Enhancing Circularity in the Construction Industry: Life Cycle Assessment of Recycled Fibers in Concrete Composites.

Nowadays, the construction sector accounts for a significant share of global energy consumption, carbon emissions, and resource depletion. To reduce its environmental impact, the entire sector must shift toward sustainable strategies, such as improving energy efficiency and using sustainable materials. In this context, fiber-reinforced concrete composites (FRCCs) made from recycled fibers are proposed as a possible solution. This research aims to evaluate the environmental impacts of sixteen formulations of reinforced concrete using different types of virgin or recycled fibers through Life Cycle Assessment. The findings showed that the environmental impacts of FRCCs depend strongly on both the fiber type and the recycling process adopted. Climate change impacts ranged from 218 to 926 kg CO2 eq per m3 of concrete composite. Compared with the conventional steel-fiber-reinforced concrete formulation, mechanically recycled fiber formulations reduced climate change impacts by 28%-61%, whereas the chemically and thermally recycled glass-fiber formulations increased them by 9% and 66%, respectively. Overall, virgin fibers and fibers recycled through thermal or chemical treatments showed higher environmental impacts across several categories due to the high energy demand and chemical inputs associated with these processes. In contrast, mechanically recycled fibers generally demonstrated lower environmental impacts, particularly for bio-based fibers. These results highlight the potential environmental advantages of mechanical recycling pathways compared to more energy-intensive recycling processes. This study contributes to the scientific literature by offering a new perspective on the use of recycled fibers in concrete composites.