Taisei Corporation

Nisshin Boseki Kabushiki Kaisha

Toshio Hatsuzaki

Yoshihiko Ogawa

Takehiko Tokoro

Hideo Senga

Toshio Hiramatsu

A mixture consisting essentially of (1) an organic polyisocyanate compound and/or a prepolymer having terminal isocyanate residues, which is derived from the reaction of an organic polyisocyanate with a polyhydroxyl compound, and (2) 2-pyrrolidone, is injected for grouting into water-leaking cracks or openings of concrete structures such as water tanks, subway constructions and tunnels. The injected mixture diffuses into the cracks or openings and is cured in short time by reacting with water at the leaking sites. The resultant polyurethane foam securely seals the water leaking sites.

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Kanagawa, Japan

Toshio Hatsuzaki