Visualization of acoustic emission monitoring of fracture process zone evolution of mortar and concrete beams under three-point bending

Abstract

By combining the b-value and acoustic emission (AE) event density, a parameter referred to as the T value was developed to construct a fracture process zone (FPZ) using AE data to study the fracture process of mortar and concrete beams under three-point bending tests. The FPZ is successfully constructed by using a T value contour map. The contour map shows that the FPZ evolved from the middle of the beam to the boundary for the mortar beam and that it evolved in the whole section of the beam at the beginning of the tests, localized in the middle of the beam and moved upward until the end of the test for the concrete beam. A quantitative analysis of the FPZ size shows that microcracks in the concrete beam are more developed and distributed in a wider range than those in the mortar beam. The mean T value in every contour map indicates that both the mortar beam and concrete beam show a decrease in the T value when reaching their peak load, which can be considered characteristic of the critical state of beams under three-point bending. When considering the use of coarse aggregate, note that the mesostructure formed by the coarse aggregate is responsible for the large-range FPZ region and the high load of the concrete beam. This method offers insight into the FPZ by AE and its successful reproduction. The T value contour map can also be applied for concrete structure damage monitoring.