Effect of agar biopolymer on shear strength behaviour of Sabarmati soil

Loose saturated sandy soils are low bearing capacity 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 is used to strengthen the loose saturated Sabarmati sandy soil due to its gel forming capability and environment friendly nature. Sabarmati soil is treated by using different concentration of agar biopolymer (0.5%, 1%, 2% & 3%) at different curing time periods of 4hrs, 8hrs, 1day, 3days & 7days. Shear strength tests are performed on Sabarmati soil before and after its treatment at different agar concentration & curing time. The settlement behavior of the treated soil is also evaluated by obtaining vertical displacement during its shear deformation, which showed significant decrease in settlement of soil after its treatment. The agar treatment technique is also 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. Thus, the agar biopolymer treatment technique is suggested for shear strength improvement of sandy soils, including moisture exposed region with some considerations of high vertical pressures & agar content.