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

Abstract

Abstract This article presents a comparative study of using three different kinds of biopolymers (xanthan gum, sodium alginate, and gelatin), environmentally friendly materials, in stabilizing collapsible soil. Modified Proctor, single oedometer, unconsolidated undrained triaxial, and California bearing ratio (CBR) tests were conducted to estimate the engineering characteristics of the soil after being mixed with various biopolymer contents. Biopolymer effect on the collapse index was investigated using different mixing conditions (dry mixing and wet mixing). Additionally, X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests were utilized to demonstrate the changes in the microstructure of the treated samples. The results showed that after mixing the soil with 4% xanthan gum content in the dry case, the collapse index decreased significantly from 13.48–1.27% and the cohesion stress increased from 47 to 144 kPa, resulting in the shear strength improvement. The results proved that the superiority of xanthan gum over sodium alginate and gelatin in shear strength improvement is approximately 38% more than sodium alginate and 72% more than gelatin at the same conditions, as well as reducing the collapse index by approximately 5% more than sodium alginate and 12% more than gelatin at the same conditions. The findings also indicated that biopolymers increase the unsoaked CBR value by about 147%, 128%, and 117% when the soil was mixed with a 3% concentration of xanthan gum, sodium alginate, and gelatin, respectively. The results of SEM and XRD studies also demonstrated the interaction between the fine-grained particles and the strings of the biopolymers.