INVESTIGATION ON DURABILITY PERFORMANCES OF CONCRETE STRUCTURES IN HISTORICAL RESIDENTIAL BUILDINGS

This paper examines the compositional quality, the state of advancement of incoming alteration processes, and the forecast of durability of hold concrete structures edified the last century in Reggio Calabria, city located in south of Italy. To this aim, preselected representative fragments of concrete structure were subjected to laboratory test by employing conventional chemical-physical and mineralogical-petrography procedures. Techniques such as optical microscopy, X-ray diffractometry, thermogravimetry, ionic chromatography plus some conventional wet chemical analyses procedures were applied. It was ascertained that buildings edified around to the second-third decade of last century are still in a good state as regard to the mix design and the structural performances. However a diffuse degradation on the exterior parts (as external walls, finishers, and other decorations) due mainly to the presence of soluble salts and ettringite (at least were the external plaster layer is lacking), were observed. Opposite, those buildings belonging to the sixth-seventh decade of the same century appear less good, more soft in the composition as if they had been composed with a less cement content or lower cementitious binder quality and/or other not well identified chemical compounds. It also seems, they today exhibit, both outside and inside the walls, a greater damages due to the interaction of the cement paste with some common environmental pollutants. A comparison between our results with other data derived from a series of common experimental non destructive tests n the same buildings, provided by another research group, were found to be in good agree.