Recent developments in asphalt-aggregate separation technology for reclaimed asphalt pavement

Reclaimed asphalt pavement (RAP) has significant recycling value because it contains nonrenewable resources including asphalt and aggregate. However, thus far, only a small part of RAP materials can be used in the construction of recycled asphalt pavement, and the usage is regarded as a low-value utilization in the underlying layers. One of the most important reasons for this shortcoming is the problem of false particle size and pseudo gradation of RAP materials. Therefore, identifying suitable asphalt-aggregate separation technology is essential for improving the utilization of RAP materials in recycled asphalt mixture and enhancing the construction quality of recycled asphalt pavement. To address this, the paper performed a systematic review of asphalt-aggregate separation technologies for processing RAP materials and their prospects. Firstly, based on the composition of the asphalt mixture and the characteristics of RAP materials after aging, the key RAP separation technologies were proposed. Then, the concept, principle, and implementation methods of physical, chemical, and biological separation methods of RAP materials were comprehensively analyzed. Moreover, the advantages and disadvantages of various separation technologies were discussed by comparing them with the related technologies in the petrochemical industry. The application prospects of various asphalt-aggregate separation methods for RAP materials can provide a reference for upgrading and expanding solid waste recycling technology for asphalt pavement.