Rubble and old tyres combine for new road surface

A blend of old tyres and building rubble could be used for road-making in a zero-waste solution to boost recycling and support the circular economy.

The new material, developed by researchers at RMIT University, combines recycled rubble and rubber in a mix designed to be used for base layers.

The recycled blend is more flexible than standard materials, making roads less prone to cracking.

Lead researcher Dr Mohammad Boroujeni said the rubble-rubber mix could deliver both environmental and engineering benefits.

Boroujeni said: “Traditional road bases are made of unsustainable virgin materials – quarried rock and natural sand.

“Our blended material is a 100 per cent recycled alternative that offers a new way to reuse tyre and building waste, while performing strongly on key criteria like flexibility, strength and permanent deformation.”

In Australia, only 16 per cent of scrap tyres are domestically recycled and about 3.15 million tonnes of processed building rubble is not reused.

In 2019, federal and state governments agreed to ban the export of whole used tyres by December 2021.

The new study published in Construction and Building Materials assessed the blended material’s performance under frictional force, or shear stress.

The team identified an optimal mixture – 0.5 per cent fine crumb rubber to 99.5 per cent RCA – that delivered on shear strength while maintaining good cohesion between the two materials.

Chief investigator Professor Jie Li said: “Solutions to our waste problems will come not only from reducing how much goes to landfill and increasing how much we recycle; developing new and innovative uses for our recycled materials is absolutely vital.”

Picture: CSIRO

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