Corrosion of Reinforcing Steel in Drilled Shafts with Construction Flaws

The construction process for drilled shafts sometimes introduces structural flaws such as voids or soil inclusions within the shaft. In that case, the reinforcing steel loses concrete cover and comes in contact with the surrounding soil medium, which creates a favorable environment for corrosion. Corrosion of steel inside concrete, as well as in soil media, has been investigated in the literature. However, the specific case of steel passing through different media (concrete and soil) simultaneously has received little attention. The results of an experimental program designed to investigate the effect of two different media of substantially different pH values on the rate of corrosion of steel reinforcement in sand and clay soils and with different anode-to-cathode-area ratios are presented. Preliminary results suggest that galvanic currents driven by dissimilar media could increase the corrosion rate of exposed steel by 3.3 to 5.6 times, particularly in environments with otherwise low corrosion potential.