An Update of Sonic Pulse Velocity Tests on Heritage Buildings: Correlation with Masonry Types

The preservation of the architectural heritage passes through a ‘knowledge process’, based on inspections and diagnostic procedures. In this context, the Sonic Pulse Velocity Test (SPVT) is a viable option among non-destructive tests as it aims at evaluating the quality of masonry walls through the transmission of elastic waves. Wave velocity qualifies the density of the tested material: the more compact it is, the faster the waves propagate, although the acquired data cannot be considered as an estimate of mechanical parameters. In this paper, a database of 286 direct SPVTs is presented; the tests were conducted in the last twelve years on 50 buildings (mainly cultural heritage buildings). The direct configuration was adopted for the tests, thus evaluating the consistency of a wall cross-section. The average sonic velocity was calculated for each test; the results were grouped as a function of the masonry type, as described by the Italian building code, to define a range of velocities which qualify a type. A total of 5 masonry textures were recognized. The data were also grouped according to the building type, to explore the quality of construction, and the geographic area to evaluate a possible correlation between the SPVT results and local building traditions. Finally, for 37 masonry panels, the effectiveness of grout injections was evaluated by defining the velocity improvement after the intervention. At last, to validate the masonry qualification obtained from the SPVTs, a correlation between sonic velocities and the mechanical parameters obtained from flat jack tests carried out on the same sampling area for 51 panels was explored.