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

Solid bricks manufactured using clays from Thessaloniki area have been anal ysed by X-ray powder diffraction and their mineralogical composition showed the presence of chlorite, muscovite, quartz. and albite. The compressive s trength values of dried and wetted bricks were determined and a decrease of about 25% was observed for water saturated bricks. Using mechanical extens iometers, stress strain diagrams and Poisson ratios were measured. In order to model the liquid diffusion through the brick and the chemomechanical da mage due to the coupled action of liquid presence and applied loads, the fr ont of a penetrating solute has been mathematically expressed by using Aifa ntis'stress-assisted diffusion theory. Pre-loaded bending specimens were sp rayed with a liquid. After a certain time the specimens were loaded until f racture. Different phenomenological constants of the stress-assisted diffus ion theory have been assumed for the compression and tension regime and a s atisfactory agreement between theoretical predictions and experimental data has been obtained. (C) 2000 Elsevier Science Ltd. All rights reserved.