Modeling of the internal damage of saturated cement paste due to ice crystallization pressure during freezing

In order to quantify the internal damage of saturated cement paste caused by frost action, a damage model is proposed based on the thermodynamics of ice growth and fracturing of hydrated cement paste. According to the pore structure of cement paste from the HYMOSTRUC3D model, the penetration of crystals of ice through the pore network is simulated and stresses on the pore walls caused by the crystallization pressure of ice are first calculated. Then, the stresses in the solid skeleton of the microstructure of cement paste are calculated with the help of a three-dimensional (3D) lattice fracture model. Local damage, expressed as micro-cracks, is created if the local damage criterion is satisfied. The creation of microcracks in saturated cement paste during freezing is illustrated in this paper. The simulated results show that the number of micro-cracks in the microstructure of cement paste increases with decreasing temperature and the volume of cement paste increases with decreasing temperature when the temperature is below zero. To validate the model, strains of cement paste during freezing by simulations in this study are further compared with those by experiment. The reliability of the pore size distribution of cement paste by HYMOSTRUC3D simulation is also discussed. (C) 2011 Elsevier Ltd. All rights reserved.