A comparative study of stabilising collapsible soil using different types of biopolymers

This paper presents a comprehensive study of using xanthan gum (XG), sodium alginate (SA) and gelatin (G) to stabilise collapsible soil. Modified Proctor, one-dimensional collapse, unconsolidated-undrained triaxial and California bearing ratio (CBR) tests were conducted to estimate the engineering characteristics of the untreated and treated soil. Additionally, x-ray diffraction (XRD) and scanning electron microscopy (SEM) tests were utilised to demonstrate the changes in the microstructure of the treated samples. It was found that biopolymers decreased the maximum dry density and increased the optimum water content. The results also indicated that a 4% content of XG, SA and G significantly reduced the collapse index by 96, 95 and 82%, respectively. Shear tests showed that biopolymers slightly reduced the internal friction angle and significantly increased the cohesion intercept, which led to shear strength improvement. The results also indicated that 4% XG-treated, 4% SA-treated and 4% G-treated samples exhibited higher shear strengths by 145, 106 and 73%, respectively, than the untreated samples under the same conditions. The findings also indicated that when the soil was mixed with a 4% concentration of XG, SA and G, the unsoaked CBR value increased by about 185, 157 and 141%, respectively.