Frost damage is caused by moisture freezing in the construction. Frost damage can occur as cracks, stone splinters and swelling of the material.
When water freezes, the volume of water increases by 9%. When the volumetric moisture content exceeds 91%, than the volume increase of water in the pores of the material caused by freezing cannot be absorbed by sufficient empty pores. This causes an increase in the internal pressure. If this pressure exceeds the tensile strength of the material, than micro cracks occur. Visible frost damage occurs after an accumulation of micro cracks as a result of several freeze-thaw-cycles.
Frost damage can be prevented by the use of frost proof materials, i.e. a material which has sufficient closed pores, by which the volume increase caused by the freezing of water in capillary pores can be absorbed by the ice-free closed pores.