A new approach to rubber recycling could lead to end-of-life tires being reused in concrete for housing, researchers in Australia say.
New research from the University of South Australiain collaboration with RMIT Universityshowed that crumb rubber concrete is a safe, green alternative for housing in Australia.
Principal Investigator, UniSA Professor Julie Mills† said the research is the first to practically demonstrate and construct the new crumb rubber concrete mix in the field.
Worldwide, approximately 1.5 billion car tires are thrown away every year, but less than one percent of this is recycled, with the rest missing or dumped in landfills. In Australia alone, about 51 million tires end up in landfills, stockpiles or dumped on mining sites.
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“Rubber tires are not biodegradable and lead to unstable landfills, breeding grounds for mosquitoes from trapped water, polluted surfaces and toxic groundwater. She [also] pose a significant risk to toxic fires,” said co-investigator Dr. Osama Youssf. “Such continuous production and disposal of waste is completely unsustainable, so we explored alternative recycling options.”
He added: “This study examined the design and processing of various crumb rubber concrete mixes for use in residential construction, assessing workability, bond strength, durability and flexural strength.
“We found that reinforced crumb rubber concrete – with up to 20 percent sand replacement by volume – is superior to conventional concrete in some respects, with higher impact strength, toughness and ductility, higher damping ratio, better thermal and acoustic insulation, and lighter weight.
“With regard to pumping, screeding or finishing the concrete surface using an electric trowel, contractors also reported no difference between using rubber crumb concrete and conventional concrete, saying that the rubber crumb mixture actually required less physical effort in all respects. .
“In addition, the turnkey cement companies reported no concerns regarding the mixing, delivery or mixing of concrete, saying that washing out the concrete truck mixer was much easier.”
As part of their research, two residential slabs (one with crumb rubber concrete and the other with conventional concrete) were poured in October 2018 on the Mawson Lakes campus of the University of South Australia. The slabs have been checked for more than two years and the crumb rubber concrete slab continues to perform well. The team’s findings were published in structures†
“This is an exciting development for both the recycling and construction sectors,” said co-investigator Prof. Yan Zhuge. “The results clearly demonstrate that rubber cement granules are a viable and promising alternative to conventional concrete in the residential concrete market.”
