Bruce A. Suprenant Concrete Construction, August, 1998
"In the United States, most floor covering manufacturers require concrete floors to reach a water-vapor emission rate of either 5 or 3 pounds/1,000 square feet/24 hours before workers can place the floor covering. Installers place the floor covering when the specified emission rate has been reached, as confirmed by a calcium chloride cup test. But research conducted by The Aberdeen Group shows that it's difficult to accurately estimate the drying time needed for concrete to reach a specified vapor-emission rate. Some of the findings of the research..."