Performing a Calcium Chloride Vapor Emission Test

The calcium chloride vapor emission test is one of the two most well-known tests which measures the amount of moisture in a concrete slab. This was developed over half a century ago to quantify the moisture vapor emission rate (MVER) in a slab and is the standard test specified by the vast majority of flooring contractors in the United States.

The test result is expressed in pounds (the equivalent weight of water) per 1,000 square feet of concrete per 24 hours. It requires the use of a gram-weight scale with a gradation of 1/10th (0.1) gram. Before and after exposing the calcium chloride test container to the concrete slab, it should be weighed so that the difference can be calculated afterwards.

Take note that the calcium chloride test is very sensitive (and accurate when done properly). So, it is ideal to carefully weigh the container prior to and directly after exposing it to the same scale. Also, certain factors such as the use of different scales and extended time between weighing can offset the test result. Never do the test unless the building environment is representative of the actual working climate so that the test will be significant to the entire flooring procedure.

Calcium Chloride Test: What to Keep in Mind

If you are to perform this test on your own, there are certain steps you need to take to ensure that the results are accurate.

  • Preparing – Before the test, make sure that you have all the necessary tools you need such as a quality gram scale, cleaning materials for the floor, and the proper test kit. Also, prior to the test, ensure that the temperature of the room is at least between 65°F and 85°F with a relative humidity of between 40% and 60% for at least 48 hours (2 days).
  • Cleaning – Clean the test site. Remove debris and adhesive residue through shot-blasting or wire-brushing. Never use cleaning solutions. Choose a spot free of cracks or damages and is not directly hit by the sun. For the first 1,000 square feet, prepare 3 tests and an additional test for the succeeding 1,000 square feet.
  • Weighing – Set the entire tape-sealed dish on the gram scale and take note of the weight, including the date and the time. Do the same thing after the test. Make sure that the same gram scale will be used for weighing throughout the entire process.

Follow the exact procedures in your test kit, and make sure that the test will remain undisturbed for 60 to 70 hours. Test several areas as much as possible so that you can have a clearer picture of the moisture emission levels of your concrete slab. The test is pretty easy, but if you really want to make sure that the test is done properly, our team at Prepco Flooring, LLC is always at your beck and call.

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