Researchers are investigating the use of repurposed old tires and plastics to construct more durable roads in the Northern Territory, aiming to address the region's challenging climate.
Approximately 400 tonnes of tires are discarded annually by Darwin residents and commercial operators. These tires are currently stored at the Shoal Bay Waste Management Facility before being sent interstate or overseas for recycling.
Research Initiatives
Charles Darwin University (CDU) researchers, in collaboration with the NT Department of Logistics and Infrastructure since late 2021, are exploring whether recycled materials, including granulated crumb rubber from ground-up tires and various plastics, can enhance NT roads. PhD student Ramin Shahbazi noted that traditional flexible asphalt pavements are susceptible to changes due to hot weather and moisture, which can lead to cracking.
Materials under investigation include:
- Crumb rubber from tires
- Plastics from sources like shrink wrap and shampoo bottles
- Reclaimed asphalt
- Crushed glass
- Recycled concrete
Environmental and Economic Benefits
Senior CDU engineering lecturer Ali Rajabipour highlighted potential benefits for council budgets and the environment through the repurposing of these materials. He stated that the NT could save about $2 million annually by recycling materials currently sent to landfill, avoiding practices like burning tire waste which produces unhealthy fumes.
City of Darwin's head of environment and waste, Nick Fewster, emphasized the council's commitment to a "circular economy" and noted that local repurposing of tires would reduce carbon emissions associated with transporting waste. Head of infrastructure, Nik Kleine, added that Darwin roads face unique weather challenges across both wet and dry seasons, leading to issues like cracking and potholes. The CDU trial is seen as an opportunity to extend the lifespan of road surfaces.
Project Status and Future Steps
Professor Filippo Giustozzi of RMIT University commented that the investigation aligns with existing evidence on the benefits of crumb rubber in asphalt but stressed the need for site-specific testing in the Northern Territory's extreme conditions to confirm durability and performance. He also stated that recycled plastics are still relatively new in road construction and often require combination with traditional materials to ensure long-term performance.
Laboratory testing is approximately 75 percent complete, with over 8,000 tests conducted. Road trials using recycled materials are expected to commence early this year. If the research proves successful, the City of Darwin plans to consider trialing the recycled materials in local roads through a tender process, prioritizing sustainability.