The Durability of Biopolymer Treated Sands to Cyclic Drying and Wetting: Mechanisms of Sample Deterioration

The use of biopolymers has received research attention for the stabilization and erosion control of course-grained soils. However, there are questions remaining on the long-term stability of biopolymer-treated soils under drying and wetting cycles. This work focuses on the performance of xanthan gum (XG) for improving mechanical properties of sands. Biopolymer-treated samples were subjected to cyclic drying/wetting according to the ASTM D559/D559M-15 code designed for soil-cement mixtures. The samples were dissected after each cycle to study the mechanism and progression of the failure. The biopolymer was extracted and studied using rheological and infrared spectroscopy (FTIR). The outer crust of the specimen seems to prevent intrusion of water inside the sample due to its low hydraulic conductivity. Rheological investigations indicate a reduction in the yield stress of the biopolymer gel in this crust compared to the rest of the specimen. FTIR showed the appearance of adsorbed CO2, which could indicate biological degradation.