Core samples were obtained from eleven 18-year to 32-year old reinforced concrete bridge and parking structures that have been under cathodic protection for 2 to 10 years. Characterization studies were conducted on the cores to assess the effects of the sustained cathodic protection current on the anode, the anode/concrete component, and the cathode/concrete component of the cathodic protection system. Characterization techniques included (1) conventional optical petrographie techniques, (2) SEM/EDS techniques, and (3) chloride ion content measurements. The 11 structures represent 8 different CP systems.

Data are also presented on cores taken from 3 ft. x 4 ft. x 6 in. (0.94 m x 1.22 m x 152 mm) reinforced concrete slabs powered for 30 months at 10 mA/ft², 20 mA/ft², and 40 mA/ft² (111 mA/m², 222 mA/m², and 444 mA/m²) under laboratory conditions using four different CP anodes.

The investigation has provided new insights into the factors controlling the performance and longevity of the various cathodic protection systems.