Stabilization of expansive soil using talcum powder and cement: swelling reduction and strength development

Abstract Expansive soils are considered one of the most problematic soil types worldwide due to their significant volume change behaviour in response to variations in moisture content. This study investigates the stabilization of expansive soil using a combination of cement and talcum powder in order to improve its engineering performance. Different percentages of talcum powder, combined with a constant cement content, were examined to evaluate their effects on swelling pressure, compaction characteristics, unconfined compressive strength, and stiffness. The results indicated that at the highest blend fraction of 24% and after a curing period of 14 days, the swelling pressure reduction increased with both increasing blend content and curing time, reaching a maximum reduction of 57.3%. The maximum dry density (MDD) increased from 16.53 kN/m³ for the untreated soil to 17.32 kN/m³, while the optimum moisture content (OMC) decreased from 21.05% to 14.94%. The relative modulus of elasticity increased from 1.04 to 1.36, indicating an improvement in soil stiffness and overall stability. These improvements suggest that the combined treatment enhances cementitious bonding and interparticle interactions within the soil matrix. Moreover, the inclusion of talcum powder contributes to reduce the brittle failure behaviour and promotes a more ductile response under loading conditions.