Abstract
Arc-sprayed zinc coatings are being used as anodes in active cathodic protection systems for steel reinforced concrete bridges of historical and economic significance on the Oregon coast. Research was recently begun to determine the service life of the zinc coatings, the effect of operating and environmental variables on coating bond strength, and the corrosion performance of metals typically found in service equipment for cathodic protection systems and other utilities. Mass loss measurements are in progress at seven bridges and eight coastal areas to determine the effects of microclimate on corrosion performance. Microclimate variables include sheltering, orientation, and the chemistry and meteorology of local environments. An atmospheric corrosion model, based on modifications of oxidation rate laws, is presented for interpreting corrosion data and the contributions of film growth and dissolution to corrosion losses. The model leads to a universal curve for atmospheric corrosion data and offers physically meaningful parameters that may prove more useful for interpreting and extrapolating corrosion data than the bilogarithmic model.
