Eco-efficiency and sustainability of corrosion protection for large steel bridges

Selecting the optimal coating system for a steel bridge is a complex challenge that requires considerations of diverse factors such as lifetime expectancy, maintenance strategy, aesthetic requirements, sustainability and costs. In this study, Eco-efficiency is evaluated to identify the most sustainable coating systems for protecting large steel bridges from corrosion over a 100-year lifespan. Four alternatives, mainly organic, coating systems were assessed to determine the most environmental sustainable and eco-efficient option. The results show that long-lasting coating systems based on the latest zinc epoxy technologies (blatt 100) perform best in both life cycle assessment (LCA) and life cycle cost (LCC) evaluations, whereas the higher environmental impacts of duplex coating systems make these systems less attractive. A system combining a mechanically strong zinc epoxy primer, which serves as the foundation of the coating system throughout the 100 years, with a maintenance strategy involving spot repairs and renewal of topcoats every 25 years to maintain aesthetic appearance, proves to be a highly attractive alternative to the blatt 100 strategy, where all coating is replaced in a single operation halfway through the 100-year lifetime. The LCA further revealed that mineral resource use and photochemical ozone formation are the impact categories with the highest scores in person-equivalents. Therefore, future development of bridge coatings should focus on: (1) Developing waterborne maintenance coatings for in-situ application. (2) Minimizing the use of zinc without compromising durability.