Corrosion of the zinc alloy coating in galvanized reinforced concrete
- Univ. of New South Wales, Canberra (Australia)
The corrosion of galvanized reinforcement in concrete is a multi-stage process. After a generally long period to the initiation of corrosion, dissolution of the galvanized coating commences with the loss of the outer pure zinc eta phase, followed by slow dissolution of the underlying zeta and delta phases. Corrosion of the parent steel does not commence till the zinc alloy layers are completely lost from extensive areas of the bar surface. This process results in the well documented delay in the appearance of corrosion of zinc coated steel reinforcement in concrete. This paper presents the results of a metallographic examination of the dissolution of the galvanized coating and the migration of the zinc corrosion product, identified as zinc oxide, away from the coating interface and into the adjacent concrete. The zinc corrosion products appear to cause little or no disruption to the cover concrete and have been observed to fill microcracks and small voids in the matrix, resulting in an apparent densification of the cement matrix, at distances up to 0.5 mm from the bar interface.
- OSTI ID:
- 351782
- Report Number(s):
- CONF-980316--
- Country of Publication:
- United States
- Language:
- English
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