Over the past 20+ years, we have learned a great deal about how galvanic anodes perform, age and protect steel in reinforced concrete over time. Long-term monitoring of galvanic anodes installed in reinforced concrete structures has provided the data required to better understand long-term anode performance. Variables like surface to mass ratio of the zinc core, the zinc core activation method and the environmental exposure conditions play a key role in the overall performance of embedded galvanic anodes. Factors such as the level of chloride contamination, moisture and temperature are also taken into account for the effects they play on the overall design of the system. The study of this data has identified an aging pattern which follows an exponential decrease in current output similar to a half-life principle where current is halved at constant periods of time. From this data, a predictive model which includes an aging-factor can be determined for any galvanic anode. In this presentation, David will explain how these factors govern the service life of zinc based cathodic protection systems and how we can achieve accurate service life designs.
1. Understand the different variables that effect performance of zinc anode systems
2. Explain the aging factor of galvanic anodes
3. Demonstrate the aging factor principle and how that effects the design process
4. Explain how high temperatures play a key role in the overall service life of galvanic anodes