The term expansive soil indicates soils that tend to swell when their moisture content is allowed to increase. Moisture can come from rain, flooding, leaking water or sewer pipes, or from a reduction in surface evapotranspiration when an area is covered by a building or sidewalk. The term cracked floors is also used for these floors because they tend to contract and crack when humidity decreases. Soils containing montmorillonite, a clay mineral, generally exhibit these properties (Komine and Ogata, 1996; Rao and Triphaty, 2003; Sivapullaiah et al. 1996; Wayne et al. 1984). There are many useful correlations for identifying potentially expansive soils. It may also be possible to identify them visually. Visual indications include (Wayne et al. 1984):1) Wide and deep shrinkage cracks occurring during dry periods2) Soil is rock hard when dry, but very sticky and soft when wet3) Damage to surrounding structures due to soil expansionExpansive soils are found primarily in arid and semi-arid regions of the world. The presence of montmorillonite clay in these soils gives them swelling and shrinkage potential (Chen, 1988). Expansive soils cover almost 20% of India's landmass and include almost the entire Decan Plateau, western Madhya Pradesh, parts of Gujurat, Andhra Pradesh, Uttar Pradesh, Karnataka and Maharastra ( Gopal Ranjan and Rao, 1991). Expansive soils are a global problem that poses many challenges for civil engineers. These are considered a potential natural hazard, which can cause significant damage to structures if not properly addressed. Such soils swell when accessed by water and shrink after drying (Al-Rawas et al. 2002). In general, expansive soils have...... middle of paper ...... stabilization tests Atterberg limits are generally used to identify expansive soil. The increase in plasticity index is considered an indicator of increased swelling potential. Chen (1988) presented a classification of expansive soils based on the plasticity index of the soil, as shown in Table 2.1. Table 2.1 Expansive classification of soils based on plasticity indexPI (%) Swelling potential0 - 15 Low10 - 35 Medium35 - 55 High55 and above Very high classification based on shrinkage index proves unreliable in predicting potential swelling of the soil. However, shrinkage index can be used along with plasticity index for identification as shown in Table 2.2. Table 2.1 Expansive classification of soils based on plasticity index and shrinkage indexPI (% ) SI (%) Degree of expansion< 12 < 15 Low12 - 23 15 - 30 Medium23 - 32 30 - 40 High > 32 > 40 Very high