| 摘要 |
PROBLEM TO BE SOLVED: To obtain a cement admixture giving a cement kneaded material excellent in flowability in a short kneading time, even a highly flow concrete composition by using a copolymer of an N-substd.-α,β-unsatd. monocarboxylic acid amide deriv. with methacrylic acid (salt) and acrylic acid (salt). SOLUTION: This cement admixture is a copolymer of an N-substd.-α,β- unsatd. monocarboxylic acid amide deriv. (A) represented by the formula with methacrylic acid or its salt (B) and acrylic acid or its salt (C). the molar ratio (%) of A:B is 55:45 to 85:15 and that of B:C is 99.5:0.5 to 55:45. The wt. average mol.wt. of the copolymer is 60,000-220,000. In the formula, R<1> is H or lower alkyl, R<2> is 1-4C straight chain or branched alkyl and X is H, an alkali metal, an alkaline earth metal, ammonium or org. ammonium. |
