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CATHODIC PROTECTION TABLE 3 Power supply data for Columbia Road Bridge Current (A) Voltage (V) Reference 1 (mV) Reference 2 (mV) Zone 1 2.96 Zone 2 1.75 3.23 3.33 –631 –554 –815 –894 FIGURE 5 to environmental conditions. The poten- tial recorded by Reference Electrode 1 in Zone 1 is unusually negative and consid- ered to be suspect. The potential re- corded by Reference Electrode 2 in Zone 1 is unusually positive, and is also consid- ered suspect. Potential Decay Test, Westway Boulevard Bridge Polarizations at the Westway Boule- vard Bridge were determined using the reference electrodes embedded in Zone 2, and at four test points located on the surface of the concrete along the north curb. Polarizations from the surface were determined using a portable saturated calomel reference electrode (SCE). Figure 4 shows potential decays over a 4-h test period. Potential decays recorded at embed- Potential decay at Columbia Road Bridge. Jackson Street Bridge Results z The ICCP system installed on the Jackson Street Bridge over 20 years ago is still operating properly. z The majority of the potential decay test points conducted on the driving lanes showed the steel was being polarized >100 mV, indicating complete protection from corrosion. Westway Boulevard Bridge The Westway Boulevard Bridge over Interstate Hwy. 90, Structure Number 1807749, was built in 1975 (Figure 3). ICCP was installed as part of a rehabilita- tion in July 1993. An expanded mesh MMO anode was installed on ~8,000 ft2 (740 m2 ) of deck surface in two separately controlled zones, and the system has operated continuously since installation. Although a complete delamination survey 34 MATERIALS PERFORMANCE November 2012 was not conducted, the wearing surface of the deck showed no visible sign of damage. The ICCP system on the Westway Boulevard Bridge was tested in October 2009, more than 16 years after installa- tion. The power supply was in good condition, and ICCP currents and volt- ages were taken on October 1, 2009 (Table 2). The currents shown in Table 2, equal to 2.0 and 1.6 mA/ft2 m2 (21.8 and 17.2 mA/ ) for Zones 1 and 2 respectively, are considered typical. The voltages for both zones are also considered typical. The potentials recorded by the reference elec- trodes embedded in Zone 1, however, are clearly in error. Ag/AgCl reference elec- trodes are usually embedded in the con- crete to monitor the performance of the system, but it is not uncommon for such electrodes to fail due to years of exposure ded Ag/AgCl reference electrodes are shown as dotted lines and decays re- corded at surface test points are shown as solid lines. Westway Boulevard Bridge Results According to NACE SP0290-2007, if the total potential decay is greater than 100 mV, the steel is being adequately protected from corrosion. The measured potential decays at Westway Boulevard Bridge indicate adequate protection at all of the test points. Average potential decay was 293 mV. Columbia Road Bridge The Columbia Road Bridge over In- terstate Hwy. 90, Structure Number 1810421, was built in 1977. ICCP was installed as part of a rehabilitation in September 1986. An expanded mesh MMO anode was installed on 10,600 ft2 (985 m2 ) of deck surface in two separately controlled zones, and the system has operated continuously since installation. This bridge is interesting since its south- NACE International, Vol. 51, No. 11 Testing Old Cathodic Protection on Ohio Bridge Decks