Due to their tendency to cause structural damage such as fractures and foundation failure, expansive soils, which have high volume changes with changing moisture levels, are a se-rious concern for civil engineers. This research examines fly ash, an industrial waste, as a replacement binder for conventional cementations resources in the field of sustainable soil stabilization. Class F fly ash of various Li/S ratios and NaOH concentrations (10, 12.5, and
15M) and Na2SiO3 concentrations were used to treat an expansive clay (Bhubaneswar, India). The resulting unconfined compressive strengths of 81 mixtures were tested after 3, 7, and 28 days of curing. The optimized mixture (4.8 MPa after 28 days curing, more than two times that of the untreated soil) showed uncfs increases with curing time and was optimized with a 12.5M NaOH concentration and 1. 25 Li/S ration, before over-activation effects decreased the strength. Confocusing on recycling cost-effective, sustainable geopolymers like fly ash will ultimately reduce the construction industry’s effects on the environment, because of its re-duction in costs and carbon emissions relative to lime or cement, as shown by economic and environmental analyses and microstructural examinations respectively. This study provides an economically viable, green solution for problematic soils through systematically optimizing the parameters of geo-polymerization in expansive soil stabilization. It also presents quantita-tive evidence for the utilization of binders from industrial waste in geotechnical applications.