Moisture Testing Prior to Installation of a Flooring Material - Timing and Simplicity is Critical

One of my main complaints in moisture testing, is that most have no idea what they are actually testing, what the results represent, and what the results DON'T represent, and how absolutely critical the timing of testing is in relation to a successful installation or a failure.

Site Testing Using ASTM F2170, F1869 and F2659

These three procedures do NOT measure moisture in the same manner and the results are non-correlative.

F2170 for example, even though it is often and FALSELY represented to measure concrete moisture, does NOT measure concrete moisture content. F2170 measures whatever water vapor (humidity) resides in any available air space. Any moisture absorbed, adsorbed or present as a liquid in concrete are NOT detectable using F2170. The standard itself does NOT claim to measure concrete moisture content, it measures humidity in the concrete.

It cannot be overstated that humidity probes have NOT been qualified nor studied for use on existing concrete. ALL the data I have read from the RH Probe suppliers is based solely and completely on the initial drying rate of concrete mix water. To use F2170 with no factual basis on ANY concrete subject to field conditions, inadvertently exposes those manufacturers who require such tests, particularly if non-compliance to this non-factual position damages others involved with or have been held accountable for moisture-related flooring failures.

I have been hammering on the various manufacturers to STOP using F2170 as a qualifier for a safe flooring installation. It is NOT a matter of if, it is a matter of WHEN a clever attorney recognizes an installer has been damaged by this requirement, resulting in an easy win for these clients, this could open the floodgates to unprecedented litigation.

F1869 measures the emittable moisture that can be absorbed with a desiccant (calcium chloride). With alkaline concrete, the alkaline components have a greater affinity for moisture and lower critical humidity threshold than the calcium chloride, which effectively retards the effectiveness of F1869. From 2002 through 2019, as cement producers began to add the alkaline CKD (cement kiln dust) into the cementing process, this has further reduced the ability of this procedure to give an accurate assessment of the moisture content of a concrete surface.

F2659 measures the moisture content of the top 0.75-1.0 inch of the concrete surface. The Tramex Concrete Meter was evaluated in field conditions using gravimetric as a baseline, proving the accuracy of this specific meter.

The changes that concrete undergoes in the field interfered with every other type of test method that had been pre-qualified along with the Tramex meter under laboratory conditions.

All of three ASTM procedures measure either water vapor (F2170 - humidity), emittable moisture (F1869 - liquid and water vapor) or (F2659 - liquid). NOTE: F1869 uses calcium chloride, a strong desiccant which absorbs moisture from liquids and vapor.

The time requirements of these three procedures are quite different; F1869 requires essentially 4 days, the F2170 requires 2 days and F2659 requires only minutes.

It is this difference, as much as any other that allows the F2659 to be used as a simple and effective quality control, ensuring the safe installation of a flooring material.

HOWEVER, Irrespective of WHAT method is used to pre-qualify or "test" a concrete surface for the purposes of installation, NONE of these methods can assure safe moisture levels at "time of installation".

ASTM Test procedures all have the caveat; results are only "accurate at time of testing". Which means ANYTHING and everything that happens post testing, like it or not, now becomes the responsibility of the flooring manufacturer and/or installer!

F2170 and F1869 cannot measure potential spikes or transient conditions in humidity and/or temperature that can occur immediately before and during a flooring installation.

The F2659 procedures on the other hand, accompanied with an infrared thermometer, digital hygrometer, measurement of ambient temperature and humidity along with a built-in dew point calculator can and WILL catch spikes in humidity, temperatures, etc., This recent example is a perfect illustration of this.

Dramatic Moisture Change on-site

David Daniels of Tramex North America was giving a demonstration last week on the the ease and rapid results that are obtainable using the Tramex Concrete Meter.

This demonstration was in a warehouse setting, where the concrete had been in place for many years. This was a polished warehouse concrete that measured 1.9% moisture content. The surface was then ground to assure an accurate reading. The results were identical at 1.9%.

As the presentation proceeded, another moisture test was conducted on the very same spot where both 1.9% readings were logged. The moisture content increased to 4.3% in only ten minutes!

This condition would otherwise be impossible to detect, much less measure using any other form of moisture testing. This is also a dramatic demonstration of why older concrete isn't necessarily "safer" for a flooring installation than newer concrete.

Older Concrete vs Newer Concrete

Several months back, I was giving a joint presentation with David Daniels (Tramex) and Larry Marvel (Tarkett) and was asked by one of the attendees why is seemed that older concrete had more problems with moisture than newer concrete.

I informed that attendee that with older concrete, over time, there can be significant accumulation of hygroscopic materials in the surface of the concrete. I stated the only effective method I found to mitigate this situation is the grind/scarify the concrete surface to remove this build-up. NOTE ADD: in minor to moderate issues, I have found Mapei and Ardex trowelable cementitious products have been effective in reducing and in some cases eliminating epoxy blistering.

Last week's demonstration David Daniels gave in that warehouse setting is VERY LIKELY an example of this build-up/accumulation of hygroscopic materials.

In the past with newer concrete, I doubt this moisture pickup would have been nearly as dramatic, and possibly not even measurable!

Newer Concrete May Now Start Behaving Like Older Concrete

With the added CKD and now Type IL cement being used in standard concrete, it is very possible, even likely that newer concrete, suffering from self-desiccation and higher alkaline surfaces, the moisture absorption of exposed concrete will be more severe and much higher in volume than what was experienced in the past...and here's the kicker: Not only are the procedures in F2170 and F1869 NOT capable of measuring or even identifying some or all of this additional moisture, in many instances, F2170 and F1869 could give a "passing" moisture result on concrete that could be effectively saturated. This is due to higher alkalinity reduces measurable humidity even if there is the same or more moisture present.

”Normal” concrete alkalinity has a stronger affinity for moisture than the calcium chloride desiccant, so F1869 might qualify a near saturated concrete as "safe" to install, even though the moisture content is at elevated levels!

This alkaline moisture remains detectable by the Tramex Concrete Meter, even as the other procedures are blind to this form of moisture.