Are Deicing Salts Necessary to Promote Scaling in Concrete?

The main purpose of the present study is to investigate the role of the material parameters such as permeability, thermal diffusivity, and pore size distribution on the mechanical behavior of cementitious structures submitted to frost action, such as surface scaling. An experimental device, in which a cement paste specimen is exposed to freezing-thawing cycles under a thermal gradient, has been developed. The experimental results show that under high thermal gradient (up to 1.5C/mm), skin damage can occur without a saline layer in contact with the frozen surface. This can be explained and quantified in the framework of poromechanics. The model is based on the coupling between liquid ice crystal thermodynamic equilibrium, liquid water transport, thermal conduction and elastic properties of the different phases that form the porous material. It eventually predicts that a less permeable sample is more susceptible to be damaged by surface defacement, which explains the observed experimental result.