Study of the effects of salt crystallization on degradation of limestone rocks

Salt crystallization is widely recognized as a cause of deterioration of porous building materials. In particular, the crystallization pressure of salt crystals growing in confined pores is found to be the main cause for damage. The aim of this study is to better understand the degradation of porous rocks induced by salt crystallization and correlate such processes with the intrinsic characteristics of materials. With this intent, an experimental salt weathering simulation was carried out on two limestones widely used in the Baroque architecture of eastern Sicily. A systematic approach, including petrographic, porosimetric and colorimetric analyses, was used to evaluate the correlation among salt crystallization, microstructural and chromatic variations of limestones. Results showed a quite different resistance of the two limestones to salt damage, and this was found to be strongly dependent on their pore structure and textural characteristics.