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MAPEI Tech Talk is a blog devoted to the flooring and construction industry. It is updated on a regular basis by the social media team at MAPEI Americas, and it will feature guest bloggers occasionally as we provide you with viewpoints from across the industry.
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August 2, 2017 - 21.27
5 things to know about 'High Performance' Mortars
by MAPEI Product Support
As tiles get larger and installations get trickier, all setting materials manufacturers have developed a category of 'high performance' mortars. If you're setting tile in a freeze/thaw environment, on above-grade areas with deflection, in submerged applications, or with really large tiles, chances are good that you're being directed to one of these higher performing mortars. What are they really, and how do you know the difference between them?
Here are 5 things to know:
1.) How is High Performance Measured?  - Mortars have to do one thing very well - stick tile to the substrate.  The cement used helps to do this by interlocking mechanically (more cement = higher performance).  The polymer additives do this by adhering chemically and allowing the cement particles to flex (more polymer = higher performance).  Standards such as ANSI and ISO use different approaches to determining the bond strength, but both do so in conditions such as high temperature, freeze/thaw, and submerged conditions.
2.) Where should I use them?  The best resource for tile installers is the TCNA Handbook for Ceramic, Glass, and Stone Tile Installation.  Inside are drawings that show how to address over 250 different situations from floors over concrete to pools to exterior installations and more.  Each method has a section on "Materials" that indicates the minimum performance requirement of the mortar for that task.  Both ANSI and ISO requirements are included.
3.) How does ISO designate high performance?  - ISO standards give different mortars letters to designate how they are used.  All cement-based mortars (a mortar to which water or a liquid additive is added to a powder and blended) start out as a C1.  Higher performance mortars are designated with a C2 rating which means that the bond developed is stronger under the conditions tested.  For ISO, there is an additional concept of 'deformability' or how much the mortar can bend before it breaks.  Two levels of performance appear in ISO, S1 and S2.  The highest performance ISO mortar is, therefore, a C2S2 mortar like our Ultralite S2.  Other letters for Extended open time (E), Fast-Setting (F), Plywood (P), and Thixotropic (T) are also added if the mortar passes the test.
4.) How Does ANSI Designate Them? - ANSI takes a different approach.  Different classes of cement mortars get their own standard.  A118.1 (unmodified) and A118.4 (modified) standards have been around for years.  The 'Improved" modified mortars fall under the relatively new A118.15 standard.  Like ISO, A118.15 tests mortars under a variety of conditions that the mortar must pass.  If the mortar does not pass the minimum requirements, it is not an A118.15 mortar.  Other letters for extended open time, fast setting, and thixotropic mortars are also added.
5.) How Do I Know if it's Fake News? - By tying TCNA Handbook methods with the appropriate mortars, installers and specifiers can be comfortable that the correct mortar is being used.  Unfortunately, most manufacturers are misidentifying their mortars as A118.15 mortars when they don't pass all of the tests.  That can lead to the wrong mortar being used for a critical application and premature bond failure.  The tests aren't easy and it's much easier to change a marketing document to call out a few tests that pass instead of improving the product to make it compliant.  MAPEI has chosen not to go this route so we only state A118.15 compliance on our products that actually comply - Ultraflex 3, Ultraflex RS, Kerabond T/Keralastic, Kerabond/Keralastic, and Granirapid.  If you aren't sure (or if all of the tests aren't listed on a products' Technical Data Sheet), ask the manufacturer for all of the test results.  If they can't be provided, it's probably not a fully compliant mortar.
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> Comments: (1)
Good day , is Ker 121 and chembond 8860 part of the high performance cements ?

<em>Response -&nbsp;</em>Both of these mortars are what I would consider &#39;mid-grade&#39; mortars, they have enough polymer to achieve A118.4 (ANSI) and C2 (ISO) ratings but not the higher levels of A118.15 (ANSI high performance) or S2 (ISO deformability). &nbsp;Thanks for your question!
Alex Villalta (August 5, 2017 - 14.06)
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