The calcium chloride test has been in use for seventy years, and is the most misused and misunderstood test testing procedure in the flooring industry. The calcium chloride test is used to measure the Moisture Vapor Emissions Rate (MVER) of a concrete slab. Unlike the Hygrometer probe test that measures the internal relative humidity of a slab, the calcium chloride test measures the moisture movement. There are many factors that affect the outcome of a calcium chloride test. The most important is the ambient temperature and humidity. Moisture vapor flow will travel to the warm dry environment. The warmer and drier the environment, the faster the movement, and the higher the MVER. It is estimated that 80 percent of the calcium chloride tests are inaccurate.
To examine protocol for conducting these tests, we need to complete the following to the letter:
You must select a section of concrete free of any cracks or hole that will change the natural flow of the moisture vapor emissions.(Photo 1) The size of the area should be at least 20” x 20”. Note the residues on the concrete surface.
You need to keep track of the following for your records:
- Location of the tests
- Test number
- Ambient room temperature
- Ambient humidity
- Start date/End date
- Start time/End time
- Exposure time (15-minute increments)
- Start weight/Ending weight
- Weight gain
- Note any unusual occurrences or damage to kit
- Results of test
- Flooring manufacturer's moisture limits for materials to be installed.
The question has been asked if there is a correlation between the calcium chloride test and the hygrometer probe test? The answer is no. The calcium chloride test measures moisture movement and the hygrometer probe test measures internal slab relative humidity.