Influence of fibre reinforcement on the initiation of corrosion-induced cracks

The initiation of corrosion-induced cracks, often running parallel to the reinforcement, becomes a turning point in the service life of a reinforced concrete (RC) structure as they promote increased corrosion rates, thus accelerating the degradation process of the structure. Compared to plain concrete, fibre reinforced concrete (FRC) provides additional confinement to the reinforcement, which has been reported to delay or even prevent the appearance of mechanically induced splitting cracks. In this study, an experimental programme has been carried out to investigate the influence of fibres on the onset of corrosion-induced splitting cracks. Cylindrical lollipop specimens with a centrally positioned 816 mm bar and varying cover depths from 40 to 64 mm were subjected to accelerated corrosion. A constant current of 100 \ub5A/cm2 was impressed through the specimens and the electrical resistance between each rebar and an external copper mesh acting as cathode was monitored. Crack initiation, determined from a drop in electrical resistance, and confirmed by visual inspection, revealed that fibre reinforcement may delay corrosion-induced cracks, an effect that was more noticeable for reduced c/ 8 ratios, featuring up to 50% higher corrosion levels at crack initiation compared to plain concrete