In regions where chloride-based deicing salts are applied to bridge decks, corrosion of the interior steel reinforcement is a major problem. Vertical electrical impedance (VEI) is an effective measurement technique to quantitatively assess the cover protection on bridges against aggressive chemical penetration of reinforced concrete. In its current form, traditional vertical electrical impedance is time-consuming and destructive because a direct connection to the reinforcing steel is required to provide a ground reference. A new method using a large-area electrode (LAE) permits VEI measurement without a direct electrical connection to the steel reinforcement. The LAE creates a nondestructive, semi-direct, low impedance connection between the measurement electronics and the reinforcing steel. In this work, numerical simulations are performed on common electrode arrangements to demonstrate the effectiveness of the LAE when significant variations in concrete conductivity exist. Physical experiments of a large-area electrode are carried out in the laboratory and field to validate the numerical simulations and to provide additional comparisons with the traditional tapped steel reinforcement method. The results of this study are a set of important design considerations for VEI utilizing a LAE to connect to the underlying rebar. Using these design considerations, the large-area electrode method was validated using both an analytical and a finite-element model, laboratory experiments, and field experiments on two bridges in Utah. The validation results indicate the LAE can replace the direct connection to the reinforcing steel. As a result of this work, a multichannel VEI scanner which uses the LAE method was built which can provide VEI information for bridge engineers and managers to better rehabilitate deteriorating reinforced concrete.



College and Department

Ira A. Fulton College of Engineering and Technology; Electrical and Computer Engineering



Date Submitted


Document Type





vertical electrical impedance, corrosion, non-destructive, bridge deck, resistivity