Investigation of permanent deformation characterisation of different asphalt mixtures

Permanent deformation has emerged as a primary distress factor in asphalt pavements, largely driven by the recent rise in tyre pressures and axle loads. This deformation significantly impacts pavement performance, safety, and driving comfort, particularly when rutting depth exceeds a critical threshold. To address this issue, polymer-modified asphalt (PMA) mixtures have been widely adopted as an effective solution to resist permanent deformation (or rutting) under high temperatures. In this study, three different asphalt mixtures—one unmodified and two PMA mixtures—were selected for permanent deformation testing, which included the wheel tracking rutting test and the repeated load axial test under various conditions. The results were then compared, analysed, and discussed. The findings demonstrated a significant improvement in permanent deformation resistance in the PMA mixtures compared to conventional mixtures at both 45°C and 60°C. Furthermore, the results indicated that the use of PMA markedly enhanced both dynamic stability and strain rate, with the improvements becoming more pronounced at higher temperatures.