Consider two other characteristics of tile adhesives. Firstly, the ‘open time’. This is defined in the international standard, ISO 13007-1, as “the maximum interval after application at which tiles can be embedded in the applied adhesive and meet the specified tensile adhesion strength requirement.” In other words, the open time is a measure of the amount of time you have for fixing the tile in its final position on the fresh adhesive. This can be critical in painstaking installations such as floors with intricate patterns where tile positioning takes longer. Another example is installation under faster drying conditions e.g. outdoors in hot weather. It is recommended good practice to provide shading but even when this is done, the open time will be appreciably shorter than the value obtained from testing under laboratory conditions. Nevertheless, an adhesive with an extended open time, identified with the “E” classification according to the ISO 13007-2 standard, gives the installer a relatively longer working period. Examples of adhesives with extended open time are Keraflex and Adesilex P9, both of which are classified C2TE. Failure to abide by the adhesive’s open time limitation will mean weakened adhesion and the increased potential of de-bonding, even if everything looks fine on completion.
Secondly, ‘deformability’, defined in ISO 13007-1 as “the capacity of a hardened adhesive to be deformed by stresses between the tile and the fixing surface without damage to the installed surface.” The need for deformability in an adhesive increases with the supporting substrate’s propensity to move under load (e.g. deflection, vibrations), and with the tile size. Small-sized tiles fixed on stable, grounded slabs pose no problems whereas large format tiles – 800 mm and  bigger – installed with rigid adhesives on large, suspended slabs (in shopping malls, for example) face the increased likelihood of failure. A deformable adhesive, acting as the intermediate layer between the tile and the support, is able to absorb most of the displacement and minimise the transfer of stresses to the bond lines and the tile. The deformability of adhesives is tested according to ISO 13007-2 and materials which pass the test are classified either as “S1, deformable adhesive”, or “S2, highly deformable adhesive”. Examples of Mapei’s deformable adhesives are Keraflex Maxi S1, classified “C2TE S1”, and Kerabond T + Isolastic, classified “C2 S2”.
The given examples show that much of the guess-work in adhesive selection and specifications can be eliminated, first of all, by identifying the important criteria for installation and service, and then matching these with the performance characteristics in the ISO 13007 classifications.

If you would like a more comprehensive coverage of the subject,  please  contact  us at [email protected] to arrange a training programme. This can be conducted in your premises (classroom only) or in our plant (classroom and practicals).
 

Products mentioned in the article

Projects

Category icon SPORT FACILITIES

Kuala Lumpur National Aquatic Centre

Kuala Lumpur, Malaysia

Floor/wall coverings

Category icon TOURISM AND WELLNESS

Equatorial Plaza

Kuala Lumpur, Malaysia

Floor/wall coverings

Category icon TOURISM AND WELLNESS

St. Regis Kuala Lumpur

Kuala Lumpur, Malaysia

Floor/wall coverings

Login or Register to
MyMapei Area to leave a comment

Keep in touch

Subscribe to our newsletter to get Mapei news