Relative Humidity in Concrete: What does it mean?

This article discusses relative humidity (RH) in concrete from the materials science viewpoint. The study attempts to answer some common questions regarding the definition of RH in concrete, as well as determining what RH measuring devices can be used and how such measurements can be practically applied to performance issues. The authors conclude that RH is useful for quantifying the state of moisture in concrete, though it is not the equivalent of moisture content. Instead, the authors note that RH is related to moisture content and can be correlated to both shrinkage and thermal strain. The authors further state that while accurate RH measurements are still a challenge, current advances in sensor technology are rapidly improving available techniques. As for practical applications of RH measurements, the authors see several areas. These include assessing the effectiveness of curing procedures and sealers, estimating concrete floor 'dryness,' and determining diffusivity.