Perspectives on the Application of Waste Materials in Asphalt Based on Molecular Dynamics Simulations: A Review

During the last few decades, industrial waste has increased at an alarming rate, and the recycling of waste materials has always been an urgent problem to be solved. While the number of vehicles per citizen has dramatically increased, as well as the traffic loading, limiting the deterioration of the pavement networks is an approach, and it can be achieved by the addition of polymers to asphalt binders and mixtures. Waste polymers are used in asphalt due to their low cost and environmental friendliness. Both asphalt and polymeric materials are complex in structure, and it is difficult for researchers to quickly and clearly understand the properties of the materials and how they change. Multiscale research approaches effectively improve the understanding of materials with macroscopic/experimental data and microscopic simulations. The Molecular Dynamics (MD) method is employed to analyze material properties from a nanoscale perspective, and it is one of the most powerful and effective tools to understand fluid and material behaviors at an atomic level. This work aims to review the application of waste materials to asphalt materials based on the MD method. A brief description was demonstrated for the model generation and property analysis of modeling asphalt molecules and waste polymer-modified asphalt, especially electronic waste materials, as well as recycled asphalt pavement (RAP) and thermoplastics. Moreover, the advantages and disadvantages of MD simulation methods were extensively discussed for the application of waste materials in engineering materials. The review may provide a more comprehensive understanding of related projects and guide subsequent research for readers.