Modelling of reinforcement corrosion - geometrical effects on macrocell corrosion

Reinforcement corrosion is still the most frequent reason for damage of concrete structures. It can be caused by carbonation or the ingress of chlorides. In cases of localized contaminations with chlorides, macrocells with very high corrosion rates can be established. Thereby the resulting macrocell current is dependent on many different boundary conditions like driving voltage, concrete resistivity and the geometrical arrangement of anode and cathode. In order to investigate macrocell corrosion, the herein presented research work was carried out by laboratory experiments and additionally by numerical analyses. First the numerical simulations were calibrated by laboratory measurements and thereafter, a numerical parameter study was carried out to increase the available database and identify the impact of changes in single parameters. As the focus is on geometrical effects, all laboratory specimens and numerical models were designed to represent practical conditions with diverse geometrical arrangements, e.g., slabs or beams with localized depassivations. In addition, parameters like concrete resistivity, driving voltage and cathode to anode surface area ratios have been varied. Thereafter, all results were used to derive cell factors for a simple macrocell current estimation. The present status of the project will be presented and discussed.