What does the ASTM D 4263 test procedure require for testing moisture in concrete?

The ASTM D 4263 test procedure, commonly known as the "Plastic Sheet Test," involves sealing a polyethylene sheet onto the surface of the concrete. The purpose of this test is to assess moisture emissions from the concrete slab. By covering an area with a clear polyethylene sheet, the test allows for the observation of any moisture that may accumulate on the underside of the sheet over a specified period, typically 24 to 72 hours. The formation of moisture droplets indicates that the concrete is emitting moisture, suggesting that it may not be suitable for certain types of coatings or floor coverings at that time.

This method is advantageous because it is a simple, non-destructive way to evaluate the moisture condition of concrete without requiring specialized equipment. The other choices involve methods that either do not comply with the ASTM D 4263 or pertain to different standards or procedures for measuring moisture in concrete. For example, while the calcium chloride test is a recognized method for measuring moisture vapor emission rates, it's not part of the ASTM D 4263 protocol. Thus, sealing a polyethylene sheet on the concrete reflects the specific requirements of the ASTM D 4263 procedure accurately.