EVALUATION AND OPTIMISATION OF CALCIUMSULFATE BASED FLOORING PLASTER WITH REGARDS TO WATER RESISTANCE

摘要

The production time for social construction can be reduced considerably by using high quality flooring plaster based on anhydrite and/or α-hemihydrate. These calciumsulfate based flooring plasters can be transported mechanically, are easy to handle, can be laid jointlessly and have a self-levelling surface. Experiments under extreme, but also realistic moisture conditions with calciumsulfate based flooring plasters, usually available on the market, were investigated. The aim was to figure out the changes of properties relevant for practice. Based on these results, anhydrite or α-hemihydrate containing mixtures were prepared and modified with different additives and admixtures, it could be seen that it is possible to increase the water resistance of calciumsulfate based materials. Scanning electron microscopic investigations of set gypsum to which additives have been added, show that the morphology and size of the gypsum crystals are clearly affected by their use. New water resistant phases were formed with the addition of hydraulic or latent-hydraulic admixtures. The paper includes the modeling of the increase of water resistance of calciumsulfate based materials in comparison to ordinary gypsum binders.