ABSTRACT
Durability of brick is related to its mineralogical composition and to its physical properties. Mineralogical composition is determined by the raw material used for the brick manufacturing and the manufacturing process (temperature and redox potential). The mineralogical composition of brick was studied by X-ray diffraction. Mineralogy and texture were examined by petrographic microscopy. Porosity was determined by mercury porosimetry. The physical properties were evaluated experimentally in the laboratory. Physical tests were also used to assess susceptibility to decay by moisture freeze-thaw cycling and salt weathering. Samples of decayed brick and salt efflorescence were taken and analysed by scanning electron microscopy (SEM) provided with energy dispersive X-ray analysis (EDX); salts were identified by X-ray diffraction (XRD).
The brick studied is from “the San Bartolomé Church tower” in Logroño city, La Rioja, Northern Spain. The study concludes that the primary cause of decay is salt crystallization caused by the upward migration of salt rich ground water into the lower part of the church. This is the result of enrichment of ground water with nitrates and chlorides and the inherent porosity of the brick.
