Structural Response of the Ballasted Railway Tracks with Partially Replaced Bitumen by Recycled Plastic Wastes

Abstract

This study addresses challenges of cracking and durability faced by conventional dense graded asphalt mixtures (DGA) in hybrid railway tracks. Stone mastic asphalt (SMA), known for superior performance but hindered by cost, is explored as alternative with recycled polyethylene terephthalate (PET) to enhance durability of the tracks while balancing investment and maintenance costs. Conventional asphalt binder was employed, and its optimal content (OBC) was determined through the marshal design method. An appropriate value for recycled PET was identified to selectively substitute a portion of the OBC. Subsequently, the PET-infused mix underwent thorough assessments for susceptibility to moisture damage, rutting, and fatigue failure. The findings were utilized to analyze the response of the aforementioned tracks through numerical analysis with 100 scenarios varying asphalt and ballast layers thicknesses, axle wheel loads, and subgrade moduli using Ansys software. Experimental results reveal that a 10% PET substitution maintains SMA stability while exhibiting good resistance to fatigue and water damage. The numerical analysis results demonstrate a favourable track response, particularly for moderate to stiffer subgrade moduli, suggesting that SMA mix with recycled plastics could serve as a viable alternative to DGA for enhancement of the lifespan of hybrid bituminous ballasted tracks at a reasonable investment cost.