PURPOSE: To provide a liquid for ground impregnation, containing a phosphate and an aqueous solution of non-alkaline silicate obtained by the acid-treatment of water glass, having easily controllable gel time, and giving a solidified product having high strength.

CONSTITUTION: The objective liquid contains (A) an aqueous solution of a silicate having a pH of usually 1W3 and obtained by spraying water glass into an acidic liquid such as sulfuric acie, or by mixing water glass forcibly in said acidic liquid, and (B) a phosphate (e.g. disodium hydrogen phosphate, tripotassium phosphate, etc.). The liquid may further contain an alkaline accelerator such as water glass, caustic alkali, a (bi)carbonate, etc.