Laboratory Investigation of the Effect of Nano-Silica on Unconfined Compressive Strength and Frost Heaving Characteristics of Silty Clay

Abstract

In order to investigate the effect of nano-silica on the unconfined compressive strength and frost heaving characteristics of silty clay, a series of indoor tests of unconfined compressive strength, frost heaving, and mercury intrusion porosimetry (MIP) was done on silty clay with different nano-silica content. The unconfined compressive strength of silty clay increased with increases in nano-silica content, and increased by 6.65 times when the nano-silica content was 5.0%. However, the frost heaving displacement decreased with increases in the nano-silica content. The results of MIP tests illustrated that the volume and number of large pores decreased, and the volume and numbers of small pores increased with increases in the nano-silica content. An increase in the nano-silica content increased the porosity and decreased the average pore diameter. The formation of viscous gel by addition of nano-silica into silty clay enhanced the bonding and filled the gaps between particles of silty clay and blocked the migration of water in the soil. The microscopic pore structure of the sample was generally uniform with increasing nano-silica content, which resulted in an increase in unconfined compressive strength and a decrease in frost heaving displacement.