Severely Corroded Reinforced Concrete with Cover Cracking

In many corroding RC structures, it is not uncommon that cover cracking, spalling and delamination have occurred. Previous research has mainly been concerned with corrosion levels leading to cover cracking along the main reinforcement, while corrosion of stirrups is often overlooked. Corrosion phenomena including stirrup corrosion were studied in an experimental investigation presented in this paper. High levels of corrosion were reached, up to 20% of the main bars and 34% of the stirrups legs. The occurrence of crack initiation, propagation and cover delamination were examined. The specimens had the shape of a beam end and were corroded with accelerated method; an imposed current was used, taking care to keep the current density as low as practically possible for the duration of the laboratory testing. The effects of this process are compared with those of natural corrosion using models from the literature. The location of the bar, middle and corner placement, the amount of transverse reinforcement and the corrosion level of longitudinal reinforcement and of transverse reinforcement were studied. The results concerning the concrete cracking in the experimental campaign are presented here. The crack patterns and widths are analysed, showing differences between specimens with or without stirrups and when stirrups are corroding or not. Finally, the effect of corrosion was simulated as the expansion of corrosion products in a finite element model, and the results, mainly the crack pattern and width, are compared with the test results. The conclusions address the importance of taking into consideration both high corrosion levels and corrosion of stirrups for the assessment of deteriorated structures.