Possibilities and problems of in situ techniques for measuring steel corrosion rates in large reinforced concrete structures

In situ measurements of steel corrosion rate in large reinforced concrete structures face difficulties of different types. The paper discusses some of the problems connected with the determination of the true value of the polarisation resistance from (i) the time constant value associated with the corrosion process, and (ii) the use of a guard ring for confining the electrical signal to a definite reinforcement area. In (i), results corroborate the assumption of a time constant value independent of the area affected by the electrical signal, albeit with some exceptions. In (ii), it is shown the great importance of achieving a critical ratio between the current intensities that flow from the guard ring and counter-electrode.