Effects of lime treatment on shear strength and small strain shear modulus response of expansive clay

Abstract

Expansive soils tend to swell on moisture ingress and shrink on moisture evaporation, which causes distress to highway/railway embankments, canal slopes, small buildings, etc. It is a common practice to stabilize expansive soils using lime. The present study investigates the effect of variation in lime content, curing period, initial matric suction, and overburden pressure on small strain shear modulus (Gmax) response of a highly expansive compacted clay along with its unconfined compressive strength (UCS) and microstructural changes. The hydrated lime was used in the dosages of 0–6% at an interval of 1%. The curing periods of 7 days, 28 days, 60 days, 90 days, and 180 days were considered in the present study. A GDS triaxial system equipped with bender elements was used to determine the small strain shear modulus at different overburden pressures. Matric suction was determined using the in-contact filter paper technique. The shear strength and small strain shear modulus were correlated with the matric suction of lime-treated expansive soil. The microstructural changes in the soil mass due to lime treatment were observed using scanning electron microscopy (SEM). The UCS of lime-treated soil specimens was found to be linearly correlated with the initial matric suction. Moreover, a multivariable linear regression fit with an R2 value of 0.84 showed the dependency of Gmax on matric suction and overburden pressure. The microstructural alterations caused by lime treatment were found to be in agreement with the changes in matric suction, shear strength, and Gmax of compacted expansive soil.