Experimental Investigation of Black Cotton Soil Stabilized with Lime and Coconut Coir

Abstract

Expansive soil occurring above the water table undergo volume changes with change in moisture content. In expansive soils, increase in water table causes swelling–shrink behaviour which leads to cracks and differential settlement resulting in several damages to the pavements, canal beds and linings, foundations, buildings, etc. An attempt is made in this paper to study the effect of adding lime-coir fiber on geotechnical properties of black cotton soil. In the present study an effort is made to obtain the optimum dosage of lime for stabilization of black cotton soil abundantly available in Karnataka state of India. The study incorporates investigation of basic geotechnical properties like grain size distribution, specific gravity, consistency limits and engineering properties like Maximum Dry Density (MDD), Optimum Moisture Content (OMC), Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR). Swelling properties have been determined by conducting Free Swell Index (FSI) test. Durability of the soil is studied by conducting wet-dry cycle and freeze-thaw cycles (WD and FT tests). Fatigue test has been conducted to determine the fatigue life of treated and original soil. Further chemical analysis was conducted to determine the chemical composition of untreated and treated soil. The optimum dosage of lime obtained was 4%. The investigations were carried out to study the effect of addition of coir fibers which are obtained from local market to evaluate the extent of modification on MDD, OMC, UCS and CBR of the soil. Maximum improvement in UCS and CBR values are observed when 1% of coir are mixed with the soil. Soil stabilized with Lime-Coir fiber has shown better results when compared to soil stabilized with lime alone. It is concluded that the proportion of 1% coir fiber in a soil is the optimum percentage of materials having maximum soaked CBR value. Hence, this proportion may be economically used in road pavement and embankments. © Springer Nature Singapore Pte Ltd. 2018.