Francesco Cuccuru

Dynamic elastic characterization of carbonate rocks used as building materials in the historical city centre of Cagliari (Italy)

This paper focuses on the dynamic characterization approach to evaluate the conservation state of carbonate building stones of monumental structures. In particular, we report the use of elastic waves at an ultrasonic frequency of 54 kHz to define quantitatively some dynamic properties of carbonate rock types used as building materials. Measurements of compressional and shear wave velocities have been carried out and the relationship between some physical properties of the investigated rocks and these geophysical measurements have been evaluated. The ultrasonic data were also supplemented by a petrographical study of these rocks to correlate their petrophysical features with the elastic ones. Based on the results of the laboratory measurements, in situ applications on a significant monumental structure have been also carried out to check zones of weakness and to assess the state of deterioration of the investigated stones. A comparison of laboratory and in situ results confirms that dynamic characterization is a useful approach.

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: (1) Cagliari town (Southern Sardinia—Italy), masonry structure and architectural element of an ancient monument. (2) 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.

An innovative methodology for the non-destructive diagnosis of architectural elements of ancient historical buildings

In the following we present a new non-invasive methodology aimed at the diagnosis of stone building materials used in historical buildings and architectural elements. This methodology consists of the integrated sequential application of in situ proximal sensing methodologies such as the 3D Terrestrial Laser Scanner for the 3D modelling of investigated objects together with laboratory and in situ non-invasive multi-techniques acoustic data, preceded by an accurate petrographical study of the investigated stone materials by optical and scanning electron microscopy. The increasing necessity to integrate different types of techniques in the safeguard of the Cultural Heritage is the result of the following two interdependent factors: 1) The diagnostic process on the building stone materials of monuments is increasingly focused on difficult targets in critical situations. In these cases, the diagnosis using only one type of non-invasive technique may not be sufficient to investigate the conservation status of the stone materials of the superficial and inner parts of the studied structures 2) Recent technological and scientific developments in the field of non-invasive diagnostic techniques for different types of materials favors and supports the acquisition, processing and interpretation of huge multidisciplinary datasets.