Friday, 5 April 2024
In a significant development for the Australian and New Zealand road construction industries, Austroads has updated its mix design procedure for asphalt compaction. Austroads has shared their findings in a new and comprehensive study, highlighting critical considerations and potential adjustments to ensure a seamless transition away from the now discontinued Gyropac to Superpave compaction settings (to align with AASHTO T312). This brings an end to a period of more than 25 years in which the Gyropac was a standard compaction device in several Australian jurisdictions.
The report aims to understand how different compaction machines affect mix design. While there are differences between the now discontinued machines and the new machines, the new compactors can be offset to achieve similar results and so ensure a smoother transition between different compaction devices.
“Following the discontinuation of the Gyropac compaction devices, Austroads has had to find a replacement method of compaction for asphalt mix design,” said Ross Guppy, manager of the Transport Infrastructure program at Austroads. “This report revises the mix design procedure and identifies suitable replacement gyratory compactor devices for the design of asphalt in Australia and New Zealand.”
The report identifies the Superpave Gyratory Compactor as a potential replacement. It offers an extensive literature review and detailed test results on the functionality of the potential new compaction device.
The literature review found that the Superpave is widely used abroad, but there is some debate over compaction levels. Some foreign jurisdictions found that Superpave compaction levels lead to durability issues and so lowered compaction levels as a result.
The testing results in the report show that a practical offset can be used to achieve equivalent densities and voids.
“Our research has provided valuable insights into the dynamics between different compaction devices,” said Ross.
Download Validation of Superpave™ Method of Asphalt Compaction for Australasia
Watch a webinar with Dr Bevan Sullivan and Sean Dorahy to learn more about the report’s findings.