Stabilization of Expansive Soil with Micro Silica, Lime and Fly Ash for Pavement

Geotechnical Engineering properties of soft clayey soil deposits such as black cotton soil may need to be improved by stabilization to make such soils suitable for construction of road pavements. Stabilization of such soils has been traditionally relied on treatment with lime, cement and waste materials such as fly ash. Micro silica is waste material obtained from electric arc furnaces. This paper presents the results of stabilization of local black cotton soil with lime, fly ash and micro silica. Series of laboratory tests have been conducted with varying percentage of these stabilizers, added individually and in combinations, to determine their optimum percentages. From the results, it is observed that CBR value, for both soaked and unsoaked conditions, increases substantially by addition of 5% micro silica along with 3% fly ash and 3% lime. The pavement designed with these improved values of CBR indicated a marked reduction in its thickness leading to economy in the construction of road pavements on or using soft clayey soils.