Numerical investigation of internal frost damage of digital cement paste samples with cohesive zone modeling and SEM microstructure characterization

This paper develops microstructure characterization and computational modeling approaches to investigate the internal-frost damage due to ice crystallization pressure. The three-dimensional (3D) cohesive zone modeling (CZM) techniques were used to simulate frost-induced damage behavior within digital cement samples under subcooling temperatures. The 3D CZM techniques were firstly applied to simulate crack propagation through multi-pore systems with compact tension tests. Then the multiphase 3D bilinear cohesive zone models were developed to investigate the internal frost damage due to ice crystallization pressure within heterogeneous cementitious samples. The pore microstructure within cement paste samples were characterized with the scanning electron microscope (SEM) imaging techniques. The 3D imaging reconstruction techniques developed by National Institute of Science and Technology (NIST) were applied to generate the 3D digital SEM samples for frost damage simulation. The pore pressure at subcooling temperatures was calculated with thermodynamic analysis. The calculated pore pressure was input for crack initiation and propagation simulation with the 3D CZM. The predicted internal frost damage within SEM digital samples was compared with captured damage in actual specimens. The favorably predicted crack paths with digital samples indicate that the developed micromechanical analysis techniques have the ability to predict the internal frost damage. This study also showed that the pore pressure due to ice crystallization is sufficient to cause internal damage during freeze–thaw cycles.