Durability and environmental performance of calcium carbide residue-based materials in improving soft clay

Despite increasing interest in calcium carbide residue (CCR)-based materials for soil stabilisation, the durability, leachability, and environmental impacts of stabilised soils remain insufficiently evaluated for applications. This study conducted wetting-drying cycle tests, tank leaching tests, and life cycle assessment (LCA) on soils stabilised with CCR alone, CCR combined with fly ash (CCR-FA), and alkaline activated CCR-FA. Soils stabilised with CCR lost integrity after two cycles, whereas CCR-FA and activated CCR-FA gained strength over seven cycles. All CCR-based stabilised soils released low concentrations of heavy metals within regulatory limits. CCR-FA effectively reduced the mobility of Cu, Cr, and As, while activated CCR-FA performed better for Pb. LCA results showed lower environmental impacts for CCR-based materials than conventional binders, with CCR-FA being the most sustainable. However, the environmental advantages of CCR and CCR–FA were strongly influenced by waste availability and energy sources. Overall, CCR-based materials demonstrate potential for eco-friendly soil stabilisation. • CCR-fly ash (FA) and activated CCR-FA improved soil strength during early cycles • All CCR-stabilised soils leached low concentrations of heavy metals over 64 days • CCR-FA immobilised Cu, Cr, and As; activated CCR-FA was more effective for Pb • CCR-based materials had environmental advantages over cement and lime. • Their benefits may diminish with waste availability and energy source