Effect of Nano Silica on Dispersion and Strength Characteristics of Silty Soil

Dispersive soils, one of the most problematic soils due to their unstable structure when unidentified, cause numerous geotechnical problems. In this study, an attempt was made to monitor the effect of nano silica on reducing the dispersive nature as well as improvement in strength characteristics of silty soil. The soil was identified as medium dispersive soil by doing the identification tests. Crumb test, double hydrometer test and pinhole test were done to identify the dispersion percentage of the soil. Nano silica (NS) was laboratory synthesized using combustion method and was added to the soil in increments of 0.50% within the range of 0.50–3% of dry weight of the soil. With 1.50% of nano silica addition, the soil was brought to a lower dispersion state. By adding different nano-SiO2 percentages, the increased values of UCS were 1.03, 1.18, 1.45, and 2.45 times than that of original soil for 0.50%, 1%, 1.50% and 3% NS, respectively. Micro-structure of the raw soil sample and treated specimens were analysed using FESEM and XRD which shows that the lower dispersion rate is due to the agglomeration of the particles which occurs due to the addition of nano silica.