Resistencia a la helada de los productos de ceramica roja: Fid-Bau Portal

Resistencia a la helada de los productos de ceramica roja

Ramires, M.V.V. / Madruga, T.P. / Bergmann, C.P.

The present work is a study about degradation occurring with red ceramics whenever they are exposed to the environmental conditions of a cold and humid climate. Four different types of clay from Rio Grande do Sul were studied: two of them from the Serra Geral formation, and the other two from the formation of Strada Nova, which are commonly used to make roof tiles. The clay was characterised to identify its chemical and mineralogical composition. Also the physical properties were researched. In the ceramic processing, the pressure with four different sintering temperatures (850, 900, 950, and 1000 degrees C) at three different intervals (3, 12, and 24 hours) was used. The ceramic materials thus obtained were characterised according to their physical properties (water absorption, total density, porosity, and porous size), and mechanical (mechanical resistance over four points). For the characterisation of the degradation mechanism, some trials were carried out to obtain the coefficient of saturation and on frost and defrost cycles. The microstructural analysis was made with a scanning electronic microscope. On the basis of the results obtained, a model for the degradation mechanism is presented, and a degradation factor, which relates the total volume of mesopores to the standard size of mesopores, is suggested. It was concluded that the red ceramic products more prone to be frost-resistant are those presenting a degradation factor below 100.