Abstract: A method and apparatus for detecting and measuring localized corrosion of a metallic surface is described. An array of electrodes fabricated from the same material as the metallic surface is exposed to the same corrosion conditions as the metallic surface. The coupling current between two electrodes of the array is measured, and the electrochemical current noise originating in the electrode array is measured. The two measurements are compared, the electrochemical current noise increasing as compared to the coupling current as the degree to which corrosion is localized increases. The electrochemical current noise originating in the coupled array electrode and the associated electrochemical corrosion potential noise are produced by the natural corrosion processes.

Abstract: A surface mounting corrosion probe comprising a frame adapted for securing to a surface of a reinforced concrete structure, and a resilient pad arranged such that when the frame is secured to such a structure a front surface of the pad is pressed against the structure surface. A reference electrode is located centrally relative to the front surface of the pad so as to contact the surface of any structure against which the pad is pressed. An annular portion of the front surface of the pad which extends radially outwards from the center towards adjacent the periphery of the pad is electrically conductive, and a terminal is provided which is electrically connected to that annular portion. Corrosion monitoring instruments are connected to the terminal and the reference electrode to monitor corrosion of reinforcement beneath the surface of a structure to which the frame is secured.