RAP, RAS and Durable Asphalt Pavements

of 63
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Information Report
Category:

Engineering

Published:

Views: 13 | Pages: 63

Extension: PDF | Download: 0

Share
Description
Presentation by Dr. Adam Hand, University of Nevada, Reno, on the latest research and performance data on the use of RAP, RAS and other Durable Asphalt Pavement Mixes. Presentation delivered during the CalAPA Fall Asphalt Pavement Conference Oct. 26-27, 2016 in Sacramento, Calif.
Transcript
  • 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. www.wrsc.unr.edu What’s 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. 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. www.wrsc.unr.edu Where is the Pendulum Headed? • Mid 1990’s Superpave without Performance Indicator Tests • Early 2000’s Rutting and Moisture Sensitivity Focus – Hamburg Wheel Track Device Proliferation – More Fine Graded Mixtures • Late 2000’s Economic Collapse and Escalating Binder Costs – Increased Competition/Collapsing Margins – Recycling Focus and Push • Mid 2010’s Mix Durability WITHOUT Forgetting Rutting • Late 2010’s BMD and Moderate Recycled Materials
  • 5. www.wrsc.unr.edu Outline • RAP & RAS Use • Agency & Industry Responses • AASHTO Standards & Related NCHRP Projects • Performance • Trends - Our Future?
  • 6. www.wrsc.unr.edu 2014 NAPA Annual Survey • 2015 Survey Soon • 2014 Trends Continued?
  • 7. www.wrsc.unr.edu RAP • 2013 to 2014 Flattening/Reduction in Use
  • 8. www.wrsc.unr.edu RAS • Reduction in Public Agency Use
  • 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. www.wrsc.unr.edu FHWA Memo October 2014 • Premature Cracking • High Recycled Binder Content – RAP & RAS – RAS
  • 11. www.wrsc.unr.edu Caltrans Memo June 2016 • Premature Cracking Failures • Caltrans NSSP – >15% RAP – Blending Charts
  • 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. www.wrsc.unr.edu Current NCHRP Projects • Many Related to High ABR Performance, RAP, RAS, Aging http://www.trb.org/NCHRP/NCHRPProjects.aspx
  • 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 85°C for 5 days) significantly under estimates long-term field aging – Preliminary - Loose mix oven aged at 95°C for 5 to 25 days • 09-58 Effect of Recycling Agents on Asphalt Mixtures with High RAS & RAP Binder Ratios – RA’s not Equal, ΔDose 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. 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. www.wrsc.unr.edu AASHTO PP78 Changes before SOM • Increase %AC over Optimum – 0.1%AC per 2%RAS • ΔTc ≤ -5°C – On Blended Virgin/RAS Binder  What is Virgin Binder ΔTc?  What is RAP/RAS/Virgin Binder ΔTc?
  • 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. www.wrsc.unr.edu High ABR HMA Performance Observations • NCHRP Report 752 • Illinois DOT • FHWA ALF • NCAT • Nevada • MinnRoad • WiscDOT – Mathey
  • 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. 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. 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. www.wrsc.unr.edu FHWA ALF Test Sections
  • 23. www.wrsc.unr.edu FHWA TFHRC ALF
  • 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. 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. 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. 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. 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. 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. 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. www.wrsc.unr.edu Nevada Study • Aggregate Source & Blend • 3 RAP Sources • 2 PG Binder Grades • All Properties – Just Fatigue Here
  • 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. 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. www.wrsc.unr.edu REOB and ΔTc Concept
  • 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 –ΔTc of 2.5°C = cracking warning limit, ΔTc = 5°C point where binder durability lost
  • 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. 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 • ΔTc is an indicator of embrittlement = difference in temp where S = 300MPa and m value = 0.3
  • 38. www.wrsc.unr.edu ΔTc Concept for REOB/Cracking What is ΔTc ? • ΔTc=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. 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, ΔTc becomes more negative
  • 40. www.wrsc.unr.edu Dry Tensile Strength at 25°C
  • 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*/SinofRAPBinder(Old) ViscosityorG*/SinofVirginBinder(New) Spec Limits 10-25% RAP Percentages of Virgin and RAP
  • 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. 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. 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. 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 ΔTc of Recovered Binder from Cores (Top 1/2") MN CTH 112 Cracking Data Total Cracking vs. ΔTc 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. www.wrsc.unr.edu PG 58-34 (neat) + 20% RAP
  • 47. www.wrsc.unr.edu PG 58-34 (PMA) + 0% RAP
  • 48. www.wrsc.unr.edu PG 58-28 (neat) Source 1 + 0% RAP
  • 49. www.wrsc.unr.edu PG 58-28 (neat) Source 2 + 0% RAP
  • 50. www.wrsc.unr.edu PG 58-28 (neat) Source 3 + 0% RAP
  • 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. www.wrsc.unr.edu MnROAD COMPARATIVE BINDER STUDY 58-28 58-34 58-40 y = -160.85x - 417.74 R² = 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 ΔTc, °C 5.5 year total cracks (Non CL) = F(ΔTc 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 R² = 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 ΔTc, °C 4 year total cracks (Non CL)=F(ΔTc 40 hr PAV AGED BINDER) 4 YEAR TOTAL CRACKS (NON CL) Linear (4 YEAR TOTAL CRACKS (NON CL))
  • 53. www.wrsc.unr.edu Findings • Blending Charts and ΔTc Provide DIFFERENT Answers • ΔTc < -5°C (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 ΔTc 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 ΔTc as mixes age
  • 54. www.wrsc.unr.edu Gerry’s Comments • All asphalt binders are not created equal – Crude source—which dictates compositional makeup affects long term performance – We all know this and yet are perplexed when OUR pavement doesn’t 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 VTB’s or gas oil – Non asphaltic materials are being used to produce finished binders (petroleum oils, bio-based oils, PPA, various types of polymers)
  • 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 ΔTc in Specs (NE & SE) – Especially if RAP &/or RAS Mixes • “Balanced” Mix Design – New Lab Aging Conditions in Mix Design – “Optimum %AC+”
  • 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. www.wrsc.unr.edu Balanced Mix Design Goals
  • 58. www.wrsc.unr.edu NCHRP BMD Problem Statement – Spring 2016
  • 59. www.wrsc.unr.edu Leading Edge • RAS – 1X State DOT’s • REOB/ ΔTc – NEAUPG – SEAUPG • Balanced Mix Design – NAPA Durability Committee – FHWA Mix ETG BMD Taskforce – State DOT’s  Louisiana, Illinois, New Jersey, Wisconsin (almost)
  • 60. www.wrsc.unr.edu Our Industry Responsibility - Get It Right • Agencies • Producers/Contractors • Associations • Academia Our Industry Our Responsibil ity
  • 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: aapt@aapt.comcastbiz.net
  • 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. www.wrsc.unr.edu Thank You!
  • Recommended
    View more...
    We Need Your Support
    Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

    Thanks to everyone for your continued support.

    No, Thanks
    SAVE OUR EARTH

    We need your sign to support Project to invent "SMART AND CONTROLLABLE REFLECTIVE BALLOONS" to cover the Sun and Save Our Earth.

    More details...

    Sign Now!

    We are very appreciated for your Prompt Action!

    x