Electrochemical investigations on the corrosion behaviour of galvanized reinforcing steels in chloride containing mortar

摘要

Corrosion of galvanized steel in chloride containing mortar is different from the corrosion of reinforcement made of carbon steel. This is based on the corrosion behavior of galvanized steel in chloride containing mortar. To describe the influence of a chloride containing zinc-hydroxide layer at the phase boundary against a zinc-hydroxide layer in chloride free mortar, different electrochemical measurements were made. The anodic and cathodic partial reaction were investigated by galvanostatic pulse measurements and potentiodynamic measurements. Especially the galvanostatic pulse measurements can describe the influence of the chloride content by the polarization resistance with pt = 20 sec. (polarization time). Additionally, corrosion current measurements were performed, coupled with potential measurements, between galvanized steel in chloride containing and chloride free concrete. Normally, the potential measurements are an indicator to localize the anodic and cathodic parts of a macro system In this case the results show that there is no formation of a significant macro element cell between chloride containing and chloride free mortar. After 1500 h of potential and current measurement the results show a more positive corrosion potential with increasing chloride content. The results of the potential/current curves show a significant different free corrosion current depending on the chloride content, the free corrosion current increase with increasing chloride contents; reasons for this behavior are discussed.