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Cover of Austroads Coober Pedy Sprayed Seal Trial: 11-year Inspection Findings
Austroads Coober Pedy Sprayed Seal Trial: 11-year Inspection Findings
  • Publication no: AP-T378-24
  • ISBN: 978-1-922994-36-3
  • Published: 24 June 2024

This report describes the results obtained from the 11‑year inspection of the Austroads Coober Pedy trial site which was constructed to compare the performance of different polymer modified binder (PMB) grades in sprayed sealing applications. The report summarises expert assessments of the different sections of the trial site which were performed 11 years after the site was constructed. It also includes an analysis of the changes in seal surface texture and binder properties which have occurred over the lifetime of the trial site.

The results obtained from expert assessments at the 11‑year inspection indicated that all sections of the trial site were performing well except for small areas of rutting and cracking which appeared to be due to failure of the underlying pavement. The trial site sections have shown an overall reduction in surface texture as the time since construction has increased. The binders in each trial section have progressively oxidised and become harder over the life of the trial site with the C170 bitumen section showing more oxidation and hardening than the PMB sections. The results obtained in time‑sweep tests indicated that the C170 bitumen binder showed the worst fatigue cracking performance after 11 years of service, while the PMBs appeared to show better fatigue cracking performance.

Watch a webinar presented by Steve Patrick and Dr Robert Urquhart, describing the findings of the inspection.

Watch a video about the project below.

  • Summary
  • 1. Introduction
    • 1.1 Earlier Austroads Reports on the Coober Pedy and Cooma Trial Sites
    • 1.2 Information Included in the Report
    • 1.3 Purpose
    • 1.4 Scope
    • 1.5 Methodology
  • 2. Trial Site Details
    • 2.1 Location
    • 2.2 Climatic Conditions
    • 2.3 Traffic Count
    • 2.4 Site Details
  • 3. Expert Assessment of the Trial Site
    • 3.1 Coober Pedy Seal Performance by Visual Assessments
      • 3.1.1 Sections A1 and A2 – C170 (Control)
      • 3.1.2 Sections B1 and B2 – S10E
      • 3.1.3 Sections C1 and C2 – S20E
      • 3.1.4 Sections D1 and D2 – S35E
      • 3.1.5 Sections E1 and E2 – Shell S5E
      • 3.1.6 Sections F1 and F2 – S15R
      • 3.1.7 Sections G1 and G2 – S15E
      • 3.1.8 Sections H1 and H2 – SAMI S20E SS
    • 3.2 Discussion on Visual Assessment Results
  • 4. Surface Texture Depth Measurements
    • 4.1 Comparison of Surface Texture Depth Changes with New Zealand Studies
    • 4.2 Summary
  • 5. Binder Sample Collection and Extraction
    • 5.1 Coring
    • 5.2 Binder Extraction Method
  • 6. Rheological Tests
    • 6.1 Binder Tests – General Introduction
    • 6.2 Stress Ratio Tests
      • 6.2.1 Background
      • 6.2.2 Information Obtained from Stress Ratio Tests
      • 6.2.3 Stress Ratio Test Results
      • 6.2.4 Comparison of Stress Ratio Test Results for Different Trial Sections
    • 6.3 Shell Sliding Plate Micro-viscometer Tests
      • 6.3.1 Introduction
      • 6.3.2 Shell Sliding Plate Micro-viscometer Results for C170 Bitumen
    • 6.4 Summary
  • 7. Time-sweep Tests
    • 7.1 Introduction
      • 7.1.1 Time-sweep Tests
      • 7.1.2 Linear Amplitude Sweep (LAS) Tests
      • 7.1.3 Glover-Rowe Parameter Tests
      • 7.1.4 Crossover Frequency and R-value
      • 7.1.5 Tc Parameter
      • 7.1.6 Selection of the DSR Time-sweep Test in the Current Study
    • 7.2 Experimental Design
    • 7.3 Time-sweep Results
    • 7.4 Comparison of Time-sweep Results with Those Obtained for Unaged Binders
    • 7.5 Summary
  • 8. Fourier Transform Infrared Spectroscopy Tests
    • 8.1 Introduction
    • 8.2 Experimental Design
    • 8.3 FTIR Results
    • 8.4 Analysis of FTIR Results Versus Field Ageing Time
      • 8.4.1 Introduction
      • 8.4.2 Carbonyl Peak Area Results
      • 8.4.3 PBD C-H Wag Peak Area Results
      • 8.4.4 PS C-H Wag Peak Area Results
      • 8.4.5 Discussion
    • 8.5 Summary
  • 9. Summary and Conclusions
  • References
  • Appendix A Site Inspection Data
    • A.1 Inspection Rating Guidelines
      • A.1.1 Rating Index Guidelines Relating to Stripping, Binder Level, Binder Condition and Surface Texture
      • A.1.2 Cracking Assessment Guidelines
      • A.1.3 Aggregate Performance Assessment Guidelines
    • A.2 Coober Pedy Inspection Rating Information
  • Appendix B Stress Ratio Test Results
  • Appendix C Time-sweep Test Results
  • Appendix D FTIR Chemical Assignments
  • Appendix E FTIR Spectroscopy Results
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Accelerated Long-term Ageing Methods for Sprayed Sealing Binders: A Field Validation Study
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