Cement-free concrete “strong, protective and environmental”

Researchers from RMIT University claimed they have successfully developed an eco-friendly zero-cement concrete which not only eliminates corrosion and pollution, but also makes use of industrial by-products.

As generic concrete corrodes over time in sewage systems due to the acidic environment, the residual lime that leaches out contributes to the environmental nightmare that is the fatberg.

Fatbergs are basically globs of congealed mass clogging sewers that consist of lime, grease, oil and non-biodegradable junk such as wet wipes and nappies; some growing to be 200m long and weighing tonnes.

These build-ups, alongside general corrosion over time in sewers and pipelines, cost billions in repairs and replacement pipes.

A group of researchers at the RMIT University in Melbourne, Victoria, have successfully created concrete that eliminates free lime, as well as provide the strength and durability to support infrastructure.

Research team leader, Dr Rajeev Roychand, said the solution is more durable than ordinary Portland cement, making it perfect for use in major infrastructure such as sewage drainage pipes.

“The world’s concrete sewage pipes have suffered durability issues for too long,” Dr Roychand said.

“Until now, there was a large research gap in developing eco-friendly material to protect sewers from corrosion and fatbergs.

“But we’ve created concrete that’s protective, strong and environmental – the perfect trio.”

The innovative cement-less concrete is made up of a mix of ingredients including nano-silica, fly-ash, slag and hydrated lime, which are all by-products of the manufacturing industry, Dr Roychand said.

In addition to supporting environmental sustainability with its use of industrial by-products, the concrete also surpasses sewage pipe strength standards set by ASTM International, Dr Roychand said.

“Though ordinary Portland cement is widely used in the fast-paced construction industry, it poses long term durability issues in some of its applications,” Roychand said.

“We found making concrete out of this composite blend – rather than cement – significantly improved longevity.”

Another benefit of the new innovation is a significant cost saving over time, according to Dr Roychand.

Due to corrosion, underground concrete pipes need to be replaced after some time which not only cost a lot of money to do, but can also cause plenty of inconvenience to nearby communities and road users.

The Water Services Association of Australia estimates the maintenance of sewage networks costs $15 million each year and billions of dollars worldwide.

The environmental cost is great too – ordinary Portland cement accounts for about five per cent of the world’s greenhouse gas emissions, RMIT said.

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“Our zero-cement concrete achieves multiple benefits: it’s environmentally friendly, reduces concrete corrosion by 96 per cent and totally eliminates residual lime that is instrumental in the formation of fatbergs,” DR Roychand said.

“With further development, our zero-cement concrete could be made totally resistant to acid corrosion.”

Dr Roychand and his team are currently looking to collaborate with manufacturers and government to develop more applications for their zero-cement concrete.