Copolymer as a water-reducing agent in a hydraulic composition and use of copolymers for improving the early mechanical strength of a hydraulic composition

A method for increasing early mechanical strength of a hydraulic composition, the method comprising:

• incorporating, into a hydraulic composition, at least one copolymer obtained by polymerization of a monomer mixture comprising:
• at least one anionic monomer (a) comprising a polymerisable unsaturated group and a carboxylic group;
• and
• at least one monomer (b) of formula (I):
• H2C═C(—R1)—(CH2)p—O-[(EO)n—(PO)m]—H (IA)
• wherein:
• R1 represents a hydrogen atom or a CH3 group,
• p is equal to 1 or 2,
• [(EO)n—(PO)m] represents a polyalkoxylated chain constituted of ethoxylated units EO and propoxylated units PO, distributed in blocks, alternating or random and
• m and n represent integers varying between 1 and 250, the sum of m and n being greater than or equal to 10, provided that the molar proportion of the ethoxylated units in the polyalkoxylated chain (n)/(m+n) is greater than or equal to 70% and less than 90%,
• wherein the monomer (b) represents from 1 to 18 mol % of the total mole number of monomers that constitute said copolymer.