Corrosion assessment and restoration strategies of reinforced concrete buildings of the cultural heritage

Since the beginning of the 20th century, in Italy as in many other countries, reinforced concrete (RC) became one of the most popular construction materials and it was used for buildings, monuments, infrastructures, etc. Several of these structures, although of recent formation, have now been included in the cultural heritage, because of their architectural or social relevance. As a consequence of the typical urban or rural exposure conditions of these buildings, they often suffer damage due to carbonation-induced corrosion of reinforcement, such as concrete spalling or cracking or rust stains that may affect the serviceability of structures. Furthermore, chloride-induced corrosion of reinforcement, may also concern buildings exposed to de-icing salts or marine environments. Due to strict requirements related to the preservation of the original materials and texture, the repair of structures that belong to the cultural heritage cannot rely on the conventional repair technique, based on the replacement of carbonated concrete. Therefore, the conservation of RC buildings of the cultural heritage is a challenge, since it requires the development of specific strategies aimed at finding the best compromise between, on one hand, the restoration of structural safety and the prevention of future damage and, on the other hand, the preservation of the original materials and surfaces. This paper analyses the results of inspections carried out on several buildings, built in Italy throughout the 20th century in different micro- and macro-climates, with the aim of showing their peculiarities with regard to steel corrosion and the selection of restorations strategies.