The invention relates to a polymer composition containing 3 to 95% by weight of a copolymer H and 3 to 95% by weight of a copolymer K, the copolymers H and K each having polyether macromonomer structural units and acid monomer structural units, which are present in the copolymers H and K in each case in a molar ratio of 1:20 to 1:1, and at least 20 mol % of all structural units of the copolymer H and at least 25 mol % of all structural units of the copolymer K being present in each case in the form of acid monomer structural units, the polyether macromonomer structural units of the copolymers H and K having side chains containing in each case at least 5 ether oxygen atoms, the number of ether oxygen atoms per side chain of the polyether macromonomer structural units of the copolymers H and K varying in each case in such a way that the corresponding frequency distribution diagrams, in which the number of ether oxygen atoms per side chain of a polyether macromonomer structural unit is plotted in each case along the abscissae and the respectively associated frequencies for the copolymers H or K are plotted in each case along the ordinates, contain in each case at least 2 maxima whose abscissa values differ in each case by more than 7 ether oxygen atoms from one another, the frequency distribution diagrams of the copolymers H and K differing from one another in that the abscissa value of at least one maximum of the copolymer H differs in each case by more than 5 ether oxygen atoms from the abscissa values of all maxima of the copolymer K and/or that the arithmetic means of the ether oxygen atoms of the polyether macromonomer structural units of the copolymers H and K differ from one another by more than 5 ether oxygen atoms.