DETERIORATION OF REINFORCED CONCRETEFOUNDATIONS DUE TO REINFORCING STEEL CORROSION INBURIED / IMMERSED SERVICE

摘要

Deterioration of atmospherically exposed reinforced concrete structures in marinernenvironments is a widely observed and documented phenomenon. Despite this experience, there is arnprevailing view in the engineering community that reinforcing steel corrosion in buried or immersedrnexposures is not of practical concern.rnThis view is based on the assumption that limited oxygen availability in buried or immersed exposuresrnresults in very low corrosion rates. This overly generalized reasoning does not fully consider the separatern& complementary anodic and cathodic reactions involved; the fact that oxygen is not required at thernanode site to support the oxidation reaction; the tendency for corrosion to be 'localized' in undergroundrnexposures, and most significantly, that anode & cathode sites may be quite distantly separated in buried /rnimmersed exposures.rnInvestigative works at Dubai Drydocks have revealed localized corrosion resulting in severe metal loss onrnburied/immersed reinforced concrete foundation structures after 20-years in service. Several examples ofrnsevere metal loss at structurally critical locations are described. Data from an extensive corrosionrnmonitoring system deployed in conjunction with the repair works also confirms macro-cell activity.