Introducing Wagner Meters’ Rapid RH testing system. For successful flooring projects, it is crucial to measure moisture below the surface of the concrete slab. Only the in situ relative humidity (RH) test is scientifically proven for accuracy and reliability. Recent scientific studies led to an ASTM F2170 update that allows official, documentable RH readings in just 24 hours. Given that other test methods typically require up to 72 hours, the in situ RH test is faster and more reliable.