Mechanical characterization of natural building stone

Experiments were performed on a medium-grained granite in order to observe and characterize the zone of localized damage at failure. Geometrically similar three-point bend beams were considered. The size and shape of the localized damage zone appearing at peak load was identified through an interferometric technique (Electronic Speckle Pattern Interferometry) and the locations of acoustic emissions. These measurements are useful in explaining why structures composed of rock can fail at a stress much lower than a strength value determined in the laboratory.