Use of a linear continuous reference electrode to monitor the chloride-induced corrosion of steel in prestressed concrete

Abstract

Failures of pre-stressed steel caused by hydrogen embrittlement as a consequence of chloride-induced corrosion are well known in the civil engineering field. In 1995, a wire-type reference electrode was proposed to monitor pre-stressed tendons corrosion potential, claiming that, once a pit occurs in any position on the steel, the potential measured by the linear reference electrode – regardless of its length – drops to values typical of active range, giving the evidence of pitting occurrence. From the practical point of view, the use of such an electrode is very appealing because of the simplicity, nevertheless, concerns on the true meaning of the potential reading arose both from theoretical point of view and because of lack of similar use in electrochemistry. Laboratory tests were performed on some linear reference electrodes simulating chloride-induced corrosion in concrete, in order to understand the meaning of the potential reading and the ability to detect the initiation of localised corrosion.