Microcracking and tension-softening properties of concrete

Abstract Tests are reported on the microcracking properties of concrete studied by means of a three-dimensional acoustic emission technique. Observed microcracking properties are discussed in connection with the phase of the fracture process zone of concrete. It is shown that the fracture process zone is already created before the peak load and that the fracture process zone expands widely after the peak load. Moreover, it is revealed that the length of the fracture process zone ahead of the notch tip seems to be independent of the heterogeneity but the width is obviously influenced by the aggregate size. The shape of the tension softening diagram determined by a numerical analysis is discussed in comparison with the acoustic emission behaviour.