Cement additive, method for producing the same, and cement composition

摘要

PCT No. PCT/JP90/00946 Sec. 371 Date Mar. 25, 1991 Sec. 102(e) Date Mar. 25, 1991 PCT Filed Jul. 23, 1990 PCT Pub. No. WO91/01282 PCT Pub. Date Feb. 7, 1991.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, there is a bond having as a structural unit at least one divalent group having the following formula (I): (I) where R1 and R2 independently denote any one of the following: where R1 is not required, if R2 is the following: and where R and R' independently denote an alkyl group of carbon number of 1 to 5.