Patent ID: 8729160

Claim:
A method comprising: adding at least one copolymer or a salt thereof acting as a plasticizer and a blocking agent to a calcium sulphate-based hydraulic binder, said copolymer comprising at least one unit of formula (I) in which: R1, R2 and R3 independently represent a hydrogen atom, a linear or branched C 1 to C 20 alkyl radical, or a —(CH 2 ) p —COOR radical or an ionized form thereof, with p being equal to 0 or 1, and R is a hydrogen atom or R is a C 1 to C 6 alkyl radical; R4 represents a hydrogen atom, a monovalent, divalent or trivalent ion, or a quaternary ammonium radical; and said copolymer comprising at least one unit of formula (II) where R5, R6 and R7 independently represent a hydrogen atom, a linear or branched C 1 to C 20 alkyl radical or a —(CH 2 ) n —(C═O) m —W—(R8-O) q —R9 radical; R8 represents a linear or branched C 2 to C 20 alkyl radical; R9 represents a hydrogen atom, or a linear or branched C 1 to C 20 alkyl radical; W represents an oxygen or nitrogen atom; n is an integer from 0 to 2; m is an integer equal to 0 or 1; q is an integer from 2 to 30; and in which the molar mass of said copolymer is from 500 to 18 000 daltons, wherein a relative proportion of unit of formula (I) with respect to unit of formula (II) is from 70/30 to 99/1.