Increased Crack Resistance of Rail Reinforced Concrete Sleepers for Anchor Rail Fasteners

Abstract

The study deals with the influence of the reinforcement layout in the cross-section and the fibre added to the concrete on increased crack resistance of reinforced concrete sleepers for anchor rail fasteners in the rail fastening zone. New methods of experimental research were developed. It has been experimentally established that increasing the reinforcement length and bringing the end reinforcement row as close as possible to the rail seat section can increase the sleeper crack resistance in the fastening zone (crack initiation moment) by 35%. It was also established that the addition of fibre can increase the concrete tensile strength, but practically does not increase the compressive strength, and in many cases even reduces it. The best indicators of increased crack resistance were obtained by adding basalt fibre and steel fibre with lengths of 24 mm and 6 mm, respectively, at contents of 6 kg/m³ and 26 kg/m³. The tensile strength in bending increased by 1.5 times, while the crack resistance criterion increased by 0.35, corresponding to an improvement of more than two fold. However, concrete with steel fibre undergoes electro-corrosive damage, so it is unsuitable for sleepers on electrified rail sections. As measures to increase the sleepers crack resistance with anchor rail fasteners in the fastening zone, it is proposed to extend the reinforcement with the approach of the end row of reinforcement to the rail seat section and/or introduce 24 mm long basalt fibres in the concrete.