Improvement of engineering properties of soils with biopolymer additives

In the literature, there are a lot studies about the usage of biopolymers in geotechnical engineering in recent years. Usage of biopolymers, which are used extently in of industry and medicine fields is rare in the geotechnical engineering field. The xanthan gum and chitosan biopolymers, which are economical polymers, have been extensively used in industry and available in the nature was selected for this study. The results of this study, if what kind of effects belonging to biopolymers on engineering behaviours are known, will be guideway on ground improvement methods.In this study, the consistency limits, swell indexes, consolidation parameters and permeability of the samples which were prepared different concentrations of biopolymers were investigated. In general results show that, the liquid limit values of kaolin and bentonit samples increased with biopolymer additives. The effects of biopolymers were distinctly seen on bentonite, because its higher liquid limit value than kaolin. In the presence of xanthan gum and chitosan biopolymers, increase in plastic limit values of bentonite sample distinctly higher than the kaolin sample. Biopolymer additives increased the shrinkage limit values of kaolin, however they decreased the that of bentonite sample. In the presence of of xanthan gum biopolymer, only the modified free swelling index of kaolin decreased. However, the modified free swell indexes of the kaolin and bentonite samples decreased in the presence of chitosan. According to these results, it was concluded that chitosan can be used for decreasing of swelling potentials of soils which have high swelling potential. The consolidation coefficients decreased when xanthan gum concentration increases under the same load