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Austroads investigates hydrated lime alternative

Austroads has released a new report investigating the feasibility of using anti-stripping additives as an alternative to hydrated lime in asphalt mixes

In an effort to address concerns surrounding the sustainability of incorporating hydrated lime in asphalt mixes to reduce the risk of moisture damage occurring, Austroads has released a new research report that assesses the suitability of using anti-stripping additives as a potential alternative to hydrated lime.

Hydrated lime is used extensively throughout Australia. However, the local asphalt industry and some state transport agencies have raised concerns regarding the future sustainability of incorporating hydrated lime in asphalt, in particular the potential risks associated with the ongoing supply of hydrated lime to meet demand and its large carbon footprint compared to some alternative anti-stripping technologies.

“When given the opportunity to choose between hydrated lime and liquid anti-stripping additives, contractors often prefer the latter due to the ease in application and lower cost,” Austroads transport infrastructure program manager Ross Guppy says.

“In order to do so, a robust moisture susceptibility assessment protocol needs to be adopted to assess viable alternatives to hydrated lime.”

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This report engaged in a literature review that determined the main benefits and disadvantages of using hydrated lime and liquid anti-stripping agents in asphalt mixes to reduce the risk of stripping.

The project also developed an interim laboratory testing protocol to assess the effectiveness of different anti-stripping additives in asphalt. The protocol comprises standard materials and asphalt mix characterisation testing, followed by a suite of moisture susceptibility tests.

“Future work is recommended to validate the interim protocol developed and improve the link between current standard moisture susceptibility test methods and field performance,” Guppy says.

The report can be downloaded here. A webinar on the topic will take place Monday April 8 at 1pm AEST – register here.

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