Choosing adhesives for ceramic tiles may seem like a simple decision. It is, as long as it is a traditional type of tile: glazed on the front, ceramic biscuit on the back, standard size, a support surface regular and established... What can happen is that we do not find ourselves in this situation. The wide variety of tiles opens a range of possibilities when choosing an adhesive that depends on the pieces and the support you have.
The first step in selecting the specific type of glue is taking into account the porosity and size of the part. If the piece does not have a pore, the material has nowhere to anchor, so it will be necessary to use an adhesive that uses a chemical process. The size of the piece influences the weight of the tile, thus requiring a stronger bond for larger pieces.
Another point to take into account is the characteristics of the support since it is not going to be the same to place a tile on plasterboard support than to place it on concrete support. The main factor to take into account is dimensional stability. The movements, contractions and retractions of the material can influence its placement. Support with less dimensional stability, which suffers deformations, will require a more flexible grip material. Added to all this are the environmental conditions and functional requirements of the place where it is to be placed.
In the classification of adhesives, in addition to cement mortars, we will have the classification of adhesives for ceramic tiles, which are classified in the letters C, D and R.
- C is a cementitious adhesive (glue cement), a mixture of hydraulic binders and mineral fillers that must be mixed with water.
- D are dispersion adhesives, organic binders in polymer form, an aqueous dispersion, additives and mineral fillers.
- R are resins whose hardening results from a chemical reaction. It is not necessary to mix with water, but the components are mixed.
Each of these classes is sub-rated 1 or 2 based on their adherence capabilities. Thus we have the characteristic of fast setting (F), extended open time (E), which is the time that elapses between the placement of the adhesive and the placement of the tile, and sliding characteristics (T) before the bonding material hardens. For class C, a sub-classification S1 or S2 is also applied depending on the deformation capacity of the adhesive, important if we have unstable or very unstable supports.