A comprehensive review of preheating temperature effects on reclaimed asphalt pavement in the hot center plant recycling

Abstract

Hot center plant recycling (HCPR) technology has been prioritized as a sustainable and cost-effective solution for asphalt pavement rehabilitation and maintenance due to its environmental and economic benefits. A critical component of HCPR is the preheating of reclaimed asphalt pavement (RAP), which aims at increasing RAP utilization rates and improving the performance of recycled asphalt mixtures. However, either insufficient or excessive preheating temperatures can negatively impact production efficiency and the mechanical properties of hot recycled mixtures containing RAP. This review systematically evaluates current RAP preheating strategies, analyzing their advantages, limitations, and practical implications. Furthermore, it reveals the influences of preheating temperature on the agglomeration and dispersion phenomena of RAP as well as the blending and fusion efficiency between aged and virgin asphalt binders, which are essential for achieving homogeneous recycled mixtures. Additionally, the study identifies relevant performance indicators for RAP and how to establish suitable preheating temperatures based on these indicators. By synthesizing existing research, this article highlights critical knowledge gaps and provides recommendations for future studies, particularly in refining the RAP preheating strategy and determining the optimal preheating temperature range.