Many residential and commercial buildings have concrete floor slabs with some type of floor covering laid upon them. Most of these flooring materials and the adhesives used to attach them are sensitive to the moisture condition of the slabs. Unless care is taken to ensure that the moisture or relative humidity (RH) of the slabs are within the tolerance limits specified by the flooring and adhesive manufacturer, severe damage to the flooring material may result which can be very expensive to repair.
As a result, interest has continued to grow in the building and finishes trades to find a reliable test procedure for determining concrete RH prior to installation of the flooring material. The result of this interest has been the evolution of test methods from the original calcium chloride (CaCl) surface test to the modern in-situ probes that now feature Bluetooth reader capabilities.
Brief History of Test Method Evolution
The CaCl test was used for many years and became governed by the ASTM standard known as F1869. However, after years of use, moisture-related flooring failures were still occurring which prompted a review of F1869 resulting in the following observations according to Howard Kanare, a leading authority on concrete moisture testing.
- F1869 measured moisture in only the top ½” to 3⁄4” of the slab
- F1869 does not accurately determine the moisture vapor emission rate (MVER)
- There is no practical way to calibrate F1869 CaCl tests
- Ambient conditions can interfere with the test results
Conclusively, it was determined that high concrete moisture levels exist at greater depths than reached by the F1869 test that could cause a MVER that would negatively impact the flooring system.
In-Situ Testing Proves Its Worth
Meanwhile, laboratories in Sweden and Finland were conducting research to determine the optimum placement depth for RH test probes in order to provide an accurate reading of the RH of a concrete slab. Swedish researchers concluded that a test boring to a depth of 40% of the thickness of the slab would be acceptable for a slab drying on one side while a 20% depth would be adequate for a slab drying from both sides. The flooring industries have since accepted the in-situ testing method and it has become the primary weapon in the war against moisture damage to flooring.
ASTM created a new standard, F2170, in 2002 to provide guidance on the performance and documentation of the in-situ test results.
The Human Factor
There are now several vendors of in-situ RH testing equipment that are compliant with ASTM F2170, but with any manual data collection process, the human factor can always influence the accuracy and integrity of the resultant data. The inevitable and sobering reality is that in the case of a dispute of who was responsible for the flooring failure, documentation may be the most effective form of protection from liability.
Bluetooth to the Rescue
Fortunately, concrete RH testing system manufacturers are releasing connectivity technology that incorporates Bluetooth device connections. Bluetooth helps mitigate the occurrence of errors with systems designed for efficient information transfer from the testing unit to an online platform. An ideal concrete moisture testing system would facilitate the gathering, recording, trending, and reporting of the in-situ concrete RH test data in a secure chain of data transfer, maintaining data integrity at every step.
Wagner Meters, for example, has released a new concrete RH testing system that provides an unbroken data chain, from the in-situ probe sensor, all the way to the final PDF report, generated by the accompanying free smart device app. Concrete moisture testing systems continue to improve and evolve. Bluetooth connectivity has shown to be of great value in maintaining data integrity as well as assisting with faster, more efficient methods of concrete slab moisture testing.