| 摘要 |
PROBLEM TO BE SOLVED: To obtain a grout reduced in the shortening of a gelation time, especially, a gelation time in earth and made proof against leak, which grout is a non-alkaline silica sol comprising water glass and sulfuric acid and specified in a molar ratio of the water glass, an SiO2 concentration, and a pH value. SOLUTION: This grout has a water glass molar ratio of 3.5-5.0, an SiO2 concentration of 2-7%, and a pH value of 3-6. Desirably, it is one comprising water glass, sulfuric acid, and an alkali agent and having a water glass molar ratio of 3.5-5.0, an SiO2 concentration of 2-7%, and a pH value of 4-9. The alkali agent used is exemplified by a soluble one such as sodium hydrogencarbonate or a difficultly soluble one such as calcium hydroxide, magnesium hydroxide, or calcium carbonate. The difficult solubility of a difficultly soluble alkali agent enables the relatively easy adjustment to, especially, a weakly acidic to neutral range.
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