Field testing of permeation grouting using microfine cement

Field tests are conducted on permeation grouting of ultra-microfine cement to examine whether zones of improved soil of a sufficient size can be created economically in sand deposits, which would be expected to contribute to improving ground conditions as a countermeasure against soil liquefaction. Four different tests are carried out under different grouting conditions, where grouting is conducted with and without forcible injection pressures, using cement solutions of different concentrations of (w/c)_cs = 8 and 12. After two and a half months, the testing site is excavated and the surface appearances of improved soil are confirmed. The study proves that columns of improved soil of diameter 1·5–2 m and height of about 2·5 m can be built up in sand deposits of depth 3 m. Some discussions are given on the filling ratio α and the ratio of mass of water to cement particles (w/c)_is of the overall improved soil, leading to the presumption that, as far as relatively clean sand deposits are concerned, the radius of a column of improved soil can be estimated solely from the volume of cement solutions injected into sand deposits.