Failure mechanism analysis of asphalt–aggregate systems subjected to direct shear loading

Dong, Ming; Hao, Yanhai; Zhang, Chao; Li, Linglin

doi:10.1617/s11527-017-1080-0

Cited by 14 publications

(3 citation statements)

References 31 publications

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“…It was also reported that the asphalt binder film on the aggregate surface in compacted asphalt mixture is the source of cohesion and adhesion, thereby affecting bonding performance in terms of durability of asphalt mixtures [2]. In addition to these adhesion-based theories in asphalt mixtures, the mechanical properties of the asphaltaggregate interfacial adhesion subjected to shear and tensile loads were also investigated experimentally [5][6][7][8]. e asphalt binder film in asphalt mixture is related to three failure mechanisms including cohesive failure (asphalt internal failure), adhesive failure (interfacial zone failure), and aggregate failure [9].…”

Section: Introductionmentioning

confidence: 99%

Estimating the Asphalt Binder Film Thickness Using Scanning Electron Microscope and Energy Dispersive X‐Ray Spectroscopy

Karim

Hussain

Hafeez

2021

Advances in Materials Science and Engineering

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Asphalt binder film thickness has relation to mixing temperature and binder content in hot mix asphalt, which influences mixture’s performance. A significant variation in assessing the asphalt binder film thickness has been observed in the literature. Development of state of the art technology and Superpave specification requires the study of actual asphalt binder film thickness at micro-level. This study estimates asphalt binder film thickness at micro-level and compares results with those obtained through analytical models from the previous studies. The study utilizes different asphalt mixtures at various mixing temperatures and binder contents. The asphalt binder film thickness around the finest particles of 500 nm (0.5 micron) size in asphalt mastic was detected and measured by image analysis (using scanning electron microscope) and elemental analysis (using energy dispersive X-ray spectroscopy) at magnifying power of ×30,000. The analytical estimation revealed that the asphalt binder film thickness for the aforementioned conditions varies from 9 μm to 13 μm, with a fair relationship to binder content and mixing temperature. However, results obtained from image analysis revealed that the asphalt binder film thickness varies from 0.5 μm to 2.4 μm, with no relation to binder content and mixing temperature. The image analysis showed that the asphalt mixtures mostly contain asphalt mortar and asphalt mastic, occurring in irregular shape. It was also found that the asphalt binder film does exist as a separate entity inside the asphalt mastic in the form of a band around the filler particles as non-absorbed binder, which fills the approximate distance of 0.5 to 2.5 microns among filler particles.

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Section: Introductionmentioning

confidence: 99%

Estimating the Asphalt Binder Film Thickness Using Scanning Electron Microscope and Energy Dispersive X‐Ray Spectroscopy

Karim

Hussain

Hafeez

2021

Advances in Materials Science and Engineering

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“…Each cluster will function as an independent system, affecting structural integrity in the aggregate, perhaps speeding up the rate of HMA degradation when exposed to traffic and the environment. The skeletal cohesion and adhesion of asphalt paving mixtures are based on the ABFT around the granular particles, which affects HMA durability [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Assessing the Asphalt Binder Film Thickness in Recycled Asphalt Mixtures Using Micro-Level Techniques

Karim

Hussain

2021

Materials

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Adequate asphalt binder film thickness (ABFT) delivers skeletal integrity in recycled asphalt mixtures, resulting in long-lasting roadways when exposed to traffic and environment. The inaccurate measurement of ABFT and the consequences of not having adequate film thickness model has substantially introduced discrepancies in predicting actual performance of recycled asphalt mixtures. Expansion of the ultra-modern expertise and SuperPave requirements necessitate the revision of authentic ABFT at micro-level. The current study identifies the weaknesses of the current methods of estimating ABFT and provides results that are reliable and useful, using modern measurement methods. Using scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDS), this study measures the ABFT around the tiniest particle of 0.2 μm magnitude, entrenched in asphalt mastic in recycled asphalt mixtures. The ABFT, obtained through image analysis, is compared with those obtained through available analytical models. The study utilizes different asphalt mixtures, containing varying proportions of recycled asphalt mixture and rejuvenators. The aggregate, virgin, and recycled binders were characterized in terms of physical and rheological properties, respectively. Marshall mix design was carried out for the conventional and recycled mixture, containing 40%, 50%, and 60% recycled materials, rejuvenated with 3%, 6%, 9%, and 12% waste engine oil (WEO) at a mixing temperature of 160 °C, based on viscosity of the virgin and rejuvenated binder. ABFT was assessed through analytical models and image analysis for the aforesaid recycled asphalt mixtures, prepared at optimum binder and rejuvenator content as per protocol outlined in ASTM D1559. The analytical estimation of ABFT, in the aforesaid recycled asphalt mixtures, revealed that the ABFT fluctuates from 6.4 μm to 13.7 microns, with a significant association to recycled asphalt mixture and rejuvenator content. However, the image analysis revealed that the ABFT, in the aforesaid recycled asphalt mixtures, fluctuates from 0.4 μm to 2 microns, without any association to recycled asphalt mixture or rejuvenator content. The image analysis indicated that the recycled asphalt mixtures typically comprise of mortar, happening in uneven shape, and are used to grip large aggregates. The asphalt mastic, a blend of bitumen and mineral filler, was found to be an interlocking agent, used to grasp only fine particles in asphalt mortar. The asphalt binder film was discovered to be a deviating stand-alone entity that only exists around the mineral fillers in the asphalt mastic as a non-absorbed binder, occupying an imprecise space of 0.4 μm to 2 microns, among the filler particles. The current findings will be useful to design asphalt pavements through the aforesaid precise limit of SEM-based ABFT rather than traditionally measured ABFT to predict the actual performance of recycled asphalt mixtures.

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“…In addition to these adhesion-based theories, the mechanical properties of the asphaltaggregate interfacial adhesion were also experimentally investigated under tensile and shear loads [20][21][22][23]. Failure of the asphalt-aggregate interface is caused by cohesive failure (internal failure of asphalt), adhesion failure (interfacial zone failure), or the combination of them [24].…”

Section: Introductionmentioning

confidence: 99%

Effect of asphalt film thickness on shear mechanical properties of asphalt-aggregate interface

Dong

Sun

et al. 2020

Construction and Building Materials

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This paper focuses on the effect of asphalt film thickness on the shear mechanical properties of asphalt aggregate interface. Firstly, an experiment controlling the asphalt film thickness was designed to build the relationship between the asphalt film thickness and the molding load. Then, a shear test was carried out to characterize the properties of asphalt-aggregate interface under different asphalt film. The stressdisplacement curves showed two modes: single and double wave peaks. The probability relationship between the two modes and the asphalt film thickness was established.Finally, the influence of asphalt film thickness on the shear failure mechanism of asphalt-aggregate interface phase was analyzed. Results show that an experimental method for controlling the asphalt film thickness is effectively developed. When the asphalt film thickness is 23.6 μm and 219 μm, only the single wave peak mode appears in the stress-displacement curves. Otherwise, the stress-displacement curves of comparison experiments with other thicknesses show single wave peak and double wave peak, respectively. The double peak probability is found to be related to the asphalt film thickness. The asphalt film thickness is the key point which determines the shear failure behavior of the aggregate-asphalt interface phase, such as cohesive failure or adhesion failure.

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Failure mechanism analysis of asphalt–aggregate systems subjected to direct shear loading

Cited by 14 publications

References 31 publications

Estimating the Asphalt Binder Film Thickness Using Scanning Electron Microscope and Energy Dispersive X‐Ray Spectroscopy

Estimating the Asphalt Binder Film Thickness Using Scanning Electron Microscope and Energy Dispersive X‐Ray Spectroscopy

Assessing the Asphalt Binder Film Thickness in Recycled Asphalt Mixtures Using Micro-Level Techniques

Effect of asphalt film thickness on shear mechanical properties of asphalt-aggregate interface

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