A review of the composition, regeneration mechanism, and performance of cold recycled asphalt mixture

This review aims to enhance the mechanical and road performance of cold recycled asphalt mixture, and advocate the application of cold recycling technology, which features lower energy consumption and reduced carbon emissions. The properties of composition materials were initially studied for cold recycled asphalt mixture, meanwhile which regeneration mechanism was subsequently revealed. Additionally, a summary of the impact of complex factors on the mechanical and road performance of cold regenerated mixtures was provided, along with a proposed method for optimizing their performance. This review summarizes the main challenges of current cold recycling technologies and discusses future research directions. From numerous studies, it is found that the composition of cold recycled asphalt mixture significantly impacts its performance. The gradation variability and dosage of reclaimed asphalt pavement (RAP) material are the main factors affecting the performance of cold recycled material. The bonding property of binder has a significant effect on the mechanical properties of the mixture. The cold regeneration mechanism of waste asphalt mixture includes the rejuvenation of aged asphalt, the bonding mechanism of binder and the enhancement impact of additives. There are many factors affecting the performance of cold reclaimed asphalt mixture. Currently, improvements in mechanical and road performance can primarily be achieved through three main avenues: controlling the quality of RAP material, modifying the binders, and incorporating high-performance additives. However, the cold recycled asphalt mixture still faces several challenges, including a low utilization rate of RAP and limited application structure layers. In addition, insufficient early strength delays the opening of traffic. In the future, it is still necessary to propose more reasonable and efficient approaches to optimize the performance of cold reclaimed asphalt mixture, diverging from traditional methods. Moreover, the intelligent monitoring, evaluation, and prediction of performance for cold recycled asphalt pavement is also highly essential.