Evaluation of the Refined Decomposition Effect of Reclaimed Asphalt Pavement Materials

To improve the quality of reclaimed asphalt pavement materials (RAPs) and reduce the variability of RAPs, a refined decomposition process was applied to treat RAPs. The change rule and variability of aggregate gradation, asphalt content, aged asphalt properties and aggregate (extracted) properties of RAPs were analyzed with different frequency parameters. In addition, the gradation variability control method and the asphalt content variability control method were used to calculate the maximum addition proportion of RAPs according to the quality control requirements of hot-mixing asphalt mixtures. The results indicate that the variability of aggregate gradation, asphalt content and asphalt properties significantly reduced for the refined decomposition RAP. Compared with the original RAP (0 Hz) of 4.75-9.5 mm and 9.5-19 mm, the "false particle" content of the refined decomposition RAP (50 Hz) reduced by 75.6% and 64.3%, respectively. The refined decomposition process is conducive to the road performance of recycled asphalt mixtures, especially the dynamic stability and the maximum bending tensile strain. Comparing the recycled asphalt mixture with the original RAP (0 Hz), the maximum bending strain of the recycled asphalt mixture with the refined decomposition RAP (50 Hz) increased by 69%, and the immersion residual stability increased to 87.9%. The refined decomposition process improves the quality of the RAP and provides a reference for recycled asphalt mixtures with a high proportion of RAPs. This study contributes to RAP high-level recycling and carbon reduction in the highway maintenance industry.