Experimental study on mixing sleeper recycled aggregate concrete and stone ballast for eco-friendly railway applications

Railway sleepers, while made by significantly stronger concrete than in conventional construction, often end up crushed for steel recovery, leaving large amounts of concrete fragments underutilised and discarded in landfills. This study explores the feasibility of incorporating sleeper recycled aggregate concrete (SRAC) into railway ballast, offering a sustainable solution for reusing 2–5 million tonnes of discarded sleepers annually. The research involves extensive laboratory testing, including Los Angeles and Micro-Deval abrasion tests, water absorption assessments, and mechanical evaluations using point load and ballast box tests. The ballast box tests subjected samples to 100,000 loading cycles to analyze settlement, ballast breakage, stiffness, and damping ratio. Results indicate that a mixture of 25% SRAC and 75% stone ballast provides an optimal balance of performance and durability for railway lines. For this mixture, the ballast box tests showed a settlement of 9.8 mm, a ballast breakage index of 0.0661, and a stiffness of 88,096 N/mm, all within acceptable ranges for railway ballast applications. The study also highlights the significant economic and environmental benefits of adopting SRAC in ballast applications, supporting sustainable railway infrastructure development.