Evaluation of Maximum and Minimum Corrosion Rate of Steel Rebars in Concrete Structures, Based on Laboratory Measurements on Drilled Cores

This paper presents a method of conducting diagnostic tests for corrosion rate in concrete structures, which has been patented by the authors. The method consists in drilling cores with embedded pieces of steel reinforcement from cylindrical structures, and arranging a three-electrode system on such cores to measure polarization with a potentiostat. The three-electrode arrangement uses a piece of steel reinforcement in concrete core as the working electrode, a stainless steel sheet placed on one of the core bases - as the counter electrode, and an electrode of constant and known potential as the reference electrode. Determining the maximum and minimum corrosion rate of a steel bar in the concrete core is the most important element of the developed method, in which changeable temperature and humidity conditions are modelled around the tested structure. Extremely adverse and highly favourable values of temperature and humidity are determined for individual tested structures. Those parameters can be monitored in a climatic chamber while measuring polarization resistance of the reinforcement. This paper also includes examples of practical application of this method in diagnostic tests conducted by the authors on responsible reinforced concrete structures