The rubble hits the road: recycled concrete and tyres make excellent base, researchers show

RMIT researchers have developed a blend of recycled rubble and tyre rubber which they say is the first such mix precisely optimised to meet road engineering safety standards.

The results of their work have been published in the journal Construction and Building Materials. The team found the optimal blend was 99.5 per cent recycled concrete aggregate (RCA) and 0.5 per cent fine crumb rubber. This  provided improved flexibility compared to regular road bases, and replaced virgin quarried rock and sad.

“Our blended material is a 100% 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,” said research lead Dr Mohammad Boroujeni in a statement.

“As we push towards a circular economy that can eliminate waste and support the continual use of resources, our recycled blend is the right choice for better roads and a better environment.”

Road base is one of four layers in constructing roads, along with sub-grade, sub-base and asphalt.

Roughly a third of construction waste currently ends up in landfill, with the country’s current landfill space predicted to be occupied by 2025. According to Tyre Stewardship Australia, “the equivalent to 27 million passenger tyres end up in landfill, stockpiles or are exported overseas” a year.

The research, titled “An experimental study on the shear behaviour of recycled concrete aggregate incorporating recycled tyre waste”, can be accessed here.

Picture: Researchers say the new material is the first to combine recycled concrete aggregate and scrap tyres in a mix that meets road engineering safety standards (RMIT)

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