Evaluation of pavement performance for reclaimed asphalt materials in different layers

Most of highways with asphalt pavements in China, especially in the developed areas, are facing serious pavement distresses such as rutting at high temperatures, cracking at low temperatures, moisture damage and fatigue cracking. The maintenance and rehabilitation of existing pavements has been the most urgent problem to solve for the transportation department. This paper aims to study the pavement performance of Reclaimed Asphalt Pavements (RAPs) materials in the top and middle layers, compared with the corresponding new asphalt mixtures with or without the same initial gradation as RAP mixtures. Four laboratory tests, including dynamic creep test, semi-circular bending (SCB) test, freeze-thaw indirect tension test and semi-circular fatigue test, were adopted to evaluate the pavement performance of asphalt mixtures. Based on the results of laboratory tests, it was found that high temperature performance of RAP mixtures declined due to the finer gradation, which means the coarse aggregates decreased and fine aggregates increased. The SCB test results showed that RAP mixtures performed worse at low temperatures, and the gradation had little impact while the asphalt binder had a large contribution to the low temperature performance. The moisture stability and fatigue performance of RAP mixtures also declined and the fatigue life had worse susceptibility to stress compared with the new asphalt mixtures.