Preliminary Evaluation of the Effect of Curing Time on the Unconfined Compressive Strength and Microstructure of Colloidal Silica Grouted Soil

Colloidal silica (CS) is a non-toxic soil stabilization solution with proven effectiveness against liquefaction in both laboratory and field tests. Specifically, CS treatment has been shown to increase unconfined compressive strength with time. However, limited knowledge exists regarding the performance of CS-treated soils after 1,000 days post treatment. This paper presents UCS test data for CS-treated sand samples of varying ages (freshly made and preserved since 2009). The fresh samples were prepared to replicate 2009 sample conditions by mixing poorly graded concrete sand, colloidal silica (5%-9% concentration), and NaCl accelerator (0.3N-0.45N). Additionally, scanning electron microscopy tests were performed to support result interpretation and monitor microstructural changes over time. The preliminary results from this study comparing freshly prepared versus the oldest known CS-treated sand specimens advances understanding of colloidal silica microstructure evolution and prediction of unconfined compressive strength over time.