The determination of chloride induced corrosion of rebars by electrochemical methods

Reinforced concrete structures are exposed to important durability problems under different environmental conditions. Evaluation of concrete degradation and rebar corrosion has significant importance on the service life of the structure.The aim of this research is to investigate the factors that influence the rebar corrosion, especially from the viewpoint of concrete ingredients and concrete production. Firstly, polarization technique which is widely used in the metallurgy and corrosion engineering has been applied to reinforced concrete specimens. The parameters affecting concrete quality, such as water/cement ratio and cement dosage, have been evaluated by this method.In the second stage, the effects of performance improving applications, such as incorporation of mineral admixtures and corrosion inhibitors, insulation applications with epoxy based materials, on the reinforcement corrosion process in normal and high performance concrete have been investigated under accelerated corrosive conditions.The effects of replacement ratio of fly ash which is most widely used in concrete production and blast furnace slag that is known for its durability against sea water, have been examined in detail during the third stage. Corrosion potentials of standard cured, steam cured and non-cured specimens were in the scope of this stage. Test results have been comparatively presented with respect to time under different exposure conditions.Finally, effect of concrete cover thickness on the corrosion behavior of rebars has been investigated. A relationship in gravimetric mass loss values and estimated values from polarization measurements has been established.In addition to determination of corrosion current density values of steel, indirect methods related with reinforcement corrosion have also been studied. Electrode potentials of reinforcement bars and rapid chloride permeability, chloride penetration depth, carbonation depth, water absorption, pH and compressive strength tests for concrete specimens have been carried out.The results obtained within the scope of this study are expected to assist understanding of the corrosion problems of reinforced concrete structures that are exposed to chloride contaminated environments.Keywords: Chloride induced corrosion, corrosion potential, corrosion current density, concrete quality, mineral admixture, curing method, concrete cover.