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Galvanic protection of piles in a marine environment
Published in Hiroshi Yokota, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations, 2021
Galvanic protection is achieved when two dissimilar metals are connected. The metal with the higher potential for corrosion (generally a zinc-based system in concrete applications) will corrode in preference to the more noble metal. With respect to a copper-copper sulfate electrode, the potential of zinc is about -1.1V and the potential of reinforcing steel in concrete is typically in the range of -0.2 to -0.5V. As the sacrificial metal corrodes, it generates electrical current to protect the reinforcing steel. Galvanic protection systems are the most commonly utilized cathodic protection technology to protect concrete piles in the corrosive marine environment. The limitation on applied voltage by zinc-based galvanic systems allows for their use to safely protect high strength prestressing steel.x
Development of half-cell potential guidelines for assessment of corrosion probability of galvanized reinforcing steel in concrete structures
Published in Airong Chen, Xin Ruan, Dan M. Frangopol, Life-Cycle Civil Engineering: Innovation, Theory and Practice, 2021
J. Zhang, B. Baldock, Z. Lounis
The half-cell potential technique has been used since the early 1970s to locate corroding reinforcing steel bars (rebar) in concrete structures (Stratfull 1973; Van Daveer 1975). The ASTM C876 standard prescribes the half-cell potential technique for use in concrete structures, but more importantly it provides the guidelines to interpret corrosion probability based on the free corrosion potential as measured by the technique, thus making it an effective and fast way of assessing active/ passive corrosion state of the embedded rebar. The ASTM guidelines correlate a 90% probability of corrosion, i.e., Active Corrosion denoted in this paper, with a corrosion potential measured to be more negative than −350 mV vs. CSE (copper-copper sulfate electrode), and 10% probability of Active Corrosion with a corrosion potential measured more positive than −200 mV vs. CSE. The guidelines provide essentially the probabilities of Active Corrosion based on a measured corrosion potential, as well as the uncertainty for a range of corrosion potential that is between −350 mV to −200 mV vs. CSE for carbon steel.
Corrosion
Published in Mavis Sika Okyere, Mitigation of Gas Pipeline Integrity Problems, 2020
Cathodic protection by an impressed current system requires an input of negative potential between 850 and 950 mV referenced to a copper/copper sulfate electrode. The negative supply is attached to the pipeline, with the positive supply connected to an anode, buried some distance away from the pipeline. The design of the location and number of these points is dependent on the resistivity of the soil, type, and extent of the pipeline coating and location of potential electrical supplies with which to provide the electricity. Where supplies of external power are unavailable, sacrificial anodes of a more noble metal, e.g. magnesium alloy, are placed on or alongside the pipeline. The anode corrodes preferentially, providing a negative potential to the steel pipeline and helping to protect it from corrosion.
Best practices for measurement, sensing, and quantifying corrosion in existing reinforced concrete structures
Published in Sustainable and Resilient Infrastructure, 2023
The numerical magnitude technique in ASTM C 876 provides rigid interpretation criteria for evaluating the probability of corrosion from half-cell measurements using a copper-copper sulfate electrode (CSE) as: Potentials more positive than −200 mV vs CSE: 90% probability that no reinforcing steel corrosion is occurring at the time of measurementPotentials between −200 mV and −350 mV vs CSE: corrosion activity uncertainPotentials more negative than −350 mV vs CSE: 90% probability that reinforcing steel corrosion is occurring at the time of measurement
Effect of settlement cracks on corrosion initiation and rate in reinforced concrete
Published in Sustainable and Resilient Infrastructure, 2023
Matthew O’Reilly, James Lafikes, Omid Farshadfar, Pooya Grayli, Osama Al-Qassag
Corrosion initiation was defined as the first week where the macrocell corrosion rate exceeded 0.3 µm/year and the measured corrosion potential was more negative than – 0.275 V with respect to a saturated calomel electrode (–0.350 V with respect to a copper/copper sulfate electrode).