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This zero-cement concrete can make wastewater pipes more sustainable

While wastewater pipes are fundamental to the provision of water services around the world, they often require costly maintenance works due to erosion. But one group of Australian researchers has developed a cement-free concrete with the aim of creating more sustainable pipe technology. 

Published in Resources, Conservation & Recycling, the research from RMIT University outlines a cement-free concrete alternative, which is more durable and much better for the environment. 

The new concrete can withstand the highly acidic environment found in sewage pipes, while also reducing residual lime — a by-product of regular concrete erosion that contributes to the formation of fatbergs. RMIT’s Dr Rajeev Roychand said the solution is more durable than ordinary Portland cement, helping to minimise corrosion in expensive infrastructure, including wastewater pipes.

“The world’s concrete sewage pipes have suffered durability issues for too long. Until now, there was a large research gap in developing eco-friendly material to protect sewers from corrosion and fatbergs,” he told RMIT news.

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

The cement-free concrete is created using large volumes of industrial byproducts — a composite of nano-silica, fly-ash, slag and hydrated lime — surpassing pipe strength standards set by ASTM International and lasting longer than regular concrete materials. 

“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.”

The new approach aims to reduce the cost and disturbances associated with wastewater pipe replacement, while also reducing greenhouse gas emissions created from Portland cement production.

Furthermore, Roychand said the use of industrial byproducts has the added benefit of eliminating residual lime within wastewater pipes, an effect of erosion that contributes to the formation of costly fatbergs. 

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

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

Roychand and his team are now seeking collaboration with manufacturers and governments to develop more applications for their zero-cement concrete.