Document Type
Thesis - Open Access
Award Date
2025
Degree Name
Master of Science (MS)
Department / School
Civil and Environmental Engineering
First Advisor
Aritra Banerjee
Abstract
This study addresses the formidable challenges of expansive clayey soils, notorious for their swelling-shrinkage characteristics, which often lead to ground instability and structural damage. While effective in mitigating soil swell-shrink potential and enhancing strength, traditional calcium-based stabilizers can react with higher sulfate content to form ettringite, causing volumetric changes and infrastructure distress. To assess the impact of stabilizing sulfate-rich soils and determining the various engineering properties, samples of both control and stabilized soils were prepared using lime, biopolymer (guar gum), and lime with guar gum at concentrations of 2% and 4% lime only, 0.5%, 1% and 1.5% guar gum only, and a blend of 1% guar gum with 2% lime by weight. The soil samples were cured for 7 days and 28 days to determine the compressive strength by UCS, the shear strength parameter by direct shear testing, stiffness through resilient modulus test, durability by freeze and thaw test, and volumetric changes. The study explored the potential of commercially available biopolymers, such as guar gum, as an alternative and found that if the biopolymer isn’t mixed properly with other stabilized material, it may change the soil pH. Furthermore, the higher percentage of lime content may impact the swelling and shrinkage behavior of the sulfate rich clayey soil. As a result, an optimum mixing proportion is suggested to obtain a better shear strength parameter, swelling behavior, and soil pH value. Field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDX), and X-ray diffraction (XRD) were utilized to observe the formation of ettringite and calcium-silicate-hydrate (C-S-H) formation after 28 days of curing and to assess the microscopic and mineralogical changes induced by the biopolymer, with the chemical element changes due to the mixing proportion.
Publisher
South Dakota State University
Recommended Citation
Bohara, Rabindra Prasad, "Biopolymer-Induced Soil Ductility Enhancement: Mitigating the Effects of Desiccation Cracks" (2025). Electronic Theses and Dissertations. 1530.
https://openprairie.sdstate.edu/etd2/1530
Rights Statement
