Legislation introduced in the UK in 2003, which prevented the use and re-use of creosoted sleepers other than for industrial and professional applications, prompted a feasibility study to determine if sleepers manufactured from recycled plastic waste are a viable alternative to creosoted softwood sleepers and, possibly, sleepers of other types. This report describes the study in which recycled plastic specimens were assessed by comparing their performance with that of wooden sleepers in a series of static bending tests and creep bending tests that were based on those specified for concrete sleepers for the rail seat area. In addition, pull-out tests were conducted on the screw spikes of the type used to secure base plates to wooden sleepers. Specimens without base plates of the preferred non-rectangular geometry that were manufactured from HDPE and wood dust were stiffer and 89% stronger than softwood specimens. Specimens with base plates of the same geometry and formulation were, on average, 62% of the stiffness of softwood specimens with base plates, but they were stronger. It was concluded that the composite action between the base plate and the material of the sleeper was less for the recycled plastic specimens than for the wooden specimens. The total permanent deformation induced in the creep tests was considered to be low for the load applied. The pull-out forces measured on the screw spikes were higher for the recycled plastic specimens manufactured from HDPE and wood dust than for softwood sleepers. The study identified a formulation and geometry for a recycled plastic sleeper that should form the basis for further development as a replacement for softwood sleepers. The composite action between the material and the cast iron base plate should be increased by using a stiffer HDPE or, if this is not possible, by the addition of reinforcement to increase the stiffness of the section and the hardness of the material around the screw spikes. Further tests to determine the permanent deformation due to the lateral forces imparted by wheel loads and environmental effects are recommended.

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