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Guangji Xu
School of Transportation, Southeast University, Nanjing 211189, China

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Journal article
Published: 03 May 2021 in Materials
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As an additive to improve the performance of asphalt binder, tire pyrolysis carbon black is gradually being used in road engineering, but the effect of carbon black (CB) with different particle sizes on asphalt modification remains to be further studied. In this study, three kinds of particle sizes and three kinds of contents of CB were used to modify asphalt, and different tests were conducted to research the high temperature performance and fatigue resistance of carbon black modified asphalt binder. It is found that the addition of CB can enhance the rutting resistance and medium temperature fatigue performance of virgin asphalt binder in general. However, for CB of 270 μm and 2.6 μm, its addition under certain contents lead to the decrease of high temperature performance and fatigue performance of the asphalt binder. For aged asphalt, the addition of CB decreases the rutting resistance and improves the fatigue resistance. The recommended content and particle size of CB are 2% and 2.6 μm. This study refines the complex effects of CB on asphalt properties, providing a reference for determining the size and content of CB in asphalt modification.

ACS Style

Kunzhi Zhong; Zhi Li; Jianwei Fan; Guangji Xu; XiaoMing Huang. Effect of Carbon Black on Rutting and Fatigue Performance of Asphalt. Materials 2021, 14, 2383 .

AMA Style

Kunzhi Zhong, Zhi Li, Jianwei Fan, Guangji Xu, XiaoMing Huang. Effect of Carbon Black on Rutting and Fatigue Performance of Asphalt. Materials. 2021; 14 (9):2383.

Chicago/Turabian Style

Kunzhi Zhong; Zhi Li; Jianwei Fan; Guangji Xu; XiaoMing Huang. 2021. "Effect of Carbon Black on Rutting and Fatigue Performance of Asphalt." Materials 14, no. 9: 2383.

Journal article
Published: 02 October 2019 in Applied Sciences
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The air voids distribution has a significant effect on the pavement performance related distresses such as rutting, cracking, moisture damage and permeability. However, most studies only quantified the air voids by average content, ignoring the heterogeneity inside the materials. This study focuses on the heterogeneity of air voids distribution inside the open-grade asphalt mixture based on 2D image analysis. Equivalent aperture is proposed to measure the area of each air void. Results showed that along both vertical and horizontal sections inside the open-grade asphalt mixture, the number of voids with 0~2 mm equivalent aperture would have a great impact on the total number of voids, while large amounts of small voids would not significantly affect the total voids number. Additionally, voids with 0~4 mm equivalent aperture account for the largest proportion, and when the equivalent aperture is beyond 4 mm, the number of voids would decrease as the equivalent aperture increases, regardless of the void areas. Furthermore, in both vertical and horizontal sections, as the equivalent aperture increases, the speed to accumulate voids area would firstly increase and then decrease. As the equivalent aperture increases, the contribution to the total voids area would increase accordingly, and it would approach the peak when the equivalent aperture reaches about 8 mm.

ACS Style

Guangji Xu; Xiao Chen; XiaoMing Huang; Tao Ma; Wei Zhou. Characterization of Air Voids Distribution in the Open-Graded Asphalt Mixture Based on 2D Image Analysis. Applied Sciences 2019, 9, 4126 .

AMA Style

Guangji Xu, Xiao Chen, XiaoMing Huang, Tao Ma, Wei Zhou. Characterization of Air Voids Distribution in the Open-Graded Asphalt Mixture Based on 2D Image Analysis. Applied Sciences. 2019; 9 (19):4126.

Chicago/Turabian Style

Guangji Xu; Xiao Chen; XiaoMing Huang; Tao Ma; Wei Zhou. 2019. "Characterization of Air Voids Distribution in the Open-Graded Asphalt Mixture Based on 2D Image Analysis." Applied Sciences 9, no. 19: 4126.

Journal article
Published: 18 April 2019 in Materials
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When a fire takes place in a tunnel, the surface of the asphalt pavement will burn and release a large amount of smoke, which is toxic to human health. Thus, in order to prevent the combustion of the asphalt pavement under fire, it is necessary to propose some methods to retard its physical and chemical reaction under the high temperature. In this study, ten different combinations of fire retardants and a control case where no fire retardant was applied were prepared for evaluation. The thermogravimetric (TG)-mass spectrometry (MS) tests were used to evaluate their effect on the fire retardance from mass and energy perspectives and the Fire Dynamics Simulator (FDS) software was used to evaluate the fire retardance from temperature and smoke distribution perspectives. In experimental analysis, the TG (thermogravimetric) and DTG (differential thermogravimetric) curves were used to analyze the mass loss rate and residual mass of the asphalt and the activation energy was calculated and analyzed as well. In addition, decay rate of mass loss rate and increasing rate of activation energy were proposed to evaluate the ease of combustion of the asphalt with and without fire retardants. The results show that in laboratory experiments, the fire retardant combination which includes 48% aluminum hydroxide, 32% magnesium hydroxide, 5% expanded graphite, and 15% encapsulated red phosphorous would lead to an improved effect of fire retardance. In numerical modeling, the temperature and smoke height distribution over time were adopted to evaluate the fire retardance effect. The temperature distribution was found to be symmetrical on both sides of the combustion point and the same combination as proposed in experimental analysis was found to have the best effect on fire retardance due to the largest decrease in temperature. Additionally, because of the highest smoke height distribution, an improved effect on smoke suppression was also found when this combination was applied.

ACS Style

Guangji Xu; Xiao Chen; Shichao Zhu; Lingdi Kong; XiaoMing Huang; Jiewen Zhao; Tao Ma; Xu; Chen; Zhu; Kong; Zhao; Ma. Evaluation of Asphalt with Different Combinations of Fire Retardants. Materials 2019, 12, 1283 .

AMA Style

Guangji Xu, Xiao Chen, Shichao Zhu, Lingdi Kong, XiaoMing Huang, Jiewen Zhao, Tao Ma, Xu, Chen, Zhu, Kong, Zhao, Ma. Evaluation of Asphalt with Different Combinations of Fire Retardants. Materials. 2019; 12 (8):1283.

Chicago/Turabian Style

Guangji Xu; Xiao Chen; Shichao Zhu; Lingdi Kong; XiaoMing Huang; Jiewen Zhao; Tao Ma; Xu; Chen; Zhu; Kong; Zhao; Ma. 2019. "Evaluation of Asphalt with Different Combinations of Fire Retardants." Materials 12, no. 8: 1283.

Journal article
Published: 27 January 2019 in Applied Sciences
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The particle clustering phenomena in reclaimed asphalt pavement (RAP) particles is one of the most important factors to affect the efficient recycling of asphalt concrete. In this study, the particle composition, clustering degree, crushing properties and clustering stability of RAP were studied by extraction test and cantabro-crushing test. It was found that the particles above 4.75 mm were composed mainly of small particles with a large degree of cluster and poor stability. The coarse particles (>4.75 mm) had a great influence on the variation of 4.75 mm sieve. Quantitative indexes of Percentage Loss rate (PL) and Stability Index (w) were proposed to evaluate the clustering degree and the stability of RAP. It provided a meaningful reference for the comparison of different RAP and the different crushing processes. In addition, the RAP could be divided into three kinds of structures, including weak cluster structure, strong cluster structure and old aggregate. The process of crushing the RAP was divided into three stages, which are weak structure-dominated, strong structure-dominated and the broken old aggregate. The weak structure had the largest degree of cluster and worst stability, resulting in a large variability of RAP, and it should be avoided in the crushing process.

ACS Style

Guangji Xu; Tao Ma; Zhanyong Fang; XiaoMing Huang; Weiguang Zhang. The Evaluation Method of Particle Clustering Phenomena in RAP. Applied Sciences 2019, 9, 424 .

AMA Style

Guangji Xu, Tao Ma, Zhanyong Fang, XiaoMing Huang, Weiguang Zhang. The Evaluation Method of Particle Clustering Phenomena in RAP. Applied Sciences. 2019; 9 (3):424.

Chicago/Turabian Style

Guangji Xu; Tao Ma; Zhanyong Fang; XiaoMing Huang; Weiguang Zhang. 2019. "The Evaluation Method of Particle Clustering Phenomena in RAP." Applied Sciences 9, no. 3: 424.

Journal article
Published: 21 August 2018 in Materials
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Aggregate is an indispensable raw material for emulsified asphalt construction. For the purpose of explaining the influence of aggregate characteristics on the demulsification speed of emulsified asphalt, the surface energy and specific surface area (SSA) characteristics of aggregates were calculated based on the capillary rise method and the BET (Brunauer-Emmett-Teller) adsorption test. Afterwards, the effect of the surface energy and specific surface area of the aggregate on the emulsified asphalt demulsification speed was systematically studied by using ultraviolet spectroscopy as well as the orthogonal test. Experimental results indicate that the specific surface energy parameter of the aggregate is certainly related to the particle size of the aggregate. That is, the surface free energy of the unit system is proportional to the surface area A and the density of the interface unit. The specific surface area parameter of aggregates increases with the decrease of particle size, when the particle size is reduced to 600 mesh, the specific surface area parameters of the three aggregates selected in this paper tend to be consistent. Orthogonal experimental analysis demonstrates that the surface energy and specific surface area have an impact on the emulsion breaking speed and they are proven to be positively correlated. Meanwhile, in the case of small particle sizes, there is no statistically significant correlation between the physical properties of aggregates and the demulsification speed of emulsified asphalt, and the physical property of aggregates is not the main factor that affects the demulsification speed of the emulsified asphalt. On the contrary, the material properties of the aggregate, such as acid-base property and chargeability, are the dominant factors.

ACS Style

Fanlong Tang; Guangji Xu; Tao Ma; Lingyun Kong. Study on the Effect of Demulsification Speed of Emulsified Asphalt based on Surface Characteristics of Aggregates. Materials 2018, 11, 1488 .

AMA Style

Fanlong Tang, Guangji Xu, Tao Ma, Lingyun Kong. Study on the Effect of Demulsification Speed of Emulsified Asphalt based on Surface Characteristics of Aggregates. Materials. 2018; 11 (9):1488.

Chicago/Turabian Style

Fanlong Tang; Guangji Xu; Tao Ma; Lingyun Kong. 2018. "Study on the Effect of Demulsification Speed of Emulsified Asphalt based on Surface Characteristics of Aggregates." Materials 11, no. 9: 1488.