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Perpetual Pavement Concepts

Perpetual Pavement Concepts. Ian Rickards | Jason Jones |Russell Clayton Greg Stephenson | Young Choi . Perpetual Pavements. Understanding the concepts Theory behind fatigue endurance limits Field validation of the concept Examples of designs Material characterisation

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Perpetual Pavement Concepts

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  1. Perpetual Pavement Concepts Ian Rickards | Jason Jones |Russell ClaytonGreg Stephenson | Young Choi

  2. Perpetual Pavements • Understanding the concepts • Theory behind fatigue endurance limits • Field validation of the concept • Examples of designs • Material characterisation • Impacts on ME pavement design approach • How to introduce into design and construction

  3. Sessions • University of California • Carl Monismith • NAPA – Asphalt Pavement Alliance • David Newcomb • University of Illinois • Marshall Thompson • National Centre for Asphalt Technology • David Timm

  4. What is a Perpetual Pavement? No deep structural distress

  5. Keep Deformation in Surface

  6. Goal of Perpetual Pavement Design Design so there are no deep structural distresses Bottom up fatigue cracking Structural rutting All distresses can be quickly remedied from surface Result in a structure with ‘Perpetual’ or ‘Long Life’

  7. Performance Goals - Avoid These Leads to Fatigue Cracking Repeated Bending Repeated Deformation Leads to Rutting HMA Base Subgrade

  8. Perpetual Pavement Concept } 38 – 75 mm (1.5 - 3”) SMA, OGFC or Superpave Zone of High Compression Rut Resistant Intermediate Course 75 – 100 mm (3 – 4”) Durable Base 100 – 250 mm (4 – 10”) Max Tensile Strain Pavement Foundation

  9. Rehabilitation • Possible Distresses • Top-Down Fatigue • Thermal Cracking • Raveling • Solutions • Mill & Fill • Thin Overlay High Quality SMA, OGFC or Superpave { 50 - 100 mm 20+ Years Later Structure Remains Intact

  10. Top-Down Cracking

  11. Perpetual Pavements • Resist Structural Distresses • Fatigue Cracking • Rutting • Withstand Climate and Traffic • Design for Subgrade Modulus • Use Strong Foundation • Mix Design • Materials Selection

  12. Materials • Foundation • Not Much Change • Soils • Granular Materials • Stabilization • Asphalt Materials and Mix Design • Base Layer • Intermediate Layer • Wearing Course

  13. Rut Resistant Upper Layers Aggregate Interlock Crushed Particles Stone-on-Stone Contact Binder High Temperature PG Polymers Fibers Air Voids Avg. 4% to 6% In-Place Surface Renewable Tailored for Specific Use

  14. Construction Foundation requirements for construction Interlayer friction Density – especially in asphalt base layer Overly stiff mixtures Segregation Joint density Asphalt layer bonding QC/QA

  15. Interlayer Bonding Ensure complete tack coverage Use trackless or polymer modified or hot tack Keep traffic to a minimum

  16. Perpetual Pavement Advantage Efficient Design – No Overdesign Avoid Reconstruction Reduce Rehabilitation Reduce Life Cycle Cost Reduce Energy Consumption Reduce Materials Use

  17. Lower Life Cycle Cost Better Use of Resources Low Incremental Costs for Surface Renewal Lower User Delay Cost Shorter Work Zone Periods Off-Peak Period Construction Why are Perpetual Pavements Important?

  18. Log e P Threshold Strain A et Log N No Damage Accumulation ev M-E Perpetual Pavement Design E1 E2 E3 D1 D2 D3

  19. Fatigue Endurance Limit Definition: The stress or strain level below which no fatigue damage originating from the bottom of the pavement occurs.

  20. SHRP Fatigue Test Equipment

  21. AustralianBeam Fatigue Apparatus(based on SHRP equip.)

  22. FATIGUE TESTING • Tensile Strain in Flexural Beam Test • Other Configurations • 10 Hz Haversine Load, 20o C, Controlled Strain

  23. HMA FATIGUE N = K1 (1 / eAC)K2 FATIGUE DAMAGE NO FATIGUE DAMAGE eAC (LOG) ENDURANCE LIMIT N (LOG)

  24. Fatigue Endurance Limit Investigated by Monismith 1972 Suggested a limit of 70  Recent Studies U. of Illinois, Carpenter, Ghuzlan, and Shen; use of damage accumulation ratio. (DDE/DE) NCHRP Project 9-38, NCAT (Auburn U.) NCHRP Project 9-44, APT (Ray Bonaquist) NCHRP Project 9-44A, U. of Arizona (M. Witczak)

  25. Fatigue Endurance Limit NCHRP Projects: 09-38: Endurance Limit of Hot Mix Asphalt Mixtures to Prevent Fatigue Cracking in Flexible Pavements – Completed 09-44: Developing a Plan for Validating an Endurance Limit for HMA Pavements – Completed 09-44A: Validating an Endurance Limit for HMA Pavements: Laboratory Experiment and Algorithm Development – Active

  26. Fatigue Endurance Limit Project 09-38 NCHRP Report 646 Fatigue Endurance Limit Test Procedure: Controlled strain 50% reduction in modulus Fatigue beam testing at different strain levels Fatigue endurance limit Strain to achieve 5 x 107 loading cycles Test Duration 50 days to test a beam to 5 x 107 loading cycles

  27. Fatigue Endurance Limit

  28. Field Strain - NCAT Test Track

  29. N8 and N9

  30. Field Strain Measurements (1/2)

  31. Strain Measurements

  32. Strain and Temperature

  33. Strain vs. Temperature

  34. Strain History – Section N8

  35. Strain Distributions

  36. No Fatigue Fatigue NCAT Test Track Results Tested to 2 x 107 ESALs

  37. Further Documentation http://www.ncat.us/reports/rep09-09.pdf

  38. The Phase One I-710 Freeway Rehabilitation Project: Initial Design to Performance After Six Years of TrafficMeeting with AAPA Study Tour GroupUCPRC, CA 8/10/2010Richmond Field Station, UC Berkeley

  39. I-710 Traffic 150,000 vehicles per day 15% heavy vehicles

  40. I-710 Project - Partnered Effort(most recent participants) • Caltrans • T. Bressette, W. Farnbach, C. Suszko • Industry • J. St. Martin, • University of California PRC • C. Monismith

  41. I-710 March 2003

  42. Rehabilitation ofInterstate - 710 • Full-Depth Asphalt Concrete • replacement under overpasses • Overlay of PCC (cracked-seated)

  43. Final mix design & structural section Design & Analysis Trial cross section Conditioning (Aging & Water) Trial mix design Performance Tests Analysis Performance Prediction Unacceptable Acceptable

  44. Long-Life Asphalt Pavement • QC/QA specifications • Polymer modified binders • Improved aggregate requirements • Modified mix design method

  45. Trial Mix Design • Range of binder contents • 4.2 - 5.7% (by wt of aggregate) • Conventional dense-graded mix, Caltrans specs. • All crushed materials

  46. Shear Test

  47. HVS Rutting Study

  48. Mix Performance Evaluation ½ inch rut depth < 20,000 reps ~ 170,000 reps

  49. Trial Pavement Sections PBA-6A* AR-8000 AR-8000 (rich bottom) subgrade

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