Moisture Sorption Behaviour of Concrete Mixtures Containing Chlorides and the Resulting Electrolytic Resistivity in Relation to the Estimated Corrosion Risk

Abstract

When using corrosion monitoring on reinforced concrete structures exposed to chloride, self-corrosion can play a decisive role in the interpretation and evaluation of the results. Only a part of the corrosion current can be measured electrochemically as element current. A significant proportion of the cathode process takes place on the measuring anode electrode itself. With decreasing water content of the concrete, the ratio of self-corrosion current to measurable element current increases. Corrosion tests on this topic are currently being carried out at the Munich University of Applied Sciences in cooperation with the Technical University of Munich. The moisture sorption isotherms determined at the beginning of the corrosion tests for the concrete mixtures investigated are presented here. Additionally, the electrolytic resistivities of the concrete mixtures in dependence on their water and chloride contents have been evaluated. In consideration of literature results, a moisture range can be evaluated that is associated with harmless corrosion processes.