Geotechnical properties of problematic expansive subgrade stabilized with xanthan gum biopolymer

This article presents a comprehensive study on the efficacy of xanthan gum (XG) biopolymer as a green construction material in treating problematic expansive subgrade. The soil was treated with various concentrations of XG (0, 0.5, 1.0, 1.5, 2.0, and 5.0%) considering long-term aging period (0, 4, 7, 14, 28, 60 and 365 days). The results showed a reduction in soil plasticity at a higher aging period with the increase in XG content. At 1.5% XG content the unconfined compressive strength, elastic modulus, resilient modulus, unsoaked and soaked CBR values of treated soil were notably increased by 5-10 orders of magnitude and regarded as optimum. Meanwhile, microstructural studies coupled with elemental analysis highlight the bridging of soil particles with stiff XG-hydrogel formation that contributes to strength development. Overall, XG-treatment exhibits an economical and sustainable solution for the treatment of problematic expansive subgrade.