Development of grouting method of fine sand with ultrafine cement grout

Grouting is an important part of construction in rock and soil for such as controlling the flow of water, filling voids in the ground and strengthening grounds. Grouting method has advantages over other soil improvement methods of not discharging slimes and requiring large spaces. However, conventional cement grout was difficult to permeate into fine sand. Chemical solution grout shows high permeability ; on the other hand, the solidified ground is not strong and durable enough. The purpose of our work is to develop grouting methods with ultrafine cement (the average particle size 1.5ìm) grout. The authors conducted both laboratory and field grouting tests. As a result, the grout permeated into a one-meter long artificial ground composed of fine sand, where conventional superfine cement grout was not able to permeate. Furthermore, unconfined compressive strength of the solidified ground was 10 times as large as that of solidified ground with chemical solution grout. As for the field test, the ball-shaped solidified ground was observed in the grouted area, and its diameter was 190cm as designed. It is concluded from the tests that ultrafine cement grout showed a great permeability and high solidified strength.