Concrete composition for making concrete moldings and method for making such concrete moldings
AssigneeDenki Kagaku Kogyo Kabushiki Kaisha
InventorsKoji Nakagawa, Yoshiharu Watanabe
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Abstract
A concrete composition for making concrete moldings of high strength is provided which comprises 400-600 kg. of Portland cement per unit m.sup.3 of concrete, 3-30% by weight of insoluble (Type II) anhydrous calcium sulfate and 0.1-3% by weight of cement dispersing agent. A method for making concrete moldings of high strength having the above components are also provided which comprises subjecting to pre-steaming and then steam curing under atmospheric pressure. According to the present invention, concrete moldings having both high compressive strength and pre-stress with reduced relaxation can be obtained only in a day without subjecting to autoclave curing.
Claims8
A cement composition for making concrete molding of high strength by steam curing comprising Portland cement, 3-30% by weight of insoluble (Type II) anhydrous calcium sulfate based on the weight of said Portland cement, 3% by weight or less of powders of puzzolanic material based on the weight of the Portland cement, and 0.1-3% by weight of cement dispersing agent based on the weight of the Portland cement, said soluble (Type II) anhydrous calcium sulfate being such that when contacting 1 g of insoluble (Type II) anhydrous calcium sulfate with 100 g of a 0.05% by weight Na.sub.2 HPO.sub.4 aqueous solution at 20.degree. C. for a period of one hour while stirring, the concentration of SO.sub.4 ions in said solution is 0.03-0.12% by weight, and said Portland cement being substantially free from 11CaO.7Al.sub.2 O.sub.3.CaX.sub.2 wherein X represents a halogen atom.
A concrete molding of high strength obtained by the steam curing of a cement composition, the cement composition comprising Portland cement, 3-30% by weight of insoluble (Type II) anhydrous calcium sulfate based on the weight of said Portland cement, 3% by weight or less of puzzolanic material based on the weight of the Portland cement, and 0.1-3% by weight of cement-dispersing agent based on the weight of the Portland cement, said insoluble Type II anhydrous calcium sulfate being such that when contacting 1 g of insoluble (Type II) anhydrous calcium sulfate with 100 g of a 0.05% by weight Na.sub.2 HPO.sub.4 aqueous solution at 20.degree. C. for a period of one hour while stirring, the concentration of SO.sub.4.sup.-- ions in said solution is 0.03-0.12% by weight, and said Portland cement being substantially free from 11CaO.7Al.sub.2 O.sub.3.CaX.sub.2 wherein X represents a halogen atom.
Dependencies are inferred from the claim text.