Quality new concrete made from 100% rubber, using only old tires

A study on the new rubber-based concrete titled "Design and strength optimization method for the production of structural lightweight concrete: An experimental investigation for the complete replacement of conventional coarse aggregates by waste rubber particles" has been published in the journal Resources, Conservation and Recycling.

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Researchers from the Royal Melbourne Institute of Technology (RMIT) University in Australia have developed a new method for creating concrete comprised entirely of recycled rubber from discarded tires. The rubber replaces the conventionally used concrete aggregates like gravel and crushed rock but still allows the end product to meet building codes. The team believes this breakthrough promises "a boost for the circular economy."

Small amounts of rubber are currently in use to partially replace some of the typical concrete aggregates, but using too much has typically resulted in weaker end results that don't meet the relevant requirements. Their new manufacturing process, which builds upon previous breakthroughs by RMIT, produces lighter and greener concrete that performs as well as traditional concrete.

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In Australia, used tires cannot be exported, so finding ways to recycle or reprocess them effectively is crucial for managing the growing number of waste tires. By 2030, around 1.2 billion waste tires are expected to be disposed of annually. Additionally, some traditional concrete aggregates like sand are becoming increasingly short-supplied, highlighting a need for an alternative manufacturing process.

"We have demonstrated with our precise casting method that this decades-old perceived limitation on using large amounts of coarse rubber particles in concrete can now be overcome. The technique involves using newly designed casting moulds to compress the coarse rubber aggregate in fresh concrete that enhances the building material's performance," said lead author and Ph.D. researcher from RMIT University's School of Engineering, Mohammad Momeen Ul Islam.

"As a major portion of typical concrete is coarse aggregate, replacing all of this with used tyre rubber can significantly reduce the consumption of natural resources and also address the major environmental challenge of what to do with used tyres. This would benefit a range of developments including low-cost housing projects in rural and remote parts of Australia and other countries around the world," said Professor Jie Li, the team leader and study's co-author.

You can read more from the study here.