Stabilization of Expansive Soil: A Review

Black cotton soil (BCS) as an expansive soil (ES) is the most problematic soil which may cause severe risk to the safety of structures that are built over it. These expansive soils may be modified by compacting effort or by introducing some special additives to such soils. For swelling and shrinkage properties of such soils, soil stabilization (SS) method using various materials such as lime, fly ash (FA), stone dust (SD), coir fiber (CF), bagasse ash (BA), and sugarcane straw ash (SSA) may be preferred. Black cotton soil may undergo severe change in its volume when the moisture absorption phenomenon takes place, and this may lead to swelling and subsequently shrinkage after evaporation of moisture from these soils. The expansive soils may possess strength in its dry state, but the strength may wipe out in its wet state.When stabilizing expansive soils with materials suited for such conditions, the strength and bearing capacity of the soils can significantly increase. Unconfined compressive strength (UCS) test as well as California bearing ratio (CBR) test may be performed in order to assess existing bearing capacity and strength of ES prior to SS as well as after the stabilization process too. Stabilization of soil may reduce compressibility as well as permeability of the soil mass. It may also modify shear parameters of the soil, thus increasing the shear strength of ES. The main objective of this paper is to review chemical as well as physical characteristics of expansive soils due to introduction of various materials in these soils. In this paper, also, a number of articles have been reviewed to emphasis on various economical as well as effective expansive additives. This study focuses on the effect of introduction of non-traditional stabilizers in the stabilization of the expansive subgrade with the use of chemical stabilization technique.