Performance of rubber tire-confined capping layer under cyclic loading for railroad conditions

The need for long-term performance of rail infrastructure has now become imperative because heavy-haul railways are expected to withstand higher speeds and heavier axle loads, especially for enhanced productivity in mining and agriculture sectors. However, the degradation of ballast particles and associated track deformation impose a significant impact on the cost of maintenance. Although various existing techniques can be used to reduce the extent and frequency of maintenance without removing the superstructure, this study elucidates a novel method of confining the upper subballast stratum (i.e., capping) with energy-absorbing rubber tire cells to provide increased stability and resiliency to the track substructure. The results of this study verify that a capping layer confined with recycled rubber tire cells can actively reduce ballast degradation and particle movement within the track substructure. A favorable reduction in track settlement and lateral spreading of particles is also attained when broadly-graded finer gravels are selected to form a compacted capping layer just beneath the ballast layer.