Ceramics-Silikáty 53, (3) 211 - 215 (2009)

The paper deals with simulation of long-lasting atmospheric moisture exposure of ceramic materials on the base of natural raw materials. The exposure causes the irreversible volume expansion, recorded by as a relative length deformation. Series of samples from mixtures of clays with dolomite and calcite were prepared and the influence of the changing composition on the deformation was studied. In the following fired bodies based on kaolinitic clays were exposed to various hydrothermal conditions, namely two exposure times and two temperatures were used. Correlation between mixtures composition and length changes (deformation) of material was confirmed. Results have shown a strong dependence of the found irreversible deformation on the content of kaolinite and hydrothermal exposure conditions. On the other hand, changes of firing regime didn’t have significant influence on the deformations.