tiles which pop off 1

[newbuilder]

Tall buildings move and the finishes suffer. We are having problems with tiles which delaminate after a few years service.

You guys in the US must have overcome this problem somehow - any idea.

Also the use of steel formwork makes the concrete surface so smooth that an effective bond between the tile backing (plaster) is not assured. Is it possible to use a roughened steel?

Thanks [sig][/sig]

 

[Ron]

I wouldn't recommend using a roughened steel form, as this would produce a greater potential for bond of the placed concrete to the form. There are several things you can do to affect a bond between the tile substrate and the cast-in-place concrete by providing a textured surface. You can use a light acid etch (muriatic (dilute hydrochloric) acid works well. This is easily neutralized by following with a baking soda wash. You can also create mechanical texturing by grit or sandblasting. This can be a bit messy on vertical surfaces but can be easily and effectively contained on horizontal surfaces. BlastTrac or similar devices are typically used for this on horizontal surfaces. These are self-contained grit blasting machines with limited swaths.

You didn't mention the type of bonding you are using for the tile or the type of tile. If ceramic tile on a horizontal surface, this is usually set in a thin set cementitious adhesion mortar. This requires a proper mechanical bond to the concrete substrate by appropriate surface preparation. If resilient tile are being used, this is usually bonded with a latex or asphaltic based adhesive. The same is true of ceramic tile on vertical surfaces.

Perhaps with a little more detail, I could provide a bit more guidance. I've done numerous bond failure investigations on tile and could share some of the things I've found that might be similar to your situation.

Ron [sig][/sig]

 

[newbuilder]

Thanks for your detailed reply Ron.

The situation we have involves a 40 storey reinforced concrete structure. The central core is actually built in advance of the "wings". Metal formwork is used as a rule for obvious reasons including durability and finish.

On the walls to receive tiling we apply a spatterdash mix which includes a bonding agent. Some time later a plaster is applied to the wall. Still later we come and use a cement/bonding agent mix to adhere the tiles to the wall.

Tests have shown that the tile to plaster bond is good, however the spatterdash to concrete bond is weak.

During construction we generally remove any hollow sounding plasters from the wall and replace them. Similarly with the tiles, we will replace them if approx 50% of the bonded area sounds hollow.

Although no tiles have come of in this project we have several projects where they have under similar circumstances. In the past it has been put down to poor workmanship however we are also looking at fabric strain now with a view of reviewing the suitability of tiles of such tall buildings.

Hope this is relevent.

[sig][/sig]

 

[Ron]

From your statement that failure is occurring at the spatterdash-to-concrete interface, I conclude two probable causes....(1) there is remaining form oil on the surface, curing compound, or both. These will prevent bond of the spatterdash. (2) the formed surface is too smooth for adequate mechanical bond of the spatterdash.

Mechanical roughening of the surface will correct either or both of these. Unfortunately, texturing vertical surfaces is expensive and messy.

If you do suspect there is a slight form oil residue remaining, you can wash the surface down with a stiff brush and tri-sodium phosphate (TSP, or you can pressure clean the surface with a light surfactant that will not leave a residue. You might then try the spatterdash without a bonding agent, as most bonding agents are acrylic polymers that do not mix well with petroleum residue, even if only a slight amount remains.

As with many other "improvements" in construction materials and methodology, we too often depend upon the magical powers of these to cure poor workmanship. A properly applied neat cement spatterdash is still a good surface preparation for subsequent portland cement plaster surfacings.

[sig][/sig]