Integrated non-destructive geophysical methods to study stone masonry walls in historical buildings: tests on laboratory-scale models

Cultural heritage diagnostics, particularly for historical buildings built with stone masonry, often represents a problem in terms of structural analysis and consequently of proper restoration. Indeed, although the construction system is often apparently known and easy to identify, the complex form of walls or the more general presence within their internal structure of non-homogeneous and anisotropic materials, creates significant problems for their study. In this work we present the results of tests carried out with non-destructive integrated geophysical methods (ground penetrating radar, electrical resistivity tomography, sonic and seismic measurements) on laboratory-reconstructed examples of common stone masonry walls, in order to study three different static conditions. Generally, the decision about the use of a particular geophysical method depends on several factors, including: physical properties of the target and its surroundings, depth of investigation, resolution, and finally logistical conditions. On the other hand the choice of adequate acquisition parameters and the use of special devices to save the integrity of the wall surface represent important aspects in cultural heritage where the collection of meaningful information and the preservation are both important objectives. In this work we show the benefits of the use of integrated geophysical methods and the intrinsic limitations, discussing what are the unsolved and solvable questions in this field.