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27 NACE INTERNATIONAL: VOL. 55, NO. 10 MATERIALS PERFORMANCE OCTOBER 2016 Electrical Testing To test the theory for application of CP, loose coke breeze was placed on a new but unused bridge deck. As shown in Figures 1 and 2, CP current can spread for a minimum radius of 25 ft (7.6 m) and adequately polar- ize the embedded reinforcing steel. This test was considered particularly severe because the loose and dry coke breeze had a specific electrical resistivity of ~200 Ω-cm. Actual Installation The Sly Park Bridge on U.S. Highway 50 is ~55 miles (88 km) east of Sacramento, California at an elevation of 4,000 ft (1,219 m) in the Sierra Nevada Mountains. The structure was scheduled for repair because ~12% of the surface area of the concrete bridge deck had spalled due to corrosion of the reinforcing steel. Composite asphalt coke breeze and asphalt concrete were placed as described above, with iron anodes being used in the coke breeze section. Currently, 98% of the steel in the 3,000- ft 2 (279 m 2 ) bridge deck is being maintained at a polarized potential more negative than –0.85 V to a saturated copper/copper sul- fate (Cu/CuSO 4 ) half cell with an impressed voltage of 2.5 V and a current flow of ~2.3 A to seven operating anodes. The current density on the reinforcing steel is estimated to be 1.5 mA/ft 2 . Using a commutated direct current ohmmeter, the gross circuit resistance between one anode and the reinforcing steel was ~1.2 Ω. In November 1973, the test installation had been in place for approximately three months and had electrically and structur- ally withstood the impact of traffic without any sign of failure. Acknowledgments This report ref lects the views of the author who is responsible for the accuracy of the data presented. The contents do not necessarily reflect the official views or poli- cies of the State of California, or the Federal Highway Administration (FHWA). This report does not constitute a standard , specification, or regulation. FIGURE 1 Distribution of potentials with current on, two anodes. FIGURE 2 Distribution of polarized potentials, two anodes. The author acknowledges the contribu- tions of the Transportation Laborator y staff, including G.H.C. Chang (principal assistant), and P.J. Jurach, E. Maggenti, and T.L. Scrimsher. Appreciation is expressed also to R.E. Hay of the FHWA and J. Fontana of the Brookhaven National Laboratory for assistance in the polymer experiment. The support and contributions of D.R. Higgins and G.A. Hood of the California Depart- ment of Transportation, Office of Struc- tures, are also acknowledged. References 1 D.L. Spellman, R.F. Stratfull, "Chlorides and Bridge Deck Deterioration," Highway Re- search Record No. 328. Continued on page 28