| 摘要 |
PROBLEM TO BE SOLVED: To obtain a cement admixture having a high water-reducing rate and excellent in slump retaining property by using a water-soluble vinyl copolymer (A) with a specified graft structure having oxyalkylene groups and a highly hydrophobic arom. terminal group and/or a copolymer salt (B) obtd. by neutralizing the copolymer A with an alkaline material as an essential component. SOLUTION: The component A is obtd. by copolymerizing a monomer represented by formula I [where R1 is H or methyl; R20 is a mixture of one or more 2-3C oxyalkylene groups; R3 is a 6-30C arom. group; and (n) is a positive number of >=100], e.g. phenoxy polyethylene glycol mono(meth)acrylate with a monomer represented by formula II [where R4-R6 are each H, methyl or (CH2 )m COOX; X is H, a mono- or divalent metal, ammonium or an org. amine; and (m) is 0-2], e.g. acrylic acid. The wt. average mol.wt. of each of the components A, B is 500-500,000 and the cement admixture is added to cement by 0.01-1.0 wt.%. |
