MIXED MODE-I AND MODE-II CONNCRETE FRACTURE - AN EXPERIMENTAL-ANALYSIS

The development of the fracture process zone associated with subcritic al crack growth in a three-point bend concrete specimen with an off-ce ntered single-edged precrack was monitored with moire interferometry. The applied load and the crack opening and sliding displacements toget her with a finite element model of the concrete specimen were used to determine the crack closing stress due to aggregate bridging. Under th is mixed-mode fracture, aggregate interlocking increased the crack clo sing stresses in the fracture process zone and hence the load carrying capacity of the concrete specimen. The dissipated energy rate in the fracture process zone also increased with aggregate interlocking.