Stabilization of expansive soil using rice husk ash and lime

Abstract

The high swelling and shrinking characteristics of expansive black cotton soils have posed several challenges for the construction works due to their low bearing capacity. Black cotton soils when exposed to changing moisture conditions exhibit high swelling and shrinking conditions. Hence, to overcome these problems, the soil needs to be stabilized. In this project, an experimental investigation is made to study the possibility of using Rice Husk Ash(RHA) and lime as a stabilizing material in the expansive black cotton soil by varying their concentrations. Laboratory tests were carried out to find the effect of RHA and lime in the index and engineering properties of the expansive soil. RHA is added and mixed with the soil at varying proportions of 10%, 15% and 20% and keeping lime concentration constant at 5% by weight of dry soil. The specific gravity test and grain size distribution tests are initially carried out for the virgin soil sample. The index properties such as liquid limit, plastic limit and shrinkage limit and strength properties using Standard Proctor compaction test, California Bearing Ratio test, Unconfined Compressive Strength tests of soil with and without these admixtures are found out. The various test results are compared and the optimum proportion of 5% Lime and 15% of Rice Husk Ash gave the maximum strength and improved index properties of the soil.