Taking a firm step towards a circular economy in the construction industry, a team of engineers from RMIT University has used rubber from discarded tyres to create a new type of concrete. The new concrete, which is greener and lighter, uses recycled tyre rubber to replace all of the conventional aggregates such as gravel and crushed rock.
The study, published in the Resources, Conservation & Recycling journal, reveals that the green concrete not only meets building codes but also promises to reduce manufacturing and transportation costs significantly.
While small amounts of rubber particles from tyres are already used to replace concrete aggregates, efforts to replace all of the aggregates with rubber have produced weak concretes that failed to meet the required standards, the team said.
According to lead author and PhD researcher from RMIT University’s School of Engineering, Mohammad Momeen Ul Islam, their precise casting method demonstrates that the 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,” Islam said.
Study co-author and team leader, Professor Jie Li said this manufacturing process will unlock environmental and economic benefits.
“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,” he said.
The RMIT team’s study underscores the importance of finding a solution to the escalating problem of waste tyres, not only in Australia but across the world. Used tyres in Australia cannot be exported, making new methods for recycling and reprocessing them locally increasingly important.
With greatly reduced manufacturing and transportation costs, the new concrete will benefit a range of developments including low-cost housing projects in rural and remote parts of Australia and other countries around the world, Li said.
The team’s manufacturing process could be scaled up cost effectively within a precast concrete industrial setting in Australia and overseas, Islam added.
The research team is now working on reinforcing the concrete to see how it can work in structural elements.
The RMIT research team also includes Professor Yu-Fei Wu, Dr Rajeev Roychand and Dr Mohammad Saberian.
Image: Concrete mixing using recycled tyre rubber particles for the complete replacement of traditional coarse aggregates. Credit: Mohammad Islam, RMIT
