Coastal bridge material selection framework: balancing economic and environmental aspects

Coastal structures are subjected to severe weather, which affects their service life. To protect concrete structures, special concrete binders can be used to increase the durability of the concrete. However, the service life of structures is not only the primary concern of decision makers – cost and environmental impacts also have to be considered. In this research, an integrated framework to enhance the service life of concrete structures was developed, considering both economic and environmental aspects, using genetic algorithms and multi-criteria decision making tools. A case study of a coastal bridge in Alexandria, Egypt, was used to demonstrate the framework. Alternative concrete binders with partial replacements of ordinary Portland cement by fly ash and ground granulated blast-furnace slag to improve durability and sustainability were evaluated. The proposed model uses life cycle assessment and costing methods to minimise initial costs, life cycle costs and global warming potential. The results show that optimising concrete binders can significantly extend the service life of concrete structures while reducing environmental impacts and overall costs.