Deformation characteristics and stress responses of cement-treated expansive clay under confined one-dimensional swelling

摘要

This study presents an investigation of the effects of cement addition to expansive clay on its deformation characteristics and stress responses during swelling. The effects were evaluated by focusing on the unconfined compressive strength, swelling-shrinkage strains under various conditions, and the lateral coefficient of earth pressure during one-dimensional deformation for artificial mixtures of two different clays at three different ratios. The clays used in this study were a Na-montmorillonite bentonite and a non-expansive Bangkok clay, mixed at different proportions to simulate naturally encountered expansive clays with different degrees of swelling potential. The experimental programme involved unconfined compression, areal shrinkage strain by unconfined drying, vertical free swelling strain, and confined swelling pressure tests. The experimental results show that the cement addition led to marked decreases in the areal shrinkage strain and vertical free swelling strain in addition to the obvious improvement of strength and stiffness of soils. The confined swelling pressure test results indicated that the cement had a greater effect in reducing vertical swelling pressure than the lateral swelling pressure of the soils during one-dimensional swelling. The measured lateral coefficient of earth pressure and stress paths of untreated and cement-treated soils and their engineering implications are discussed.