Rethinking railway sleepers: Exploring cleaner material solutions with geopolymers, acetylated wood, and recycled plastics

This study evaluates and compares the technical and environmental performance of three innovative and sus tainable railway sleeper materials: geopolymer concrete (GC), acetylated wood (AW), and recycled polymer with steel inserts (RP). The evaluation combines a technical performance assessment with a Life Cycle Assessment (LCA) based on the ReCiPe 2016 method, applied at both midpoint and endpoint levels. Key midpoint indicators include climate change, human toxicity, freshwater and terrestrial ecotoxicity, fossil and mineral resource scarcity, and land use, while endpoint indicators assess impacts on human health, ecosystem quality, and resource availability. The findings reveal clear trade-offs among the alternatives when compared to traditional concrete sleepers (CS). GC sleepers, produced with industrial by-products and reinforced with steel, achieve reductions of approximatively 10–20% in key impact categories such as global warming potential, human toxicity, and resource depletion, indicating a more balanced environmental profile. AW sleepers, although derived from renewable sources, are negatively affected by the energy-intensive acetylation process, resulting in a 35% in crease in Global Warming Potential (GWP). RP sleepers, made from recycled plastics, demonstrate the lowest overall environmental impacts, achieving up to 50% reductions in GWP and toxicity indicators. Endpoint results support these trends, with RP sleepers delivering approximately 80% lower resource depletion, around 50% reduction in ecosystem damage, and over 40% improvement in human health indicators, positioning them as the most sustainable option among those assessed. This study offers valuable insights into the environmental and technical performance of emerging sleeper materials and highlights the importance of adopting integrated, multi-criteria approaches, encompassing both midpoint and endpoint indicators, to guide material selection in line with circular economy principles and long- term sustainability goals.