The Effects of Asphalt Migration on the Dynamic Modulus of Asphalt Mixture

Hui Wang,Shihao Zhan,Guojun Liu

doi:10.3390/app9132747

Hui Wang, Shihao Zhan + Show 1 more

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https://doi.org/10.3390/app9132747

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Abstract

Asphalt migration is one of the significant detrimental effects on asphalt pavement performance. In order to simulate the state after the occurrence of asphalt migration amid asphalt pavement layers and further investigate the effects of asphalt migration on the dynamic modulus of asphalt mixture, samples with different asphalt contents layers were firstly separated into the upper and lower half portions and then compacted together. By conducting the dynamic modulus test with the Superpave Simple Performance Tester (SPT), the variation laws of the dynamic modulus (|E*|) and the phase angle (δ) at different testing temperatures and loading frequencies were analyzed in this paper. Further, the dynamic modulus and the stiffness parameter (|E*|/sinδ) at the loading frequency of 10 Hz and testing temperature of 50 °C were illustrated. Simultaneously, the master curves of the dynamic modulus and phase angle of asphalt mixtures under different testing conditions were constructed to better investigate the effects of asphalt migration on the dynamic modulus by means of Williams–Landel–Ferry (WLF) equation and Sigmoidal function. Results show that, after the asphalt migration, the dynamic modulus of asphalt mixtures increase with the increasing loading frequency while they decrease with the increasing testing temperature; the dynamic modulus and the stiffness parameter are the highest when asphalt mixtures have the optimum asphalt content layers, and then decrease with the incremental difference of asphalt content in the upper and lower half portions. Besides this, different from the master curves of dynamic modulus, the master curves of phase angle firstly increase with the increase of loading frequency to the highest point and then decrease with the further increase of loading frequency and are not as smooth as that of dynamic modulus. It can be concluded that the asphalt migration has compromised the mixture’s mechanical structure, and the more asphalt migrates, the weaker the mechanical properties of asphalt mixture will be. Additionally, based on the shift factors and master curves in the time–temperature superposition principle (TTSP), the effects of asphalt migration on the dynamic modulus and the variation laws of the dynamic modulus of asphalt mixture after the occurrence of asphalt migration can be better construed at the quantitative level.

Highlights

Permanent deformation, which can be caused by asphalt migration is considered a main distress in asphalt pavements and a high concern for road engineers, in hot climate and rainy areas, such as southern China
After the asphalt migration, the dynamic modulus of asphalt mixtures increase with the increasing loading frequency while they decrease with the increasing testing temperature; the dynamic modulus and the stiffness parameter are the highest when asphalt mixtures have the optimum asphalt content layers, and decrease with the incremental difference of asphalt content in the upper and lower half portions
In order to investigate the effects of asphalt migration on the dynamic modulus of asphalt

Summary

Introduction

Permanent deformation (rutting), which can be caused by asphalt migration is considered a main distress in asphalt pavements and a high concern for road engineers, in hot climate and rainy areas, such as southern China. Studies have shown that the rutting of asphalt pavement has a good correlation with the number of load cycles [4]. Ghazi et al [5] demonstrated that the difference of rutting depth at 19,200 loading cycles between limestone and basalt asphalt mixtures was statistically significant. Overloads (even with short duration), and small load cycles can result in road rutting and accelerate its further development [6,7]. Results revealed that the high temperature stability of the asphalt intermediate course had the greatest effect on the rutting development. To this end, they developed some new materials to improve the road performance of asphalt pavement [9]

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