Researchers at the University of South Australia (UniSA) have developed a new eco-friendly material that can be used as an alternative to traditional cement sewer pipes, which are often prone to cracking and corroding.
Engineers combined sludge, a byproduct of the drinking water purification process, with blast-furnace slag to create a new corrosion-resistant material that they claim is more than 50 percent stronger than cement.
The new material also reportedly limited the penetration of sulphur-oxidising bacteria and slowed acid-reduced degradation.
UniSA civil engineering PhD candidate Weiwei Duan says another major benefit of innovating this new material is that it offers a cost-effective and sustainable way to deal with water treatment residue.
“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,” Weiwei says.
The need for alternatives to concrete
Concrete is widely used for making sewage pipes due to its availability, affordability and structural strength.
However, it is highly susceptible to acid and microbial corrosion in sewers, requiring ongoing repairs and maintenance that cost Australian taxpayers close to $70 billion each year.
The scale of sewage networks is immense. An example cited by the UniSA researchers noted that South Australia alone maintains over 9300km of sewage piping.
Globally, the combined length of these networks is estimated to circle the equator multiple times.
A new study published in the Journal of Building Engineering evaluates the effectiveness of the alkali-activated materials (AAMs) and demonstrates why they could revolutionise sewage infrastructure worldwide.
Samples containing 20-40 percent of alum-based water treatment sludge (AWTS) retained over 50 percent higher compressive strength compared to 100 percent ground granulated blast furnace slag (GGBS), which is used in the production of cement.
Principal supervisor and lead researcher on the project Professor Yan Zhuge says the findings suggest that partially replacing the blast furnace slag with 20-40 percent of water treatment sludge makes them “promising candidates” for use in sewers.
“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.
“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,” Zhuge says.
Image: Supplied
