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Acoustic emission (AE) has been used to investigate characteristics of the fracture process zone (length, width and macro crack propagation) in a concrete specimen subjected to four-point bending, using probability and statistical methods. To understand the process' of crack growth and fracture, a technique based on AE has been developed. The results are treated according to the laws of probability and statistics. It is shown that these results agree more or less in comparison to those obtained using other techniques.

This paper deals with two aspects of the characterization of the fracture process zone (FPZ) in quasi-brittle materials such as concrete. An overview is given of the possibility of using a destructive technique, such as the scanning electron microscope, and a numerical model, such as the nonlocal isotropic damage model (NLIDM), to detect FPZ characteristics, e.g., length and width of the FPZ. The fracture of concrete requires the consideration of progressive damage, which is usually modelled by a constitutive law and can be studied by a numerical method. The object-oriented finite element method (OOFEM) has recently been used in damage studies, and thus the FPZ is calculated on the basis of one of the damage models (the NLIDM). The results obtained from the experimental investigation are similar to those obtained using the NLIDM, which has proven to be a useful tool for analysis of the cracking process.

In this study, a Scanning Electron Microscope (SEM) is used to understand the micro level aspect of the Fracture Process Zone (FPZ) in a concrete beam. It is mainly based on the preparation and analyzing samples which are considered as being a very important part of SEM (poor preparation techniques can lead to erroneous diagnosis of the concrete study). Numerically, the fracture of concrete requires the consideration of progressive damage, which is usually modeled by a constitutive law. This latest relies on numerical methods to obtain adequate solutions. It is shown herein that by using the Object Oriented Finite Element Method (OOFEM), obtained results agreed more or less with those of others researchers. On the other side, experimental results compromise those obtained by the use of the non-local isotropic damage model. It is finally proven throughout this study that the FPZ is defined by two parameters: the length and the width.