Because this is our Troubleshooting Reference Guide, I thought we could use a look at one of the largest growing problems in the commercial side of our business. But without giving away the cause, let me show and tell you the effects. The following photos are from a commercial (revitalization/rehabbed building) application of VCT 12-18 months after it was installed. The customer complained of the unevenness of the tile surface and the cleanability of the floor covering. But the contractor who installed the tile is concerned with one very important aspect, adhesion. What you can't see in the photos is the fact that the tile can be lifted from the concrete substrate, which is above grade, with little or no effort. Gravity is the strongest force holding down these tiles. In Photos 1 and 2, we see what appears to be adhesive ridges telegraphing up into the surface of the VCT, but is that the problem?

In Photo 2, we see the premature wear on the surface of the telegraphing ridges. What could cause this?

You Make the Call!

With a few tiles removed, we see what is beneath, a white powdery substance we all recognize when a pH test is performed (Photo 3). A very high 12-13 pH level is evident, and what's puzzling is "Where's the adhesive?" The adhesive has literally disappeared. Well, if adhesive was used, and we know some had to be, there has to be a residual trail somewhere. At this point, the amount used at the time of installation may be very hard to determine, right? But wait a minute, what about the telegraphing trowel ridges? Are they ridges from the glue that has disappeared? At this point, we ask a lot more questions, like who or what was used to level the substrate prior to the installation?

As we found out, the original concrete, an above-ground slab, was in poor shape, so a 2-3-inch layer was skimmed over it to improve the levelness. This was not a self-leveling type fix, although it should have been; in an effort to save money, an ad hoc mix of Portland, sand and pea gravel was used as a top coat to cover what was described as a pitted, spalling and irregular 30-year-old slab. The flooring contractor did not put the skimmed ad hoc on the substrate, the building owner did. But who checked for moisture and alkalinity? Hey, it's a 30-year-old slab; how much alkalinity could there be, right? Wrong! How long did the ad hoc mix cure before the tile was laid? Not long enough! The alkaline salts were formed after the tile was installed, so there was water vapor moving upward through the slab. And, if the original slab was in such poor shape, then whatever caused it should have been investigated further. Regardless of the amount of adhesive used, it could not overcome the high-alkaline environment it was asked to perform in! But Photo 4 does show, under UV illumination, that there was a proper trowel used, and the residue could be viewed, but not without the UV light source. And, the telegraphing trowel ridges were from the 2-3-inch ad hoc mix boys, not the floor covering installers. Never say never. Assume the worst-case scenario, even if your eyes tell you something different. The amount of time and money needed to fix this problem may well be three times the original cost! Again, thanks for reading and have a great day!