Monday, 16 July 2029
Road agencies can now make more informed decisions about bitumen selection to reduce premature cracking and extend the life of sprayed seals, supported by a new Austroads test method for assessing the long-term performance of aged bitumen.
Sprayed seals are one of the most widely used road surfacing treatments across Australia and New Zealand, and Austroads member agencies collectively invest around $1 billion each year in bituminous binders to build and maintain the road network. The new method provides a more reliable way to assess how bitumen performs as it ages, helping agencies identify materials that are less likely to become brittle and crack over time.
The research found that the industry's long-standing durability test does not always reflect how aged bitumen performs under the conditions where cracking occurs. In response, Austroads developed a new test method that provides a more direct measure of resistance to age-related cracking.
“Road agencies want confidence that the materials they specify today will continue performing well many years into the future,” said Ross Guppy, Austroads Program Manager Transport Infrastructure.
“This research provides a more fundamental measure of how aged bitumen resists cracking, giving agencies better information to support material selection and asset management decisions.”
The project assessed a range of international testing approaches before evaluating bitumen samples from Australia, New Zealand and overseas sources. Researchers compared traditional durability measures with direct assessments of cracking resistance and identified a more reliable way to predict long-term performance.
“The existing durability test has played an important role for decades, but it was developed around equipment and testing approaches that are now becoming outdated,” Ross said.
“This method takes advantage of modern technology to assess aged bitumen under conditions that are much more relevant to how cracking develops in service.”
The new method measures the complex modulus of bitumen after laboratory ageing, helping road agencies identify materials that are more resistant to age-related cracking and better suited to long-term performance.
Download the test method: Complex Modulus (G*) of Aged Bitumen
Download the supporting research report: Investigations into Fatigue Cracking Performance Tests for Aged Bitumen
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