From nano to macroscale: A new experimental approach to mechanical characterization of rock materials

In crystalline rocks, micro-cracks play a key role in determining the rock’s mechanical response under loading conditions. The present research suggests an innovative multiscale approach in rock material characterization to correlate the rock behavior at the scale of the laboratory sample to the cracking observed at the micro-cracks scale (nano and micro scale). The rock under investigation, a marble, exhibits two textures (granoblastic and xenoblastic), differing in micro-cracks porosity, mainly extending along the grains contacts. The investigated marble’s behavior under states of stress was investigated involving portions of the rock’s sample varying in size from nano to micro and macro-scale through also innovative techniques in the Rock Mechanics field. The nano and microscale investigations allowed to identify different crack initiation, propagation, coalescence and failure mechanisms in the two textures. Furthermore, the observed cracking justified the behavior of the two investigated marbles in terms of strength and deformability and stress-strain relationship, at the scale of the laboratory sample (macro scale).