Role of Nano-silica Additive on the Strength Behaviour of a Highly Plastic Clay Found in an Indian Paddy Field

Paddy soils are typically cohesive deposits that undergo deformation with changes in their moisture content. The enhancement of the geotechnical characteristics of paddy soils is essential as more and more land was utilised for urban or industrial development. This study investigates the influence of nano-silica addition on the physical properties and strength characteristics of paddy clay. Laboratory tests were performed with varying concentrations of nano-silica (0.5%, 1%, 1.5%, and 2%) to determine the plasticity, compaction, compressive strength, and shear strength parameters of treated paddy clay. The incorporation of 1.5% nano-silica caused a remarkable and progressive increment in strength and stiffness. The UU triaxial test results revealed that the cohesive strength of nano-silica treated paddy clay was increased by 67% compared to the untreated soil after a curing period of 28 days. In addition, XRD, SEM, and FTIR tests were conducted to elucidate the microstructural mechanism of nano-silica particles on the treated paddy clay.