Improvement of Strength of Expansive soil with waste Granulated Blast Furnace Slag Anil Kumar Sharma 1 and P.V. Sivapullaiah 2 1 Research Scholar, Department of Civil Engineering, Indian Institute of Science, Bangalore-560012, Karnataka, India; PH (+91) 9535145760; email: ceanil@gmail.com . 2 Professor, Department of Civil Engineering, Indian Institute of Science, Bangalore- 560012, Karnataka, India; PH (+91)-80-22932672; email: siva@civil.iisc.ernet.in ABSTRACT Utilization of industrial waste materials in the improvement of problematic soils is a cost efficient and also environmental friendly method in the sense that it helps in reducing disposal problems caused by the various industrial wastes. The main objective of the present study is to improve various engineering properties of the soil by using waste material Ground Granulated Blast Furnace Slag (GGBS) as an alternative to lime or cement, so as to make it capable of taking more loads from the foundation structures. This paper reports the findings of laboratory tests carried out on local Indian expansive black cotton soil with GGBS mixed with the expansive soil in different proportions. The specimens compacted to their respective Proctor’s optimum moisture content and dry density (which varied from mixture to mixture) were cured for a period of 7, 14 and 28 days and their unconfined compression strengths were determined. It is observed that the strength improvement depends on the amount of GGBS used and the effect of curing period is less pronounced. Further it was shown that the initial tangent modulus values generally increases with increase in GGBS content. INTRODUCTION Expansive soils cause major damage to property. These soils contain mineral such as montmorillonite clays that is capable of absorbing water. When they absorb water they increase in volume. The more water they absorb the more their volume increases. This change in volume can exert enough force on a building, sidewalks, driveways, basement floors, pipelines and even foundations to cause damage. These distress problems have resulted in loss of billions of dollars in repairs and rehabilitation (Nelson and Miller 1992).While mechanical compaction, dewatering and earth reinforcement can improve the strength of the soils, other methods like stabilization using admixtures are more advantageous. Various admixtures available are lime, cement, fly ash, blast furnace slag etc. Cement and lime stabilization have been widely used to improve the strength of the expansive soils (Yong et al. 1996; Du et al. 1999). But cement and lime being costlier these days increase the overall cost of the project. Therefore research has concentrated on reducing the cost of the binders. Another issue that the world is facing today is the disposal of industrials wastes like Fly ash, Ground granulated blast furnace slag (GGBS). There is a great need to utilize 3920 GeoCongress 2012 © ASCE 2012