Impact of Thickener Biopolymer on Lime Treated Sand-Bentonite Blends

Abstract

Compacted Sand-Bentonite (SB) mixtures are used as a liner material at the waste disposal site. Clay liner, which is an integral part of a landfill, acts as a barrier between the leachate and the ground water being contaminated due to migration of the leachate. Similarly, sand content has a definite controlling behavior on the various engineering properties of SB mixtures; where the behavior depend on how effectively the bentonite fills the void spaces formed between the sand particles. Soil stabilization using biopolymer is an environment friendly alternative. Lime or cement soil stabilization are also one of the most popular means of soil stabilization. The amount of lime or cement added to soil varies depending on the soil characteristics. More lime or cement is added, if soil exhibit higher plasticity value. Since both of the additives are similar, lime and cement are grouped together commonly and used as a binder in many geotechnical fields. The goal of this study is to evaluate effect of Xanthan Gum (XG) biopolymer on lime treated SB mixtures. SB mixtures mixed in a proportion of 40:60 (SB60), 60:40 (SB40), 80:20 (SB20) and 90:10 (SB10). These mixtures were treated with XG biopolymer (0.5, 1, 1.5 and 2 %) and lime (1, 2 and 3 %) was used for this investigation. In the present study, addition of optimum XG to the lime stabilized SB mixtures produced positive results in terms of plasticity and strength. The UCS test of SB-lime-XG mixtures reveals that there is a significant change in the soil strength due to addition of optimum dosages of both admixtures. Based on the favorable results obtained, it can be found that various proportionate SB mixtures using a liner material in landfill can be successfully stabilized by the combined action of optimum XG biopolymer and lime.