Patent ID: 7125944

Claim:
An admixture for cement comprising two polymers, namely a polymer (A1) and a polymer (B1), as essential constituents in a ratio of polymer (A1) to polymer (B1) between 1 to 99 to 99 to 1 by mass, wherein the polymer (A1) is a polymer comprising, as essential constituent units, a constituent unit (I) derived from an unsaturated (poly) alkylene glycol ether monomer (a1) represented by the general formula (1): YO (R 1 O) m H (1) wherein Y represents an alkenyl group containing 2 to 8 carbon atoms, the m R 1 O groups are the same or different and each R 1 O represents an oxyalkylene group containing 2 to 18 carbon atoms and m is a mean addition number of moles of the oxyalkylene group and represents a number of 1 to 500, and a constituent unit (II) derived from an unsaturated monocarboxylic acid monomer (b), wherein the constituent units (I) and (II) each accounts for not less than 1% by mass relative to all constituent units but the constituent unit (I) accounts for not more than 50 mole percent relative to all constituent units, and, wherein the polymer (B1) is an oxyalkylene group- or polyoxyalkylene group- and carboxyl group-containing polymer, and wherein the number of milliequivalents of carboxyl groups contained in each gram of the polymer (A1) as determined on an unneutralized basis is 0.2 to 5.0 meq/g.