Assessment of the Selection of Asphalt Binder for Full Cross-Section Asphalt Waterproof Layer in High-Speed Railway Ballastless Track

Abstract

In China, the application of asphalt layers in high-speed railway ballastless tracks has two functions. Asphalt layers can be used as a support layer or a waterproof layer; one of these functions is chosen in general design. The main purpose of this work was to apply and evaluate a full cross-section asphalt waterproofing layer in a slab ballastless track. The asphalt layer was intended to support the static and dynamic loads of a high-speed train and protect the internal structure from the effects of environmental temperature. Three types of performance-grade (PG) binders were selected in the asphalt mix design as part of the top surface layer of the subgrade bed of the CRTS III slab ballastless track. These binders (normal, high, and modified-grade binders) are PG64-22, PG70-22, and PG76-22. The efficiency of the asphalt mixture is evaluated through laboratory tests based on permanent deformation and fatigue resistance, and by applying criteria used to assess the mechanical properties in high-speed railways. After analyzing the dynamic response of each layered structure using the 3D finite element model, the laboratory results indicated that the PG76-22, or modified asphalt binder, is suitable for use in ballastless track when applied as a full cross-section asphalt waterproof layer. In addition, the prediction of the model shows that the asphalt waterproof layer performs better than the traditional structure in reducing the stress and vibration of the track.