The Road to a Greener Future: Can Old Tyres Be the Answer?
In a bold move towards sustainability, researchers at Charles Darwin University (CDU) are exploring an innovative solution to strengthen roads in the Northern Territory's harsh climate. But here's where it gets controversial: they're suggesting we use old tyres, a waste product, to build better roads.
Every year, Darwin residents and businesses discard a staggering 400 tonnes of tyres. These tyres are currently sent to the Shoal Bay Waste Management Facility, stored, and then shipped interstate or overseas for recycling. However, CDU researchers believe there's a more efficient and environmentally friendly way to utilize these discarded tyres.
The research team, in collaboration with the NT Department of Logistics and Infrastructure, has been investigating the potential of recycled materials, specifically granulated crumb rubber from ground-up tyres and plastics, to enhance the durability of NT roads. This approach aims to address the unique challenges posed by the territory's extreme weather conditions.
PhD student Ramin Shahbazi explains that flexible materials are commonly used in road construction, but a different strategy is required in regions like the NT. "When we have a flexible pavement made of asphalt, it constantly changes due to hot weather and moisture from rain," he says. Shahbazi and his team aim to replace regular pavement materials with recycled alternatives while maintaining or even improving performance.
Reclaimed asphalt, crushed glass, recycled concrete, and crumb rubber from tyres and plastics are all being tested to enhance road durability. Senior CDU engineering lecturer and PhD supervisor Ali Rajabipour highlights the potential benefits to both council budgets and the environment by giving these alternative materials a new lease of life. "Some countries burn tyre waste, which is not an ideal solution as it produces unhealthy fumes," he points out.
Dr. Rajabipour estimates that the NT could save approximately $2 million annually by recycling materials that would otherwise end up in landfills. This initiative aligns with the City of Darwin's commitment to a "circular economy," where waste materials are reused and recycled.
However, achieving this goal is not without its challenges, according to Nick Fewster, the council's head of environment and waste. "Repurposing disused tyres locally would reduce the environmental impact of freight activity, as transporting waste produces carbon emissions," Fewster explains.
Nik Kleine, the council's head of infrastructure, adds that Darwin roads face unique weather challenges during both the wet and dry seasons, which can shorten the lifespan of road surfaces. "You'll see cracking and potholes," he says. Kleine sees the CDU trial as an opportunity to give new life to products that would otherwise be destined for landfills.
If the research proves successful, the City of Darwin may consider trialling these recycled materials on local roads. "It's done through a tender process, and this project would definitely meet the sustainability and environmental criteria," Kleine states.
Filippo Giustozzi, professor of civil and infrastructure engineering at RMIT University, supports the investigation, citing existing evidence of the benefits of crumb rubber in asphalt. However, he cautions that its effectiveness must be proven under the specific conditions of the Northern Territory. "Challenging environments require site-specific testing to confirm durability, ageing behaviour, and moisture resistance over time," Giustozzi emphasizes.
Professor Giustozzi also notes that recycled plastics are relatively new in road construction and often need to be combined with traditional materials to ensure long-term performance.
The NT Department of Logistics and Infrastructure reports that laboratory testing is approximately 75% complete, with over 8,000 tests conducted so far. Road trials using recycled materials are expected to begin early this year, offering a potential glimpse into a more sustainable future for road construction.
