Corrosion of reinforcing steel is an electro-chemical process, and the behaviour of the steel can be characterised by measuring its half-cell potential. The greater the potential the higher the risk that corrosion is taking place. This technique is used for assessment of the durability of reinforced concrete members where reinforcement corrosion is suspected, and to evaluate the corrosion state of the rebars after repair work and thus evaluate the efficiency and durability of repair work. The measurement can be applied regardless of the depth of concrete cover and the rebar size. Half-cell potential measurements indicates corroding rebars not only in the most external layers of reinforcement facing the reference electrode but also in greater depth.
CIMEC is equipped with Proceq Profometer 650 AI (Corrosion meter) for half-cell potential measurements. The methodology involves measuring the potential of an embedded reinforcing bar relative to a reference half-cell placed on the concrete surface. The concrete functions as an electrolyte and the risk of corrosion of the reinforcement in the immediate region of the test location can be related empirically to the measured potential difference. The procedure is firstly to locate the steel and determine the bar spacing using a cover meter. The concrete coveris removed locally over a suitable bar and an electrical connection is made to the steel for half-cell potential measurements.