Cement-additive for inhibiting concrete-deterioration
AssigneesNippon Chemical Industrial Co., Ltd., Railway Technical Research Institute
InventorsHidenobu Tatematsu, Tohru Nakamura, Hitoshi Koshimizu, Toshihiko Morishita, Hideki Kotaki
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Abstract
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.
Claims7
A cement additive for inhibiting concrete deterioration, consisting essentially of (i) an inorganic cation exchanger which is a calcium zeolite having a calcium substitution ratio, 2Ca.sup.2+ /(2Ca.sup.2+ +Na.sup.+), of at least 0.9 and (ii) an inorganic anion exchanger which is a hydrocalumite represented by the general formula 3CaO.Al.sub.2 O.sub.3.CaX.sub.2/m.nH.sub.2 O wherein X is an ion selected from the group consisting of NO.sub.2.sup.-, NO.sub.3.sup.-, OH.sup.-, CO.sub.3.sup.2- and SO.sub.4.sup.2- ;
- m is a valence number of X;
- and n.ltoreq.20,
- wherein the weight ratio of said (i) calcium zeolite to said (ii) hydrocalumite is within the range between 0.1:0.9 and 0.9:0.1.
A cement composition inhibiting concrete deterioration, comprising:
- (a) a cement powder;
- and
- (b) a cement additive consisting essentially of (i) an inorganic cation exchanger which is a calcium zeolite having a calcium substitution ratio, 2Ca.sup.2+ /(2Ca.sup.2+ +Na.sup.+), of at least 0.9 and (ii) an inorganic anion exchanger which is a hydrocalumite represented by the general formula 3CaO.Al.sub.2 O.sub.3.CaX.sub.2/m.nH.sub.2 O wherein X is an ion selected from the group consisting of NO.sub.2.sup.-, NO.sub.3.sup.-, OH.sup.-, CO.sub.3.sup.2- and SO.sub.4.sup.2- ;
- m is a valence number of X;
- and n.ltoreq.20,
- wherein the weight ratio of said (i) calcium zeolite to said (ii) hydrocalumite is within the range between 0.1:0.9 and 0.9:0.1, and
- wherein said additive is present in said cement composition in an amount of 4 to 35 wt % based on the total weight of said cement.
Dependencies are inferred from the claim text.