Which adhesive should I use?

The second question implied by the  one in the main title could also be: Why  are there so many adhesives available? 

There are so many adhesives available  due to technical and commercial reasons.  However, from a technical point  of view, the most suitable adhesive  system should be chosen according to  the installation conditions and requirements.  Let’s start by taking a look at  how adhesives for ceramic materials  are subdivided according to Euronorm  EN 12004 and then go on to examine,  in more detail, a typical application example. 

How are tiling adhesives classified  (EN 12004)? 
1. According to the chemical nature  of their binder:  • C – cementitious adhesives  • R – resin-based adhesives  • D – ready-mixed water-based  adhesives 

2. According to their performance  characteristics:  • class 1 with adhesion strength  ≥ 0.5 N/mm² (5 Kg/cm²)  • class 2 with adhesion strength  ≥ 1 N/mm² (10 Kg/cm²)  • F = rapid-setting** 

3. Other characteristics  (not mandatory)*:  • F = rapid-setting**  • E - extended open time  • T = non-slip  • S = deformability (only for  cementitious adhesives) 


If we take the above into consideration,  an adhesive classified according  to EN 12004 standards as C2 T E S1  is cement-based (C) with improved adhesion  (2), is non-slip (T) with extended  open time (E) and is deformable (S).  These characteristics are easily recognisable,  regardless of the product’s  trade name or the information given by  the manufacturer or retailer, because  they are supplied on the Technical Data  Sheet and, often, on the packaging of  the material. 

Here are a few examples of products  from the Mapei range: Granirapid  (C2FS1), Kerabond + Isolastic  (C2ES2), Ultralite S1 (C2TES1),  Keralastic T (R2T), Ultramastic  3 (D2T), Elastorapid (C2TEFS2). 

Would we be able to identify the characteristics  and performance of these  adhesives just by reading their classification? 
What do they mean to us?

Let’s  look at an example. 

APPLICATION EXAMPLE

Let’s imagine we have to install ceramic  tiles on the facade of a building,  a system widely adopted in Italy. The  tiles to be installed are 400 x 400 mm  x 8 mm thick and will be bonded on  render. 

Which adhesive should I use?  

I could rely on the experience I have  built up over the years and choose an  adhesive I already used in the past for  similar work. Or, I could use an adhesive recommended by a trusted retailer  or by an expert who works in this  particular sector. Even though their  advice may be helpful, it is not always  based on empirical data or on a sufficiently  large number of similar examples.  In this particular case, however,  for example the Italian UNI 11493-1  regarding the installation of ceramic  materials, and with specific reference  to the EN 12004 classification system  for adhesives, would guide the choice .

It is  quite clear that the successful installation  of ceramic materials does not  depend solely on the actual adhesive  system; other factors need to be taken  into consideration (the double-buttering  method, adequate grout lines, UNI  11493 – Substrate preparation and  characteristics). But during the design  phase, or during the purchasing and  application phases, the category of the  most suitable adhesive required for that  particular type of installation may be  identified by a correct interpretation of  the documentation available regarding  adhesives. Having this knowledge reduces  the risk of indecision or choosing  the wrong product, safeguards consumers  and improves the skill level of  professionals operating in this sector.  

Marco Albelice. Mapei SpA Technical Services Department

* See EN12004 - section 4: SPECIFICATIONS  

** Note: for rapid-setting adhesives this characteristic  is mandatory where present