2D cohesive zone modeling of crack development in cementitious digital samples with microstructure characterization

This paper presents two-dimensional (2D) cohesive zone modeling (CZM) techniques to simulate microscale crack propagation with cementitious digital samples under various loading conditions. The 2D multiphase bilinear cohesive zone models were employed to investigate the fracture behavior within heterogeneous cementitious material samples. The microstructure of concrete and cement paste samples were characterized with scanned surface (SS) and scanning electron microscope (SEM) imaging techniques, respectively. The digital concrete sample was generated from gray-scale SS images in millimeter. The single-edge notched beam (SEB) simulation on crack propagation within aggregate-cement microstructure was favorably compared with the tested sample. The digital cement samples with pores and unhydrated cement particles were generated from SEM images in micron scale. The compact tension (CT) test was simulated to predict crack propagation through pores. The study finally simulated the internal frost damage caused by ice crystallization with the SEM digital sample. The pore pressure calculated from thermodynamic analysis was input for model simulation. The CZM predicted the crack initiation and propagation within cement microstructure. The favorably predicted crack paths in concrete and cement paste samples indicate the developed CZM techniques have the ability to capture crack initiation and propagation in concrete or cement microstructure system with multiphase and associated interfaces.