CORROSION TESTING OF BRIDGE DECKS

When the corrosive half-cell potentials on a bridge deck exceed about 10 percent or when corrosion-caused delamination exceeds about 1 percent of the deck area, a chloride analysis generally would not be required because the chloride content is already too great. For the average depth of reinforcing steel, the quantity of chloride apparently needed to cause corrosion was statistically related to the maximum amount at the 95 percent confidence limits of 1.0 lb/ cu yd (0.59 kg/ cu m). The accuracy of chloride determinations was about equal whether the concrete was drilled or cored. Although the half-cell potential of -0.35 volts CSE is indicative of active corrosion, an equipotential contour map is the most reliable means for evaluating the corrosion activity of steel in concrete. After repair of concrete delaminations, the percentage of corrosive potentials decreased by about 50 percent. Repairing concrete delaminations does not prevent or necessarily control corrosion at other locations.