Flooring industry professionals will be thrilled with ASTM International’s just-released update to the F2170 standard for relative humidity (RH) testing in concrete floor slabs.
The update stems from an ASTM-commissioned Precision and Bias (P&B) study conducted in 2014. That study found that RH measurements take at 24 hours, a full 48 hours ahead of the previously required 72-hour mark, are essentially the same as RH readings taken later. In other words, 24 hours allows ample time for moisture equilibrium to occur within the drilled test holes in the concrete.
Benefits of the Change
Changing the ASTM F2170 standard to a 24-hour wait time is very good news for contractors and flooring professionals for several reasons:

1. It saves the project team 48 hours on the testing procedure and allows for quicker, documentable concrete moisture test results with which to make installation decisions.

2. When an RH reading taken at 24 hours is below the moisture threshold for a given flooring product, the project team can move forward immediately on the finished floor installation, essentially shaving two full days off the project timeline.

3. On the other hand, when those RH readings are higher than the maximum allowable moisture specification for a given flooring product, the team has the option to begin taking mitigation steps immediately, again effectively shortening the project timeline by two full days.

4. Regardless of what the RH readings reveal, the ASTM P&B study enables the project team to obtain valuable, reliable information much sooner than in the past.

5. Furthermore, being able to respond to the RH readings at 24 hours versus 72 hours reduces costly delays and potentially enhances project profitability.
   

Other Study Findings
An independent laboratory ran the P&B study. They tested RH probes from six manufacturers, and took temperature and RH readings at 1, 2, and 4 hours, as well as 24, 48, and 72 hours.
Readings after 24 hours were extremely close to the 72-hour readings and well within the acceptable range as specified in ASTM F2170.
This finding removed any previous doubt about how long one must wait to get the necessary moisture data for deciding to move forward on a flooring project. Reliable test results are now clearly obtainable within 24 hours.
The study also yielded another major finding: Readings of the various manufacturers’ RH probes gave very similar results. This squelched past concerns about RH sensor consistency among manufacturers.
In other words, this study showed that the sensors for the six manufacturers participating in the P&B study give basically consistent moisture readings when compared to one another. This means installers can conduct in situ RH testing in accordance with the ASTM F2170 procedures using any of the six manufacturers’ RH probes, and be confident that they are obtaining valid, reliable readings of the moisture conditions in the concrete slab. 
Accelerates Project Workflow
Thanks to the P&B study results and the changes to the ASTM standard, contractors and flooring professionals now have a scientifically valid way to accelerate their project workflow by a full 48 hours.
The P&B study findings also demonstrate that RH testing provides fully accurate and usable results significantly faster than the 72 hours required by other tests. So not only does RH testing – based on verifiable scientific evidence – deliver the best, most accurate assessment of the moisture conditions of concrete slabs, but it also provides results in a fraction of the time.
At Wagner Meters, we are excited about the study’s findings and the update to the ASTM standard, though none of this comes as a total surprise. It’s fairly common knowledge that we have long designed our Rapid RH® system to give you very close readings within the first hour, generally within ± 3-5% of the final reading at either 24 or 72 hours.
Just keep in mind that in order to obtain official readings in full compliance with the ASTM standard, you must always allow at least 24 hours. That’s the new, faster number for 100 percent confidence in the accuracy and reliability of your RH moisture testing. And it’s a number that can’t be matched by other moisture tests in concrete floor slabs.
Author: Jason Spangler 
Bio: Jason has over 20 years’ experience in sales and sales management in a spectrum of industries and has successfully launched a variety of products to the market, including the original Rapid RH® concrete moisture tests. He currently works with Wagner Meters as our Rapid RH® product sales manager. Call Wagner Meters today at (800) 585-7614 and ask for Jason, or visit www.wagnermeters.com.