Comparative Life Cycle Assessment of Steel and GFRP Reinforced Concrete Bridge Decks

The deterioration of reinforced concrete infrastructures is primarily caused by corrosion of steel reinforcement, particularly in aggressive environments, which significantly reduces expected service life and intensifies maintenance needs. For such a reason, in the civil engineering field, Glass-fiber-reinforced polymers (GFRP) are emerging as an alternative to steel 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. Through an integrated methodology, this thesis evaluates the replacement of steel reinforcement with GFRP in bridge deck applications. First, a comprehensive literature review examines degradation mechanisms observed experimentally, such as moisture diffusion, fiber leaching, matrix plasticization, and interface debonding. Then, the long-term evolution of mechanical properties, including tensile strength, elastic modulus, interlaminar, transverse, and horizontal shear strength, and flexural strength, is analyzed along with predictive degradation models, whose results provide the basis for defining realistic durability scenarios. Subsequently, a comparative Life Cycle Assessment is conducted in accordance with ISO 14040 and ISO 14044 standards, adopting a cradle-to-grave system boundary and using Environmental Product Declarations for concrete, steel, and GFRP materials to construct the Life Cycle Inventory and perform the Impact Assessment. As recommended by the European Commission, normalization and weighting phases are included in the analysis to provide a better understanding of the overall impacts of the alternatives studied. In parallel, a Cost Analysis based on Net Present Value 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 corrosion-resistant 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 over longer time spans. The Envision-based evaluation further confirms the potential contribution of GFRP reinforcement to higher sustainability ratings in infrastructure projects.