Identification of wetting and molecular diffusion stages during self-healing process of asphalt binder via fluorescence microscope

Sun, Daquan; Sun, Guoqiang; Zhu, Xingyi; Pang, Qi; Yu, Fan; Lin, Tianban

doi:10.1016/j.conbuildmat.2016.11.137

Cited by 59 publications

(15 citation statements)

References 21 publications

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“…Such micro-cracks can decrease the bonding strength between aggregates, causing pavement cracking, potholes or raveling [ 25 ]. Rejuvenators were proposed to be used in hot recycling to repair those micro-cracks [ 26 ]. A micro-crack closure analysis was suggested to address the contribution of using rejuvenators in hot recycling.…”

Section: Experimental Methodsmentioning

confidence: 99%

The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis

Wang

Zi-peng²,

et al. 2017

Materials

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Using a rejuvenator to improve the performance of asphalt pavement is an effective and economic way of hot asphalt recycling. This research analyzes the rejuvenating effect on aged asphalt by means of a Mortar Transfer Ratio (MTR) test, which concerns the ratio of asphalt mortar that moves from recycled aggregates (RAP aggregates) to fresh added aggregates when aged asphalt is treated with a regenerating agent and comes into contact with fresh aggregates. The proposed MTR test analyzes the regeneration in terms of the softening degree on aged asphalt when the rejuvenator is applied. The covered area ratio is studied with an image analyzing tool to understand the possibility of mortar transferring from RAP aggregates to fresh aggregates. Additionally, a micro-crack closure test is conducted and observed through a microscope. The repairing ability and diffusion characteristics of micro-cracks can therefore be analyzed. The test results demonstrate that the proposed mortar transfer ratio is a feasible way to evaluate rejuvenator diffusion during hot recycling. The mortar transfer ratio and uncovered area ratio on fresh aggregates are compatible, and can be used to quantify the contribution of the rejuvenator. Within a certain temperature range, the diffusing effect of the rejuvenator is better when the diffusing temperature is higher. The diffusion time of the rejuvenator is optimum when diffusion occurs for 4–8 h. When the rejuvenator is properly applied, the rough and cracking surface can be repaired, resulting in better covered aggregates. The micro-closure analysis visually indicates that rejuvenators can be used to repair the RAP aggregates during hot recycling.

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Section: Experimental Methodsmentioning

confidence: 99%

The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis

Wang

Zi-peng²,

et al. 2017

Materials

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“…These calculations neglect the possibility of trapped bitumen or mastic in the contact points of aggregates due to capillary forces. Furthermore, the asphalt mortar mixture with 5wt% bitumen exhibited self-healing, which was attributed to the adhesion of the crack surfaces due to initial contact and the increase of the contact areas due to surface tension (Sun et al, 2017) and thermal expansion.…”

Section: 4self-healing Limit Due To Flowmentioning

confidence: 99%

The composition of the material phase responsible for the self-healing of macro-cracks in asphalt mortar beams

Großegger

García

Airey

2020

Road Materials and Pavement Design

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The self-healing of asphalt is assumed to be a flow process where bitumen flows into cracks to close these. Hence, the rheological behaviour of bitumen is one of the main factors affecting the self-healing. Other important factors are the damage history, healing duration and pressure, either due to a compressive external force or internally through thermal expansion. Filler has a main influence on the rheological behaviour of bitumen and the filler bitumen interaction influences the asphalt properties. It is hypothesised that the material flowing into cracks during self-healing is a mixture of bitumen and filler and eventually fine aggregates. Therefore, the self-healing of macro-cracks in asphalt mortar has been investigated in this paper. The self-healing ratio was determined by mechanical testing and the self-healing was accelerated by an increase of temperature to 100 °C during healing. Material draining from the asphalt mortar beams into a horizontal gap, representing a crack, was found to be a mixture of bitumen and aggregates. The mixture was proportional to the mixture of the beams and an increasing self-healing ratio was observed with increasing bitumen and filler content. To estimate a lower limit of the bitumen content of the mixture (which would still allow self-healing), the thickness of bitumen films on glass slides was combined with the surface area of the aggregates. For the mortar mixture used in this study, a bitumen content of about 5.4wt% was identified to be the limit for self-healing due to the flow of a material phase in the mixture.

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“…The bitumen microstructure has been intensively investigated with different microscopic methods, such as optical microscopy [24,25], fluorescence microscopy [26][27][28], transmission electron microscopy [28], atomic force microscopy [29][30][31] and scanning electron microscopy (SEM) [32][33][34]. Among these methods, SEM is a promising one to investigate the microstructure morphologies of various binders [35,36].…”

Section: Introductionmentioning

confidence: 99%

ESEM observation and rheological analysis of rejuvenated SBS modified bitumen

et al. 2021

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Observing the microstructure of bituminous binders with an environmental scanning electron microscope (ESEM) can contribute significantly to reveal the underlying rejuvenation mechanism. In this study, three rejuvenators were selected to regenerate the aged SBS modified binders at five dosages, and their rheology was evaluated using a dynamic shear rheometer. ESEM was employed to examine the microstructure of binders as well, and a series of microstructure parameters were quantified with image analysis. The results demonstrated that the chemical composition changes correspond to the evolution of microstructure morphological and rheological properties. Moreover, the rheological and microstructure characteristics were analyzed with Principal Component Analysis (PCA) and regression analysis. Based on PCA results, the microstructure of rejuvenated binders has shown a good correlation with stiffness after combining various principal components. According to regression analysis, the distance between adjacent fibrils exhibited a significant correlation with J nr3.2 and the complex modulus index. Overall, the results of this study strengthen the hypothesis that the ESEM microstructure is intimately correlated with chemical composition and rheological properties, rather than with irrelevant surface phenomena. Bitumen, polymer modified bitumen, rejuvenator, microstructure, rheology, environmental scanning electron microscopy.

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Identification of wetting and molecular diffusion stages during self-healing process of asphalt binder via fluorescence microscope

Cited by 59 publications

References 21 publications

The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis

The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis

The composition of the material phase responsible for the self-healing of macro-cracks in asphalt mortar beams

ESEM observation and rheological analysis of rejuvenated SBS modified bitumen

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