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Concrete Dec 2018

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Page 37 of 43

SPONSORED CONTENT 38 CONCRETE COVERED DECEMBER 2018 COATINGSPROMAG.COM Corrosion Protection Current (mA) Instant On (mV) Instant Off (mV) Depolarization (mV) Notes Static/native -458 On 725 16 hrs 228 -997 -825 -367 vs static 20 days 98 -931 -652 -238 4 hours 90 days 72 -912 -657 -293 21 hours 118 days n/a -905 -667 -209 vs static 270 days 54 -867 -664 -236 2 hours 594 days 67 -924 -679 -330 14 hours 1673 days 49 -988 -751 -237 29 hours e alkali-activated galvanic CP jackets installed on the South Florida bridge are monitored by FDOT. Monitoring parameters include corrosion potentials, system current, polarization, and calculated service life (see Figure 4). Since the jackets have been installed, the jacketed columns have met or exceeded NACE SP0290 CP criteria by polarizing the reinforcing steel more than 100 mV. e monitored alkali-activated galvanic jackets used on the Niles Channel project were installed in 2012 and have been monitored by FDOT since that time. As with the South Florida project, corrosion potentials, current, and polarization have been monitored (Figure 5). e monitored jacketed column has met or exceeded NACE's CP criteria for more than five years. In conclusion, galvanic jackets offer a durable, low-maintenance CP solution to mitigate pile corrosion w ithout the need for external power or monitoring. It is important to consider environmental exposure condi- tions to ensure that an appropriate galvanic jacket system is selected. T his is important since the performance of galvanic jacket systems w ill depend on the exposure zone where it is installed. Regardless of the exposure zone, a galvanic jacket system can be designed to meet NACE CP criteria by polarizing the reinforcing steel 100 mV or greater. To ensure the highest quality installation, galvanic jackets should be designed, inspected, and energized by a CP specialist experienced w ith concrete structures. CP References G.C. ClemeƱa, D.R. Jackson, "Evaluation of Anodes for Galvanic Cathodic Prevention of Steel Corrosion in Prestressed Concrete Piles in Marine Environments in Virginia." VTRC 00- R3. Virginia Transportation Research Council, Charlottesville, VA. 1999. W.H. Hartt, M. Rapa, "Condition Assessment of Jackets Upon Pilings for Florida Bridge Substructures." Final Report, WPI No. 0510803. Florida Department of Transportation, Tallahassee, FL. 1998. Reprinted with permission from Maritime News (Fall 2018, Figure 5: Long-term monitoring of PVC/alkali-activated galvonic cathodic protection jacket on Niles Channel Bridge in the Florida Keys. Corrosion Protection continued from p. 36

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