There are some things that just need to be done a certain way.
When it comes to measuring moisture in concrete – be it the slab floor in a commercial/industrial setting or the basement of a home – there's one method that supersedes all others: the ASTM F-2170. In fact, it's the standard.
But with a name that doesn't give away much, what does the ASTM F-2170 mean and why does it set the bar for measuring moisture in concrete?
In this article, we'll dig into exactly that, as well as:
Though the methodology of testing relative humidity (Rh) in concrete the ASTM F-2170 employs had been used in Europe for a few decades prior, the standard was brought to the U.S. in 1999 and published in 2001.
Born out of a need for a more accurate & reliable moisture measurement method for concrete slabs and to get the upper hand on floor failures, the ASTM F-2170 took a new approach to qualifying moisture presence.
But first, a quick step back.
Prior to the adoption of the ASTM F-2170, those testing concrete for moisture relied on several different methods. In addition to accuracy, the problem with other methods was consistency with results. Take, for instance, the calcium chloride method – what the ASTM F-2170 replaced as the standard for concrete moisture testing.
Though it produced results, calcium chloride moisture tests didn't always provide a true representation of moisture presence. The testing method involves putting an anhydrous calcium chloride crystal (a salt) onto the surface of concrete and waiting at least 72 hours. During that time, the crystal absorbs moisture and becomes heavier. At the end of the test, the crystal is weighed. Suffice it to say, a higher weight means more moisture exposure.
The trouble with this moisture measurement methodology is the results are indicative of all the moisture the crystal was exposed to, which can be more than what passed through the concrete. For instance, should a high humidity or even rainy day occur – more moisture is likely to pass through the material. Consequently, even floors that checked out with acceptable moisture levels still failed later as the test was inadequate (we'll come back to this later).
Back to the ASTM F-2170 ...
Unlike other testing methods, quantifying moisture in concrete under the ASTM F-2170 goes under the surface to take a different type of measurement. More specifically, the standard uses the in situ method (more on putting this to practice later) to perform concrete Rh tests from inside sealed holes in a slab using a hygrometer probe.
Why is the in situ relative humidity testing the preferred way?
A few reasons:
The in situ concrete Rh testing method is a relatively straightforward process.
After identifying an area of concern within a concrete slab, properly administering an in situ test to ASTM standards requires using a hygrometer, probes, and following seven steps:
A Word on In Situ Probes for Concrete Options
Reusable and disposable hygrometer probes are both used for concrete slab Rh testing. Though reusable probes are typically more expensive than their disposable counterparts, they offer two primary advantages that are hard to ignore.
From an economic standpoint, reusable probes can be used multiple times, making them more cost-effective over the long term. From a technical standpoint, reusable probes are more accurate than disposable because of the type of sensor technology they employ.
While there's never a wrong scenario to check moisture in concrete if there's a concern, there's one where the test matters the most: before installing flooring overtop concrete.
Why? That takes us back to the reason the ASTM F-2170 came to be: the need for a standardized and accurate way to gauge moisture presence in one of the hardest building materials.
Think of your favorite big-box retailer.
Chances are its floors are tile – tile that's installed overtop a giant concrete slab. If that slab is improperly tested for moisture and if it doesn't have an appropriate vapor barrier, the chance of a flooring buckling or lifting (tile tenting) somewhere is all but certain at some point. Diagnosis of the issue and the accompanying repairs are very costly, not just from a labor standpoint, but also because it may require shutting down areas of the store.
The same holds true for any part of a building with a concrete base: be it a home or other commercial property. Concrete slabs that aren't tested to ASTM standards are an expensive repair bill waiting to happen.
As the standard for gauging moisture in a concrete slab, the ASTM F-2170 brings clarity to a process that was once inconsistent and unreliable for decades.
Providing a more accurate and reliable approach to measuring moisture in concrete, the ASTM F-2170 provides a way to confidently assess the integrity of a slab floor.
Our MMS3 Flooring Kit has all the tools and equipment you'll need: