When tiles are damaged due to frost, pieces of tiles of varying sizes (from a few millimeters to several centimeters) break off. Typically, the damage is in the shape of a triangle, and often entire parts of the tile break off and separate from the base. The mechanism of the effect of frost has already been discussed in the section “Frost resistance”. Both the surface layer and the entire floor or wall structure are damaged due to an increase in the volume of water that has penetrated into the structure during the process of freezing, that is, turning into ice. The consequences of such damage are mainly functional, although the aesthetic characteristics of the facing surface also deteriorate.
Causes
The first step is to determine whether the quality of the tiles complies with the EN ISO 10545-12 Standards, checking for frost resistance. If the test results show that the frost-resistant tiles are in fact resistant to frost, then it is certain that the poor quality of the tiles caused the defect.
But, basically, such defects arise due to errors at the planning and design stage: the choice of non-frost-resistant tiles (in the sense that such characteristics were not taken into account when choosing tiles) and the choice of materials for the base (cement-lime and adhesive mortars and grouts) not resistant to frost or not sufficiently dense and impermeable. Further poor design decisions will result in an increased risk of frost damage. Let's give a simple example: laying tiles with closed joints. As has already been repeatedly emphasized, this method of laying makes the surface more rigid, which, in turn, significantly increases the internal loads on the surface due to the movements of the underlying layers.
It is important to remember that the entire floor or wall structure must be frost-resistant, and not just the tile itself. The choice of frost-resistant tiles that meet the established requirements is a necessary measure, which, however, is not enough to ensure the absolute reliability of a floor or wall structure. Materials for the base under the tiles and grout must also be frost-resistant. Experience shows that even when using frost-resistant tiles, the floor or wall does not always withstand the effects of frost. The reasons are shortcomings at the planning and design stage. In this regard, it is necessary to take into account the fact that the standard test method does not always effectively determine the performance characteristics of the tiles, because actual operating conditions are not taken into account. Such tests simulate real conditions in the laboratory and in a fairly short time frame; naturally, in this case it is impossible to predict all possible situations. That is, if you choose frost-resistant tiles, you cannot say with one hundred percent certainty that under certain conditions the tile will not be damaged under the influence of severe frost. When planning and designing surface cladding, it must also be remembered that the lower the water absorption of the tile, the higher the frost resistance indicators.
And finally, the occurrence of such a defect can be caused by errors in the installation process, i.e. (I) voids under the tile, (II) uneven adhesion of the tile and the base or porosity of the base itself due to improper application of the material, (III) permeability of the joints due to poor back sealing of the seams. Obviously, the process of determining the cause of the defect in this case is very complex, since all the materials used in the structure and the people involved in the design and installation play a fundamental role for the successful operation of the surface in the future. There are, however, two cases where the cause of the defect can be more confidently determined. The first is the use of non-frost resistant tiles in frost-prone environments because no one has asked for confirmation of these tile characteristics. This is a planning and design error for the cladding system. And the second case is when the tiles declared to be frost-resistant, in fact, based on the test results, do not meet the requirements established by the Quality Standard. In this case, responsibility falls entirely on the supplier. In other cases, it is extremely difficult to determine the cause, since too many people and materials are involved in the cladding.
Prevention
Prevention of defects lies in careful planning and design, depends on the correct choice of all materials of the cladding structure, as well as on the method of installation (we repeat once again that the risk is much less when laying with open joints) and on the thoroughness of the work itself, with regard to waterproofness surfaces and structures in general. Planning, design and the cladding itself are fundamental factors in the successful operation of the surface, especially in harsh conditions exposed to low temperatures.