## 1 Introduction  
Permanent deformation (rutting), which can be caused by asphalt migration is considered a main distress in asphalt pavements and also a high concern for road engineers, particularly in hot climate and rainy areas, such as southern China. When asphalt pavement transforms from anhydrous to water-saturated status, its failure mode changes from fracturing to shear deformation [1; 2], which is subjected to temperature and overlarge stress in the upper layers of asphalt pavement [3], easily leading to structural damage of the pavement. Studies have shown that the rutting of asphalt pavement has a good correlation with the number of load cycles [4]. [PERSON] et al. [5] demonstrated that the difference of rutting depth at 19,200 loading cycles between limestone and basalt asphalt mixtures was statistically significant. High temperature, overloads (even with short duration), and small load cycles can result in road rutting and accelerate its further development [6; 7]. [PERSON] et al. [8] evaluated the effects of properties of the sensitive layer on the rutting at different temperatures by statistical analysis. Results revealed that the high temperature stability of the asphalt intermediate course had the greatest effect on the rutting development. Subsequently, to this end, they developed some new materials to improve the road performance of asphalt pavement [9]. A phenomenon called asphalt migration (also termed flushing/bleeding), where asphalt travels in one direction upwards (down to top) amid pavement layers in the wheel path, happens under adverse factors. An underlying substrate that becomes too soft under the effect of high temperature and heavy load may render the aggregates pushed into the lower layers of pavement, so the asphalt travels to the upper layers [10]. Besides the permanent deformation, the migrated asphalt can even trigger safety concerns by coating the micro surface of aggregates and then creating a slick pavement surface with a lower skid resistance [11]. Thus, it is necessary to investigate the variation laws of the mechanical properties of asphalt pavement after the occurrence of asphalt migration. One way to do that is to study and analyze asphalt mixture's corresponding mechanical parameters, such as the dynamic modulus (\(\mathrm{|E^{*}|}\)), stiffness parameter (\(\mathrm{|E^{*}|/sin\delta}\)), and phase angle (\(\delta\)), etc. by simulating the post-state of asphalt migration in laboratory test. Currently, Superpave Simple Performance Tester (SPT) is commonly used to obtain these parameters of asphalt mixture due to its good applicability, accuracy, and operability [12; 13; 14]. It is known that asphalt mixture is a typical viscoelastic material and can show different mechanical behaviors at different temperatures. Moreover, its fabrication and paving temperature ranges from \(-40\) to \(160\)\({}^{\circ}\mathrm{C}\)[15; 16; 17]. Due to the limited experimental conditions and technologies, however, it is difficult to obtain the dynamic modulus of asphalt mixture over such wide of testing temperature and loading time (or frequency) [18]. However the master curve is a good solution to this concern. Based on the time-temperature superposition principle (TTSP), the master curve can effectively exhibit and predict the mechanical properties of asphalt mixture in a wider range of temperature and loading time or frequency [19]. In TTSP, the effects of temperature and loading time (or frequency) on the mechanical properties of viscoelastic materials are considered equivalent, i.e., the mechanical properties of viscoelastic materials at a low temperature are equivalent to that at a short loading time (or higher frequency) and vice versa [20]. Consequently, according to the TTSP, the master curves of the dynamic modulus and phase angle of asphalt mixture can be plotted based on shift factors and non-linear least squares regression analysis [21; 22].