A preliminary study of stress-assisted fluid penetration in ceramic bricks

Solid bricks manufactured using clays from Thessaloniki area have been analysed by X-ray powder diffraction and their mineralogical composition showed the presence of chlorite, muscovite, quartz. and albite. The compressive strength values of dried and wetted bricks were determined and a decrease of about 25% was observed for water saturated bricks. Using mechanical extensiometers, stress strain diagrams and Poisson ratios were measured. In order to model the liquid diffusion through the brick and the chemomechanical damage due to the coupled action of liquid presence and applied loads, the front of a penetrating solute has been mathematically expressed by using Aifantis'stress-assisted diffusion theory. Pre-loaded bending specimens were sprayed with a liquid. After a certain time the specimens were loaded until fracture. Different phenomenological constants of the stress-assisted diffusion theory have been assumed for the compression and tension regime and a satisfactory agreement between theoretical predictions and experimental data has been obtained. (C) 2000 Elsevier Science Ltd. All rights reserved.