Old Tires Could Build Stronger Roads in Australia's NT

What if the solution to crumbling roads was sitting in your local landfill? Researchers at Charles Darwin University think they've found it in old tires and recycled plastics.

Every year, Darwin residents and businesses discard about 400 tonnes of tires. Those tires get shipped interstate or overseas for recycling, racking up carbon emissions along the way. But scientists are testing whether grinding them into crumb rubber and mixing them with road materials could create tougher surfaces built for Australia's Northern Territory.

The NT presents a brutal challenge for roads. Blistering heat alternates with drenching tropical rains, causing traditional asphalt to crack and buckle. PhD student Ramin Shahbazi explains that flexible pavements constantly expand and contract under these extreme conditions, leading to expensive repairs.

The research team has been working with the NT Department of Logistics and Infrastructure since late 2021. They're testing combinations of crumb rubber, recycled plastics from shrink wrap and bottles, crushed glass, and reclaimed asphalt. Laboratory testing is now 75 percent complete, with over 8,000 tests conducted so far.

The numbers tell a compelling story. Dr. Ali Rajabipour, who supervises the project, estimates the NT could save about $2 million yearly by repurposing materials currently dumped in landfills. That money stays in local communities instead of funding overseas recycling operations.

The Ripple Effect

This project fits perfectly into Darwin's commitment to a circular economy, where waste becomes a resource instead of a problem. Nick Fewster, head of environment and waste for the City of Darwin, points out that processing tires locally eliminates the carbon footprint of shipping waste abroad.

The benefits extend beyond Darwin's borders. Countries worldwide struggle with tire disposal, and some resort to burning them, which releases toxic fumes. This research could provide a blueprint for other regions facing similar road challenges and waste management issues.

Professor Filippo Giustozzi from RMIT University notes that crumb rubber in asphalt already shows promise in other locations. The key question is whether it can handle the NT's unique combination of extreme heat, UV exposure, and intense rainfall. That's where real-world testing comes in.

Road trials using the recycled materials are expected to begin this year. If successful, the City of Darwin plans to incorporate them through their standard tender process, giving preference to projects that meet sustainability goals.

The project transforms a disposal problem into an infrastructure solution, proving that environmental wins and practical benefits can work hand in hand.