New cement-free concrete ‘reduces corrosion by 96pc’

An
eco-friendly zero-cement concrete that all but eliminates corrosion has been
developed by researchers from RMIT University.

Concrete corrosion in wastewater pipes is a significant maintenance issue, as are residual lime leaks that contribute to the formation of fatbergs – congealed lumps of fat, grease, oil and non-biodegradable wipes and nappies.

But RMIT engineers have developed a cement-free concrete that can withstand the corrosive acidic environment found in sewage pipes while greatly reducing lime leaching.

The key
ingredients of the cement-less concrete are byproducts of the manufacturing
industry – nano-silica, fly-ash, and slag. Hydrated lime is also used in the
composite mix.

The
resulting concrete surpasses sewage pipe strength standards set by ASTM
International.

RMIT’s Dr Rajeev Roychand said the solution is more durable than ordinary Portland cement and will help minimise corrosion in expensive infrastructure, including wastewater pipes.

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

“Our zero-cement concrete is environmentally friendly, reduces concrete corrosion by 96 percent, and totally eliminates residual lime that is instrumental in the formation of fatbergs,” Dr Roychand said.

The research team is looking to collaborate with manufacturers and governments to develop more applications for zero-cement concrete.