Effects of injection pressures on injectability and engineering properties of microfine cement grouted sand.

摘要

The applied pressure used to inject a cement grout into granular soil is an important factor that affects the injectability of the grout and the engineering properties of the grouted sand. Microfine cement grout at three different W:C ratios was injected into 6-inch and 36-inch long sand-packed columns using either constant, variable, or pulsing injection pressures. The effects of various injection pressure ranges and durations on the effluent flow rate, volume of effluent, cement content of wet grouted sand, and the permeability and strength of hardened grouted sands were studied. Higher cement content did not necessarily correlate with lower permeability and higher strength of grouted sand. Typically, using variable injection pressure resulted in higher cement content and strength of grouted sand compared to injections using constant pressure. Property improvement of sand grouted by applying pulsing pressures was dependent on the pressure range, rate of pulse, and the length of the injection column.