The invention describes amphiphilic polymer compounds which have been prepared by a) reacting a di-, tri- or tetraglycidyl compound (A) with an optionally unsaturated reactive component (B) consisting of C.sub.8-C.sub.28-fatty acid, a C.sub.8-C.sub.28-alcohol or a secondary C.sub.8-C.sub.28-amine, and then b) allowing the reaction product from stage a) to react with an aliphatic or aromatic polyisocyanate compound (C) and finally c) reacting the reaction product from stage b) with a polyalkylene oxide compound (D) of the general formula (I) in which R.sup.1 is H or a linear or branched and optionally unsaturated aliphatic hydrocarbon radical having 1 to 12 C atoms, R2 is a linear or branched and optionally unsaturated aliphatic hydrocarbon radical having 1 to 30 C atoms or phenyl, m is from 0 to 250, n is from 3 to 350 and x is from 1 to 12,and the ethylene oxide or higher alkylene oxide units can be arbitrarily distributed in the polyalkylene oxide compound (D). The polymer compounds proposed in accordance with the invention are exceptionally suitable as agents for preventing or suppressing efflorescence on surfaces of cured, hydrometrically settable building materials and/or for hydrophobization of the corresponding hydraulically settable systems. Moreover, owing to the admixtures proposed in accordance with the invention, the corresponding products absorb substantially less water, with the result that frost damage and rapid rusting of the steel reinforcement can be substantially reduced.