Revisiting concrete frost salt scaling: On the role of the frozen salt solution micro-structure

We simulate the glue-spall stress due to mechanical interactions between a frozen saline solution (brine-ice composite) and a non-air entrained concrete surface including the impact of the micro-structure of the frozen solution. The presence of brine channels at the ice/concrete interface was found to be a prerequisite to induce stress during freezing and hence for scaling to occur. Pure ice does not result in scaling as it does not have brine channels. Furthermore, the size of the brine channels and their distribution was found determinant for the magnitude of the glue-spall stress in the concrete and the experimentally observed pessimum effect of a medium salt concentration was explained based on the change of the microstructure of the brine-ice composite at different salt concentrations and temperatures. The predicted results are in good agreement with the experimental observations and the few numerical demonstrations related to frost salt scaling in the literature.