| 摘要 |
PROBLEM TO BE SOLVED: To prepare a cement admixture which has the specific maximum particle diameter and can impart a good material-separating property, a good injecting property, an excellent strength development and the like to a cement composition, by formulating calcium aluminate, an inorganic sulfate, a lithium compound and a curing retarder. SOLUTION: This cement admixture comprises calcium aluminate obtained by thermally treating a calcareous raw material, an alumina raw material and the like, an inorganic sulfate such as anhydrous gypsum, a lithium compound such as lithium hydroxide, and a curing retarder such as citric acid, and has the maximum particle diameter of <=40μm. The calcium aluminate preferably has the maximum particle diameter of <=40μm and a Blaine specific surface area of about 4,000 to 9,000 cm2/g, and is contained in an amount of 10 to 80 pts.wt. per 100 pts.wt. of the cement admixture. The inorganic sulfate salt has the maximum particle diameter of <=40μm and a Blaine specific surface area of about 4,000 to 9,000 cm2/g, and is contained in an amount of 10 to 80 pts.wt. The lithium compound and the curing retarder are contained in amounts of about 0.5 to 15 pts.wt. and about 0.5 to 10 pts.wt., respectively.
|
