Patent ID: 7803225

Claim:
A non-efflorescing cementitious mortar composition, free of reactive silica material, in the form of a dry-mortar composition or an aqueous mortar composition, comprising a) from 1% by weight to 10% by weight of ordinary portland cement, based on the dry weight of the cementitious mortar composition b) from 1% by weight to 30% by weight of calcium aluminate cement, based on the dry weight of the cementitious mortar composition c) from 1% by weight to 15% by weight of calcium sulfate, based on the dry weight of the cementitious mortar composition and d) from 0.5% by weight to 30% by weight, based on the dry weight of the cementitious mortar composition, of an aqueous polymer dispersion or a water-redispersible polymer powder of polymers based on one or more monomers from the group consisting of vinyl esters, (meth)acrylates, vinyl aromatics, olefins, 1,3-dienes and vinyl halides and, if required, further monomers copolymerizable therewith, the weight percentage of aqueous polymer dispersion based on the weight of solids in the dispersion, wherein reactive silica material means non-crystalline silica which is in metastable form and can react with cement hydration product calcium hydroxide to form hydrated calcium silicate, and wherein in the cementitious mortar composition, the components a), b), c) and d) are present in a weight ratio of a):b):c):d) of 1 to 1.5:2 to 4:1 to 1.5:2 to 4.