Description

This report, which focuses on the reflective cracking of asphalt overlays, documents the findings of project APT6330. The project comprised two main phases. The purpose of the first phase was to undertake a laboratory testing program to characterise the cracking resistance of typical asphalt overlay mixes based on the Texas overlay tester. Nine typical asphalt materials with conventional and polymer modified binders were selected for the testing. The second phase focused on understanding the available Texas Transportation Institute (TTI) methodology and, particularly, the associated software for asphalt overlay thickness design and analysis. The suitability of adopting the TTI methodology and models within the context of Australian and New Zealand design methods for flexible pavements was assessed, and an exploratory assessment using a targeted sensitivity analysis was undertaken with TTIassociated software for a specific case example. Based on the findings, the project provided general guidance and recommendations. It identified that research on the in-service reflective cracking performance is necessary to calibrate the currently available models, and develop a method for temperature characterisation across the wide range of Australian and New Zealand climates.