[automatically translated] This paper describes a non-invasive methodology it even less destructive to study the degradation of the surface layers of stone artefacts, correlating it to the mechanical strength parameters. The methodology uses as a diagnostic tool the propagation of elastic waves in the medium in question. In particular, whereas the order of magnitude of the sought thickness is comprised between fractions of a millimeter and a few centimeters, the frequency of the elastic waves can be used are those ultrasonic, from tens of kHz to MHz (and therefore, with the propagation speed of ' order of 4000 m / s, with wavelengths from centimeters to fractions of a millimeter). This methodology, called GTT (Global Tomographic Traveltime, and Italian dromocrona global tomographic), expected to perform on the manufactured article a series of ultrasonic waves propagation speed measurements on specially arranged paths, so as to assess the level of degradation and the thickness of the weathered surface layer. The measurements of the propagation times in fact are reported to appropriate graphic dimensional time-distances (ie the so-called "dromocrona") and the performance of experimental points in this chart enables the evaluation of the sought parameters. The methodology, which can be considered a one-dimensional simplification of a three-dimensional tomographic pad, and relatively rapid for the execution times and gave interesting results, some of which are presented. However, some problems remain, especially it] data acquisition of so-called "
|Number of pages||8|
|Publication status||Published - 2008|