RAP PG64-22 L11: 40% ABR RAP PG58-28 WMA Evotherm L3: 20% ABR RAS PG64-22 L5: 40% ABR RAP PG64-22 ALFCyclesto200"Cracking Lane and Material
  25. 25. www.wrsc.unr.edu FHWA ALF Crack Life Ratio 100 73 38 30 28 16 11 0 10 20 30 40 50 60 70 80 90 100 L1: 0% ABR Control PG64- 22 L9: 20% ABR RAP PG64-22 Foamed WMA L4: 20% ABR RAP PG64-22 WMA Evotherm L6: 20% ABR RAP PG64-22 L11: 40% ABR RAP PG58-28 WMA Evotherm L3: 20% ABR RAS PG64-22 L5: 40% ABR RAP PG64-22 CrackLifeRatio(%) Lane and Material
  26. 26. www.wrsc.unr.edu FHWA ALF Findings Use of Recycled Materials Significantly Impacts Cracking (Fatigue) Performance Virgin, low RAP, high RAP, RAS Grade Bumping Down improves Performance Slightly Foaming helps with low RAP at WMA Temperatures FHWA Determining How Much Additional Virgin Binder over Optimum is Need for Recycle Mixes to Achieve Equal Cracking Performance to Virgin Mix VTRC (VDOT) 0.1%/10% RAP ABR 0.X/10% RAP ABR
  27. 27. www.wrsc.unr.edu RAP/RAS Compatibility with Polymer Modified Asphalt Binders NCAT Test Track Florida DOT Top Down Cracking RAP and RAS Nevada RAP Only
  28. 28. www.wrsc.unr.edu NCAT Test Track (FDOT top down cracking test sections) 2 Mile Oval, Conventional Construction, Highway Trucks 4 Mix/Binder Combinations No Distress Except Top Down Cracking at 10M ESALs PMA-0% RAP GTR-0% RAP PMA-20% RAP PMA-20% RAP + 5% RAS
  29. 29. www.wrsc.unr.edu NCAT Test Track (FDOT top down cracking test sections) 0 10 20 30 40 50 60 70 80 90 100 0 2000000 4000000 6000000 8000000 10000000 12000000 PercentLaneCracking Traffic (ESALs) PMA-0% RAP GTR-0% RAP PMA-20% RAP PMA-20% RAP + 5% RAS Stiffer polymer- modified binders should not be used in conjunction with RAP/RAS mixtures because this causes mixes to be too stiff
  30. 30. www.wrsc.unr.edu Other NCAT Technology News Updates 2016 Go to Florida DOT high traffic mix PG76-22 (No RAP/RAS Allowed) Michigan DOT Design Air Voids = 3% to increase Optimum %AC Colorado DOT Revised Section 403 CDOT has ability to adjust contractor mix design optimum %AC up & only fine graded mixes or SMA for surface course to improve Durability
  31. 31. www.wrsc.unr.edu Nevada Study Aggregate Source & Blend 3 RAP Sources 2 PG Binder Grades All Properties Just Fatigue Here
  32. 32. www.wrsc.unr.edu Influence of %RAP on Fatigue of Mixes with Polymer Modified Binder 300,000 1,200,000 4,500,000
  33. 33. www.wrsc.unr.edu Nevada Study 100 4 2 14 51 3 2 0 10 20 30 40 50 60 70 80 90 100 FatigueLIfeRatio
  34. 34. www.wrsc.unr.edu REOB and Tc Concept
  35. 35. www.wrsc.unr.edu Backgroud Concerns with long term pavement performance related to binder durability is not new Predates Superpave & PG binders Focus of many studies simply related to binder aging Asphalt Institute - Anderson 2011 REOB Concerns Rheological & ductility of PAV binders and binders recovered from aged field mixtures Relationship to non-load associated distress Tc of 2.5C = cracking warning limit, Tc = 5C point where binder durability lost
  36. 36. www.wrsc.unr.edu Fatigue Cracking Rutting PAV - aging RTFO - aging No aging Time Construction [RV] [DSR] Low Temp Cracking [BBR] [DTT] Superpave PG Binder Specification
  37. 37. www.wrsc.unr.edu Binder Relaxation Properties Bending Beam Rheometer measures Stiffness and m value BBR m value measures relaxation or ability of binder to relieve stress at cold temperatures As binder ages m value continues to decrease indicating loss of relaxation properties (embrittlement) while the stiffness increase levels off Tc is an indicator of embrittlement = difference in temp where S = 300MPa and m value = 0.3
  38. 38. www.wrsc.unr.edu Tc Concept for REOB/Cracking What is Tc ? Tc=BBR S Tcritical BBR m Tcritical Is negative value for m-controlled binders 2xPAV 980 mN (100 g) Load Asphalt Beam Deflected PositionAsphalt Beam Original Position
  39. 39. www.wrsc.unr.edu So Why is Any of This Important? As Binders age they lose the ability to relax stresses, mechanical or thermal Stiffness Increases Ductility Decreases Brittleness Increases Having a means of identifying when we can expect field problems would be worthwhile Spread between BBR S & m Tcritical values increase, Tc becomes more negative
  40. 40. www.wrsc.unr.edu Dry Tensile Strength at 25C
  41. 41. www.wrsc.unr.edu Blending Charts Do they help? Are they enough? 0 20 40 60 80 100 100 80 60 40 20 0% RAP % New ViscosityorG*/SinofRAPBinder(Old) ViscosityorG*/SinofVirginBinder(New) Spec Limits 10-25% RAP Percentages of Virgin and RAP
  42. 42. www.wrsc.unr.edu Comparative Crude Source Study 2006 Mathy constructed 5 test sections for MNDOT on Olmsted CTH 112 near Rochester, MN 3 test sections compared performance of 3 different crude sources of the same PG Grade, all (NEAT) PG 58-28 Source #1, 0% RAP PG58-28 Source #2, 0% RAP PG58-28 Source #3, 0% RAP 2 test sections compared PG 58-34 PMA (0% RAP) and PG 58-34 (NEAT) + 20% RAP
  43. 43. www.wrsc.unr.edu 0.0 4.0 8.0 12.0 16.0 20.0 24.0 PG58-34 (neat)+20% RAP PG58-34 (PMA)+0% RAP PG58-28 S1 (neat)+0% RAP PG58-28 S2 (neat)+0% RAP PG58-28 S3 (neat)+0% RAP Longitudinal/TransverseCracking,m FatigueCracking,m2 MN CTH 112 Cracking Data 4 Years Transverse Longitudinal Fatigue
  44. 44. www.wrsc.unr.edu 0.0 4.0 8.0 12.0 16.0 20.0 24.0 PG58-34 (neat)+20% RAP PG58-34 (PMA)+0% RAP PG58-28 S1 (neat)+0% RAP PG58-28 S2 (neat)+0% RAP PG58-28 S3 (neat)+0% RAP Longitudinal/TransverseCracking,m FatigueCracking,m2 MN CTH 112 Cracking Data 5 Years Transverse Longitudinal Fatigue
  45. 45. www.wrsc.unr.edu 0 50 100 150 200 250 300 350 400 450 500 550 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 TotalCracking,m Tc of Recovered Binder from Cores (Top 1/2") MN CTH 112 Cracking Data Total Cracking vs. Tc of Recovered Binder (8 Years) PG58-28 S2 (neat)+0% RAP PG58-34 (PMA)+0% RAP PG58-28 S1 (neat)+0% RAP PG58-28 S3 (neat)+0% RAP
  46. 46. www.wrsc.unr.edu PG 58-34 (neat) + 20% RAP
  47. 47. www.wrsc.unr.edu PG 58-34 (PMA) + 0% RAP
  48. 48. www.wrsc.unr.edu PG 58-28 (neat) Source 1 + 0% RAP
  49. 49. www.wrsc.unr.edu PG 58-28 (neat) Source 2 + 0% RAP
  50. 50. www.wrsc.unr.edu PG 58-28 (neat) Source 3 + 0% RAP
  51. 51. www.wrsc.unr.edu MnROAD Test of 3 Binders Constructed September 1999 3 Binders PG 58-28 PG 58-34 PG 58-40 Trafficked until April 2007 Annual Distress Surveys Conducted
  52. 52. www.wrsc.unr.edu MnROAD COMPARATIVE BINDER STUDY 58-28 58-34 58-40 y = -160.85x - 417.74 R = 0.9957 0 100 200 300 400 500 600 700 800 900 1000 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 LINEARFEETOFCRACKING Tc, C 5.5 year total cracks (Non CL) = F(Tc 40 hr. PAV) 5.5 year total cracks (Non CL) Linear (5.5 year total cracks (Non CL)) RATIO CRACKS IN YEAR 5.5 TO YEAR 4 BINDER YEAR 5.5 YEAR 4 RATIO 58-28 126 20 6.3 58-34 13 0 58-40 924 77 12 58-28 58-34 58-40 y = -12.935x - 29.753 R = 0.9946 0 10 20 30 40 50 60 70 80 90 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 LINEARFEETOFCRACKING Tc, C 4 year total cracks (Non CL)=F(Tc 40 hr PAV AGED BINDER) 4 YEAR TOTAL CRACKS (NON CL) Linear (4 YEAR TOTAL CRACKS (NON CL))
  53. 53. www.wrsc.unr.edu Findings Blending Charts and Tc Provide DIFFERENT Answers Tc < -5C (i.e. more negative) for the 40 hour PAV is associated with the increased levels of pavement distress after approximately 5 years of service Use of some blend additives can accelerate the decrease of Tc at equal dosage levels This is exacerbated when trying to accommodate high RAP &/or RAS binder replacement levels Use of RAS in mixes at levels 4% will significantly accelerate the decrease in Tc as mixes age
  54. 54. www.wrsc.unr.edu Gerrys Comments All asphalt binders are not created equal Crude sourcewhich dictates compositional makeup affects long term performance We all know this and yet are perplexed when OUR pavement doesnt ALL perform well Not all binders are refined to grade, more likely today than previously In some cases binders are post refining blends of stiffer materials with lower stiffness VTBs or gas oil Non asphaltic materials are being used to produce finished binders (petroleum oils, bio-based oils, PPA, various types of polymers)
  55. 55. www.wrsc.unr.edu Our Future? ABR used vs. % RAP or %RAS Allowable %RAP ABR likely 15-25%? Allowable %RAS ABR or Disallowed 2-3% RAP &/or RAP with PMA or Disallowed Allowable RAP &/or RAS different for Surface vs. Base Mixes REOB Disallowed &/or Tc in Specs (NE & SE) Especially if RAP &/or RAS Mixes Balanced Mix Design New Lab Aging Conditions in Mix Design Optimum %AC+
  56. 56. www.wrsc.unr.edu Balanced Mix Design Volumetrics + Rutting/MS Test + Cracking Test Raw Material Properties Volumetrics DCT?SCB? Rutting/MS HWTD? Durability At What Temp? At What Temp?
  57. 57. www.wrsc.unr.edu Balanced Mix Design Goals
  58. 58. www.wrsc.unr.edu NCHRP BMD Problem Statement Spring 2016
  59. 59. www.wrsc.unr.edu Leading Edge RAS 1X State DOTs REOB/ Tc NEAUPG SEAUPG Balanced Mix Design NAPA Durability Committee FHWA Mix ETG BMD Taskforce State DOTs Louisiana, Illinois, New Jersey, Wisconsin (almost)
  60. 60. www.wrsc.unr.edu Our Industry Responsibility - Get It Right Agencies Producers/Contractors Associations Academia Our Industry Our Responsibil ity
  61. 61. www.wrsc.unr.edu 92nd AAPT Annual Meeting and Technical Sessions The 2017 Annual Meeting will be held March 19-22, 2017 The Island Hotel, Newport Beach, California USA 2017 Annual Meeting The Annual Business Meeting and Technical Sessions of the Association of Asphalt Paving Technologists (AAPT) will be March 19- 22, 2017 in Newport Beach, California at The Island Hotel (www.islandhotel.com). The annual meeting includes asphalt-related technical sessions comprised of peer-reviewed papers, and invited presentations on specific topics in the Leading Edge Workshop, AAPT- ISAP International Forum, and Symposium. Please see the Annual Meeting page (http://asphalttechnology.org/annual-meeting.html) for more details as they become available. Important dates August 15, 2016 - deadline for submitting papers (CLOSED) October 10, 2016 - peer reviews completed November 4, 2016 - notification of paper acceptance December 2016 Annual Meeting registration opens March 19 to 22, 2017 - Annual Business Meeting and Technical Sessions Our 2017 venue For the latest information please check our web site at: http://www.asphalttechnology.org AAPT Office: 6776 Lake Drive, Suite 215 Lino Lakes, MN 55014 Phone: 651-293-9188 Fax: 651-293-9193 or Email: [email protected]
  62. 62. www.wrsc.unr.edu http://asphalttechnology.org/membership. html Become an AAPT Member! Have access to a wealth of information and emerging technologies Be an integral part of a technical community comprised of individuals from all parts of the asphalt industry (material suppliers, researchers, agency owners, consultants, and equipment manufacturers) Enjoy the camaraderie of colleagues in the field during annual meetings at attractive venues Be a part of lively debates on important technical issues Belong to a North American-based organization with significant international membership and focus Be a member of an association that operates without organizational biases; policies set by and for individual members by an elected Board, rather than by companies or organizations Support the next generation of asphalt technologists through a robust student scholarship program
  63. 63. www.wrsc.unr.edu Thank You!

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