A major council-led trial of recycled rubber roads is having positive environmental results, according to an analysis by researchers from RMIT.
The demonstration project led by the Southern Sydney Regional Organisation of Councils (SSROC) aims to test whether adding crumbed rubber from end-of-life tyres to asphalt can boost durability, performance, and environmental sustainability.
As part of the project Bayside, Burwood, Canada Bay, Canterbury-Bankstown, City of Sydney, Georges River, Inner West, Randwick, Sutherland, Waverley and Woollahra, and Northern Beaches councils each resurfaced a road with asphalt mixed with recycled rubber in 2023.
Three sites in Burwood Council, City of Sydney and Northern Beaches Council areas were selected for an in-depth investigation by researchers by RMIT University, who report their findings in a paper titled Life Cycle Assessment and Potential Environmental Benefits of Crumb Rubber Asphalt using Field Data.
Final report handed to SSROC
The researchers say the findings of their study support the use of crumbed rubber in asphalt.
“The extended service life and reduced environmental impacts underscore the importance of incorporating recycled materials, like CR, in asphalt for sustainable infrastructure development,” they say.
“The study’s outcomes support the adoption of CR in asphalt mixes through policy incentives and awareness programs promoting sustainable practices in local council roads.”
The study’s outcomes support the adoption of CR in asphalt mixes through policy incentives and awareness programs promoting sustainable practices in local council roads.
RMIT study
SSROC President and Burwood Mayor John Faker says the findings present a strong case for the benefits of rubber roads.
“Using crumb rubber in asphalt pavement construction and maintenance operations makes a substantial contribution to low-carbon infrastructure, minimising long-term maintenance costs, maximising performance, and promoting a more sustainable approach,” he said.
Direct and indirect benefits
The research team assessed the carbon footprint and other environmental impacts of recycled rubber asphalt pavements compared to conventional asphalt mix, which was laid at the same location and exposed to similar traffic and weather conditions.
They found that recycled rubber extends pavement service life, reduces demand for raw materials, and lowers environmental impacts.
The research showed that incorporating recycled rubber into asphalt mixes using what’s known as a wet method – where crumb rubber is mixed into bitumen at high temperature -can reduce environmental impacts during the production and construction phase compared to conventional asphalt.
Adding 10 per cent crumb rubber by weight of the total binder also resulted in lower environmental impacts compared to using 1 kg of conventional bitumen, because of reduced emissions during the construction phase.
The study also showed indirect environmental benefits, including the diversion of waste tyres from landfills.
The researchers noted separate research which demonstrates rubber-modified asphalt can reduce the environmental impacts associated with the maintenance by up to 30 per cent.
“The calculations done by RMIT University regarding project-level environmental impacts at SSROC councils have demonstrated that incorporating crumb rubber into asphalt roads using the wet method holds significant promise for reducing the total carbon footprint of these roads by up to 30 per cent throughout their service life,” RMIT Civil and Infrastructure Engineering Professor Filippo Giustozzi said.
“This can potentially offset the environmental impacts generated by new road construction and ongoing maintenance operations, therefore contributing to the decarbonisation of the road infrastructure.”
Sustainable infrastructure
The project had the support of Tyre Stewardship Australia (TSA) and the Australian Flexible Pavement Association (AfPA).
TSA Chief Executive Officer, Lina Goodman said the results are now in on the benefits of crumb rubber in asphalt.
“The extended service life and reduced environmental impacts underscore the importance of incorporating recycled materials, like recovered crumb rubber, in asphalt for sustainable infrastructure development.”
AfPA Executive Director Technology and Leadership, Anna D’Angelo said using crumb rubber from end-of-life tyres can help Australia cut down on the more than 450,000 tonnes of waste tyres generated annually.
“This project is a great example of circular economy,” he said.
Queensland council trials OTR tyres
Meanwhile, Sunshine Coast Council in Queensland is trialing the use of crumb rubber from off-the-road (OTR) tyres from Boral’s quarry operations.
The project is a joint endeavour by Sunshine Coast Council and Boral and its subsidiaries and is being led by the AfPA.
The trial will assess the right mix of rubber binder and asphalt for optimum performance in low to high traffic conditions.
Recycled rubber from end-of-life tyres has been used in Australia’s roads for some time, but it’s exciting to look at the potential for OTR crumb rubber to help build resiliant and sustainable roads, Ms Goodman says.
“The use of locally sourced tyre-derived materials in regional, rural, and remote infrastructure, has the potential to put a big dent in the 245,000 tonnes of OTR rubber products generated each year,” she said.
“The Sunshine Coast is in a critical catchment area with a high concentration of OTR rubber product usage.
“If successful, this project has the potential to have a positive impact, by creating reliable economic opportunities for local industry and businesses and enabling local OTR rubber product users to find a local homegrown market for their products.”
Sunshine Coast Council’s Community and Transport Portfolio Councillor Rick Baberowski says council is looking forward to seeing the results of the trial, which will provide other councils in regions where off-the-road tyres are used with technical information to use the model in their local government area.
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