Modeling of path-dependent phase change in sorption and freezing of pore water for cementitious materials
Fuyuan Gong, Stefan Jacobsen, Pengfei Li, Zhao Wang, Koichi Maekawa, Marcin Koniorczyk
Abstract
Many physical and mechanical behaviors of cement-based materials can be affected by the phase change and phase equilibrium of pore water, such as shrinkage, creep, ion transport, frost damage etc. In addition, the thermodynamic behavior and sorption of pore water are closely related to the pore size distribution (PSD) and pore shape. Practical prediction of liquid/gas/ice content during adsorption-desorption and freezing-thawing process is thus needed for an engineering purpose. This paper presents a path-dependent phase change model based on the empirical PSD model, in consideration of the humidity history, temperature history and the hysteresis during drying-wetting and freezing-thawing. The adsorption-desorption curves and ice formation during freezing-thawing are calculated for different mix proportion and different environmental conditions. A good agreement can be found with the selected experimental data. The developed empirical formulations can be beneficial for further theoretical models and numerical simulations.