New perspectives in Structural Health Monitoring of restored elements of cultural heritage monuments

The acoustic activity generated in marble specimens under elementary loading schemes (direct tension and uniaxial compression) is studied in terms of the average energy of the acoustic signals recorded. It is highlighted that several seconds before the macroscopic disintegration of the specimens the temporal variation of the specific quantity exhibits a clear plateau, which is terminated just a few tenths of a second before fracture. The specific conclusion is verified by considering the temporal variation of the average energy of the acoustic events against the respective variation of the Pressure Stimulated Currents produced while a restored marble epistyle of the Parthenon Temple is loaded under multi-point bending. It is thus safely stated that the onset of the specific plateau can be considered as an interesting pre-failure signal warning about entrance of the system into its critical stage.