Researchers from RMIT University, Australia, have demonstrated that old, discarded rubber tyres can be upcycled into eco-friendly crumb rubber concrete for residential construction, giving a new purpose to end-of-life tyres.
An estimated 1.5 billion vehicle tyres are discarded every year worldwide, with less than 1 per cent reused and the rest dumped in landfills. In Australia, around 51 million tyres end up in stockpiles, landfills, or dumped on mine sites.
Professor Julie Mills, the study’s lead researcher, stated that the research is the first to demonstrate and construct a new crumb rubber concrete mix in the category, taking the work from “lab to slab”.
“By recycling old rubber tyres in concrete, limited natural resources can be conserved, and there would be fewer tyres in the landfills,” said Prof Mills.
The research studied the design and processing of different crumb rubber concrete mixes in residential constructions, assessing their bond strength, durability, flexural strength, and constructability.
According to the researchers, they found that the reinforced rubber concrete (with up to 20 per cent sand replacement by volume) is on a par with conventional concrete in some aspects, having higher impact resistance, ductility, higher damping ratio, better acoustic and thermal insulation, and is lighter in weight.
Dr Osama Youssf, co-researcher of the study, shares that the accumulation of end-of-life tyres is a global problem for the environment.
“Rubber tyres are not biodegradable and lead to unstable landfills, breeding grounds for mosquitoes from trapped water, polluted surfaces and toxic groundwater,” explains Dr Youssf.
With regards to screeding, pumping, or finishing the concrete surface using a power trowel, contractors engaged in the study reported that they found no difference between using crumb rubber concrete and conventional concrete, saying that the crumb rubber mix is easier to work with.
In addition, ready-mix cement companies reported no concerns relating to concrete batching, delivery or mixing and said that the washout of the concrete truck mixer was far easier.
“This is an exciting development for the recycling and construction industry,” shares Professor Yan Zhuge, co-researcher.
“We strongly recommend that the concrete industry consider crumb rubber concrete a sustainable alternative to conventional concrete in reinforced residential constructions in Australia.”
