Read the Instructions BEFORE you have problems...
Failing to precisely follow the installation instructions for glass mosaic tiles can result in a catastrophic failure of the tiles or specialty coatings. Most men have an aversion to reading instructions or taking advice. Let's face it, it's a guy thing... whether it be a road map (before we get lost) or the assembly instructions for that new kid's bicycle on Christmas morning (before we curse and swear Santa and the Elves for not bringing it fully assembled!).
The Manufacturer's include Directions for a reason...
I recently reviewed an installation where the glass tiles seemed to be disintegrating right before the owner's eyes. The grout in some areas of the installation was intact & beautiful. In other areas of the installation (and coincidentally around the failing tiles), the grout appeared to be forming a white gel like coating on the surface. I immediately knew what was happening, but now had to determine WHY. Perfectly good tile was being destroyed by a shoddy installation.
The tiles in the above pictures were not subject to saturation from the fountain, and therefore the ASR had not formed (yet). Click on the image to see a larger view.
In the above image, you can clearly see the white gelatinous material forming between the tiles... almost like a white slime. Click on the image to see a larger view.Alkali Silica Reactivity (ASR)
Alkali Silica Reactivity (ASR) is nothing new. The phenomenon has been around for centuries. It is based in science & chemistry. To explain it in simple terms, when high alkali cements are exposed to silica (a basic element in glass), the cement will turn gelatinous.
This gelatinous material expands as it forms, causing the cement to crack. Certain colors of glass can actually accelerate this reaction. The finer the particles of glass within the cement, the more severe the reaction. This is a real concern where ground glass is added to cement as an aggregate (recycling) or for decorative reasons (sparkles in the glass).
The ancient Romans used to add pozzolans (volcanic ash) to their cements to help prevent this from occurring. I doubt that they knew why it worked, but it did. Today, there are chemicals & other additives that can be incorporated into the cement to prevent this from occurring. Lithium, metakaolin (produced from kaolin clay), and fly ash are all used in different applications to control and prevent ASR.
Where the wheels fell off...
The tile in this case was from a quality source... Sicis. I have used Sicis in the past & continue to use their materials. I have found them to be first rate, and I do not intend to insinuate that the product is inferior in any way. The problem here, is that the installer created a chemical reaction that could be created with ANY brand of glass tile.
As with any material, you have to follow the installation directions. The installation instructions from the material manufacturer ALWAYS takes president over any other published standard or guidelines. After all, the manufacturer knows best, as to what works with their products.
After talking to the property owner & their installer, I quickly realized that the installer had relied upon what I have previously referred to as a set of the "daddy-dids" standards. He installed the tile the way his "daddy dids it," "the way I always have." However, had he bothered to read the instructions from the tile manufacturer, he would have clearly seen a large warning in the instructions. He had added calcium to the leveling bed, in order to accelerate the hardening, and therefore allow him to set the tile quicker (after all time is money, right??).
The instructions clearly state to avoid using high alkali cements & products where the tiles will be exposed to high levels of humidity (moisture). In a fountain or swimming pool, do you think that the humidity level is high??? Like maybe 100% !!!??? His addition of calcium to the mortar and failure to install a waterproof membrane accelerated the demise of this project.
Click on the above document to open a larger version for review. Under the left column "Laying & Sealing" heading, the second paragraph clearly states "adhesives containing alkaline-earthy hydrates (e.g.,. calcium carbonate) should not be used..."
Hiring quality installers
This is another example of the old adage... "You get what you pay for." Just because someone is a tile installer, does not mean that he is a glass tile installer. Glass tile installations take a special set of skills & knowledge. The installers that I know & use, have been installing glass tiles for decades. They have a intimate knowledge of the various standards that they must adhere to (TCNA, ANSI 108.5, etc.).
The best installers know what questions to ask, create mock-ups for testing & for the client to approve, and most importantly - they read the directions from the tile manufacturer. They use the recommended setting materials, and even read the directions of those products.
Documentation is also important in glass tile installations. Keeping track of when certain areas were floated, set, & grouted ensures that the proper curing times were adhered to.
Tracking & recording the production lots of the various setting materials used, also allows for "reverse engineering" and a linear accountability in the even of any issues of this sort. And of course, tons of pictures. Digital images are free, so there is no excuse to not take thousands of them!
The only means to correct this failing installation, is to strip the entire job and start over. Where's the money savings now??
In this close up image, not only is the ASR gelatinous growth visible, but the additional calcium (lime) is bleeding out of the grout joints. Click on the image to see a larger view.Hire quality designers, craftsmen and specifiers and you'll actually save yourself a lot of heart aches and money in the long run!
Paolo Benedetti - Aquatic Artist"Creating water as art."™Aquatic Technology Pool & Spa©www.aquatictechnology.com
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