Microclimate and Salt Crystallization in the Crypt of the Lecce's Duomo

Ancient masonry structures are often damaged by soluble salt crystallization which is activated by even small microclimatic variations. Unsuitable environmental conditions can accelerate this process, affecting the type and the quantity of salts and the consequent damage to the masonry. Therefore the importance of monitoring salt diffusion to control salt crystallization and microclimate over time is widely recognized. This paper proposes an integrated monitoring methodology to obtain information on the relationship between salt efflorescence and microclimate in the Crypt of the Duomo of Lecce (South Italy). By combining Ion Chromatography, powder X-ray diffraction and Raman microscopy with environmental monitoring and deterioration maps, salt components were identified and efflorescence diffusion on masonry was monitored over time. Due to this a possible explanation for the process is finally given.