A research team at IIT Guwahati has developed an innovative solution to two major global challenges – industrial waste management and sustainable construction.
Led by Prof Anil K Mishra from the Department of Civil Engineering, the team’s research focuses on creating a geopolymer using industrial byproducts and waste materials, including water treatment sludge (WTS), fly ash (FA) and ground granulated blast furnace slag (GGBS).
With the rapid pace of urbanisation and industrialisation, managing industrial waste has become a critical global issue.
Among the various types of industrial waste, water treatment sludge poses significant challenges due to its high-water content and organic components.
Water treatment plants worldwide generate approximately 100,000 tonnes of sludge daily. Traditional disposal methods, like landfilling or using sludge as soil additives, have proven to be costly and environmentally risky, as heavy metals can leach into groundwater.
One of the key applications of the WTS-FA-GGBS geopolymer is in road construction.
The research team evaluated the mechanical properties of the geopolymer, specifically its suitability as a subgrade material for roads and pavements.
The subgrade layer forms the foundation of roads, determining the pavement’s strength and longevity. Using the WTS-based geopolymer as a stabiliser was found to significantly enhance road performance, particularly in soft or weak soils.
In addition to WTS, the team is also focused on geopolymerising construction and demolition (C&D) waste, which exceeds 10 billion tonnes annually, and constitutes over 35 per cent of global waste.
The team has developed applications for C&D waste, including base and subbase layers for road pavements and paver blocks, contributing to effective waste management and reduced environmental impact.
Moreover, the team is investigating the treatment of landfill-mined fine fractions from old municipal solid waste dumpsites, offering promising solutions while supporting circular economy initiatives. They are also exploring the stabilisation of petroleum sludge by incorporating fly ash and GGBS, aiming to immobilise hazardous heavy metals and prevent environmental leaching.
Tests conducted by the team, including Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) assessments, revealed that the WTS-FA-GGBS geopolymer exceeds the minimum strength requirements for cement-stabilised subgrade materials.
Durability tests confirmed its ability to withstand extreme environmental conditions, making it a reliable choice for infrastructure projects across diverse climates. Crucially, the geopolymer is non-toxic. Leaching tests demonstrated that heavy metal concentrations in the geopolymer leachate are well within the safety limits set by the U.S. Environmental Protection Agency (USEPA), ensuring that it poses no risks to the environment or human health, even in large-scale applications.
The research addresses several key concerns in modern civil engineering and waste management. By recycling industrial waste, the project helps reduce landfill burden and minimises the environmental damage caused by traditional disposal methods.
The innovative geopolymer technology opens new avenues for industries, municipalities and governments to adopt eco-friendly construction practices while addressing the growing issue of industrial waste disposal. As India continues to urbanise and industrialise, innovations like this play a vital role in building a greener and more sustainable future.
