Fibre reinforced concrete sleepers for sustainable Railway

With the increase in railway traffic and axle loads over the last few decades, traditional sleepers are experiencing more premature failure, resulting in significant maintenance costs. Indeed, recent studies have revealed that sleepers made of either timber, steel or prestressed concrete are not entirely adequate for modern railway operational conditions. While concerns about sleeper materials have long been acknowledged, replacement with composite alternatives remains limited in practice. This paper presents an overview of fibre reinforcement technology, namely macro synthetic fibres, that improve the structural reliability, life cycle cost and sustainability of conventional prestressed concrete railway sleepers. The macro synthetic fibre reinforcement adopted is high-performance polypropylene structural fibres typically used to increase toughness and ductility and eliminate durability concerns due to corrosion. Because of these encouraging benefits in the fundamental mechanical properties of concrete, extensive experimental and numerical investigations were conducted to evaluate the optimum fibre dosage and assess the full-scale structural performances compared with conventional sleepers. Indeed, the results achieved with a hybrid integration of macro synthetic fibres at 1.0% volume ratio were most beneficial in improving the residual capacity, cracking resistance and overall ductility of both the material and structural responses. Although a relatively high investment cost, the long-term financial benefits (i.e. life cycle costs) of macro synthetic fibre reinforcement in sleepers are acknowledged as the design delivers extended service life through a structurally adequate and more sustainable reinforcement system. Accordingly, the application of recycled fibre reinforcement in prestressed concrete sleepers has been proposed to improve the current design towards a sustainable railway industry.