mechanical properties of masonry with environmental degradation

The exposition to environmental actions produces several degradation patterns in masonry textures, mainly as a function of the chemical reactivity of the masonry materials. Blistering of the bricks and powdering of the mortar can reduce locally the thickness of structural elements and introduce eccentricity of the thrust path. In the paper, the results of a preliminary analysis of typical degradation and repair situations is presented. By comparing existing experimental data with site data acquisitions it is possible to link the main data of salt concentration, humidity and temperature ambient variation and rate of pulverization of brick faces and mortar decay. The role of initial porosity is pointed out and some data on the increase in porosity due to salt attack are useful to define an analytical relationship among parameters. Finally, two examples of site investigations in Venice and Ancona sea front zones are presented in order to highlight the role of rheological properties and weather conditions as driving factors of the observed decay patterns.