Cleaner, stronger, harder: New tech improves sustainable concrete

Cleaner, stronger, harder: New tech improves sustainable concrete
Credit: RMIT University

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 tires 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 Rubberized 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 said.

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

"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," Wu said.

Rubber from waste tires 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 tons 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.

Ph.D. researcher and RCP-Tech co-creator, Syed Kazmi, said 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 said.

The findings, "Application of tire and recycled aggregates in concrete products: A new compression casting approach," are published in the journal Resources, Conservation and Recycling.

More information: Syed Minhaj Saleem Kazmi et al. Application of waste tire rubber and recycled aggregates in concrete products: A new compression casting approach, Resources, Conservation and Recycling (2021). DOI: 10.1016/j.resconrec.2020.105353

Provided by RMIT University

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