Application of asphalt based materials in railway systems: A review

[Display omitted] •Asphalt based materials used in railway system were summarized into six categories.•The timelines for the emergence and development of six categories of asphalt based materials were concluded.•Six categories of asphalt-based materials were comprehensively reviewed based on various performances.•More attentions should be shifted from qualitative comparison to quantitative evaluation. Ballast railway system and non-ballast railway system, two main railway types, have encountered impeding challenges with the increasing axle loads, traffic volumes and speed. This field has therefore been seeking reliable and maintenance-free railway systems. Although Asphalt Based Materials (ABM) as possible solutions have attracted a lot of attentions, concerns on performance exist before their extensive application in railway systems around the world. For further promoting the application of ABM in practice, this review paper tried to comprehensively evaluate existing application forms in terms of design and construction, evaluation and performance, challenge and opportunity, as well as economy and environmental impact. In conclusion, their application experience in railway system demonstrated a problem-oriented developing trend. Six subfields of ABM were proposed in this study, including Asphalt Stabilized Ballast (ASB), Asphalt Underlayment (AUL), Asphalt Overlayment (AOL), Cement Asphalt Mortar layer (CAM), Asphalt Slab Track Bed (ASTB) and asphalt based impermeable layer. Each subfield showed positive effects as well as new challenges, and AUL, AOL and CAM were believed to be more reliable. To solve the challenges encountered by ABM, future studies were suggested to focus on the advancements in material property, structural design method, life cycle assessment, and optimization on materials and structure. Meanwhile, researches on modified test method and non-destructive tool were encouraged to provide essential data basis for construction and understanding the evolution of field performance of ABM. Consequently, the popularization and application of ABM around the world needed to be considered comprehensively according to local requirements and conditions.