For flooring and concrete professionals, ASTM F provides the standard for using relative humidity RH testing when measuring moisture content in concrete slabs. Meeting this standard provides the groundwork for limiting moisture-related flooring problems and the many liabilities and mitigation problems that can result from excess moisture. The standard provides precise guidelines for RH testing methods. While any professional must understand the exact requirements of standard F the most recent version , the following are 10 guidelines to help ensure that you have met the criteria laid out in ASTM F These requirements for the standard apply regardless of the RH test method being used. Is this acceptable or compromise the test?
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Concrete slab moisture is a major cause of concrete flooring failure. When concrete is mixed and poured, water vapor migrates from the bottom of the slab to the surface to evaporate.
This process requires time and quantifiable concrete moisture measurements to verify. ASTM F formally recognizes the use of in situ probes as a means of conducting relative humidity testing. In lay terms, the American Society for Testing and Materials recognizes that floor coverings often fail due to unsuitable concrete moisture levels beneath them.
In that case, builders did not allow the slab sufficient time for concrete moisture levels to equilibrate reach equilibrium moisture content according to relative humidity RH. Concrete slab moisture problems can cause floor covering delamination, peeling, blistering, staining and sweating. In-situ probes deepen concrete moisture measurement.
The MVER is defined as the rate of water vapor emissions from the surface of concrete and is determined with the use of a desiccant material sealed to the slab surface for a specified time period, then measured.
It has been believed that the change in the desiccant weight could be translated into a moisture ratio for the concrete beneath. In-situ concrete moisture testing places sensors, or probes, inside the slab itself. As concrete dries, moisture migrates from the bottom of the slab to the surface where it can evaporate away. Logically then, moisture levels at the bottom of a slab will read higher from those at the surface. In this way, in situ measurement provides a composite picture of overall slab moisture levels, and provides the data necessary to make business decisions regarding flooring installations.
Relative humidity RH in a concrete slab can fluctuate with environmental changes. Concrete absorbs water vapor from the air under high ambient humidity; concrete releases more water vapor when the humidity of the surrounding air is low. Surface-based test results will fluctuate, even more, under these changes in environmental conditions.
General contractors must bear in mind two interactive processes when they are looking at construction schedules: concrete slab drying, and internal changes in relative humidity. Sub-grade water vapor can permeate even well-mixed and applied slabs. Many contractors use vapor barriers directly under the slab to slow moisture permeation.
And moisture can still be an issue at grade so concrete foundations must be designed to include proper moisture drainage. Without it, even a well-dried and functioning foundation can end up with concrete slab moisture problems. In situ moisture measurement systems are evolving rapidly as a result of ATSM F and reflect the industry realities of the concrete installation business. And installers are finding results are more accurate and more dependable with RH testing.
Close Menu Home. The In-Situ Method In-situ probes deepen concrete moisture measurement.
10 Guidelines for ASTM F2170 Preparation and Testing
ASTM International is an organization that defines and sets various standards for ensuring quality and safety for different products and services. Globally, the organization has released over 12, standards. ASTM F is the standard for testing relative humidity in concrete floor slabs used by contractors all over the U. But, why is this standard so important to any contractor dealing with concrete? When there is excessive moisture in a concrete slab, it can have a negative impact on any flooring systems installed over the slab. This lack of consistency throws off moisture content measurements because moisture meters need to be calibrated for a specific set of physical characteristics to ensure accuracy. The ASTM F testing method circumvents this problem by gauging the relative humidity RH conditions deep in a concrete slab instead of trying to directly gauge the water-to-solid mass ratio.
ASTM F2170 Explained