Influence of Different European Cements on the Hydration of Cover-Zone Concrete during the Curing and Postcuring Periods

The durability of reinforced concrete structures depends, in the main, on the performance of the cover-zone concrete, which protects the steel from the external environment. This paper focuses on the use of discretized electrical property measurements to study depth-related features during both the curing and postcuring period, thereby allowing an integrated assessment of the protective properties of the cover region. In the current work, use is made of a small, multielectrode array embedded within the surface 75mm of concrete specimens. Concretes were manufactured with different European cements (CEM) and water/binder ratios representing mixes that satisfied the minimum requirements for a range of environmental exposure classes, including exposure to chlorides. Electrical resistance measurements were taken over a period in excess of 300days which showed ongoing hydration, pozzolanic reaction, and pore-structure refinement; in addition, in the postcuring period, when exposed to a cyclic chloride ponding regime, measurements could be used to study the convective zone and ionic enrichment of the surface layer.