Investigation of the biopolymer additives effect on permeability and shear strength of clayey and sandy soils

Many methods are used to improve the engineering properties of the soils. while the some of the developed methods cannot produce an effective solution, some of them are not economical for practical solution. in this study, permeability and shear strength behaviors of natural kaolin, bentonite and sand mixtures have been investigated in the presence of three different biopolymers (xanthan gum, chitosan and chitin) and different concentrations (0.25-0.50-0.75 and 1%). the results have shown that, the xanthan gum and chitosan addition decreased the permeability coefficient almost 30 hold. while the biopolymer effect on shear strength behavior is investigated, 1% xanthan gum and chitosan concentration addition provided 15-10% increase in angle of internal friction. the obtained test results have shown that, biopolymers can be used in dams and landfills at impermeable clay liner applications.