Process for waterproofing gypsum materials

Abstract

The invention provides a process for water-proofing gypsum materials which comprises adding, to a pulverulent gypsum plaster composition containing from 10 to 90% by weight of gypsum based on the total weight of the composition, a mixture of a) from 1.0 to 15% by weight, based on the total weight of the composition, of one or more dispersion powders redispersible in water and based on vinyl acetate copolymers with ethylene and/or vinyl esters of C.sub.5 -C.sub.15 -monocarboxylic acids, styrene copolymers with acrylic esters of alcohols having from 1 to 18 carbon atoms, vinyl chloride copolymers with ethylene and/or vinyl esters of C.sub.2 -C.sub.15 monocarboxylic acids, and b) from 0.05 to 5.0% by weight, based on the total weight of the composition, of one or more thixotropic additives from the group consisting of polyacrylic acids and their salts, smectites, bentonites, carboxymethylcelluloses and melamine-formaldehyde condensates.

Dependencies are inferred from the claim text.