Permeation grouting is a deep-soil improvement technique in which grout is injected into the voids, fissures and cavities in a soil formation in order to improve resistance to liquefaction, strength and durability and to reduce its permeability and deformability. The objective of this research is to investigate the parameters that affect the strength of cement grouted granular soils through laboratory testing. With this objective, cement grouting is applied, by using a special apparatus assembled for injection, into two different types of granular soil samples each of which is prepared to have 25, 50, 75 and 100% relative densities. Test samples are then grouted using cement grouts with different water/cement ratios by weight of 0.7, 1.0 and 1.5, by applying different levels of grouting pressures of 100, 150 and 200 kPa. At the end of the curing period, which is either 7 or 28 days, the test specimens are subjected to unconfined compression test. Large values of unconfined compression strength (as much as 19 MPa) reached by the test specimens verify the effectiveness of permeation grouting in granular soils. Test results also indicate that permeation grouting is most effective when the water/cement ratio is in the range of 0.7 to 1.0.
Key words: Soil improvement, granular soils, permeation grouting, low pressure grouting.
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