Effect of Nano-Silica on Consolidation and Permeability Properties of Lateritic Soil

Abstract
A reddish-brown lateritic soil obtained from Zaria; Nigeria was treated with up to 2.5% nano-silica. Consolidation properties (i.e. Pre-consolidation pressure, compression index, coefficient of volume compressibility and coefficient of consolidation) of treated specimens were assessed using one dimensional consolidation test. The permeability property of treated soil was also evaluated. The results obtained showed that the pre-consolidation pressure generally increased with increasing percentage of nano-silica content and curing time. The compression index (Cc) increased steadily with higher percentage of nano-silica contents up to 2.5% treatment for 7 and 14 days of curing, but decreased after 28 days curing period. The recompression index (Cr) on the other hand generally increased with increase percentage of nano-silica content and curing period. The coefficient of volume compressibility (Mv) did not follow any definite trend, but at 2.5% nano-silica content, the Mv decreased for all curing periods considered. The coefficient of consolidation (Cv) also, did not give a definite trend with increase in nano-silica content, suggesting that increasing the amount of nano-silica content in the soil has little or no impact on the time rate of settlement. The coefficient of permeability (k) decreased as the soil was treated with nano-silica especially beyond loading pressure of 40kN/m2. This study showed that nano-silica (up to 2.5%) can be used to stabilize lateritic soil to improve its consolidation properties.