Application of non destructive ultrasonic techniques for the analysis of the conservation status of building materials in monumental structures

Some examples of application of ultrasonic methods were chosen in different test areas located in Southern Sardinia (Italy) and Northern Greece coastal areas: - Cagliari town (Southern Sardinia – Italy), masonry structure and architectural element of an ancient monument. - Dion archeaological site (N. Greece). The study on the above mentioned monument was focused on the application of ultrasonic techniques in the low frequency range (24-54 kHz), with the aim to verify the conservation status of their building materials by means of the study of the longitudinal ultrasonic pulses propagation. Compressional velocity has been related to the physical, textural and mineralogical-petrographic features of the investigated materials, to correlate their intrinsic properties with the elastic ones. On the base of the laboratory ultrasonic measures, in situ investigations have been performed to identify the areas affected by degradation, quantify the intensity of weathering and monitoring his evolution. In addition, the methodological approach used in this study has proved to be useful also to reconstruct the texture of walls under the plaster or in the outcropping masonry structures, where the degradation makes it difficult the macroscopic identification of building materials.