Nippon Chemical Industrial Co., Ltd.

Railway Technical Research Institute

Hideki Kotaki

Nobuo Takagi

Tomohiro Banda

Takashi Hara

Tohru Nakamura

Hitoshi Koshimizu

Toshihiko Morishita

Hidenobu Tatematsu

Disclosed is an aqueous solution of a chromium salt, in which the oxalic acid content is 8% by weight or less relative to chromium. In the aqueous solution of the chromium salt, the total organic carbon content is 4% by weight or less relative to chromium. The chromium salt is preferably a chromium chloride, a chromium phosphate, or a chromium nitrate. The chromium chloride preferably contains a basic chromium chloride represented by the composition formula Cr(OH)Cl(wherein 0&#x3c;x&#x2266;2, 1&#x2266;y&#x3c;3, and x+y=3). The chromium phosphate is preferably one represented by the composition formula Cr(HPO)(wherein n is a number satisfying 2&#x2266;n&#x2266;3). The chromium nitrate is preferably a basic chromium nitrate represented by the composition formula Cr(OH)(NO)(wherein 0&#x3c;x&#x2266;2, 1&#x2266;y&#x3c;3, and x+y=3).

Aqueous solution of chromium salt and method for producing same

A cement additive for inhibiting concrete deterioration contains as an effective component a powder mixture of an inorganic cation exchanger, such as a highly calcium-substituted zeolite, and an inorganic anion exchanger, such as hydrocalumite. The cement additive inhibits the alkali-aggregate reaction and the corrosion of reinforcing steel, thereby protecting concrete constructions from deterioration.

Cement-additive for inhibiting concrete-deterioration

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Yamaguchi, Japan

Hideki Kotaki