HERITAGES OF STONE: MATERIALS DEGRADATION AND RESTORATION WORKS

The use of calcarenitic stones in the constructions of historic and artistic interest is widespread in the regions of the Mediterranean area. These materials, known with different local names (Matera calcarenite, Lecce stone, Malta calcarenite, etc ..), are characterized by the easiness of quarrying and processing in complex shapes as well. The calcarenitic materials also have a high porosity that makes them poorly durable and vulnerable to different degradation phenomena caused by the synergistic action of physical, chemical and biological agents. The types and the extent of the degradation phenomena vary according to the environment in which the artefact is located. Consequently, each intervention of restoration should be considered as a unique case due to the complex relationships that occur between the materials, the exposure environment and the different types of products used in the restoration works. This paper describes the degradation phenomena of calcarenitic materials in different exposure environments and illustrates the results obtained in the last decades from the application of protective and consolidating products, highlighting their weaknesses and strengths.