Comparative Environmental and Economic Performance of Steel- and GFRP-Reinforced Concrete Bridge Decks Under Durability-Based Service Life Scenarios

Glass-Fiber-Reinforced Polymer (GFRP) bars are emerging as an alternative to steel reinforcement in concrete structures thanks to their high mechanical performance and intrinsic resistance to corrosion. Nevertheless, their actual sustainability must be verified through an assessment that considers long-term durability, life cycle environmental impacts, and economic feasibility. The replacement of steel reinforcement with GFRP in concrete bridge decks is herein evaluated through an integrated methodology. First, a comprehensive literature review examines the degradation processes observed experimentally and the associated long-term evolution of mechanical properties, providing the basis for defining realistic durability scenarios. Subsequently, a comparative Life Cycle Assessment is conducted adopting a cradle-to-grave system boundary and using Environmental Product Declarations to build the Life Cycle Inventory and perform the Impact Assessment. Normalization and weighting phases are included for a better understanding of the overall impacts of the two alternatives. In parallel, a Cost Analysis is performed consistently with the system boundaries and scenarios considered in the Life Cycle Assessment. Finally, the Envision protocol, a framework to evaluate sustainability and resilience of infrastructures, is applied to identify credits directly influenced by the adoption of GFRP reinforcement. The results show that steel reinforcement exhibits lower initial environmental impacts and remains more economical over short service life horizons. However, if the extended durability of GFRP is considered, the reduction in heavy maintenance activities allows this solution to achieve superior environmental performance and improved economic balance. The Envision-based evaluation further confirms the potential contribution of GFRP reinforcement to higher sustainability ratings in infrastructure projects.