DECAY TIME

These results confirm that the depolarization rate is dependent on the environment to which the concrete is exposed, and as a result the different zones depolarize at different rates. The atmospheric zone depolarizes at a much higher rate than the splash zone. In the atmospheric zone at 24 hours, a substantial percentage of depolarization was obtained. The 49% obtained at 24h in the splash zone indicate, however, that 24h is not sufficient and that a longer period should be allowed for depolarization. A period of 4 to 24 hours seems to be a suitable decay time period for the atmospheric zone, however for splash conditions, a period of 2 to 4 days seems more appropriate.

REFERENCES

1. European Standard (2000), " EN 12696: 2000, Cathodic Protection of Steel in Concrete", CEN, Brussels.

2. NACE (2000), "Standard RP0290-2000, Impressed Current Cathodic Protection of Reinforcing Steel in Atmospherically Exposed Concrete Structures", NACE, Houston.

3. Funahashi, M. and Bushman, J.B. (1991), " Technical Review of 100 mV polarization Shift criterion for Reinforcing Steel in Concrete", Corrosion 5, p376-386.

4. Glass, G.K., Hassanein, A.M. and Buenfeld, N.R. (1999), "Cathodic Protection Criteria for Reinforced Concrete in Marine Exposure Zones", Journal of Materials in Civil Engineering.

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