Effect of Xanthan Gum on the mechanical properties of fiber-reinforced sandy soil

Due to the loose structure and low cohesion of natural sand, many improved techniques have been tried to overcome this deficiency. When fiber reinforcement technology is applied to reinforce sand, there are deficiencies such as low cohesion and limited strength improvement effect. This paper studies the effect of xanthan gum (XG) for the improved fiber reinforcement technique. Biopolymers are popular in soil improvement as an environmentally friendly alternative. Unconfined compressive strength (UCS) tests, direct shear tests, and Brazilian splitting tests were performed to investigate the effect of different XG content and drying times on the mechanical properties of fiber-reinforced sandy soils treated with XG. The scanning electron microscope (SEM) was used to investigate the microstructure of the materials. The test results show that the extension of drying time and the increase of XG content have a positive effect on strength and the optimal content of XG is 4% for UCS and 3% for tensile strength and shear strength. The maximum UCS and elastic modulus are 4829 kPa and 171.65 MPa, respectively, the maximum shear strength, cohesion, and tensile strength can be increased to 938.9 kPa, 620 kPa, and 807 kPa, respectively, and the optimal drying time is 14 days. SEM analysis showed that the XG enhanced the strength by filling the pores between the particles, adhering to the surface of the soil particles and the fiber mesh, increasing the roughness and interlocking force of fibers. The conclusion shows that XG, as an environmentally friendly improvement material, has a great effect on improving the strength of soil and can provide a solution to solve the deficiency of fiber reinforcement technology and improve its application in sandy soil.