Recycled tyres for sustainable roads
October 9, 2023
Roads and Infrastructure explores Alex Fraser’s recycled tyres for sustainable roads.
According to Tyre Stewardship Australia (TSA), Australia generates around 459,000 tonnes of waste tyres annually. Thanks to the support of both government and private industry, as well as development by companies such as Alex Fraser, approximately 70 per cent of these waste tyres are recovered (per Tyre Stewardship Australia).
Alex Fraser’s expertise and eagerness to develop sustainable solutions for the betterment of the industry has led to the development of TyrePave rCB (Recovered Carbon Black), one of its newest innovations in tyre recycling.
The Pound Road West Upgrade was the first Victorian major project to trial the use of rCB, a recovered carbon product made from end-of life tyres used as a carbon saving substitute for limestone needed to produce asphalt.
‘rCB’ has been engineered to be a sustainable alternative to fine ground limestone in asphalt.
It helps to reduce the reliance on mining natural resources and the carbon emissions associated with the extraction of virgin materials and the production of asphalt.
Over time, the availability of ground limestone and filler materials has depleted in cities like Melbourne due to the increased, long-term demand for its growth and infrastructure needs.
Therefore, the cost and cartage requirements to attain these limited, carbon-heavy, natural resources has increased.
By replacing fine ground limestone with rCB the carbon emissions of asphalt production can be significantly reduced.
Alex Fraser’s Asphalt GM Brendan Camilleri says the possibility of developing a new high-recycled product utilising a priority waste stream like tyres was an enticing prospect.
“Alex Fraser first began innovating with recycled materials derived from tyres in 2021. We retro fitted our Narangba asphalt plant to operate utilising tyre derived fuel oil – an alternative fuel supply made from end-of-life tyres in place of fossil fuels. That’s when we discovered that another end-of-life tyre by-product could be used as a filler substitute in asphalt production,” he says.
“Alex Fraser’s Sustainability Charter drives our focus on innovating heavy construction materials to incorporate priority recycled content.”
The birth of rCB
The ‘Recycled Tyres for Sustainable Roads’ project represents a collaboration between Alex Fraser, Seymour Whyte Constructors, Major Road Projects Victoria, ecologiQ, NTRO (National Transport Research Organisation), TSA and Entyr – the accumulation of many months of research, planning and innovation.
Camilleri says that Alex Fraser embraced the support of its industry partners.
“The Pound Road West trial is a great demonstration of what can be achieved in infrastructure sustainability when our industry’s innovators work together.”
“A key focus of the collaboration was ensuring alignment with the specifications and registration for the new asphalt mix.”
Camilleri says that without this registration, the mix would not be acceptable for use in the major road network.
As such, Alex Fraser and its partners completed thorough testing and trialling of the product against a set of key criteria.
This included material compliance, bitumen performance characteristics, stripping potential, as well as rutting and cracking resistance.
“In innovating infrastructure sustainability, our key driver is to ensure that our products are infinitely recyclable. Our roads are not rubbish tips,” Camilleri says.
Our recycled materials must meet the highest quality standards and be perpetually recyclable.”
As part of a TSA-funded research program, the NTRO and Entyr – an end-of-life tyre innovator – investigated the effects of adding one per cent of rCB (by mass) into an asphalt mix. ecologiQ also played a key role in progressing the trial.
Alexis Davison, Executive Director Engineering and Program Services, Major Road Projects Victoria, says working with project teams early helps to maximise opportunities to integrate recycled materials into the design of road projects.
“ecologiQ started working with the Pound Road West Upgrade project team in 2021 during the planning for the project,” Davison says.
“As part of our role, we held a series of workshops with the team to identify opportunities to optimise the use of recycled and reused materials on the project. One of the opportunities identified was to conduct a trial of a new sustainable asphalt product.”
A 500-metre section of the Pound Road West Upgrade is the first Victorian road to be built with a high-recycled content ‘Green Roads’ asphalt mix containing rCB.
Wearing course works were completed at night to minimise disruption and to improve rideability, a shuttle buggy enabled longer, uninterrupted runs; achieving a superior pavement with minimal construction joints.
Alex Fraser completed the remaining asphalting works with its Green Roads Construction Materials products, containing up to 40 per cent recycled content.
It is estimated that using Green Roads Construction Materials on this project has helped reduce carbon emissions by 291 tonnes.
Davison says such projects work to encourage innovation to accelerate greater acceptance of sustainable materials.
“The recent trial on the Pound Road West Upgrade is a great example of how government, projects and suppliers are collaborating to look at innovative ways to transform waste into a resource and work towards a greener infrastructure future,” she says.
“Following the successful trial, we are now looking to develop a new specification for this material to enable wider use.”
Camilleri believes the trial validates the use of rCB as a potential solution for the wider industry, for its performance and environmental benefits, but also long-term reductions in environmental impacts.
“We are pleased with the performance of the rCB used in place of naturally extracted fillers in the trial section of Pound Road West Upgrade,” Camilleri says.
Works on the upgrade were completed in June this year, ahead of schedule. The upgrade is expected to reduce congestion, improve traffic flow and safety for pedestrians and cyclists, while providing enhanced connections for the community.
Gary Foster, Entyr CEO says the company was delighted to provide technology and recycled products to the project.
“Using Entyr’s recovered carbon black and tyre-derived fuel oil in the creation of asphalt avoids the use of virgin resources and creates a superior asphalt proven in both laboratory tests and road use,” Foster says.
The end result for Pound Road West will be a measurable improvement in safety and sustainability.”
Camilleri says the collaborative nature of the project, as well as the successful trials are a standout example of creating positive change in infrastructure sustainability.
“By recycling tyres into asphalt we’re collectively combatting the global challenge of tyre waste. rCB has the potential to substitute 100 per cent of extracted fillers,” he says. “We are confident that this finished pavement will prove to be a durable and long-lasting road that provides exceptional ride-ability and improved sustainability outcomes.”
This article was originally published in the September edition of Roads and Infrastructure magazine. To read the magazine, click here.