A review of polymer-modified asphalt binder: Modification mechanisms and mechanical properties

The significant increase in the number of vehicles, traffic speed, and load has significantly reduced the lifespan of pavements and increased maintenance costs. Therefore, the incorporation of polymers into bituminous binders is imperative to enhance pavement quality and performance. Nowadays, polymer-modified asphalt binders (PMBs) play a crucial role in pavement engineering. This polymer absorbs asphalt molecules to form a network connecting the entire binder, giving it better viscoelasticity than the base asphalt. Although polymers do enhance the properties of asphalt to some extent, there are still certain limitations hindering the future development of polymer-modified asphalt, such as high costs, low resistance to aging, and poor storage stability. Additionally, there is limited literature available that reviews the advantages and disadvantages of various polymer modifiers. The aim of this paper is to conduct a systematic review that evaluates the benefits and drawbacks of different polymer types in modifying asphalt materials. This comprehensive synthesis study thoroughly examines the historical evolution of polymer modified binders (PMBs) for asphalt pavement, including selection criteria for polymers used in asphalt modification, current state-of-the-art knowledge regarding the internal structure and morphology of PMBs, evaluation methodologies for PMB properties, binder specifications specific to PMBs, recommendations based on findings, and future research. This review will not only merit research from an academic perspective, but also provide guidance for pavement engineering.