Evaluation effect of aggregate contact length on rutting potential of hot-mix asphalt

In addition to low-temperature cracks and fatigue cracks, the high-temperature rutting is one of the main failures of asphaltic mixtures. In previous research, in order to investigate the rutting potential for hot-mix asphalt, it has been underestimated that these mixtures are non-homogeneous combinations of aggregate materials, bitumen and voids, and the macro-structural parameters such as rut depth are often used to evaluate the mechanical performance of the mixture, while the aggregate arrangement and parameters such as contact length seem to play an important role in the rutting performance of the mixture. In this paper, using image processing (iPAS2 software) on the cut samples, the contact length of aggregates and its effect on the rutting performance of 16 types of mixture (two types of grading, two types of bitumen, two types of aggregate and two types of filler) is analyzed and evaluated. The rutting performance of the mixture is investigated using dynamic creep and wheel tracking tests. The results show that the rutting performance is dependent on the contact length of aggregates in the asphalt mixtures, and in this sense, the analysis of asphalt mixtures provides very useful information which can be used even as a control tool in the design of asphalt mixtures.