Which method evaluates corrosion activity of reinforcing steel in concrete?

The method that evaluates the corrosion activity of reinforcing steel in concrete is the electrical or half-cell potential method. This technique is based on measuring the electrical potential difference between a reference electrode placed on the concrete surface and the embedded steel reinforcement. The resulting measurements can help indicate the likelihood of corrosion occurring, as changes in the potential can correlate to the presence and severity of corrosion.

This method is particularly valuable because it allows inspectors to assess the condition of the reinforcing steel without requiring invasive procedures that could compromise the integrity of the structure. The electrical potential is influenced by factors such as moisture levels, the presence of chlorides, and other environmental conditions that accelerate or inhibit corrosion, thereby providing insights into the structural health of the concrete bridge.

Other methods, such as magnetic particle testing, ultrasonic testing, and eddy current testing, are primarily used for nondestructive testing of materials and components to detect surface or subsurface defects rather than evaluating corrosion activity in concrete structures. These techniques, while useful for certain applications, do not provide the specific insights into corrosion processes affecting reinforcing steel that the electrical or half-cell potential method does.