Effect of GGBS and Lime on the Strength Characteristics of Black Cotton Soil

In agriculture-based country like India road network plays a major role. The life and maintenance of roads mainly depend on the strength of both sub-base and subgrade of soil and traffic intensity. In India about 20% of the total area is covered by Black cotton soil. Because of the high swelling and shrinkage characteristics under varying water contents Black cotton soil poses problems in road construction and maintenance. This paper presents experimental results illustrating the behavior of Black cotton soil stabilized with Ground Granulated Blast furnace Slag (GGBS) and GGBS-lime mix. In order to estimate the strength of the stabilized soil, tests such as Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) tests were performed. Tests were conducted on soil-GGBS mix for GGBS dosages 3, 6, 9, and 12% by weight of dry soil and soil-GGBS-Lime mix with 2 part GGBS and 1 part Lime for dosages 3, 6, 9, and 12% by weight of dry soil. Tests were conducted on both unsoaked and soaked samples, unsoaked samples were cured for 7 and 28 days whereas soaked samples were cured for 3 days and soaked for 4 days. The effect of binder content, curing period and soaking on the UCS and Elastic modulus were studied and subsequently the effect of binder content on CBR values were also studied. With the increase in binder content and curing period the strength of the treated soil was found to be enhanced. Soaking resulted in the decrement of the strength of the stabilized soil. From the experimental results it is clear that GGBS-lime mix is a superior binder content than GGBS for the improvement of black cotton soil, when used as a sub-base material in flexible pavement.