Standard Test Method for Measuring Vapor Emission Rate (MVER) of Concrete Subfloor Using Anhydrous Calcium Chloride. Apparatus – the kit plus a gram. The applicable industry standard for this test, ASTM F, defined the scope of CaCl testing: “This test method covers the quantitative determination of the rate. Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Carbide.

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In light of such research, the American Society for Testing and Materials made two changes to moisture measurement industry standards. Work Item s – proposed revisions of this standard. Historical Version s – view previous versions of standard. But their truth has entered a new era and the challenges of moisture emissions-based testing are becoming increasingly clear.

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At that point, it was safe to install floor covering over a concrete substrate. The CaCl moisture test produced data based on moisture vapor emission rate MVERthe quantitative indication of how many pounds of slab moisture evaporated from square feet of concrete over a hour period.

This led to continued moisture problems when that moisture eventually reached a covered concrete surface where they could no longer evaporate. The moisture vapor emission rate only reflects the condition of the concrete floor at the time of the test. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.


The CaCl moisture test is a building practice with lineage. All concrete subfloors emit some amount of moisture in vapor form. The results obtained reflect the condition of the concrete floor surface at the time of testing and may not indicate future conditions. In fact, moisture-plagued concrete slabs certified by ASTM F protocol proved to be a patterned and persistent challenge to the concrete flooring industry — so much so that industry professionals began to investigate the scientific integrity of the CaCl moisture test.

Builders, then, made threshold floor covering decisions based on errant readings. Concrete moisture vapor migrates from the bottom of concrete slabs to their surfaces in order to evaporate.

Home to ASTM F1869

Concrete floor installers began using the calcium chloride CaCl moisture test back in the early s to conclude when a new concrete slab was fit for floor coverings. Although builders continue to use the CaCl moisture test, post-installation moisture problems eventually redefined it as a test method worthy of scrutiny.

Submit a Comment Cancel reply Your email address will not be published. Link to Active This link will always route to the current Active version of the standard.

All floor coverings are susceptible to failure from excessive moisture vapor emissions. Concrete moisture emission is a natural process driven by environmental conditions. Over decades, CaCl gained industry acceptance as a practical standard. This site uses Akismet to reduce spam.

Generally, high ambient RH slows concrete drying as the slab absorbs moisture vapor; low ambient RH causes concrete to emit moisture vapor. Your email address will not be published. The moisture vapor emitted from a concrete slab is measured in pounds.


The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. This is how concrete dries. The calcium chloride moisture test has been the industry standard for making this determination and is a practical, well-established and accepted test of dynamic moisture.

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ASTM F1869

Where the challenge became clear was in determining whether the surface emission rate determined by desiccant weight gain truly reflected the moisture conditions deeper in the slab. This measurement is the equivalent weight of water evaporating from ft 2 of concrete surface in a 24—h period. Therefore, the natural migration process of concrete moisture drying is influenced by environment.

CaCl measured only the top one-half to three-quarters inch of the slab. It 1f869 produce quantified results directly applicable to flooring manufacturer’s specifications.

It is the responsibility of the user of this standard to establish appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use. CaCl tended to underestimate the true moisture conditions at the high end of the moisture spectrum, while it tended to overestimate the moisture conditions of older slabs.