COVER STORY Y SOLUTION


ices at Norcros Adhesives, looks at the creeds in time-sensitive tiling installations.


based adhesives, it did not improve the drying times required before tiling could commence.


Reductions in drying time can be achieved with the use of a gypsum-based adhesive. This eliminates the formation of ettringite, a chemical reaction which occurs between a wet cementitious adhesive and the gypsum in the screed, causing tiles to loosen and debond. Additionally, tiling can be carried out when the screed reaches 85% RH, rather than the 75% RH, required when fixing tiles in cement- based adhesive. A number of tile adhesive manufacturers are now offering a tile-to-gypsum product.


THE ADOPTION OF ONE OF THESE NEW SYSTEMS WILL ALLOW CONTRACTORS TO DERIVE ALL THE BENEFITS


OF RAPID AND EASY POURING OF AN ANHYDRITE SCREED, WITHOUT INVOLVING DELAYS ON THE JOB.


However, the latest innovation is a fast-track system which is a complete game changer in terms of the drying times required. The new preparation systems now coming on to the market make it possible to tile with a cement-based adhesive on to anhydrite screeds which have a relative humidity as high as 95%. This can normally be achieved in just seven days, at which point tiling can commence.


It can reduce the time required for the overall build-up of the floor surface by ten weeks, which clearly has a very significant impact on timescales and costs on-site.


These latest generation systems work by taking a systematic approach, comprising all the required elements – a primer, a moisture suppressant and a gritted primer to provide a ‘key’ on to which the ceramic tile adhesive can form a strong bond.


The adoption of one of these new systems will allow contractors to derive all the benefits of rapid and easy pouring of an anhydrite screed, without involving delays on the job caused by having to wait for an extended drying period.


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Norcros Pro-Gyp Base Fast Track Sealer: A Closer Look


Now Norcros Adhesives aims to speed up tiling on to green screeds with its latest system solution.


Pro Gyp-Base Fast Track Sealer greatly reduces the minimum drying times normally applicable for anhydrite (calcium sulfate) screeds. The new product comprises a three-stage preparation system for fixing ceramic and porcelain tiles on to screeded surfaces. It is sold as a kit containing all the elements necessary to achieve a successful bond, including a primer, moisture suppressant and gritted primer.


Used together, the system allows for fast-track tile installation without detracting from the overall screed strength. It also avoids the need for a special tile-to- gypsum adhesive, which is normally required for tiling on to anhydrite screeds to prevent the tiles from debonding.


Pro Gyp-Base Fast Track Sealer can be used on either heated or unheated anhydrite screeds. A 15kg kit contains everything required to prepare and seal approximately a 25sq m area. In an ambient temperature of 20oC, drying times are down to two hours for the first primer coat and 24 hours for the second primer coat. The moisture suppressant and gritted primer require a total of three hours drying time before tiling commences. Screeds need to be a minimum of seven days old and have a maximum relative humidity of 95%.


After drying, tiles may be fixed with the new Norcros Pro Gyp-Base Adhesive. This is a white cement- based, flexible, fibre-reinforced, thin bed cementitious adhesive specially formulated for fixing fully vitrified porcelain, ceramic and stone tiles to Norcros Pro Gyp-Base Fast Track Anhydrite Screed Sealer. It has a setting time of three hours at 20oC permitting early trafficking of the tiled installation. The adhesive has excellent thermal ageing properties making it suitable for use on heated floors. It is sold in a 20kg pack.


Mandy Searle, Head of Technical Services at Norcros Adhesives, said: “This new system from Norcros Adhesives is designed to tackle one of the key issues associated with the increasingly popular anhydrite screeds, namely extended drying times, which can be up to 80 days for a 60mm screed.


“It should prove a real benefit onsite for flooring contractors and tile fixers.”


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