Quasi-Liquid Layer on Ice and Its Effect on the Confined Freezing of Porous Materials

Freezing of the water confined in thin pores can be destructive to the porous frame, but the effect of the quasi-liquid layer (QLL) between the confined ice and the pore walls remains still far from being fully understood. In the present study, the physical origins of the intermediate phase of QLL were discussed by thermodynamic analyses. Different interactions on QLL bring different models to estimate its thickness, which generally decays with temperature decreasing. Four representative models of QLL thickness were selected to unveil its effect on the growing rates and extents of ice in a concrete. The engineering consequences of the confined freezing were then discussed in the aspects of effective pore pressures built from the confined ice growth and deformations framed by a poro-elastic model. Overall, thickening QLL depresses ice growing rates and contents and, consequentially, decreases pore pressures and material deformations during freezing. The QLL corrections also narrow the gaps between the predicted and measured freezing deformations. The findings of this study contribute to profound understandings of confined freezing that may bridge over physical principles and engineering observations.