Multi-functional cement dispersants and hydraulic cement compositions

A multi-functional cement dispersant comprising salts of graft copolymers obtained by:

• a first step of obtaining copolymers with average numerical molecular weight 3000-50000 by radical polymerization of a mixture of radical polymerizable monomers containing maleic anhydride and monomers of form given by Formula 1 below, together in an amount of 85 weight % or more of said mixture and at molar ratio of 50/50-80/20;
• a second step of obtaining graft copolymers by a graft reaction, in the presence of a basic catalyst, of 100 weight parts of said copolymers obtained in said first step and 3-35 weight parts of one or more selected from the group consisting of polyoxyalkylene monoalkylester, polyoxyalkylene monoalkylether and polypropyleneglycol with repetition number of oxypropylene units equal to 3-15;
• and
• a third step of obtaining said salts of graft copolymers by neutralizing said graft copolymers obtained in said second step with one or more selected from the group consisting of alkali metal hydroxide, alkali earth metal hydroxide and amines;
• CH2═CH—CH2—O—A—O—R (Formula 1)
• where R is acyl group with 1-18 carbon atoms, alkyl group with 1-3 carbon atoms or hydrogen, and A is a residual group obtained by removing all hydroxyl groups from polyalkylene glycol with repetition number of oxyalkylene units equal to 5-80, said oxyalkylene units consisting only of oxyethylene units or of both oxyethylene units and oxypropylene units;
• where said polyoxyalkylene monoalkylester has a block addition of a total of 2-10 moles of ethylene oxide and propylene oxide to one mole of aliphatic carboxylic acid with 1-6 carbon atoms;
• and
• where said polyoxyalkylene monoalkylether has a block addition of a total of 2-10 moles of ethylene oxide and propylene oxide to one mole of aliphatic alcohol with 1-6 carbon atoms.