| abstract |
A gypsum mixture is disclosed which has hydrophobic additive substantially uniformly dispersed therein and which comprises gypsum, a first silane of the general formula (RO)3SiR or of the general formula (RO)2SiR2, and a second silane of the general formula (RO)3SiR' or of the general formula (RO)2SiRR', wherein each R is the same or different and represents a lower alkyl group, and R' represents a lower alkyl group which is substituted by a substituent selected from an amino, amino-lower alkyl-amino or dialkylenetriamine group. Preferably, the first silane is methyltrimethoxysilane and the second silane is N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. Also disclosed is a method for preparing said gypsum mixture. |