ARRB is currently conducting a 22 month National Specification Project to ascertain whether crumb rubber binders can be specified in terms of the same tests when they are used in both sprayed seals and asphalt.
This work is sponsored by Austroads and Tyre Stewardship Australia. Additional funding has also been obtained from the Australian Government Transport Infrastructure Council (TIC) so that the project can be completed 5 months earlier than originally proposed.
Incorporating crumb rubber (from used vehicle tyres) into the bitumen used to construct roads is a way that end-of-use tyres can be re-purposed to improve road performance. Crumb rubber binders have been used in Australia for several decades to construct sprayed seals. Over the past few years, work has been conducted by Queensland Department of Main Roads and Main Roads Western Australia (as part of the NACOE and WARRIP programs) to determine whether crumb rubber binders can also be used in asphalt. As this work has focused on adopting US asphalt mix technologies, crumb rubber binders used in asphalt are currently specified using different tests/testing protocols than when crumb rubber binders are used in sprayed seals.
The project that ARRB is working on will harmonise the specified properties of crumb rubber binders in asphalt and sprayed seals by comparing the test results obtained for laboratory blends which are representative of those previously used in sprayed seals and asphalt. The results obtained when these binders are subjected to US tests will also be compared to those obtained in conventional Australian tests. The ARRB laboratory will additionally investigate the relationship between the amount of crumb rubber in a binder and asphalt performance (i.e. wheel tracking and fatigue). The asphalt performance work will provide baseline information which can then be used by Australian jurisdictions and local government to select appropriate types of crumb rubber binders for roads with different traffic loadings/environments.
For more information on rumb rubber in asphalt and seals, please contact Robert Urquhart.