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Asphalt Institute Research Update

Asphalt Institute Research Update. FAA Airport Pavement Working Group Meeting April 26, 2012. Past Airfield Projects. Fairchild AFB HMA design verification in 2011 using Superpave Shear performance test Recent adjustment to test specification. Current Research. Completed Recently

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Asphalt Institute Research Update

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  1. Asphalt Institute Research Update FAA Airport Pavement Working Group Meeting April 26, 2012

  2. Past Airfield Projects • Fairchild AFB HMA design verification in 2011 using Superpave Shear performance test • Recent adjustment to test specification

  3. Current Research • Completed Recently • FHWA: WMA laboratory aging and with modulus & performance testing

  4. Current Research • Continued work on NCHRP Co-op • Warm Mix Asphalt (WMA) binder extraction testing • Long-term effect of laboratory ambient aging • How long can lab samples set before testing without changing properties? 4 days? 20 days? 80 days? • RAP / RAS (recycled asphalt pavement / shingles) • What effect is current practice having on mixture performance?

  5. Current Research • Kentucky field density investigation on mixture performance (Part 2) • Writing new ASTM standard for Toluene extraction and recovery of asphalt from a mixture

  6. Current Research • MN ROAD Cracking Study • Optimal Timing of Preventive Maintenance for Addressing Environmental Aging in Hot-Mix Asphalt Pavements • Minnesota Road Research Facility pavement cores and performance • Measure the effect of maintenance treatments on pavement aging versus depth

  7. Acknowledgments • TPF-5(153) • Participating Agencies • Minnesota (Lead State) • Maryland • Ohio • Texas • Wisconsin • Local Road Research Board (LRRB) • Thomas J. Wood, Lead Agency Contact

  8. MnROAD Low Volume Road

  9. MnROAD Cell 24

  10. Task 4 Cores:Recovered Binder Testing • Extraction/Recovery • Centrifuge extraction using toluene/ethanol • Recovery using Rotavapor • 2 Cores (150-mm diameter x 12.5-mm thickness) • ~50 grams asphalt • Cracking and energy tests Top (A) 12.5-mm Mid (B) Bottom (C)

  11. AAPTP 06-01 Test Procedures for Predicting Non-Load Associated Cracking of Airfield HMA Pavements Prime AMEC – Doug Hanson

  12. Acknowledgments • Airfield Asphalt Pavement Technology Program (AAPTP) Project 06-01 • Techniques for Prevention and Remediation of Non-Load-Related Distresses on HMA Airport Pavements • AAPTP sponsors and research panel • Federal Aviation Administration • AAPTP Director Monte Symons • AAPTP 06-01 Project Panel • Member Companies of the Asphalt Institute

  13. General Concept • Impact of in-service aging is oxidation and loss of flexibility at intermediate and low temperatures • Block-cracking • when environmental (non-load) conditions create thermal stresses that cause strain in the asphalt mixture that exceeds the asphalt’s failure strain • Preventing or mitigating distress • identify a property of the asphalt binder or mixture that sufficiently correlates with its flexibility • provide a procedure to monitor when flexibility reaches a state where corrective action is needed

  14. AAPTP 06-01 Question • As the Airport Manager… • What test do I run or what calculation can I do that will tell me when the pavement is expected to begin showing significant non-load related distress?

  15. Concept 100 90 80 Non-Cracking 70 60 Cracking Value Critical Range 50 40 30 Cracking 20 10 0 Year 0 5 10 15

  16. AAPTP 06-01 Plan • Lab Study • Asphalt Binder Study • Various aged conditions • Asphalt Mixture Study • Various aged conditions • Field Study • Limited validation of lab findings • Asphalt binder and mixture tests

  17. Asphalt Binders • Three asphalt binders representing different expected aging characteristics • Selected based upon the relative relationships between low temperature stiffness (S) and relaxation (m-value) • West Texas Sour (PG 64-16) • 3.1°C m-controlled • Gulf Southeast (PG 64-22) • 1.3°C m-controlled • Western Canadian (PG 64-28) • 0.6°C S-controlled

  18. Lab Study Aging Matrix

  19. Mastercurve Procedure 12 10 y = 0.035x - 0.670 8 R² = 0.853 6 Ductility at 15°C, 1cm/min (cm) 4 2 0 1E-04 1E-03 1E-02 1E-01 G′/(η′/G′) at 15°C, 0.005 rad/s (MPa/s) WTX GSE WC

  20. Relationship between G′/(h′/G′) and DTc 1E-01 1E-02 1E-03 1E-04 G′/(η′/G′), MPa/s 1E-05 1E-06 1E-07 -6.0 -3.0 0.0 3.0 6.0 9.0 12.0 Difference Between Tc,m(60) and Tc,S(60), °C West Texas Sour Gulf Southeast Western Canadian

  21. Black Space Diagram: Western Canadian Asphalt Binder 1.00E+09 1.00E+08 1.00E+07 Original PAV-20 1.00E+06 PAV-40 G*, Pa PAV-80 1.00E+05 1.00E+04 1.00E+03 0 10 20 30 40 50 60 70 80 90 Phase Angle, degrees

  22. Mix Testing: Disk-Shaped Compact Tension Test

  23. Disk-Shaped Compact Tension

  24. Field Validation

  25. Field Cores

  26. Core Preparation • Cut top 25mm (1in) from the surface of each core • Binder test • Mix test

  27. Relationship between G′/(h′/G′) and ΔTc (with Field Cores) 1E-01 1E-02 1E-03 1E-04 G′/(η′/G′), MPa/s 1E-05 1E-06 1E-07 -6.0 -3.0 0.0 3.0 6.0 9.0 12.0 West Texas Sour Difference Between Tc,m(60) and Tc,S(60), °C Gulf Southeast Western Canadian Recovered

  28. Concept 100 90 80 Non-Cracking 70 60 Cracking Value Critical Range 50 40 30 Cracking 20 10 0 Year 0 5 10 15

  29. Concept Non-Cracking G′/(η′/G′) or ΔTc 9E-04 MPa/s or 2.5°C Critical Range Cracking 0 2 4 6 Year

  30. Disk Shaped Compact Tension Results

  31. Disk Shaped Compact Tension Results

  32. Study Limitations and Future Research Needs • Only three asphalt binders were evaluated in the laboratory studies • May or may not represent the range of expected aging performance of asphalt binders in the United States • No modified asphalt binders were evaluated • The relationships found between physical properties and aging of unmodified asphalt binders may not be valid for modified asphalt binders • (N.B. modified asphalt binders may not be routinely used in GA airport asphalt pavements, rendering this limitation somewhat irrelevant).

  33. Study Limitations and Future Research Needs • Only three airport asphalt pavements were studied in the field validation portion of the study • From three airports in two sets of environmental conditions • Unfortunately, none of the four pavements exhibited high levels of cracking needed to validate the proposed parameters.

  34. Study Limitations and Future Research Needs • The recommended use presumes that an airport manager will have the desire, time, and resources to conduct testing and analysis throughout the pavement’s life. • Prequalification testing of the asphalt materials could be used to identify the risk for early cracking

  35. Recommended FAA Research Based on Upcoming New Asphalt Technologies

  36. Recommend Research • Effect of Warm Mix Asphalt (WMA) on FAA pavements • Strong presence in US and growing • Potential use of drainable bases • Useful to drain large paved areas • Timing of preventative maintenance

  37. Thanks!

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