Compressibility and Settlement Analysis of Waste-Ceramic Dust Stabilized Sand-Clay Mixture

Clayey soils are widely encountered in engineering practice but are often characterized by high compressibility and excessive settlement, which pose serious challenges to foundation performance and long-term structural stability. This study investigates the compressibility and settlement behavior of sand–clay mixtures stabilized with waste ceramic dust (WCD) as a sustainable improvement technique. Natural clay was blended with 50% sand and varying WCD contents (5–20%), and laboratory compaction and one-dimensional consolidation tests were conducted to evaluate changes in density, void ratio, compression index (Cc), coefficient of compressibility (aᵥ), and settlement characteristics. The untreated clay recorded a maximum dry density (MDD) of 1.93 g/cm³ and exhibited the highest compressibility with a Cc value of 0.10 and settlement of 1.512 mm. Sand inclusion significantly improved soil structure, reducing Cc to 0.051 and settlement to 1.382 mm. Further stabilization with WCD produced progressive improvements, with the optimum performance observed at 10% WCD, where Cc reduced to 0.044, representing over 55% reduction in compressibility relative to natural clay. The coefficient of compressibility also reduced by up to 60% at low effective stress levels, indicating enhanced stiffness. Overall, WCD acted as an effective micro-filler and stabilizing agent, reducing void ratio and settlement. The study concludes that sand–WCD stabilization provides a cost-effective and environmentally friendly solution for mitigating compressibility and settlement problems in clayey soils.