INFLUENCE OF CATHODE-TO-ANODE AREA RATIO AND SEPARATION DISTANCE ON GALVANIC CORROSION CURRENTS OF STEEL IN CONCRETE CONTAINING CHLORIDES

Corrosion of steel embedded in concrete was modelled using a 4m long beam containing a bar in seven segments, one mild steel and six stainless steel, which could be electrically connected or isolated by external switches. The concrete mix was dosed with 3% Cl to initiate corrosion. The current flowing between the mild steel and the stainless steel was monitored using a zero resistance ammeter for a range of connections to investigate the influence of the ratio of cathode/anode area and cathode-anode separation. It was found that the current increased with increasing cathode/anode area ratio but the rate of increase decreased with increasing cathode/anode ratio. The current decreased with increasing separation between the anode and cathode although the cathode elements most distant from the anode contributed a significant current.