Use of recycled rubber inclusions with granular waste for enhanced track performance

Abstract

The application of recycling waste materials such as coal wash (CW), steel furnace slag (SFS), and recycled tyre products in transport infrastructure developments is an efficient way of minimising waste accumulation in stockpiles. Apart from significant economic and environmental benefits, it helps to improve the stability and longevity of infrastructure foundations. This paper presents two of the recent novel studies on (i) a synthetic energy absorbing layer (SEAL) by mixing SFS, CW and recycled rubber crumbs (RC) for railway subballast, and (ii) under sleeper pads (USPs) to increase track stability and reduce ballast degradation. The track performance incorporating SEAL with different rubber contents and USP with various stiffnesses was investigated using large-scale laboratory tests and numerical modeling. The test results and the numerical simulation indicate that the inclusion of USP acts as an energy absorber and reduces the deformation and ballast degradation; the SEAL with 10% rubber can efficiently reduce the lateral dilation and ballast breakage and increase the energy dissipation with an acceptable level of settlement.