| 摘要 |
PROBLEM TO BE SOLVED: To provide a polycarboxylic acid-based copolymer for a cement admixture, which can eliminate a setting delay of concrete and suppress a viscosity increase of concrete, to provide the cement admixture containing the polycarboxylic acid-based copolymer, and further to provide a cement composition which contains the polycarboxylic acid-based copolymer and allows the setting delay of concrete to be eliminated and the viscosity increase of concrete to be suppressed.SOLUTION: The polycarboxylic acid-based copolymer for a cement admixture includes a structural unit derived from a (I)specific unsaturated polyalkylene glycol ether-based monomer (a), a structural unit (II) derived from an unsaturated monocarboxylic acid-based monomer (b), and a structural unit (III) derived from an unsaturated dicarboxylic acid-based monomer (c) . The content rate of the structural unit (I) derived from the specific unsaturated polyalkylene glycol ether-based monomer (a) in the polycarboxylic acid-based copolymer is 50-98 wt.% and that of the structural unit (II) derived from the unsaturated monocarboxylic acid-based monomer (b) in the polycarboxylic acid-based copolymer is 1-25 wt.% and that of structural unit (III) derived from the unsaturated dicarboxylic acid-based monomer (c) in the polycarboxylic acid-based copolymer is 1-25 wt.%. |
