Probabilistic Modelling of the damage induced by salt crystallization in fiber reinforced clay brick masonry

Masonry buildings suffer continuous and various attacks due to the changes induced from the surrounding environment. Those conditions also influence materials interacting with the substrate, due to intervention techniques. Nowadays, Fiber-Reinforced Cementitious Matrix (FRCM) are increasingly used to strengthen and retrofit existing structures, also belonging to historical contexts. Nevertheless, the durability of composite systems applied on existing substrates, particularly for masonry, has not been sufficiently investigated yet. In this paper, to examine durability against sulphates, a series of salt crystallization tests were carried out on small masonry assemblages reinforced with FRCM. Carbon fibers open meshes, embedded in layers of matrix based on two hydraulic binders, were used. The loss of material from the surface was assumed as parameter of damage, as well as the bulging of the material under the fibers. That loss was computed on the vertical section of the specimens through a computer code, which elaborated successive readings of the surface decay measured with a laser profilometer. The randomness affecting the damage due to the salt crystallization and the consequent loss of material layers under the fibers, suggested the adoption of a probabilistic approach, where the continuous deterioration of specimens can be assumed as a stochastic process. Preliminary results are discussed in the paper.