Agglomerated tiles are generally 90-95% natural stone chippings that are set in a resin-based binder in large moulds and then cut into tiles after a curing period. Agglomerated tiles should not be confused with resin backed tiles which as the name suggests have only resin on the back face (and no other faces) to resist cracking during transportation.
Due to the fact that agglomerated tiles are predominantly natural stone (marble, granite, quartz) they have similar performance characteristics to natural stone tiles. However, they do show varying degrees of moisture sensitivity and the most sensitive tiles can ’curl’ due to differential expansion. For this reason it is essential that substrates are allowed to fully dry and cure as per BS5385. Cementitious floor screeds must have a relative humidity of 75% (2% by weight). Agglomerated tiles are not recommended for use externally or within any water restraining structure.
The coefficient of thermal expansion of agglomerated tiles is generally higher than other more common tiles and as such a higher frequency of movement joints should be considered as per the recommendations within BS5385. The differential expansion of the substrate and the agglomerate tile will also increase the stresses exerted onto the tile adhesive bonding the two materials together.
When agglomerated tiles are to be used in areas of significant thermal change such as conservatories or heated floors, the tiler/specifier should make sure they have consulted with the manufacturer of the tile to confirm suitability. Approval from the manufacturer should also be sort when the agglomerated tiles are to be used in intermittently wet areas such as showers and wetrooms. Substrates to receive agglomerated tiles should be dry, flat, rigid and cohesively strong with any contamination removed. Priming with weber PR360 will depend on the type of substrate and porosity.
When selecting an adhesive for agglomerated tiles the physical properties of the tile needs to be considered. Due to the differences in thermal expansion and moisture sensitivity of agglomerated tiles, Weber would recommend that an S2 rapid classification tile adhesive is used. In the current range this would mean using weberset rapid plus combined with weber AD250 additive, or weberset pro lite rapid.
The use of an S2 solution offers superior flexibility compared to standard adhesives to cope with the differences in thermal expansion between tile and substrate, reduces the water content of the mix and thus reduces the risk of curling and also increases bond strengths. Additionally, by the nature of being rapid-setting, water is locked into the mix sooner further reducing the chances of the tiles ‘curling’. Weber have a proven track record using this solution on applications including high profile airport terminals, commercial and domestic buildings. Once cured, the tiles should be grouted with a flexible grout from Weber such as weberjoint premium or weberjoint wide flex.
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