Detecting the fracture process zone in concrete using scanning electron microscopy and numerical modelling using the nonlocal isotropic damage model

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.