Researchers fine-tune rubble-rubber road combo

Researchers at RMIT University have developed a new material that combines recycled building rubble and tyres in a mix optimised to meet road engineering safety standards. 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 environmental and engineering benefits. “Traditional road bases are made of unsustainable virgin materials – quarried rock and natural sand,” he said. “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. “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.” In Australia, only 16 per cent of scrap tyres are domestically recycled, according to RMIT. About 3.15 million tonnes of processed building rubble – known as recycled concrete aggregate (RCA) – is added to stockpiles each year rather than being reused. RCA can potentially be used on its own for road base layers, but adding recycled rubber can significantly enhance the finished product. In previous research, the RMIT School of Engineering team has shown their rubble-rubber blend performs well when tested for stress, acid and water resistance, as well as strength, deformation and dynamic properties. Its low shrinkage and good flexibility reduce the risk of cracking. The new study published in Construction and Building Materials looked at how the mix would withstand the pressures of being driven over by countless vehicles over its lifetime. Researchers used special machinery to assess the blended material’s performance under frictional force, or shear stress, and compared different types of crumb rubber (fine and coarse) mixed into the RCA at different ratios. 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. ‘An experimental study on the shear behaviour of recycled concrete aggregate incorporating recycled tyre waste’ is published in Construction and Building Materials (DOI: 10.1016/j.conbuildmat.2020.120266).

Researchers fine-tune rubble-rubber road combo

Industry Queensland

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