Statistic comb polymers obtainable by the radical copolymerization of a vinylic poly(alkylenoxide) compound (A) with an ethylenically unsaturated monomer compound (B) according to the catalytic chain transfer method (CCT). The comb polymers are extremely suitable for hydraulic binder suspensions based on cement, lime, gypsum and anhydrite as they have, for the same dosage, an improved water reducing power over conventional flow agents. The corresponding building material mixtures are characterized by a substantially reduced stickiness and plastic viscosity once said comb polymers are added, which dramatically improves the plasticity of very cement-rich building material mixtures, such as concretes. The building material mixtures using the inventive flow agents have a considerably increased slump flow and an increased shear-thinning behavior as compared to conventional concretes without the tendency to segregate.