In a new report, Austroads has warned that using recycled plastics in asphalt and sprayed seals on roads comes with a number of safety risks and called for a governance framework to guide further research and planning.
The growing interest in using recycled plastics in road and other infrastructure follows overseas countries such as China and Indonesia banning the import of waste from Australia.
In its new report, Austroads conducted a comprehensive local and overseas literature review into the issue and found that some waste plastics can be a partial aggregate replacement in bituminous mixes and a binder extender without significantly influencing asphalt properties.
However, most laboratory trials conducted overseas had not been performed in accordance with Australian bitumen standards and specifications, and very little is known about the manufacturing processes of the commercially available proprietary products currently being trialled on Australian and New Zealand roads.
Christina Chin, Principal Consultant & State Manager (Victoria), Level 5 Design, and principal report author, said this means there are concerns about hazards road workers could be exposed to while handling recycled plastics.
“Some plastics, when heated, release toxic emissions such as chloride, formaldehyde, toluene and ethylbenzene. Another major concern is microplastics leaching out from our pavements into waterways, posing a serious threat to our marine life,” Ms Chin said.
Austroads therefore strongly recommended a precautionary approach until more research has been conducted, and called for the adoption of a governance framework for using recycled plastics on Australian and New Zealand roads.
Ms Chin said this framework should contain information about the pavement’s long-term durability; comprehensive health, safety and environmental risk assessments; and storage stability based on Austroads specifications and local working conditions.
The report also recommended conducting an independent review of the most commonly used proprietary products containing recycled plastics to give road authorities a better understanding of their properties.
“It is worth calculating the lifecycle impacts of recycled plastic-modified asphalt and comparing these with impacts of conventional asphalt to quantify their sustainability benefits. These can be established by using the Infrastructure Sustainability Materials Calculator developed by the Infrastructure Sustainability Council of Australia,” Ms Chin said.
Other recommendations in the report include:
- Developing performance-based specifications to allow producers more flexibility to innovate; in return, they are required to provide performance guarantees regarding their products
- Nationally monitoring, assessing and sharing results of road trials conducted in Australia and New Zealand
- More research into the viability of using recycled plastics in sprayed seals
Download the report Viability of Using Recycled Plastics in Asphalt and Sprayed Sealing Applications here.
