Defect dynamics and damage of concrete under repeated compression, studied by electrical resistance measurement

The electrical resistance of concrete in the stress direction increased during compressive loading in the first cycle, due to defect generation. It decreased during loading in all subsequent cycles, due to defect diminution. It increased during unloading in the first and all subsequent cycles, due to defect extension. The baseline resistance and the amplitude of resistance variation increased with cycling, due to minor damage. The interface between mortar and coarse aggregate contributed to the defect dynamics, particularly defect diminution.