Indirect Impedance for Corrosion Detection of External Post-tensioned Tendons: 2. Multiple Steel Strands

•Indirect impedance used to detect corrosion of steel strands in extracted bridge tendons measurements sensitive to localized corrosion in field applications only if made near the corroding strands.•Experimental results supported by finite-element simulations The use of indirect impedance measurements to detect corrosion is extended to systems in which many steel strands are encased within a plastic duct. Indirect impedance measurements were applied to an extracted external tendon section from a segmentally-constructed bridge. The results, supported by numerical finite-element simulations, showed that indirect impedance measurements are sensitive to localized corrosion in field applications only if the measurements are made very near to the corroding strands.