<b>Study on Stabilization of Black Cotton Soil by using Copper Slag for Pavement Subgrade</b> Soil stabilization improves various engineering properties e.g. bearing capacity, compressibility, strength, and various other properties of soil. In this study the impact of Copper slag to improve the strength of soil.Copper slag is a by product of copper smelting and refining process. As refineries draw metal out of copper ore, they produce a large volume of non metallic dust, soot, and rock.The effect of varying percentage of Copper slag on properties of Expansive Soil.To study the variation of Liquid Limit, Plastic Limit, Plasticity Index, Dry density, OMC, CBR Soaked and Un soaked of soil. The strength has been compared on the basis of CBR for virgin soil and soil with Copper slag soaked conditions.The Unsoaked CBR value of the raw soil is 5.42 and after mixing of Copper Slag in the soil, there i s remarkable change in CB R value from 5.42 to 12.28 . when Copper Slag is increased from 0 to 16 is effective beyond also there is a decrease in CBR of soil from 12.28 to 10.47 when Copper Slag is increased from 16 to 24 . 6-9 Issue-1 Volume-7 Amar Jaiswal | Afzal Khan