ELECTROCHEMICAL REMOVAL OF CHLORIDES FROM CONCRETE BRIDGE DECKS

Results of laboratory and on-site tests of removal of NaCl from concrete surrounding reinforcing steel in bridge decks as the result of electroendosmosis are described. Voltages of 100 or more dc impressed on reinforcing steel in concrete reduced concentration of NaCl near the bars more than 79%; bars were cathodically polarized, and the effect of the NaCl removal persisted for 3 months. The experiments involved 100 V dc at current densities up to 100 A/sq ft for approximately 24 hours. Rebars were positive in a cell comprising the NaCl containing concree, which was submerged in a solution of Ca hydroxide. Platinized Ti anodes were negative. Tests were made with and without ion exchange resin removal of the expelled NaCl. It was concluded that this technique was technically feasible, and results of core evaluations and potential tests indicated that rebars stopped corroding after the treatment.