Silica Fume Effect on Engineering Properties of Superfine Cement–Grouted Sands

In this experimental study, the effect of silica fume on the grouting performance of superfine cement and the engineering properties of grouted sand was examined. The experiments were first launched with rheological property determination tests. Bleeding, setting time, and viscosity tests were performed on superfine-cement suspensions with or without silica fume in different water/cement (W/C) ratios. Then, groutability tests were performed on fine to medium sand mixtures prepared in various gradations. Finally, unconfined compression strength (UCS) and falling-head permeability tests were performed on the samples that were successful in the grout test at different time intervals. With the addition of silica fume to superfine cement, the initial and final setting times as well as viscosity values increased, whereas bleeding values decreased. With the addition of silica fume to the superfine cement, the groutability slightly decreased, but the grouting pressure values increased. With the addition of silica fume to superfine cement, UCS values increased, although the permeability values decreased. Sand samples grouted with a superfine-cement suspension with silica fume additive gained strength later than sand samples grouted with superfine-cement suspensions with no additive. Experimental studies have shown that the addition of silica fume to superfine cement improves the engineering properties of the grouted sands.