The mechanical property known as "strength at young ages" of cement matrices or hydraulic binders may be significantly improved by adding dispersions of mineral fillers and dispersing agents. The dispersing agents of the present invention comprise copolymers prepared by the radical copolymerization of at least one alkoxy-, aryloxy-, alkylaryloxy- or arylalkyloxy-polyalkylene glycol ethylenic urethane monomer with at least one anionic monomer and at least one non-ionic monomer, and optionally, an alkoxy-, aryloxy-, alkylaryloxy- or arylalkyloxy-polyalkylene glycol acrylate or methacrylate or an alkyloxy-, aryloxy-, alkylaryloxy- or arylalkyloxy-polyalkylene glycol allyl ether, and/or a crosslinking agent.