This defect occurs on both floor and wall surfaces. It consists in the loss of fastening of the tile with the sub-cladding layer, that is, when tapping on some tiles, an “empty” sound is heard, in the future, complete separation of the tile from the surface may occur due to the influence of normal loads.
If we compare this description with the problem of violation and sagging of facing floors, we can find many common features. In principle, the defect of breaking and sagging of facing floors can be considered a special case of this defect, although it is characterized by a certain behavior. In this case, however, the phenomenon of tile separation is more general and can have different characteristics and be caused by a variety of reasons. Indeed, the loads, which are the main cause of the occurrence of defects in breaking and sagging of facing floors, in this case are only of a secondary nature.
First of all, it should be noted that tile failure can occur in four directions: between the tile and the base, inside the base, between the base and the supporting structure, and inside the supporting structure. By looking at the separated tile, you can easily determine where the adhesion failure occurred. Such a defect is mainly functional in nature, as it affects the integrity of the entire system. The severity of such a defect depends on the area of damage; even if at first glance a small part of the surface is affected, this may be the beginning of a destructive process, the completion of which is a matter of time.
Cause
The reason for the loss of bond between the tile and the base is, of course, insufficient adhesion of the base. There could be several reasons:
- Selecting a substrate with inappropriate characteristics in relation to the quality of the tile (for example, conventional cement-lime mortars or adhesive mortars based on organic substances in an aqueous environment with high-density tiles such as porcelain stoneware, i.e. impervious tiles). Conventional cement-lime mortars interact well with porous tiles, and adhesive solutions in an aqueous environment require the removal of a significant portion of the water to ensure normal adhesion. The reason in this case is incorrect planning and design of the surface cladding.
- Extraction of water from cement-lime mortar is porous, and therefore absorbent tiles when using mortars. In this case, the top layer of mortar in the place where the tiles came off will be loose. This can happen in cases where the tiles were not sufficiently wetted before laying, i.e. absorbs water, or if the solution is not prepared correctly. The reason lies in an error in laying the tiles.
- Layering of dust and dirt on the back side of the tiles in case of long-term storage of the tiles. Wetting the back of the tile helps remove this dust and dirt. Naturally, the reason for this is improper laying of the tiles. In this regard, it is necessary to emphasize the influence of aluminum powder, which manufacturers apply to the back side to avoid sticking of the tiles to the roller kiln supports. As a rule, this effect is very minor, since the amount of aluminum sprayed is very small and is only present on certain parts of the tile.
- Failure of fastening due to external reasons, for example, water penetration, low temperatures, and so on. In this case, an error may have occurred at the planning and design stage, but only in cases where the effects of humidity, water and low temperatures were foreseen, but not taken into account, by environmental conditions, or the choice of base for the tiles did not meet the operating conditions.
- Insufficient interaction between tile and substrate due to insufficient contact with the substrate. This may be caused by: poor positioning of the tiles, the tiles are not pressed well into the mortar; in cases where, when laying on an adhesive mortar, the tiles were laid after the open time or lifetime of the mortar had expired; when using the wrong installation method or using inappropriate tools (for example, using the wrong size notched trowel).
All of these reasons are tile laying errors. It should be noted that in these cases, the tiles that have moved away from the surface always have remnants of the base. It is clear that the tile and adhesive solution interact only in a small area.
As for the failure of adhesion within the base itself (in this case, part of the base remains on the tile, and part on the supporting surface), it is obvious that this is a defect in the internal bonding, which can be caused by an unsuccessful choice of adhesive solution (in cases where the choice does not correspond to the conditions operation, such as high humidity, low temperatures, which were not taken into account during planning and design) or improper preparation and application of the adhesive solution. It is also possible that the quality of the tile base does not meet the agreed requirements.
Poor adhesion between the substrate and the supporting structure is usually due to improper ply construction methods, such as insufficient surface cleaning, building material residues, dust and dirt, oil and any other substances that can affect adhesion. An error may also be made at the planning and design stage: for example, cement-based adhesives are applied to a gypsum support surface that has not been pre-primed.
And finally, if the adhesion failure occurs within the supporting structure itself, then the fault is caused by errors made at the planning and design stage, as well as during the laying of the tiles. To lay tiles, it is necessary to ensure a dense and stable structure.
Prevention
The precautions that should be taken at the planning and design stage in order to avoid or mitigate the occurrence of a defect are described in the article Bond failure and sagging of tiled floors , and there is no point in repeating them. However, it is necessary to emphasize the enormous importance of tile laying work in the formation of such pathology. Experience shows that high-quality work by a paver helps to eliminate mistakes made at the planning and design stage of surface cladding.