Advances in Soil Stabilization Using Calcium Carbide Residue (CCR) and Industrial by-Products: A Circular Economy Approach to Enhancing Mechanical Performance

This state-of-the-art review synthesizes recent advances in soil stabilization using calcium carbide residue (CCR) combined with selected industrial by-products, including fly ash, lime, rice husk ash (RHA), and polypropylene fibers, with a focus on applications in road engineering. While CCR alone can improve unconfined compressive strength (UCS) to approximately 0.5 MPa at 28 days, its performance is often constrained by shrinkage cracking, moisture sensitivity, and potential environmental concerns. The reviewed literature indicates that hybrid CCR-based systems can substantially enhance mechanical performance and durability: CCR–fly ash blends have been reported to achieve UCS values exceeding 3.0 MPa with high strength retention under wet–dry cycling; CCR–RHA mixtures significantly reduce swelling potential; and fiber-reinforced formulations improve tensile resistance and crack control under dynamic loading. These performance trends are commonly attributed to combined effects associated with pozzolanic reactions forming calcium silicate and aluminate hydrates (C–S–H and C–A–H), matrix densification, and fiber-induced crack-bridging mechanisms, although quantitative isolation of individual component contributions remains limited in existing studies. The review further highlights performance-oriented mix design strategies, microstructural characterization approaches (e.g. SEM and XRD), and curing considerations relevant to long-term stability. Emerging data-driven and machine-learning-based predictive models are also discussed as promising tools for optimizing CCR-based formulations across diverse soil types and climatic conditions. Overall, CCR-based composite stabilization systems demonstrate strong potential as sustainable alternatives to conventional cement–lime treatments, consistent with circular economy principles, while continued field validation and long-term assessment remain essential for widespread implementation.