Which method is used to indicate moisture in the ASTM F 1869 test?

The calcium chloride test, described in ASTM F 1869, is specifically designed to measure the moisture vapor emission rate from concrete surfaces. This method involves placing a pre-weighed calcium chloride dish on the concrete surface and sealing it with a plastic covering for a specific duration. After the exposure period, the amount of moisture absorbed by the calcium chloride is weighed, providing a quantifiable measurement of moisture emissions.

This test is valuable because it helps determine whether the moisture emissions from a concrete slab are within acceptable limits for various flooring systems or coatings. Understanding moisture levels is critical in coatings applications since excessive moisture can compromise adhesion and lead to failures such as blistering or peeling.

In contrast, the other methods mentioned serve different functions or have different applications. An electronic moisture meter measures moisture content within materials, but it provides information that is not directly comparable to vapor emission rates. The plastic sheet method is used for a different assessment of moisture presence over a period but does not quantify vapor emissions in the same manner as the calcium chloride test. The capillary test assesses water absorption by concrete but is not aligned with the criteria set out under ASTM F 1869.

Thus, the calcium chloride test is the specific method utilized according to ASTM F 1869 to indicate moisture