Correlation of elastic and mechanical properties of consolidated granular media during microstructure evolution induced by damage and repair

Evolving cracks in consolidated granular media cause a modification of the microstructure in the area surrounding the damaged zone. As a consequence, the mechanical properties (flexural strength) and the elastic characteristics (linear modulus and nonlinear parameters) change as well. The same happens during repair, which could be considered as the symmetric counterpart of mechanical damaging. Starting from ultrasonicmeasurements of the resonance and nonlinear properties of concrete prisms during progression of damage and repair, we propose a description of the microstructure evolution, which allows to predict the observed phenomenology. Also, we demonstrate the existence of a correlation between ultrasonic elastic parameters and mechanical properties of the samples at each damage/repair state, pointing out symmetries and differences observed in the two processes