An engineering team from Royal Melbourne Institute of Technology (RMIT) University (Melbourne, Australia) has managed to replace 100 percent of conventional aggregates in concrete, such as gravel and crushed rock, with rubber from discarded tires that meets building codes. The RMIT University team says that the new greener and lighter concrete promise to reduce manufacturing and transportation costs significantly, along with a boost for the circular economy.
The study published in Resources, Conservation & Recycling journal reveals a manufacturing process for structural lightweight concrete where traditional coarse aggregates were completely replaced by rubber from used car tires. While small amounts of rubber particles from tires had already been used to replace concrete aggregates, previous efforts to completely replace aggregates with rubber had produced weak aggregates that failed to meet required standards.
According to Mohammad Momeen Ul Islam, the study’s lead author and a PhD researcher from RMIT University’s School of Engineering, his team’s findings debunked a popular theory on what could be achieved with recycled rubber particles in concrete.
“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,” Islam says. “The technique involves using newly designed casting molds to compress the coarse rubber aggregate in fresh concrete that enhances the building material’s performance.”
Professor Jie Li, the study’s co-author and team leader, says 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 tire rubber can significantly reduce the consumption of natural resources and also addresses the major environmental challenges of what to do with used tires,” he says.
Li adds that the greener and lighter concrete could greatly reduce manufacturing and transportation costs.
“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.”
The team’s manufacturing process could be scaled up cost effectively within a precast concrete industrial setting in Australia and overseas, Islam says. Following successful testing in the workshop, the team is ow looking into reinforcing the concrete to see how it can work in structural elements.
This research builds on the breakthrough invention of a technique to manufacture concrete from recycled materials developed by RMIT University engineers Professor Yufei Wu, Dr. Syed Kazmi, and Dr. Muhammad Munir, along with Professor Yingwu Zhou of Shenzhen University (Shenzhen, China). Several national phase patent applications are now filed to continue production of this technology.
Source: RMIT University, www.rmit.edu.au.