Dynamic Shear Modulus of Treated Expansive Soils

Dynamic shear modulus of expansive soils treated with lime, salt, and lime-salt combination has been determined by the resonant column technique to study the parametric effects of confining pressure, shear-strain amplitude, degree of saturation, treatment level, type of additives, and soil structure. The effect of each of these parameters on the dynamic shear modulus was found to be significant and could be explained in terms of the change in macrostructure and corresponding change in physiochemical properties of the soil. It was found that the use of additives to stabilize expansive soils not only improved the static properties by reducing swelling and increasing the shear strength, but also improved the dynamic properties. The treatment with lime-salt combination was found to be the most effective as the addition of salt to bentonite clay-lime mixture produced a catalytic acceleration of pozzolanic reactions and new cementitious minerals. It was also found that the dynamic shear modulus showed a good correlation to the static shear strength of the soil.