Utilization of Cementitious Material from Residual Rice Husk Ash and Lime in Stabilization of Expansive Soil

Geological disasters often occur due to expansion and shrinkage properties of expansive soil. This paper presents a cementitious material combined with rice husk ash (RHA) obtained from biomass power plants and lime to stabilize expansive soil. Based on compressive and flexural strength of RHA-lime mortars, blending ratio of RHA/lime was adopted as 4:1 by weight for soil stabilization. When mix proportion of RHA-lime mixture varied from 0% to 20%, specific surface area of stabilized expansive soil decreased dramatically and medium particle size increased. The deformation and strength properties of stabilized expansive soil were investigated through swelling test, consolidation test, unconfined compression test, direct shear test, and so on. With increase in RHA-lime content and curing time, deformation properties including swelling potential, swelling pressure, compression index, crack quantity, and fineness of expansive soil lowered remarkably; meanwhile, strength properties involving unconfined compressive strength, cohesion, and internal friction angle improved significantly. Considering engineering performance and cost, mix proportion of 15% and initial water content of 1.2 times optimum moisture content were recommended for stabilizing expansive soil. In addition, effectiveness of RHA-lime to stabilize expansive soil was achieved by replacement efficiency, coagulation reaction, and ion exchange.