Energy-Based Approach to Assess the Performance of a Granular Matrix Consisting of Recycled Rubber, Steel-Furnace Slag, and Coal Wash

Ballasted track progressively deteriorates due to ballast degradation and track deformation under dynamic loading, and this process accelerates when train speeds increase and axle loads become heavier as the railways are seeking to serve the enhanced productivity of the mining and agriculture sectors; on this basis, improving track performance is imperative. One effective solution is to incorporate energy-absorbing materials in the rail track, particularly when these materials are recycled from mining waste and recycled rubber. In this paper the performance of the track specimen with a synthetic energy absorbing layer (SEAL) (i.e., a matrix of recycled rubber crumbs with mining waste) is investigated by a series of large-scale (prototype) cubical triaxial tests. The test results indicate that the inclusion of rubber inside the SEAL matrix has a significant influence on the lateral movement, vertical deformation, ballast degradation, and energy distribution of the track specimen. To facilitate a better understanding of the energy-absorbing mechanism with the addition of rubber, an energy-based analysis has been adopted to identify the critical amount of rubber crumbs needed to efficiently distribute the accumulated energy, hence improve track performance. It is shown that adding 10% of rubber into the SEAL matrix will provide superior performance with less ballast breakage, less vibration (as reflected by the elastic energy), and comparable settlement compared to traditional track.