| 摘要 |
PROBLEM TO BE SOLVED: To provide a cement admixture having an excellent effect of suppressing the heat of hydration in a wide temperature environment from an ordinary temperature to high temperature region, having reduced influence on the strength development, having satisfactory strength development from a middle period over a long period, and exhibiting an effect, e.g., of obtaining a cement composition which can remarkably reduce temperature cracks when being applied to mass concrete and prestressed concrete, and to provide a cement composition. SOLUTION: Disclosed is a cement admixture comprising: a reaction product obtained from humic acid produced from brown coal and nitric acid, lightweight magnesia and a silicic substance; and dextrin. In the cement admixture, the silicic substance is composed of sandstone. In the cement admixture, the grain size of the reaction product is≤600μm, In the admixture, the ratio of the dextrin is 10 to 70 pts. in 100 pts. of the cement admixture composed of the reaction product and dextrin. In the cement admixture, the ratio of the dextrin soluble in cold water is 0 to 80%. Also disclosed is a cement composition comprising cement and the cement admixture. COPYRIGHT: (C)2009,JPO&INPIT |
