HIGH FREQUENCY SOUND WAVES AS FUNCTION OF THE DENSITY AND WATER CONTENT: EXPERIMENTAL STUDIES ON CALCARENITIC STONES OF SOUTHERN APULIA

In Apulia Region there is a dense historical-architectural and archaeological heritage built with soft calcarenitic stones. These materials present significant problems of conservation related to their low durability and therefore know the intrinsic characteristics is crucial to evaluate the performance properties and their susceptibility to degradation. To evaluate the physical-mechanical characteristics of the stone materials is very useful to use non-destructive and non-invasive technologies such as ultrasonic, applicable both in situ and in the laboratory. The factors influencing the propagation of elastic waves in the rocks are the structure, density, size and shape of the granules, porosity, anisotropy, the water content, stress and temperature. In this paper the effects of saturation on the elastic wave velocity and the relationship between density and elastic wave velocity were studied on some Apulia's porous calcarenites such as Leccese stone, the Ostuni stone and the calcareous "Tufo delle Murge". The ultrasonic P and S wave velocity measurements were performed on cubic samples, under natural condictions (e.g. without applying external pressure on the samples), using the transmission method. Variations of P and S wave velocity were related to density and percentages of water content. Furthermore in order to study the frequency influence on seismic velocities.