This paper presents the use of GGBS (ground granulated blast furnace slag) an industrial byproduct, blended with bentonite and Portland cement (PC) as a liner in a landfill to prevent groundwater contamination. Experimental investigations were conducted to study the effect of GGBS blended with bentonite and PC mixtures such as liquid limit (LL), free swell index (FSI), compaction, unconfined compressive strength (UCS) and hydraulic conductivity tests (k). Deionized water (DIW) and diesel oil contaminant (DOC) was used as permeating fluids in this study. DOC is an organic effluent from automobile industry which is a spillage/leakage contaminating ground water. The results obtained from the blends show that LL, FSI and k decreases, and optimum moisture content, maximum dry density and UCS (at 0, 14 and 28 days curing period) increased with increase in GGBS content. On examining the UCS samples by scanning electron microscope and X-ray diffraction, it reveals the formation of cementitious compounds which increases the strength. The k of the blends decreased with increase in GGBS content irrespective of permeating fluids. Leachability of heavy metals was also analyzed. Based on the results an optimum percentage of GGBS to be used as a liner should be in the range between 15% and 20%.