Predictive approach to assessing the lifetimes of heavy-duty coating systems for steel bridges

Abstract

This paper proposes an estimation method for the lifetime of coating systems for bridges in corrosive environments described by the ISO 9223 categories. Accelerated corrosion tests were conducted to simulate ISO 11997-1 Cycle D by subjecting the specimens to cycles of salt mist exposure, condensation, and evaporation. Circular defects with diameters of 1, 3, and 5 mm were introduced to the coatings as initial deterioration to match the ASTM D610 rust patterns for 0.03 %, 0.1 %, 0.3 %, 1 %, and 3 % coverage as rusted areas of the coating. The collected data suggest a logistic growth curve model for the deterioration rate. Durability curves (R² > 0.98) were developed to estimate the lifetimes of the coatings in ISO 9223 corrosive environments. Thus, this study presents a method for predicting the remaining life until repainting is required for deteriorated sections of the coatings. These models improve maintenance planning and aid in prolonging the effective service lives of coated steel bridges.