SURFACE ZONE CONCRETE: DRYING, ABSORPTION, AND MOISTURE DISTRIBUTION

A combination of gravimetric, internal relative humidity, and electrical measurements were used to study moisture changes and spatial distribution of moisture within the surface 100 mm of concrete. Specimens were subjected to a repeated drying and wetting regime. The testing program highlighted the influence of binder type, water/binder ratio, initial curing regime, and cyclic drying/wetting on surface-zone absorption and desorption characteristics. It is shown that electrical measurements taken at discrete points within the surface 100 mm can be used to estimate the zone of concrete most influenced by evaporative and wetting processes. A relationship was established between the integrated area between conductivity profiles and cumulative water uptake by the surface region. Over the 12-month test period, electrical conductivity measurements also indicated ongoing hydration and pozzolanic reactions.