Sustainable Reuse of Construction and Demolition Waste for Geopolymer-Based Soil Stabilization

Low bearing capacity, high compressibility, and excessive settlement or instability in civil engineering structures can occur with soft clay soils. Cement and lime usually stabilise these types of soil, but their manufacturing processes produce significant amounts of greenhouse gases and environmentally harmful chemicals. In addition to these traditional methods, a new sustainable method to improve soil properties through polymer technology has become popular. Due to the lower carbon footprint associated with polymer products compared to cement-based products, geopolymer technology has received increasing use to enhance soil properties by providing excellent binding properties. Construction and demolition waste (CDW) contain a lot of silica and alumina and, therefore, can be used as a precursor or starting point in producing geopolymeric binders that will help stabilise soft clay soils. This research project evaluated the effectiveness of using CDW-derived geopolymeric binders for stabilising soft clay soils. Of the various variables evaluated during study, results demonstrated that NaOH molarity has a major impact on the development of strength in CDW-derived geopolymeric binders and the subsequent improvement in geotechnical properties of the solidified soil. The improvement of geotechnical (engineering) properties is exemplified through the increased strength and reduced compressibility of the solidified soil when using a geopolymeric binder derived from CDW. Further, as CDW can be reused, this approach supports green waste management and efficient use of resources. Ultimately, the use of CDW-derived geopolymers provides an environmentally friendly and financially viable solution to stabilising soft clay soils.