Fracture grouting of sand by microfine cement grouts

Model tests have been carried out to simulate the fracture grouting technique in loose granular soils with various fine contents. A microfine cement grout with varying water/solids ratios was used. During the tests, grouting pressures and injected volumes were recorded, and at the end of the tests the grouted soil samples were carefully exposed. Additionally, final grout shapes were observed and the soil and grouting parameters were correlated. The amount of heave occurred at the top of the specimen during injection was recorded for each test. It is seen that fracturing pressure generally decreases with an increase in the water content of the grout. Also, the fracturing pressure generally increases as the fine content of the soil increases: the increase is less at higher water/solids ratios. A higher relative density of the granular soil and a higher applied geological stress on the specimen increase the fracturing pressure significantly. The volume of grout injected into soil specimens before fracture occurs tends to increase as the water/solids ratio decreases. Soils prepared at higher relative densities and with higher fines percentages accept lower intakes before fracture.