| 摘要 |
PROBLEM TO BE SOLVED: To obtain an additive capable of effectively decreasing air entrainment and having excellent fluidity holding property by containing a copolymer obtained by copolymerizing 2 kinds of polyalkylene glycol ester monomers, a carboxylic acid monomer and other monomers copolymerizable therewith in a specific ratio. SOLUTION: The cement additive contains the copolymer obtained by copolymerizing 0.0-4 wt.% (expressed by % hereafter) polyalkylene glycol ester monomer expressed by formula I, 5-96.99% polyalkylene glycol ester monomer expressed by formula II, 94.99-3% carboxylic acid monomer expressed by formula III and 0-50% other monomer polymerizable therewith. As other monomer, one containing 0.01-30 wt.% hydrophobic monomer having <=20 MPa1/2 solubility parameter to a monomer mixture is preferable. In the formula, each of R1,4,7 expresses H or methyl group, each of R2O and R5O expresses a 2-18C oxyalkylene, each of R3,6 is a 1-30C hydrocarbon, each of (m) and (n) expresses 2-300 and M expresses H, a 1-2-valent metal, NH4 or an organic amine. |
