Hot central-plant recycling technology: A systematic review on raw materials and performance-influencing factors

The hot central-plant recycling (HCPR) technology has been widely concerned by researchers in pavement engineering because of its excellent economic benefits and positive environmental outcomes. Over the last few years, the application of HCPR technology in highway construction and maintenance has increasingly expanded. However, despite this wider adoption, critical issues concerning the composition of raw materials and performance-influencing factors of hot central-plant recycled asphalt mixtures (HCPRAM) necessitate careful consideration and deeper understanding. Therefore, conducting a detailed interpretation and systematic analysis of each component material and performance-influencing factors holds tremendous significance for advancing the design methodology, optimizing the production process, and enhancing the overall quality and durability of HCPRAM. This paper comprehensively reviews the current state-of-the-art research pertaining to the raw material composition and the crucial factors affecting the road performance of HCPRAM. Firstly, the functionality of recycled asphalt pavement (RAP) materials, virgin asphalt, virgin aggregates, rejuvenators, and fibers in the mixtures are introduced. Then, the influencing factors of the performance of HRAM are described in detail from both internal and external factors. Finally, the paper further discusses persistent challenges and knowledge gaps identified in the current research landscape of HCPR technology. Based on this critical analysis, pertinent recommendations are suggested to guide productive avenues for future research and development.