Vertical Electrical Impedance Scanner for Concrete Bridge Deck Assessment without Direct Rebar Attachment

Chloride-induced corrosion of steel reinforcement in concrete bridge decks is a major concern for bridge owners and managers. Bridge decks in marine areas and cold regions experience rapid and widespread steel corrosion due to the presence of elevated concentrations of salts that are either naturally present in the marine environment or deliberately applied in cold regions for safety.

Because corrosion at an early stage occurs internally where it is not visible, visual inspection alone is not adequate to evaluate the protection against chloride ingress that is offered to steel reinforcement. By the time delamination and spalling of the concrete occur, rehabilitation is costly and often involves traffic disruption to perform the necessary repairs.

NCHRP IDEA Final Report 202: Vertical Electrical Impedance Scanner for Concrete Bridge Deck Assessment without Direct Rebar Attachment examines one of the many techniques available for assessing the condition of concrete bridge decks. Remarkably, the Vertical Electrical Impedance (VEI) scanner is able to operate in conditions where other techniques fail or provide inadequate diagnostic capability. For example, the VEI scanner can successfully scan bridge decks with a variety of different overlay types and can be operated during the day or night.

The VEI scanner provides valuable data that support decision-making by bridge managers responsible for appropriately selecting among preservation, rehabilitation, and replacement options available within their bridge management programs.