Hardwood Floors June/July 2018

By Jason Spangler

ASTM’s Precision and Bias Study The P&B study involved testing six manufacturers’ RH products in which the laboratory took temperature and RH readings after one, two, and four hours, as well as 24, 48, and 72 hours. The study found that readings taken at 24 hours using the manufacturers’ RH sensors were essentially identical with readings taken at 72 hours. Although there was some slight variation, it fell well within the acceptable range as specified by the standard. In addition, RHmeasurements taken at 24 hours are just as accurate as those taken at 72 hours. This finding led to the ASTM committee’s decision to change the standard to 24 hours. Most accurate moisture test Based on other scientific studies, including at Lund University in Sweden during the 1990s, RH testing has been shown to be the most accurate, reliable method for assessing the true moisture condition of a concrete slab. An important reason is that it is a depth-specific test based on what we know about howmoisture gradients formwithin a concrete slab. RH

at 24 hours fall within the range specified for your finished floor products, you can move forward with your flooring installation with confidence. No more waiting 72 hours for test results.

Similarly, if your RH readings are not within the floor product specifications at the 24-hour mark, you’ll again have your answer two days sooner and can immediately put in place mitigation steps as needed for drying the concrete slab. Regardless of whether or not the readings are acceptable for your floor installation, RH testing provides this valuable information very quickly. The result? You avoid costly delays and enhance project profitability. The change to 24 hours in the F2170 standard, along with the P&B study findings, provide just one more reason why the RH test can be considered superior to other moisture testing methods. Not only does in situ RH testing generate reliable data to help ensure successful flooring project outcomes, but it does so in a fraction of the time – 24 hours instead of the 72 hours required by other tests. So now you can move ahead with ASTM-compliant decisions for your flooring project just one day after initiating an in situ RH test, much faster than with other concrete moisture tests. For access to the current version, visit astm.org/Standards/F2170. Jason Spangler has more than 20 years’ experience in sales and sales management in a spectrum of industries. He currently works with Wagner Meters as the Rapid RH® product sales manager, in Rogue River, Oregon. He can be reached at jspangler@wagnermeters.com or 800.207.2478, or visit wagnermeters.com. RH measurements taken at 40 percent depth (when the slab is drying from one side) give a reliable indication of the moisture that the finished floor will “see.”

measurements taken at 40 percent of the slab thickness when drying from one side (or 20 percent when drying from two sides) have been shown to be an excellent indicator of the amount of moisture the finished floor will “see” after installation. Surface-based tests do not give this same kind of information with any reasonable degree of reliability.

A surface test is not a reliable method for determining the true moisture condition of a concrete slab.

Accelerates project workflow With the P&B study results and the changes to the ASTM standard, you also have a scientifically valid way to accelerate your project workflow by two full days. If the RH test readings

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