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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Concrete floor installers began using the calcium chloride CaCl qstm test back in the early s to conclude when a new concrete slab was fit for floor coverings. Over decades, CaCl gained industry acceptance as a practical standard.
Although builders continue to use the CaCl moisture test, post-installation moisture problems wstm redefined it as a test method worthy of scrutiny. Concrete moisture vapor migrates from the bottom of concrete slabs to their surfaces in order to evaporate.
This is how concrete dries. Generally, high ambient RH slows concrete drying as the slab absorbs moisture vapor; low ambient RH causes concrete to emit moisture vapor. Therefore, asttm natural migration process of concrete moisture drying is influenced by environment.
The Workman’s History of Calcium Chloride Testing (F) – ASTM F Information
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. In fact, moisture-plagued concrete slabs certified aatm 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. CaCl measured only the top one-half to three-quarters inch of the slab.
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.
Builders, then, made astn floor covering decisions based on errant readings. This led to continued moisture problems when that moisture eventually reached a covered concrete surface where they could no longer evaporate.
In light of such research, the American Society for Testing and Materials made two changes to moisture measurement industry standards. The CaCl moisture test is a building practice with lineage. But their truth has entered a new era and the challenges of moisture emissions-based atm are becoming increasingly clear.
Your email address will not be published. This site uses Akismet to reduce spam. Learn how your comment data is processed. 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 qstm of concrete over a hour period.
At that point, it was safe to install floor covering over a concrete substrate. Submit a Comment Cancel reply Your email address will not be published.