South Australian test could see a doubling of old tyres used to create better roads
In December, a 335 metre stretch of innovative road surface was laid in the City of Mitcham at Stanlake Avenue, St Marys, in South Australia. The asphalt trial is being funded by Tyre Stewardship Australia (TSA) to support research and development that can increase local markets for tyre-derived product.
Crumbed rubber asphalt has been extensively overseas, in climatic conditions similar to Australia, with long term use in California, Arizona and South Africa delivering excellent road performance results and highly desirable sustainability outcomes.
The testing by the City of Mitcham is of a specific warm mix dense-graded crumb rubber modified asphalt already laboratory tested and suitable for use in challenging underlying soil conditions, such as reactive clay. It will be focused on a range of performance factors, such as cracking, rutting, moisture retention and general durability. If successful, the test will contribute to a doubling of the use of recycled tyre rubber in Australian road building, leading to an increase in the percentage of annual volume of old tyres consumed, from around 5% to 10%, within a very short time.
According to City of Mitcham Mayor, Heather Holmes-Ross “We are trialing the crumb rubber asphalt because of the significant environmental benefits as well as the opportunity to improve the quality and life of road pavements, particularly in areas of reactive clay soils.
The City of Mitcham recycled approximately 850 used tyres in the trial asphalt resurfacing of Stanlake Avenue, with 1.5 end-of-life tyres being used for every ton of asphalt laid. In addition, the laying of the asphalt, which was mixed at 160 degrees and laid at 140 degrees, occurred without any workability or fuming issues, despite an over 35C ambient temperature.
TSA’s work in the crumbed rubber asphalt space has also recently resulted in the publication, with the Australian Asphalt Pavement Association, of two national specifications for commonly used forms of crumbed rubber asphalt.
Acting CEO of Tyre Stewardship Australia, Steve Clifford welcomed the foresight of the City of Mitcham in conducting the test. “The Council is to be congratulated for grasping the opportunity to deliver better infrastructure whist addressing a sustainability challenge. The work done in South Australia will play an important role in creating valuable domestic recycling outcomes for end-of-life tyres. Outcomes that can also deliver new green jobs.”
Ongoing testing is scheduled to run for two years, with results monitored on a regular basis to assess the key performance parameters.