Australian researchers have made a breakthrough by being able to turn water treatment sludge into sustainable concrete.
University of South Australia (UniSA) engineers have combined sludge with blast furnace slag into a new material that has shown corrosion-resistant properties. These properties mean the material could be an alternative to traditional cement sewer pipes.
“Sludge is usually disposed of in landfill sites, which not only reduces available land for other uses, but also harms the environment, creating CO₂ emissions from transporting the waste,” UniSA civil engineering PhD candidate Weiwei Duan said.
The researchers published their new findings in the Journal of Building Engineering. Their study examines the potential of alkali-activated materials (AAMs) in the global sewage infrastructure.
The findings showed samples containing 20 per cent to 40 per cent of alum-based water treatment sludge (AWTS) retained over 50 per cent higher compressive strength compared to 100 per cent ground granulated blast furnace slag (GGBS).
While concrete is used for making sewage pipes due to its affordability and structural strength, it can also be prone to acid and microbial corrosion in sewers. The new material also showed an ability to limit the penetration of sulphur-oxidising bacteria and slowed acid-reduced degradation.
“This has the potential to extend the service life of sewage pipes, reduce maintenance costs, and promote the reuse of water treatment byproducts, thus contributing to the circular economy,” Professor Yan Zhuge said.
“The construction industry is one of the world’s biggest greenhouse gas emitters, so if we can cut down on the need for cement, we will be helping to lower carbon emissions.”
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