A unique method of recycling rubber could result in end-of-life tires being repurposed into concrete for residential buildings. Made possible by a team of researchers from the University of South Australia (UniSA), the research demonstrates that it can offer a cost-effective, feasible and sustainable substitute for traditional concrete.
Approximately 1.5 billion vehicle tires are discarded each year. Image Credit: University of South Australia.
Collaborating with RMIT University, the scientists showed that crumb rubber concrete is a safe, eco-friendly substitute for residential construction in Australia, establishing a much-desired commercial space for end-of-life tires.
Lead scientist, UniSA’s Professor Julie Mills, states that this study is the first to practically show and create the new crumb rubber concrete mix in the real world, basically transferring their efforts from lab to slab.
Internationally, about 1.5 billion vehicle tires are thrown away per annum. Less than 1% of these tires are reused, with the others being thrown in landfills or unaccounted for. In Australia, around 51 million tires wind up in stockpiles, landfills or discarded in mine locations.
By repurposing end-of-life tires in concrete, critical natural resources can be preserved, and the existing tire landfill issue can be partly resolved.
Dr. Osama Youssf, co-researcher states that the buildup of end-of-life tires is a worldwide and constantly increasing issue for the environment everywhere.
Rubber tyres are not biodegradable and lead to unstable landfills, breeding grounds for mosquitoes from trapped water, polluted surfaces, and toxic groundwater. They pose a significant risk for toxic fires.
Dr. Osama Youssf, Co-Researcher, University of South Australia
Dr. Youssf continued, “In Australia, two-thirds of tyres end up in landfill. Such continuous waste production and disposal is entirely unsustainable, which is why we have been investigating alternative recycling options. This research investigated the design and processing of various crumb rubber concrete mixes for use in residential constructions, assessing its constructability, bond strength, durability, and flexural strength.”
We found that reinforced crumb rubber concrete (with up to 20 per cent sand replacement by volume) is superior to conventional concrete in some ways, with higher impact resistance, toughness and ductility, a higher damping ratio, better thermal and acoustic insulation, and a lighter weight.
Dr. Osama Youssf, Co-Researcher, University of South Australia
Dr. Youssf added, “With respect to pumping, screeding, or finishing the concrete surface using a power trowel, contractors also reported no difference between using the crumb rubber concrete and conventional concrete, saying that the crumb rubber mix actually required less physical effort across all aspects.”
Additionally, the ready-mix cement companies reported no concerns relating to concrete batching, delivery or mixing, and said that the wash out of the concrete truck mixer was far easier.
Dr. Osama Youssf, Co-Researcher, University of South Australia
Co-researcher UniSA’s Professor Yan Zhuge explains that this study demonstrates just how appropriate crumb rubber concrete is for residential buildings.
This is an exciting development for both the recycling and construction industry, The results clearly show that crumb rubber cement is a viable and promising alternative to conventional concrete in the residential concrete market. We strongly recommend that the concrete industry considers crumb rubber concrete as a sustainable alternative to conventional concrete in reinforced residential constructions in Australia.
Professor Yan Zhuge, Co-Researcher, University of South Australia
Journal Reference:
Youssf, O., et al. (2022) Practical Application of Crumb Rubber Concrete in Residential Slabs. Structures. doi.org/10.1016/j.istruc.2021.12.062.