Petrography and decay of a marly limestone in the cloister of a medieval cathedral in Sicily

The paper deals with a significant process of dechesion of a marly limestone,taking place in the clioster of the modieval Cathedral of Cefalù, a pleasent town of the northern coast of Sicily.After desalination with deionized water and consolidation with etyl silicate, the decay of the stonr became faster. The aim of our study is to characterize the phenomena. The stone, that is a poor building material indeed, is characterized by means of petrographical, chemical and physical analyses on samples taken from the monument. Furthermore, experimental tests are performed in the laboratory in ordrr to highlight the causes of incomatibility betweeen the stone and the applied treatments.