Residual Strength of Xanthan Gum-Treated Soils

This study presents the results of a laboratory testing program to investigate the effects of xanthan gum treatment on the residual shear strength of fine-grained soils. This study used two different fine-grained soils, and ring shear tests were performed on untreated soils and soils mixed with 0.5%, 1%, and 3% xanthan gum. The test specimens were prepared at water contents near their liquid limits, consolidated, and then sheared to evaluate residual strength parameters. Also, Atterberg limit tests were performed on samples mixed with 1% xanthan gum to see changes in the liquid limit, plastic limit, and plasticity index. The results demonstrated that xanthan gum significantly influenced the soils’ plasticity and residual shear strength. Atterberg limit tests indicated increased liquid limit and plasticity index for both soils tested. Residual shear strength tests revealed soil-specific trends: Brabston soil exhibited the highest strength at 0.5% xanthan gum, beyond which strength decreased. In contrast, Brunswick soil showed a steady increase in residual shear strength with higher xanthan gum content. These contrasting responses highlight the complexity of biopolymer-soil interactions and the need for more research.