Abstract
Asphalt mastic plays an important role in asphalt mixtures for pavement engineering. Understanding the asphalt–filler interaction behavior is essential to improve the pavement performance of asphalt mastics. The objective of this paper was to evaluate the asphalt–filler interaction ability based on macro-rheological measurements and to investigate the asphalt–filler interaction mechanism associated with microstructural characteristics of asphalt mastics. First, the asphalt–filler interaction was characterized using macro-rheological features of asphalt mastics based on dynamic shear rheometer (DSR) tests. Second, the physico-chemical interaction between the asphalt and filler was qualitatively evaluated using a Fourier transform infrared (FTIR) spectrometer. Third, the asphalt–filler interaction behavior was investigated in terms of the micro-morphological properties of mineral fillers and asphalt mastics by conducting scanning electron microscopy (SEM) and atomic force microscope (AFM) tests. Finally, the grey relational analysis (GRA) was employed to identify the correlation between the properties of mineral fillers and the macro–micro performances of asphalt mastics. The results show that a higher content of alkaline mineral filler within the critical volume fraction range produced a greater interaction ability between the asphalt and filler. The asphalt–filler interaction is mainly a physical action since no obvious new adsorption peaks appeared in the FTIR spectrum. The micro-morphological characteristics of asphalt mastic mainly depended on the adsorption effect of mineral fillers on polar fractions and the dispersion effect of mineral fillers on wax crystals in the asphalt binder. Based on the results of the GRA, the acidity and content of mineral fillers exhibited a great influence on the micro-morphological and macro-rheological characteristics of asphalt mastics, and the specific surface area of the mineral filler exerted a significant influence on the asphalt–filler interaction ability. Furthermore, the K-B- index was more appropriate for evaluating the asphalt–filler interaction ability.
Highlights
During the long-term service period of asphalt pavement, severe distress related to repeated traffic loads, freeze–thaw cycles, and other external factors lead to a significant reduction in the serviceability of asphalt pavement [1]
The viscoelastic properties and mechanical behaviors of an asphalt mastic are affected by the asphalt–filler interaction, which is sensitive to the particle size, distribution, content and the acidity of mineral fillers, etc
In conclusion,the theindexes indexesofof phase surface height, and surface roughness were to be effective in quantifying the micro-morphological characteristics of asphalt mastics, which could shown to be effective in quantifying the micro-morphological characteristics of asphalt mastics, reflect thealso effect of thethe asphalt–filler interaction on theinteraction phase morphologies of asphalt mastics.of which could reflect effect of the asphalt–filler on the phase morphologies asphalt mastics
Summary
During the long-term service period of asphalt pavement, severe distress related to repeated traffic loads, freeze–thaw cycles, and other external factors lead to a significant reduction in the serviceability of asphalt pavement [1]. Coarse aggregate as the dispersed phase is distributed in asphalt mortar. As for asphalt mortar, fine aggregate as the dispersed phase is scattered in asphalt mastic, which consists of mineral filler and asphalt binder. Many studies have shown that the interaction between asphalt binder and mineral filler (asphalt–filler interaction) would affect the viscoelastic properties and mechanical behaviors of asphalt mastics, which further impose great impacts on the overall pavement performance of asphalt mixtures, such as fatigue damage resistance, low-temperature cracking resistance, high-temperature stability, and moisture stability [3,4]. Evaluating the asphalt–filler interaction ability, exploring related influential factors of asphalt–filler interactions, and revealing the interaction mechanism associated with microstructural characteristics of asphalt mastics are of great significance to better understanding the performance of asphalt mastics and effectively reducing pavement distress
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