The cement used to construct concrete sewerage systems around the world does a mighty job of helping wash away our waste but does have its shortcomings.
Scientists in Australia have developed a new cement-free solution they say is better equipped to handle the corrosive nature of these environments, while also helping avoid the buildup of troublesome and costly fatbergs. The new cement-free concrete was developed by scientists at Australia’s RMIT University, where we have seen a number of innovative approaches to producing enhanced forms of concrete. These include re-using steel slag as a concrete aggregate and working building rubble into new types of road materials, and now RMIT scientists are turning their attention to the free lime.
Free lime is a chemical compound used in large amounts in the production of common Portland cement but also makes it vulnerable to corrosion in the highly acidic environments of sewerage systems. Furthermore, residual lime can bleed out of the concrete and contribute to fatbergs, the greasy masses of oil, fat and non-biodegradable matter that can grow to weigh several tonnes and clog up pipes.
The RMIT researchers went a different way to produce cement-free concrete by largely using by-products of the manufacturing industry, combining nano-silica with fly ash, slag, and hydrated lime. In testing, the team found its concrete surpassed the strength standards required of sewage pipes, with the unique blend significantly improving longevity.
“Our zero-cement concrete achieves multiple benefits: it’s environmentally friendly, reduces concrete corrosion by 96 percent, and totally eliminates residual lime that is instrumental in the formation of fatbergs,” said Dr. Rajeev Roychand, who led the research.
