Cover of Maximising the Use of Reclaimed Asphalt Pavement in Asphalt Mix Design: Field Validation
Maximising the Use of Reclaimed Asphalt Pavement in Asphalt Mix Design: Field Validation
  • Publication no: AP-R517-16
  • ISBN: 978-1-925451-09-2
  • Published: 20 April 2016

The use of recycled asphalt pavement (RAP) in asphalt mixes provides a vital basis for sustainable development. Maximising the re-use of RAP in its highest value application, as new asphalt product, has significant economic and environmental benefits.

The overall goal of the study was to provide guidance on the design and specification of RAP mixes and to reduce uncertainty surrounding the performance of asphalt mixes designed and manufactured with RAP. It was found that the binder blend characterisation according to AGPT/T193 is valid for a wide range of asphalt mixes and therefore it can be used with confidence for designing the binder blend in mixes containing RAP. It was also found that the addition of RAP to asphalt mixes, with different percentages of RAP and manufactured in different types of asphalt plants, does not have an adverse impact on the performance. This was assessed by using performance-based tests such as flexural stiffness, wheel-tracking and moisture sensitivity. Test results showed that the addition of 40% RAP, validated on large-scale asphalt production, did not have a negative effect on the in situ workability and thermal segregation.

A feasibility study concluded that the RAP can be subjected to recycling multiple times. A long-term monitoring of RAP sources showed that there is little variation within a stockpile; however, there is significant variation within stockpiles over time. A comprehensive sensitivity study, using the Monte Carlo simulation, was performed as part of the validation process to provide insight into the variability, impact and risk assessment for asphalt mixes containing RAP. Binder blend characterisation should be required for asphalt mixes with RAP content greater than 15%.

The report notes the importance of implementing a RAP management plan and proposes amendments to the Guide to Pavement Technology Part 4B: Asphaltto incorporate the binder blend characterisation for mix designs containing RAP.

  • Summary
  • 1. Introduction
    • 1.1. Objectives and Scope
    • 1.2. Summary of Year 1 ‒ Binder Blend Characterisation in the
    • 1.3. Summary of Year 2 ‒ Asphalt Mix Validation in the Laborat
    • 1.4. Scope of Year 3 ‒ Asphalt Mix Validation in the Field
  • 2. Asphalt Plant Validation of the Binder Blend Characterisation
    • 2.1. Binder Blend Design
    • 2.2. Calculation of the Binder Blend Viscosity
    • 2.3. Methodology of the Plant Validation Process
    • 2.4. The Role of Rejuvenator in Asphalt Recycling
  • 3. Sample Collection and Laboratory Testing
    • 3.1. DSR Test – Temperature-frequency Sweep
    • 3.2. Repeated Recycling of RAP
    • 3.3. Variability of RAP
    • 3.4. Asphalt Plant Validation of the Binder Blend Calculation in RAP Mixes
    • 3.5. C320 Equivalent RAP Mix and Control Mix Production
    • 3.6. C600 Equivalent RAP Mix and Control Mix Production
      • 3.6.1. Purpose and Background of the Validation Project
      • 3.6.2. Scope of Work
      • 3.6.3. Preparation and Design
      • 3.6.4. Asphalt Manufacture and Paving
      • 3.6.5. Infrared Camera Pictures
      • 3.6.6. Finished Surface and Cores
      • 3.6.7. Laboratory Test Results, Binder Blend Validation
      • 3.6.8. In situ Workability and in situ Air Voids Contents
    • 3.7. Performance-based Test Results
      • 3.7.1. Flexural Modulus
      • 3.7.2. Wheel-tracking
      • 3.7.3. Moisture Sensitivity
  • 4. Assessing the Variability by using the Monte Carlo Simulation
    • 4.1. Input Data for the Sensitivity Analysis
    • 4.2. Sensitivity Runs
  • 5. Conclusions and Recommendations
    • 5.1. Outcomes and Conclusions of the Plant Validation Study
    • 5.2. Proposed Implementation
      • 5.2.1. RAP Management Plan
      • 5.2.2. Proposed Update of Austroads Guide to Pavement Technology Part 4B: Asphalt
  • References
  • Appendix A Volumetric Properties of the Asphalt Mixes and Grading and Binder Content of the RAP Sources
  • Appendix B DSR Viscosity Test Results, 60 C, 1 RAD/s
  • Appendix C Flexural Modulus Temperature-Frequency Sweep Test Results
  • Appendix D Moisture Sensitivity Test Results