What Does Calcium Chloride Vapor Emission Test Mean?
The calcium chloride vapor emission test quantifies the volume of water vapor emitting from a 1,000-square-foot area of concrete slab surface over 24 hours.
This test is directly specified by the vast majority of the flooring industry as the primary measure of moisture acceptability for floor covering/coating installation. This test was developed in order to determine whether the slab is within acceptable moisture limits.
The calcium chloride vapor emission test is also known as the Rubber Manufacturers of America (RMA) test and the moisture dome test.
Corrosionpedia Explains Calcium Chloride Vapor Emission Test
The calcium chloride vapor emission test was developed in 1950 to measure the volume of water vapor radiating from a concrete slab surface over time. Slabs with high moisture content are likely to cause damage to overlying flooring materials. The amount of moisture emission from concrete impacts the type of sealant or covering choices for the concrete floor.
The migration of water vapor through concrete slabs and walls is often the primary cause of adhesion-related failures in:
- Floor coatings
- Floor toppings
- Primary containment linings
Osmotic blistering and delamination are often the result of high moisture vapor emissions. Costs associated with these types of coating failures amount to millions of dollars annually. This test is necessary to determine whether too much moisture is present within the concrete or is migrating through the concrete.
The test takes advantage of the fact that calcium chloride absorbs moisture like a sponge. A small container of salt is weighed before and after it is exposed to the concrete slab for 60 to 72 hours. The weight difference as a percentage of the original weight of the calcium chloride used gives the moisture vapor emitted by the slab. It is usually expressed in pounds per 1,000 square feet of concrete per 24 hours. It should be noted that the environment of the air space in the building is of critical importance during the test series.
The majority of flooring material manufacturers have adopted the calcium chloride vapor emission test because it is:
- Simple to conduct
- Informative for making decisions
Obtaining meaningful results in this testing is only possible when tests are conducted in a representative interior climate. Testing in a non-acclimated environment leads to erroneous results.