Correlated fracture precursors in rocks and cement-based materials under stress

This paper presents experimental results on the evolution of damage by acoustic-emission and electrical resistance measurements in rock and cement mortar specimens during uniaxial compression tests. Once defined a specific damage parameter in terms of cumulated number of acoustic emission events, evaluated by their magnitude, two scaling laws are proposed which correlate respectively the electrical resistance variation and the acoustic emission b-value with the cumulative damage D. The electrical resistance variation is expressed as the ratio R0/R, where R0is the resistance of the undamaged specimen and R is that obtained during the test. The first scaling law describes a relevant correlation between acoustic emission and electrical resistance measurements, while the second one shows internal consistency of two metrics both derived from acoustic emission data.