Realkalization can be described as the equivalent of ECE for corroding steel in carbonated concrete structures. It is a shorter term treatment (days instead of weeks), and the proprietary system uses a calcium carbonate electrolyte as an aid to regenerating the alkalinity in the concrete and around the rebar. The same anode systems are used as for ECE. The treatment is most commonly applied to buildings with carbonation damage but with at least moderate cover of the reinforcing steel (greater than about 10mm.). The literature is still contradictory about the use of the calcium carbonate electrolyte to maintain alkalinity after treatment and the extent to which it migrates into the concrete. The pH of calcium carbonate is not far above the pH corrosion threshold for steel in concrete. The use of phenolphthalein indicator causes some concern as its colour change at pH 9.5 is below the corrosion threshold for steel in concrete at pH 11.