Effect of Sampling Method on Strength of Stabilized Silty Sands with Colloidal Nano Silica

Treatment of liquefiable deposits is one of the most important topics in geotechnical earthquake engineering. In this study, the stabilization of liquefiable silty sands with colloidal nano-silica under two different conditions was investigated and the effect of disturbance on the strength of stabilized samples was discussed. First, four cylindrical samples (as undisturbed samples) consisted of sand with variation in silt content from 0 to 30% prepared by sedimentation method in colloidal nano-silica at concentrations of 4.5 wt% and after a curing time of 6 weeks the strength of stabilized samples were investigated by means of unconfined compressive tests. Then, four box models were used to simulate the stabilization of the same soil specimens with permeation of colloidal nano-silica in soil formations using 5 low-head injection and 2 extraction wells. After delivery of colloidal nano-silica was completed the models were cured for 6 weeks. Then the treated soils were excavated and a few samples (as disturbed samples) were extracted for unconfined compressive testing. According to the results colloidal nano-silica can be successfully delivered in silty sand formations and improve the strength characteristics. The strength of disturbed samples was approximately 63-85% of the strength of undisturbed samples. This study also examined the potential for applying scanning electron microscope (SEM) analysis to investigate soil stabilization with colloidal nano-silica.