| 摘要 |
A cement additive is added to increase flowability of a cement composition and to prevent a slump loss, but those characters are insufficient, or the cement additive becomes ununiform in the cement composition and causes a trouble of the hardening inferiority. Thus, to solve the subjects, the present invention provides a cement additive composed of a crosslinked polymer in which, between main chains having a water-soluble polymer structure of a molecular weight from 500 to 100,000, a bond having as a structural unit at least one group selected from divalent groups as shown in the following formula ( I ) is formed. ... ( I ) ¢ In the formula ( I ), R1 and R2 independently denote any one of the following. , , , and -CH2- , However, R1 may not be required in a case of that R2 is the following. Moreover, R and R' independently denote an alkyl group of carbon number of 1 to 5. ! |
