The interaction of Si-organic compounds with an organic gypsum-matrix is the subject of the paper on hand. Moreover the differences in reactivity, and the properties resulting from it, are shown, especially concerning hydrophobizing. Si-solid nuclear magnetic resonance spectroscopy, infrared spectroscopy, scanning electron microscopy, x-ray powder diffractometry, x-ray fluorescence analysis, mercury porosimetry and calorimetry were analytic methods. The very good hydrophobizing effect of polymethylhydrogensiloxane on the gypsum has been confirmed, however the in the literature supported thesis of the method of action could be refuted. The hydrophobizing effect is not based on the reaction of polymethylhydrogensiloxane with water to silanol under the formation of hydrogen, but requires a non-reacted polymethylhydrogensiloxane. The formation of a "film"of polymethylhydrogensiloxane molecules, which lines the poresurface of the cured gypsum and hydrophobizes it, is only possible with polymethylhydrogensiloxane, but not with its reaction product, the polymethylhydrogensilanol, which is produced during the hydrolylisis of polymethylhydrogensiloxane.     «

The interaction of Si-organic compounds with an organic gypsum-matrix is the subject of the paper on hand. Moreover the differences in reactivity, and the properties resulting from it, are shown, especially concerning hydrophobizing. Si-solid nuclear magnetic resonance spectroscopy, infrared spectroscopy, scanning electron microscopy, x-ray powder diffractometry, x-ray fluorescence analysis, mercury porosimetry and calorimetry were analytic methods. The very good hydrophobizing effect of polymet...     »