Aging Characteristics and Spatiotemporal Evolution Model of Rubberized Reclaimed Asphalt Under Acceleration of Artificial Climate
The aging of reclaimed asphalt under environmental climate conditions is the main internal factor contributing to the performance degradation of regenerated pavements.Accurately characterizing and predicting the aging characteristics of recycled asphalt with respect to temporal and spatial variations is of great significance for assessing the aging degree of asphalt and the service condition of pavements.Therefore,this study mainly investigated the variation rules of rubberized reclaimed asphalt in both time and space dimensions under accelerated aging of artificial climate.Specifically,the aging characteristics of asphalt extracted from an aged rubberized reclaimed asphalt mixture in layers were investigated.The spatiotemporal variation rules of aging characteristics and the effects of material composition were clarified through dynamic shear,multiple creep recovery,and Fourier transform infrared spectroscopy tests.Then,a spatiotemporal evolution model based on Fick's second law was established,and aging prediction based on this model was analyzed.The results indicate that the evolution of aging characteristic parameters,such as rutting factor,the reciprocal of the non-recoverable creep compliance,recovery rate,carbonyl index,aromatic ring index,and sulfoxide index,have an opposite trend in both the time and space dimensions,with the greatest reduction at 0-12.5 mm in depth,gradually approaching 0 thereafter.The incorporation of rubber powder,hard matrix asphalt,and reclaimed asphalt pavement(RAP)can increase the rutting factor,reciprocal of unrecoverable creep compliance,and recovery rate of rubberized reclaimed asphalt by at least 20％,while the addition of rubber powder has no significant effect on the functional group index of reclaimed asphalt.The spatiotemporal model effectively reflects the evolution of aging characteristic parameters,with the model's coefficient of determination mostly above 0.9.Based on the spatiotemporal evolution model,the predicted results show that when the relationship between the carbonyl index and time follows a square root function at the pavement surface,the milling depths for recycled pavement after 5 and 10 years of service are 0.027 m and 0.086 m,respectively.These results provide valuable references for determining maintenance periods and milling depths during pavement management and rehabilitation.
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