| 摘要 |
PROBLEM TO BE SOLVED: To provide a cement additive which does not increase the air amount accompanied by the extension of the kneading time during manufacturing a cement composition but can stably maintain the amount of entrained air, and to provide a cement admixture and a cement composition having the above air entraining property and high water reducing performance. SOLUTION: The cement additive contains a compound (A) expressed by general formula (1): R1-O-(R2O)n-XR3 as an essential component. In formula (1), X represents -CO- or -CH2CH2NHCO-, R1 is a 1-30C hydrocarbon group, a plurality of R2O are same or different and represent 2-18C oxyalkylene groups, n is the average molar number of oxyalkylene groups added and ranges from 1 to 300, and R3 is a group having at least one carboxy group or sulfonyl group or a salt of these. |
