J.A. Larbi

Influence of Brick Properties on Salt Crystallization Damage / Einfluss der Eigenschaften von Ziegeln aus gebranntem Ton auf den durch Salzkristallisation hervor gerufenen Schaden

The quality of the materials constituting masonry has a major influence on the type and seriousness of the damage that can occur due to salt crystallization. In the case of brick, the composition of the original clay, together with the production process, determine the quality of the final product and its eventual susceptibility to salt decay. The paper describes a case study where different bricks, exposed to the same environmental conditions show a considerable difference in their resistance to deterioration by salt crystallization. Using the condition survey of the church tower in Oostkapelle, the possible relation between the damage and the physical and chemical properties of the bricks was investigated. Bricks showing very serious damage (orange bricks) as well as bricks showing no damage (purple bricks) were sampled and characterized mainly by polarization and fluorescence microscopy. The type and the quantity of salt present in the different bricks were also investigated. The observed damage was evaluated in the light of the results obtained from the analysis performed and a relation between the quality of the original material and the firing conditions of the brick to its susceptibility to salt decay could be dawn