International correspondent, Joe Simpson writes that new gel adhesives from Kerakoll are set to revolutionise the tiling industry.

Driven by the legendary research and development (R&D) spend by market leaders Mapei, the past decade has seen many major advances in adhesive and grout formulations. Rapid-setting, ultra-flexibility, extended pot times, high initial grab, and extended workability have all been brought to the market by companies like ACT, Ardex, Bostik, Building Adhesives, CTA, Custom, Laticrete and PCI. Progressive technologies have emerged such as low-dust, fibre-reinforced, water-based epoxies, lightweight, high yield, ultra-white, air-flow as well as fix and grout.

But one recent adhesive launch really does deserve the term revolutionary. Kerakoll’s Biogel is a new type of adhesive manufactured using gel technology.  Gone are all of the different formulations for different substrates and tile types that exist with standard C2 cement-based adhesives. With Biogel adhesives there are only two choices to be made: powder-form Biogel No Limits or two-part Biogel Extreme. Both are suitable for internal and external use on any substrate, even deformable ones, and can be used to fix ceramic, stone and porcelain, as well as practically any other surfacing material.

The product is the recipient of The Tile Association’s 2018 Innovation Award in the UK.

Apart from the simplicity of choice, the range has many other advantages. The adhesives maintain the same consistency as when first mixed, even after a long period in the bucket. The mix does not shrink, so tiling contractors can make it exactly the right thickness for the job. Biogel is also soft and easy to work with.

The consistency means that Biogel wets the entire tile as well as the substrate, giving an excellent bond and superior performance. It is high-grab and non-slip, even when used on walls. And the inclusion of resins gives it a high shear strength, so it can be used on the most deformable substrates.

More importantly, this type of resin has a low environmental impact, giving Biogel No Limits a GreenBuilding Rating of 5. Biogel No Limits is available in grey or White Shock, a white so pure it claims to make other brands of white adhesives look positively grey.

Biogel is the latest development from the nine eco-friendly R&D laboratories that are part of the forward-thinking Kerakoll GreenLab. Kerakoll bills this Italian facility as: “A place dedicated to research and technological development in the field of natural construction materials”.

Improving adhesives

The challenge for Biogel’s R&D team was to address some of the technical shortfalls of traditional C2 cement-based adhesives. These tend to thicken quickly in the bucket, and so users feel they require a stiff mix to ensure that the adhesive does not shrink. As a result, the mix can by quite difficult to work with.

It also forms a film quickly and so does not wet the tile thoroughly. And, of course, performance varies from one adhesive to another, making it hard for tiling contractors to make the right choice.

Kerakoll believes it has addressed all these issues with the two Biogel formulations. These do not thicken in the bucket, remaining in the “as mixed” state for long periods. Fixers and contractors can also make the mix to the consistency they choose, knowing Biogel does not shrink. The resultant mix is also soft, and so can be worked with less effort.

This unique formulation also wets the entire tile, even after a long time. Furthermore, the company is confident in asserting that the adhesive’s performance is superior to the competition, and it works “for everything and on everything.

To achieve this, Kerakoll has opened a new frontier in research technology, by investigating how natural ingredients actually behave and then formulating an innovative adhesive that acts like a gel. The result, Biogel No Limits, is thixotropic, smooth, and light at any thickness. It also works well on walls, with no tile slippage.

Biogel No Limits stands up to stresses on the most deformable substrates thanks to the excellent shear strength of the its low-environmental-impact resins. Pure white Carrara marble from Kerakoll’s quarries is an exclusive ingredient that renders products workable, delivers what the company asserts is unmatched performance, and gives the white versions an unmistakable white colour uniformity.

Highly deformable and workable, hybrid gel adhesive bonds everything and has been tested under the most extreme working conditions. The adhesive strength is 500% superior to a class C2 (4.5 N/mm²) cement-based adhesive after 24 hours, and 10 times more deformable than a class S2 (> 50 mm) cement-based adhesive.

It is also easy to spread, being five times less viscous than a polyurethane adhesive.

Biogel has strong environmental credentials, that have been assessed using the GreenBuilding Rating; an evaluation method for measuring and improving the environmental performance of building materials. It is formulated using locally-sourced minerals meaning lower greenhouse gas emission during transportation. It contains recycled minerals, thus reducing the damage to the environment caused by extracting pure raw materials. The natural mineral content of the grey variant is 61% and the white is 64%. The recycled mineral content of the grey is 33%, rising to 61% with the white.

Kerakoll has produced PDF guides to both formulations that include application methods and a detailed performance analysis. These show a pot life for Biogel No Limits, at 23ºC, of six hours for white and eight hours for grey. Tiles can be grouted or accept foot traffic after 20 hours with white, or 24 hours with grey. Shear adhesive, for porcelain tiles, is 2.5N/mm² after 28 days, and the tensile adhesion is also 2.5N/mm² after 28 days.

Biogel Extreme is marketed as an improved reaction resin adhesive for all internal and external tiling. It similarly out-performs standard C2 adhesives in terms of bond strength, stress resistance, and spreadability. It achieves shear adhesion, after seven days, of 6.5 N/mm².

Tiling contractors are creatures of habit, hard to lure away from their favourite brands, and tried-and-trusted adhesive formulations. This is what makes the positive reaction to Kerakoll’s Biogel products so unusual and compelling.

It may not be scientific, but the tilers quizzed by the author about their experience of using Biogel have been unfailingly positive. The ease of use and spreadability were universally praised, as was the ultra-white colouration. Professional fixers also enjoyed the on-site benefits of using a product that maintained a stable consistency over a long period. They were also reassured by the exceptional wetability and coverage, which helped overcome the doubts many held about working with XXL tile formats and fully vitrified wall tiles. If this straw poll is replicated across the wider tiling community on a global scale, Kerakoll may be on to a real winner!