PROBLEM TO BE SOLVED: To provide an additive for soil-pressed shield process in which reduction of viscosity of a slurry-adding agent is low even in the presence of a remaining strong acid or alkali and good pit face stability and pressing ability of pump can be held, in a soil-pressed shield process for improving a ground, particularly a weak ground by a chemical treatment, especially reaction of sodium silicate called as water glass or sodium silicate derivative with sulfuric acid to give silica gel and sodium sulfate so as to solidify a ground. SOLUTION: In the process, a water soluble polymer is combined with a specific alkaline earth metal salt and zeolite. One or more of cellulose ether and/or polyacrylaminde as the water soluble polymer is preferably used. As the cellulose ether, carboxymethyl cellulose is preferable. COPYRIGHT: (C)2006,JPO&NCIPI
