The moisture retaining capacity of Black Cotton soil undergoes climatic changes and which shows poor sub grade characteristics due to its swelling and shrinking properties. To avoid this problem BC soil was stabilized using various conventional stabilizers like lime, fly ash etc. In the present research work BC soil was replaced by MW and additive as Steel Slag to improve the plasticity and stability properties of BC soil.MW was replaced by BC soil with 10,20,30,40 and 50%. Various geotechnical tests such as Atterberg limits, compaction tests, CBR, UCC and swell pressure were carried out. Based on the Optimum quantity of MW, Steel Slag was used as additive in steps of 10% up to 50% to improve the engineering properties of BC soil.