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

This article presents a comprehensive study of using xanthan gum, sodium alginate, and gelatin to stabilize 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 utilized 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 xanthan gum, sodium alginate, and gelatin 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% xanthan gum-treated samples, 4% sodium alginate-treated samples, and 4% gelatin-treated samples exhibited higher shear strengths by 145%, 106%, and 73%, respectively, than the untreated sample under the same conditions. The findings also indicated that when the soil was mixed with a 4% concentration of xanthan gum, sodium alginate, and gelatin, the unsoaked CBR value increased by about 185%, 157%, and 141%, respectively. The results of SEM and XRD studies also demonstrated the interaction between the fine-grained particles and the biopolymers.