Experimental investigation on the shear strength and deformation behaviour of xanthan gum and guar gum treated clayey sand

Soil stabilization is widely used to favourably amend the soil behaviour. The use of biopolymers to treat soil is not only an eco-friendly but is also a sustainable approach. Biopolymers, xanthan gum and guar gum are used to augment the strength of clayey sand. Xanthan gum is anionic while guar gum is non-ionic. Triaxial tests were conducted on treated soil samples to understand the effect of biopolymer treatment on clayey sand at different dosages and curing periods. Shear strength parameters –angle of internal friction and cohesion increases appreciably on treating soil with xanthan and guar gum for all dosages investigated, though angle of internal friction decreases with the curing period in case of xanthan gum treated soil. Xanthan gum performs better in enhancing the strength and deformation behaviour of the soil compared to guar gum. There is a substantial gain in early strength but as the curing period increases further, the rate of increase in strength is marginal. The deformation modulus at failure also increases with the biopolymer content. The reduction in post-peak strength of treated soil is sudden and drastic indicating brittle behavior. The energy absorption capacity of the biopolymer treated soil increases with increase in biopolymer content and curing period. The strength gain in soil can be ascribed to the formation of hydrogels that are cementitious in nature. Strength is also improved through the ionic / hydrogen bonds that are formed by biopolymer addition.