Laying ceramic tiles on metal staircases with VAT ELASTIC reactive resin adhesive

Descripción sistema

In the construction of a new building intended to be a warehouse for construction materials, a galvanised steel metal staircase was clad with large-format porcelain stoneware tiles with a wood look, to give it a warmer and more aesthetic finish.

These are two flights of stairs of approximately 10 galvanised steel steps. The tiles are porcelain stoneware with <3% absorption and 150 x 25 cm format.

Reason for the intervention

To give the staircase an aesthetic and warm finish, as well as high durability and high resistance to wear and tear.

Challenges and constraints

“Laying tiles on a metal substrate with optimum adhesion, while allowing for the metal’s own deformation with changes in temperature.
“The use of large format tiles (also known as ceramic sheets) is always a challenge for the adhesive.

Molins Solution

“Thorough cleaning of the galvanised steel substrate.
“Laying the tiles with the two-component epoxy-polyurethane adhesive VAT® ELÁSTIC, a high-performance reactive resin adhesive for ceramic tiles, classified as R2T according to UNE-EN 12004, which allows laying on low-absorbent substrates such as metal with very high adhesion (> 2 N/mm2) while at the same time possessing high elasticity and deformability that allows it to withstand the movements of the metal substrate due to changes in temperature.
“Grouting of the corners and step edges with BORADA® PORCELÁNICA special cementitious mortar for joints.

Execution

“Thorough and exhaustive cleaning of the metal substrate with xylene type solvent, to ensure the removal of dirt and especially of any grease residue that would prevent the adhesive from adhering.

” VAT® ELASTIC is a two-component epoxy-polyurethane adhesive in two pre-weighed components that must be mixed together. Component B is supplied in a small container inside the component A container.
“3. For proper mixing it is necessary to pour the entire contents of the component B container on top of the component A (paste) and mix with a drill equipped with a stirrer at 500 rpm until a homogeneous mass is obtained.

“4. Whenever tiles are laid with high demands, it is necessary to use the double bonding method, i.e. spread a uniform layer of adhesive on the substrate and then comb with a notched trowel and apply combed adhesive to the entire back of the tiles.

” 5. Approximately 12 hours after the tiles have been laid, the joints between the tiles are sealed with the special cementitious mortar for ceramic joints up to 4 mm BORADA® PORCELAIN (CG2WA according to EN 13888).
“The perimeter joints and joints between steps are sealed with BETOFLEX single-component flexible polyurethane mastic so that the shrinkage-dilatation movements of the metal substrate are absorbed by the mastic and do not contribute to creating tensions that could cause the tiles to detach.

Technical note

The correct adhesion when laying ceramic tiles on low-absorbent substrates is a major challenge, which also increases if the tiles are large-format.

The new standard UNE 138000:2017- General rules for the installation of adhered ceramic tile coverings, defines the type of adhesive to be used depending on the use of the tile.
adhesion, defines the type of adhesive to be used depending on the use of the ceramic tiling, the absorption capacity and size of the tiles, and the type of substrate. On metallic substrates, it requires in all cases the use of an R1 or R2 adhesive (reactive resin adhesive according to EN 12004-1).

VAT® ELASTIC is a reactive resin adhesive classified as R2T which has the particularity of being based on mixed epoxy-polyurethane polymers, which give it special properties.

In general, adhesives based on epoxy resins provide high adhesion on metal, but are very stiff. By combining polyurethane polymers with epoxy polymers in the formulation, a certain flexibility of the adhesive can be achieved without impairing the high adhesion on metal. This flexibility allows the adhesive to absorb the shrinkage-dilatation movements of the metal helping to achieve high durability adhesion of the tiles.