Researchers have developed an environmentally friendly cement-free concrete that eliminates corrosion and keeps grease mountains free.
Concrete corrosion and fatbergs plague sewage systems around the world, leading to costly and disruptive maintenance.
But now, engineers at RMIT University have developed concrete that can withstand the corrosive acidic environment of sewer pipes, while significantly reducing the residual lime that leaches, contributing to grease mountains.
Fatbergs are coarse blobs of congealed mass that clog sewers with grease, grease, oil and non-biodegradable junk such as wet wipes and diapers, some of which reach 200 meters in length and weigh tons.
This build-up of grease, oil and grease in sewers and pipelines, as well as general corrosion over time, costs billions in repairs and replacement pipes.
The RMIT researchers, led by Dr. Rajeev Roychand, created a concrete that eliminates free lime – a chemical compound that promotes corrosion and grease build-up.
Roychand said the solution is more durable than regular Portland cement, making it perfect for use in large infrastructure, such as sewer pipes.
“The world’s concrete sewer pipes have been struggling with sustainability issues for too long,” Roychand said.
“Until now, there has been a major research deficit in the development of environmentally friendly material to protect sewers against corrosion and grease mountains.
“But we made concrete that is protective, strong and environmentally friendly – the perfect trio.”
Manufacturing industry by-products are key ingredients of the cementless concrete – a cement-free composite of nano-silica, fly ash, slag and hydrated lime.
Not only does their concrete use large amounts of industrial by-products, supporting a circular economy, it exceeds the sewer pipe strength standards set by ASTM International.
“Although common Portland cement is widely used in the fast construction industry, it presents long-term durability issues in some applications,” Roychand said.
“We found that making concrete from this composite mix – instead of cement – significantly improved life.”
Replacing underground concrete pipes is a tedious job, breaking open the ground is expensive and often has the ripple effect of long-term traffic congestion and neighborhood nuisance.
The Water Services Association of Australia estimates that maintaining sewer networks costs $ 15 million every year, billions worldwide.
The environmental costs are higher: Ordinary Portland cement is responsible for about 5 percent of global greenhouse gas emissions.
However, the RMIT study has shown that certain byproducts are suitable to replace cement and can withstand the high acidity of sewer pipes.
“Our zero-cement concrete has several advantages: it is environmentally friendly, reduces concrete corrosion by 96 percent and completely eliminates lime residues that play a role in the formation of fat mountains,” says Roychand.
“With further development, our cement-free concrete could be made fully resistant to acid corrosion.”
Cement-free concrete prevents corrosion and eliminates fatbergs
Concrete corrosion and grease mountains plague sewage systems
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