Choosing Appropriate Adhesives Is Critical For Installing Large Format Tiles
Mapei Construction Products India Pvt. Ltd.
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Over the last few years, manufacturers of ceramic tiles have extended their range of large format tiles. Apart from the 3mm and 5 mm thick 3 m x 1 m formats, they are now proposing formats that can reach sizes of up to 1.6 m x 3.2 m and thicknesses ranging from 5 mm up to 12 mm. The article discusses about installation and precautions to be taken during installation of Large format tiles.
Choosing The Right Adhesive
Choosing the right adhesive is fundamental to ensure a durable, sound bond over the years and depends on the type of substrate, the type and format (dimensions and thickness) of the tiles, the area of use and the surrounding conditions.
If we bear in mind the prescriptions of current standards, when installing this type of material, it is recommended to use high adhesion cementitious adhesives, that is, class C2 according to EN 12004 and ISO 13007. For certain types of substrates, it is more appropriate to use reactive adhesive, or class R2 according to EN 12004 and ISO 13007. Standards always prescribe the use of deformable adhesives, class S1 or S2 according to EN 12004 and ISO 13007. For medium sized formats class S1 adhesives are recommended, while for large formats it is strongly recommended to use highly deformable class S2 products. The deformability of adhesive is determined through flexural tests (the method described in EN 12004 - ISO 13007) which measures transversal deformation. A sample of adhesive is subjected to a load test as shown in diagrams 1 to 3 below. To achieve class S1, the deformability of the sample must be at least 2.5 mm and for class S2 it must be at least 5 mm.
Procedure For Installation Of Large Format Tiles
Allow all receiving concrete substrates to get completely cured. Ensure that the receiving substrate is sound and stable. Level and repair any damaged or degraded substrate with approved materials. Remove from the surface cement laitance, loose particles or contamination (e.g. form-releasing agent) that may compromise the adhesion of the subsequently applied materials.
Levelling The Walls
Levelling concrete walls and cementitious render may be levelled with the following products:
- NIVOPLAN + PLANICRETE levelling mortar for internal and external walls, applied at a thickness from 2 to 20 mm, used in combination with PLANICRETE synthetic latex rubber to improve the performance of cementitious mortar at a rate of 2 kg per bag of NIVOPLAN. Remove from the surface cement laitance, loose particles and every trace of powder or grease. Level the concrete floor substrate with screed mortar TOPCEM.
Levelling The Floor
Concrete: Concrete must be well cured. The defection in floor slabs must be less than 1/360 of the total span. Concrete substrates must be free of loose areas and surface treatments which could potentially compromise the bond.
Conventional Cementitious Screeds: The thickness of the screed must be enough to cope with the design requirement, equal to at least 4 cm in the case of unbounded screeds. The composition of the mix must be assessed according to the mechanical performance required. The flatness of the surface must be checked as described previously.
The screed must be compact and homogenous through its entire thickness and any cracks in the screed must be monolithically sealed with epoxy resin, such as EPORIP. Screeds must be cured sufficiently: the waiting time before installation is around 7-10 days per centimetre of thickness. Waiting times when installation on conventional screeds, therefore, may be particularly long Screeds made from special binders or pre-blended mortar.
Waiting times before laying large tiles may be reduced considerably by using special binders or pre-blended, normal-setting, quick-drying mortar such as TOPCEM.
TOPCEM: Screeds made using TOPCEM are characterised by their normal setting times, with similar workability characteristics to conventional screeds, short drying times and controlled shrinkage. Large tiles may be laid on these types of substrate 24 hours after installation.
Creating Flat Surfaces: As mentioned previously, the flatness of the surface is the most important characteristic of the substrate when laying Large tiles. If there are gaps under the tiles, they would represent a weak point in the finish. Irregularities in the surface, therefore, must be eliminated before laying the tiles with a suitable levelling mortar.
Floors: Levelling concrete substrates and cementitious and special binder-based screeds Levelling internal surfaces may be carried out using ULTRAPLAN ECO 20: self-levelling, ultra quick-hardening smoothing and levelling compound for internal surfaces applied at a thickness from 1 to 10 mm.
Self Leveling Smoothing Compound:
Tile Installation: Large Format tile shall be installed with Mapei’s KERAFLEX MAXI S1, a single-component improved adhesive, with properties of (i) No Vertical Slip, (ii) Extended Open Time, belonging to C2TES1 class in compliance with European Norm EN 12004 & ISO 13007-1.
Mixing Of Adhesive: Pour Liquid into clean bucket, and then pour the Powder component and mix it with a mechanical stirrer.
Laying with adhesive
1st: a scratch coat
2nd: a notch coat
3rd: coat tile/stone back
Back Buttering: The adhesive has to be applied in the same direction on the substrate and on the rear side of the tile. Use the back-buttering system on the support and the backside of the tiles in order to avoid wholes. Ensure that the adhesive has not formed a “skin”. If it has, re-notch it and place tiles with firm pressure. Observe “Open Time”.
Facades are external vertical tiled surface, higher than 3 m. Taking into strong consideration possible risk resulting from the tiles detachment and the severe service conditions due to the extreme thermal range, when tiles are fixed on facades special precautions must be adopted:
In case of tiles with a side larger than 30 cm, the back buttering technique must be prescribed to ensure the full adhesive layer. This prescription should be adopted also for smaller size; in case of tiles with a side larger than 30 cm the designer should consider the use of a mechanical anchoring safety system, in addition to the adhesive.
When high strength and high chemical resistance combined with a decorative, attractive finish are required the following Epoxy grouts may be used:
- KERAPOXY two-component, acid resistant epoxy mortar available in 26 different colours for joints at least 3 mm wide, class RG according to EN 13888.
- KERAPOXY DESIGN two-component, acid resistant decorative epoxy mortar available in 15 different colours for joints, class RG according to EN 13888.
As with any floor and wall dressing, the durability and functionality of slim porcelain is also highly dependent on precise design parameters, appropriate substrate preparation and correct installation methods using adhesives, grouting mortars and joint sealants, which have been chosen according to the type of dressing material and its area of use. It is recommended to use the right adhesives, waterproofing materials along with good joint grouts for complaint free wet / dry areas.
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