Researchers from RMIT University, Victoria have developed a new technology to manufacture concrete made from recycled materials that is stronger and more durable than the traditional product.

Recycled concrete aggregates made with everything from coffee cups to building rubble offer huge environmental benefits, from reducing landfill and CO2 emissions, to saving natural resources and boosting the circular economy.

Despite ongoing improvements however, challenges with matching the strength and durability of traditional concrete have hindered the practical application of these sustainable alternatives.

Now researchers from RMIT have developed a new method for casting prefabricated concrete products made with rubber tyres and construction and demolition waste that are up to 35% stronger than traditional concrete.

Professor Yufei Wu from the School of Engineering led the development of the Rubberised Concrete Processing Technology (RCP-Tech) and said it offered an efficient and inexpensive solution.

“This technology can be used to significantly improve the strength, hardness and durability of any type of concrete material, such as rubber concrete, recycled aggregate concrete, and even ordinary concrete,” he says.

The method involves combining a mix of course and fine aggregates with rubber tyre waste, cement and water which is then compressed to its minimum volume using pressure in a customised mould.

“By enhancing the properties of the recycled waste without the use of any additional materials, we have developed a feasible and practical solution that addresses the performance issues affiliated with waste recycling in concrete,” Yufei explains.

Rubber from waste tyres is the cause of significant health, environmental and land fill problems worldwide owing to its chemical, flammable and non-decomposable nature.

From 2015-16 Australia generated around 450,000 tonnes of waste rubber, 63% of which was sent to stockpiles or landfills and Victoria alone produces the equivalent volume of the Eureka Tower every four years.

PhD researcher and RCP-Tech co-creator, Syed Kazmi, says the team was now looking to partner with the precast concrete industry to manufacture and test prototypes of products like blocks and roadside barriers, wall panels, beams and slabs.

“The technology can be easily applied in the precast concrete industry and requires very little change to existing manufacturing processes with the addition of just one extra step in the final stage of production,” he says.

Kazmi and fellow PhD researcher Muhammad Munir presented the technology at the City of Melbourne Open Innovation Competition 2020 where they were finalists. They were also awarded the RMIT LaunchHUB prize for their work.