Recycling Tire-Derived Aggregate as elastic particles under railway sleepers: Impact on track lateral resistance and durability

Abstract

The use of recycled Tire-Derived Aggregate (TDA) under railway sleepers has been demonstrated to be a sustainable and effective way to improve the durability and mechanical behaviour of ballasted train tracks. This solution enables the optimization of a track’s vertical performance, as different rubber quantities can be employed depending on track vertical requirements, while recycling a waste material abundantly available. However, before the widespread adoption of TDA, joined to previous studies focused on track vertical behaviour, it is still necessary to assess its influence on the lateral resistance of the track, given the importance of this parameter on the infrastructure’s quality and safety. Thus, the present paper focused on determining the effects on the lateral resistance of the section when employing varying quantities of rubber particles under the sleeper, along with its impact depending on the level of track degradation. For this study, laboratory tests were carried out to simulate realistic traffic conditions on full-scale sections. Results showed that TDA under sleepers could lead to higher lateral oscillations of the track due to the flexibility of the rubber particles, but resulting in similar, or even lower, permanent displacements to those in conventional ballasted tracks, as long as not excessive rubber volumes are applied. Particularly, for the study cases assessed in this article, it was seen that quantities up to around 1500–2000 cm3 (applied under half sleeper) could reduce permanent lateral movements due to dynamic efforts up to 45% in reference to traditional ballasted tracks, while increasing close to 130% the number of loads required to reach a lateral displacement of 10 mm (selected as example of failure criteria).