Waste-Derived Materials for Concrete Railway Sleepers: A Systematic Review

Concrete railway sleepers are safety-critical precast components whose feasibility depends on the coupled requirements of prestress transfer, flexural capacity, crack control, fatigue and impact resistance, durability, and industrial manufacturability. In parallel with increasing decarbonization and circular-economy pressures, waste-derived materials have been investigated as partial replacements for clinker-intensive and virgin constituents in sleeper-grade concrete. This study presents a systematic review of English-language journal articles indexed in Scopus and Web of Science on waste-derived materials for concrete railway sleepers. The literature was interpreted through railway-specific performance requirements rather than generic concrete metrics. The evidence indicates that slag- and fly-ash-based systems, geopolymer and cementless binders, and selected dense low-clinker matrices currently represent the most mature pathways for sleeper sustainability. Recycled aggregate systems are technically feasible, particularly in railway-to-railway circularity routes, but remain highly dependent on source quality, moisture control, and shrinkage management. Rubberized systems can improve damping, impact tolerance, and crack evolution, although their structural penalties require hybridization with fibres and high-performance matrices. Overall, the field has progressed beyond exploratory substitution studies, yet it is still limited by the small number of full-scale sleeper investigations and the weak integration of structural, durability, fatigue, and life-cycle evidence. Future work should prioritize full-scale validation, manufacturing compatibility, railway-specific durability interpretation, and service-life-based sustainability assessment.