Looking at Concrete Moisture Testing Differently

// Photo by juhajarvinen via Getty Images.

Addressing issues with concrete slab moisture is a never-ending topic in the flooring installation industry. You can say that Dean Craft, president and CEO of ISE Logik, is an expert on the topic. In his doctoral dissertation titled, The Fallacy of Current Industry Approach to Assessing Concrete Moisture before Flooring Installation, Craft’s research took him back nearly 50 years, to some of the industry’s earliest traces of concrete moisture-related issues. Based on his research, Craft is challenging us to look at new ways to address this hot topic.

FCI: One of the most common concrete moisture issues we hear about is adhesives not standing up to the job. Would you agree?

Craft: That is one source of moisture that can cause an issue, and this also leads into the fallacy of the flooring industry’s approach. The reason being is that when there’s an issue in the field, post-failure analysis, a flooring inspector comes out and say your flooring is peaking or whatever, the current process is to test the slab prior to installing the adhesive. If you look at that test itself, it says the results are only valid for that point in time. Then you spread a water-based adhesive. What test is there on top of that adhesive to make sure the concrete has not absorbed more moisture from the adhesive, therefore changing the moisture profile of the concrete? There isn’t one.

Then you spread, or lay down, nearly an impermeable cover. Maybe the wrong trowel size. Maybe too much adhesive was used. Maybe a dew point situation occurred because the ridges weren’t rolled correctly. Maybe another source of moisture was introduced. All the post failure analysis tells you is that under this failed floor, you have an elevated moisture result. What it does not tell you is the source of the moisture. But, universally the concrete’s blamed because the concrete is what is being tested.

FCI: How should installers go about choosing the right adhesive for a particular job?

Craft: This leads me to a very, associated discussion with ASTMs 31 91, the process substrate absorption test. That test is probably one of the more important tests, I would argue even more so than moisture testing, because it really helps the installer determine what type of adhesive to use or how much adhesive. A lot of adhesives out there will say, for porous substrate, use the large notch trowel, because of it’s going to soak in. For the non-porous substrate, maybe put it on with a paint roller, put a very thin layer, because there’s no place for that residual excess adhesive to go. If the wrong trowel is used on a non-porous substrate, then it tacks off and there’s no touch. The layer of adhesive touching the concrete may still be wet. Put the flooring in, it doesn’t cure properly, the adhesive doesn’t do what it’s supposed to do because it’s not allowed to dry. It is going to look like a quote, unquote, concrete moisture-induced flooring failure. In actuality, it was just the wrong spread rate. But this almost laser-focus to rush in and do a post-failure analysis moisture test, see that it’s high, and then basically stop the investigation saying, elevate a moisture. That’s the cause but it doesn’t tell you the source.

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FCI: Since you wrote your dissertation, have you changed your views on the way the industry looks at this problem?

Craft: The industry hasn’t changed how it’s looking at the problem. Let me give you some other things to further support my research and possibly the conclusions I’ve drawn. These are going to come straight from the test themselves. First of all, both the calcium chloride and the 2170 test clearly state that they only for the point in time. Well if anything is a point in time test, it’s a static test. Well, the movement of moisture is a dynamic issue. You can’t use a static measurement for dynamic issue. For instance, speed. Speed is distance over time, miles per hour. You have to use velocity to measure it, you can’t just use a yardstick because it doesn’t give you speed because you’re using, you’re losing the element of time. So you might be able to instantaneously measure something, but you cannot measure with the right tool.

The calcium chloride in the RH test, very clearly in the ASTM language say they’re only for the point in time, meaning they’re not predictors, but a lot of those who present from the flooring industry give the impression that if you pass the moisture test, that is a clear indicator of future flooring success. That’s not correct.

// Dean Craft, president and CEO of ISE Logik. Photo: Dean Craft.

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FCI: So if that’s not correct, what should we be doing?

Another document, ACI 302.2, which is the guiding American Concrete Institute document for slabs to receive moisture, clearly states that there is no relationship between the RH of the concrete and adhesion of resilient flooring. So think about that. If there’s no relationship of the RH of the concrete to the adhesion of resilient flooring, why are we pretesting the RH of concrete? Carry that forward. Not only is the test point in time, it’s only for the exact location of the test. Well, the RH test is about the diameter of a quarter. So the only relationship that would have to some future flooring change or future issue, is if that issue manifested just on top of that quarter. If it happens one foot away, there’s no correlation because you did not test there. And therein lies one of the biggest fallacies.

FCI: Based on your research, how do you suggest the installation industry go about addressing these common issues differently?

Well, I would actually ask, first of all, have an open mind and just step back and ask themselves, does the process actually result in the fulfillment of what the owner wants on time and within budget? Not about what a particular manufacturer wants for increased revenue or particular contractor for change order. I’m talking about from the project perspective. And then take a hard look at all these documents and resources that they’re referring to and just ask themselves, have they themselves critically read them. If you do that, I think it will be kind of shocking when you realize that by the documents themselves, do not support the message that’s currently being espoused. And so to sum it up, we evolve in our understanding. We evolve, we grow, we learn. All I’m asking is to apply that same approach to this problem. If we’ve been dealing with this problem for so long—and the problem I’m talking about is not a floor failing, I’m talking about not being able to install on time because of elevated moisture reading—if that is such a big issue and it has been for so long, maybe we’re not doing it right. And there are other ways.

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