Use of agar biopolymer to improve the shear strength behavior of sabarmati sand

Loose saturated sandy soils are low shear strength soils, which are also prone to liquefaction under earthquake conditions. Many soil treatment techniques using admixers are available such as cement, chemical grouts, epoxy, acrylamide, phenoplast, polyurethane, etc. However, these admixtures have negative impact on environment or ecosystem. In the current research, the agar biopolymer has been chosen to strengthen the loose saturated Sabarmati soil (cohesionless soil) due to its gel forming capability and environment friendly nature. Sabarmati soil has been treated using different concentration of agar biopolymer (0.5, 1, 2, and 3%) at different curing time (4hrs, 8hrs, 1, 3, and 7 days). A series of shear strength tests has been performed on Sabarmati soil before and after its treatment to evaluate its shear stress behavior at different agar content and curing time. The settlement behavior of treated soil has been evaluated by obtaining vertical displacement during its shear deformation, which showed significant decrease in settlement of soil after its treatment. The agar treatment technique has also been evaluated for its applicability in moisture exposed region by performing shear strength tests on treated soil after water soaking, which exhibited small reduction in the shear strength of treated soil after moisture absorption.