Acceleration of steel corrosion in concrete by cyclic wetting and drying: effect of drying duration and concrete quality

To investigate the influence of concrete quality and drying duration on steel corrosion rate when cyclic wetting and drying is used to accelerate corrosion propagation. To inform future similar experimental work in the area of accelerated steel corrosion in concrete. Concrete prisms (100 × 100 × 240 mm) were made using two w/b ratios (0.40 and 0.65) and three binder types. After elimination of the corrosion initiation phase using an impressed current technique, the specimens were exposed to cycles of wetting (2 days) and drying (1, 3, 5, or 7 days). Steel corrosion rate was monitored using a coulostatic technique, over a period of ca. 170 days. Both the duration of drying and concrete quality profoundly affect corrosion rate of steel in concrete in a cyclic wetting and drying regime. A general inference from the results is that with drying, the denser microstructure concretes with high resistivity exhibited resistivity corrosion control while the less dense microstructure concretes with low resistivity exhibited both cathodic and resistivity corrosion controls. In accelerated corrosion testing using cyclic wetting and drying, the combined effects of concrete quality and drying duration need to be considered in determining corrosion rate.