Abstract: An dispersant for plaster comprising a copolymer prepared by copolymerizing (a) a polyalkylene glycol monoester monomer having 2 to 300 mols of an oxyalkylene group(s) each having 2 to 3 carbon atoms, with (b) at least one monomer selected from among acrylic monomers, unsaturated dicarboxylic monomers and allylsulfonic monomers. When the dispersant of the present invention is used in preparing a plaster board, the foam stability is maintained so that the quality of the plaster board composition can be easily controlled.

Abstract: An admixture for concrete comprising, as an essential component, a copolymer prepared by copolymerizing (a) a polyalkylene glycol monoester monomer having 110 to 300 mols of an oxyalkylene group(s) each having 2 to 3 carbon atoms, with (b) at least one monomer selected from among acrylic monomers, unsaturated dicarboxylic monomers and allylsulfonic monomers. When this admixture is used in preparing concrete, the resulting concrete composition undergoes little change in the slump for a lengthened time, so that the quality of the concrete composition can be easily controlled.

Abstract: Cement and aggregates are mixed with each other by the use of a dispersant to the effect of water reduction and prevention of slump loss, the dispersant comprising (1) (I), (IIa), and an amine reaction terminator of (IIb), (IIc), (IVg) and/or (IVh); (2) (I), (IIb) and/or (IIc) and (IIIe) and/or (IIIf); or (3) (I), (IIa) and (IIIe) and/or (IIIf), in which formulae, R is hydrogen or an alkyl having 1 to 6 carbon atoms; X is an alkali metal; X.sub.1 is hydrogen, an alkyl having 1 to 6 carbon atoms, carboxylic acid group, an alkali metal salt carboxylate, sulfonic acid group, an alkali metal salt sulfonate, hydroxy or methoxy; Y.sub.1 is carboxylic acid or an alkali metal salt carboxylate, sulfonic acid or an alkali metal salt sulfonate; Y is hydrogen or an alkali metal; Z is hydrogen, an alkyl having 1 to 6 carbon atoms or --CH.sub.2 SO.sub.3 M; and M is hydrogen or an alkali metal.