Fracture process zone in notched concrete beam under three-point bending by acoustic emission

Investigation on fracture process zones in notched concrete beams under three-point bending is performed by applying acoustic emission (AE). The tests were conducted on beam specimens with different notch depths and the maximum sizes of aggregate in concrete to clarify the generation mechanisms of micro-cracks in the fracture process zone. SiGMA (simplified Green's functions for moment tensor analysis) procedure was applied to analyze AE signals. The experimental results show the fracture energy increases with increase in the maximum size of aggregate. It is found that dominant motions of micro-cracks vary with the notch depth, regardless of the maximum size of aggregate. The widths of the fracture process zone were estimated from results of AE source location. It is confirmed that the fracture energy correlates with the width of AE cluster, as the energy increase when the width of fracture process zone expands.