scholarly journals Shear Deformation Behavior of a Double-Layer Asphalt Mixture Based on the Virtual Simulation of a Uniaxial Penetration Test

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3700
Author(s):  
Changjiang Kou ◽  
Xiaohui Pan ◽  
Peng Xiao ◽  
Aihong Kang ◽  
Zhengguang Wu
Keyword(s):  
Shear Deformation ◽  
Double Layer ◽  
Deformation Behavior ◽  
Lower Layer ◽  
Asphalt Mixture ◽  
Element Model ◽  
Discrete Element ◽  
Asphalt Mixtures ◽  
Penetration Test ◽  
Coarse Aggregates

This paper aims to clarify the shear deformation behavior of double-layer asphalt mixtures using the virtual uniaxial penetration test (UPT) with a discrete element method. For this purpose, asphalt mixtures with two different nominal maximum aggregate sizes were designed for the preparation of double-layer wheel tracking test specimens. Then, the cylindrical cores were prepared from the specimens and were cut for capturing the longitudinal profile images. These images were used to reconstruct a two-dimensional discrete element model (DEM) of the uniaxial penetration test specimen. The results indicate that the shear deformation behavior of the asphalt mixtures showed corresponding changes under the virtual loading. The tensile and compressive stress were distributed unevenly within the upper layer after the test, and both coarse aggregates and asphalt mortars bore a greater shear stress. Therefore, cracks were more likely to occur in the upper layer, leading to the failure of the specimens. This process enhanced the bonding between the asphalt mortars and the mineral aggregates. The aggregate particles in the upper layer moved more vertically, while those in the lower layer generally moved more laterally under the virtual loading. This behavior reveals the rutting mechanism of asphalt pavement.

scholarly journals Effects of Aggregate Mesostructure on Permanent Deformation of Asphalt Mixture Using Three-Dimensional Discrete Element Modeling

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3601 ◽  
Author(s):  
Deyu Zhang ◽  
Linhao Gu ◽  
Junqing Zhu
Keyword(s):  
Surface Texture ◽  
Deformation Behavior ◽  
Negative Impact ◽  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Discrete Element ◽  
Asphalt Mixtures ◽  
Creep Tests

This paper investigated the effects of aggregate mesostructures on permanent deformation behavior of an asphalt mixture using the three-dimensional (3D) discrete element method (DEM). A 3D discrete element (DE) model of an asphalt mixture composed of coarse aggregates, asphalt mastic, and air voids was developed. Mesomechanical models representing the interactions among the components of asphalt mixture were assigned. Based on the mesomechanical modeling, the uniaxial static load creep tests were simulated using the prepared models, and effects of aggregate angularity, orientation, surface texture, and distribution on the permanent deformation behavior of the asphalt mixtures were analyzed. It was proven that good aggregate angularity had a positive effect on the permanent deformation performance of the asphalt mixtures, especially when approximate cubic aggregates were used. Aggregate packing was more stable when the aggregate orientations tended to be horizontal, which improved the permanent deformation performance of the asphalt mixture. The influence of orientations of 4.75 mm size aggregates on the permanent deformation behavior of the asphalt mixture was significant. Use of aggregates with good surface texture benefitted the permanent deformation performance of the asphalt mixture. Additionally, the non-uniform distribution of aggregates had a negative impact on the permanent deformation performance of the asphalt mixtures, especially when aggregates were distributed non-uniformly in the vertical direction.

scholarly journals Investigating the Functions of Particles in Packed Aggregate Blend using a Discrete Element Method

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 556 ◽  
Author(s):  
Yinghao Miao ◽  
Weixiao Yu ◽  
Yue Hou ◽  
Liyan Guo ◽  
Linbing Wang
Keyword(s):  
Discrete Element Method ◽  
Mechanical Characteristics ◽  
Asphalt Mixture ◽  
Discrete Element ◽  
Asphalt Mixtures ◽  
Coarse Aggregates ◽  
And Function ◽  
Skeleton Structure ◽  
Element Method ◽  
Aggregate Particles

In asphalt mixture, aggregates account for up to 90% of the total volume and play an important role in the mechanical characteristics of asphalt mixture. The proportions of fine and coarse aggregates in gradation, as well as the function of aggregate particles, are important factors for the skeleton structure performance of asphalt mixtures. However, the existing asphalt mixture design methods are mostly based on empirical methods, where the non-uniformity and complexity of the composition of asphalt mixtures are not fully studied. In this study, the skeleton structure of aggregate mixture and function of aggregate are studied and analyzed using the Discrete Element Method (DEM). The Particle Flow 3D (PFC3D) DEM program is used to perform the numerical simulation. The average contact number and interaction forces by aggregate particles of different sizes are obtained and studied. The skeleton structure of aggregate mixture and function of aggregate particles are further analyzed from the meso-structural perspective.

scholarly journals Cross-Functional Test to Explore the Determination Method of Meso-Parameters in the Discrete Element Model of Asphalt Mixtures

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5786
Author(s):  
Xingyu Yi ◽  
Huimin Chen ◽  
Houzhi Wang ◽  
Zhiyun Tang ◽  
Jun Yang ◽  
...  
Keyword(s):  
Asphalt Mixture ◽  
Ct Scanning ◽  
Element Model ◽  
Discrete Element ◽  
Asphalt Mixtures ◽  
Model Parameters ◽  
Aggregate Model ◽  
Dem Simulation ◽  
Tensile Adhesion ◽  
Tensile Adhesion Test

In order to obtain more accurate parameters required for the simulation of asphalt mixtures in the discrete element method (DEM), this study carried out a series of cross-functional asphalt mixture experiments to obtain the DEM simulation meso-parameters. By comparing the results of simulation and actual experiments, a method to obtain the meso-parameters of the DEM simulation was proposed. In this method, the numerical aggregate profile was obtained by X-ray CT scanning and the 3D aggregate model was reconstructed in MIMICS. The linear contact parameters of the aggregate and the Burgers model parameters of the asphalt mastic were obtained by nanoindentation technology. The parameters of the parallel bonding model between the aggregate and mastic were determined by the macroscopic tensile adhesion test and shear bond test. The results showed that the meso-parameters obtained by the macroscopic experiment provide a basis for the calibration of DEM parameters to a certain extent. The trends in simulation results are similar to the macro test results. Therefore, the newly proposed method is feasible.

scholarly journals Laboratory Evaluation of the Use of Florida Washed Shell in Open-Graded Asphalt Mixtures

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7060
Author(s):  
Mohammad Alharthai ◽  
Qing Lu ◽  
Ahmed Elnihum ◽  
Asad Elmagarhe
Keyword(s):  
Tensile Strength ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Indirect Tensile Strength ◽  
Laboratory Evaluation ◽  
Void Content ◽  
Coarse Aggregates ◽  
Significant Difference ◽  
Indirect Tensile ◽  
Marshall Stability

This study investigates the substitution of conventional aggregate with a Florida washed shell in open-graded asphalt mixtures and evaluates the optimal substitution percentage in aggregate gradations of various nominal maximum aggregate sizes (NMASs) (i.e., 4.75, 9.5, and 12.5 mm). Laboratory experiments were performed on open-graded asphalt mixture specimens with the coarse aggregate of sizes between 2.36 and 12.5 mm being replaced by the Florida washed shell at various percentages (0, 15, 30, 45, and 100%). Specimen properties relevant to the performance of open-graded asphalt mixtures in the field were tested, evaluated, and compared. Specifically, a Marshall stability test, Cantabro test, indirect tensile strength test, air void content test, and permeability test were conducted to evaluate the strength, resistance to raveling, cracking resistance, void content, and permeability of open-graded asphalt mixtures. The results show that there is no significant difference in the Marshall stability and indirect tensile strength when the coarse aggregates are replaced with Florida washed shell. This study also found that the optimum percentages of Florida washed shell in open-graded asphalt mixture were 15, 30, and 45% for 12.5, 9.5, and 4.75 mm NMAS gradations, respectively.

Comparison of Test Methods for High-Temperature Performance of Asphalt Mixtures

2013 ◽  
Vol 361-363 ◽  
pp. 1629-1634 ◽  
Author(s):  
Guo Xiong Wu ◽  
Xiao Ke Zhang ◽  
Rui Lin Wang
Keyword(s):  
Elastic Modulus ◽  
High Temperature ◽  
Shear Test ◽  
Asphalt Mixture ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Penetration Test ◽  
Shear Elastic Modulus ◽  
Temperature Performance ◽  
Slant Shear

Through a comparative study of high-temperature asphalt mixture performance by three methods: the standard rutting test, uniaxial penetration test on cylindrical specimens, and slant shear test, this paper displays that the shear elastic modulus gained by both cylindrical uniaxial penetration test and slant shear test can reflect well the properties of shear deformation of asphalt mixture under high temperature. However, there are certain limitations in these test methods.

scholarly journals Study on Permeability and Blocking Resistance of Composite Specimen with Double-Layer Permeable Asphalt Mixture

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Xiaoge Tian ◽  
Huitong Yuan ◽  
Ren Zhang ◽  
Yichao Xu ◽  
Xiaofei Wang
Keyword(s):  
Double Layer ◽  
Digital Image Analysis ◽  
Asphalt Mixture ◽  
Particle Sizes ◽  
Penetration Test ◽  
X Ray ◽  
Vertical Permeability ◽  
Layer Composite ◽  
Critical Particle Size ◽  
Composite Samples

In order to study the permeability and antiblocking performance of composite specimens with double-layer permeable asphalt mixture, three types of PAC-10 asphalt mixture with different target porosity (20%, 22%, and 24%) and PAC-16 asphalt mixture with a target porosity of 22% were designed, and the double-layer Marshall specimen was fabricated through “hot + hot” method. Their orthogonal vertical sections were scanned with X-ray CT. The pore distribution and its characteristics of the specimens were analyzed by digital image analysis technology. The permeability of composite specimens was studied through penetration test, and their blocking resistances were studied through using different particle sizes of fine machine-made sands as blocking materials. The results show that the permeable capacity increases linearly with the increase of porosity. The permeable capacity of PAC-16 with 22% porosity is greater than PAC-10 (20%, 22%, and 24%) porosity. The porosity of the upper layer increases, and the permeability of the double-layer composite samples increases linearly. The critical particle size causing blocking is 0.15 mm, followed by 0.3 mm. The vertical permeability coefficient decreases exponentially with the increasing of blocking times.

scholarly journals The Effect of Morphological Characteristic of Coarse Aggregates Measured with Fractal Dimension on Asphalt Mixture’s High-Temperature Performance

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Hainian Wang ◽  
Yin Bu ◽  
Yanzhe Wang ◽  
Xu Yang ◽  
Zhanping You
Keyword(s):  
Fractal Dimension ◽  
High Temperature ◽  
Los Angeles ◽  
Coarse Aggregate ◽  
Asphalt Mixture ◽  
Great Influence ◽  
Asphalt Mixtures ◽  
Morphological Properties ◽  
Coarse Aggregates ◽  
Temperature Performance

The morphological properties of coarse aggregates, such as shape, angularity, and surface texture, have a great influence on the mechanical performance of asphalt mixtures. This study aims to investigate the effect of coarse aggregate morphological properties on the high-temperature performance of asphalt mixtures. A modified Los Angeles (LA) abrasion test was employed to produce aggregates with various morphological properties by applying abrasion cycles of 0, 200, 400, 600, 800, 1000, and 1200 on crushed angular aggregates. Based on a laboratory-developed Morphology Analysis System for Coarse Aggregates (MASCA), the morphological properties of the coarse aggregate particles were quantified using the index of fractal dimension. The high-temperature performances of the dense-graded asphalt mixture (AC-16), gap-graded stone asphalt mixture (SAC-16), and stone mastic asphalt (SMA-16) mixtures containing aggregates with different fractal dimensions were evaluated through the dynamic stability (DS) test and the penetration shear test in laboratory. Good linear correlations between the fractal dimension and high-temperature indexes were obtained for all three types of mixtures. Moreover, the results also indicated that higher coarse aggregate angularity leads to stronger high-temperature shear resistance of asphalt mixtures.

scholarly journals How to Achieve Efficiency and Accuracy in Discrete Element Simulation of Asphalt Mixture: A DRF-Based Equivalent Model for Asphalt Sand Mortar

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yu Liu ◽  
Peifeng Su ◽  
Miaomiao Li ◽  
Hui Yao ◽  
Junfu Liu ◽  
...  
Keyword(s):  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Wall Stress ◽  
Element Model ◽  
Discrete Element ◽  
Reduction Factor ◽  
Equivalent Model ◽  
Asphalt Binders ◽  
Volumetric Features ◽  
Diameter Reduction

The clump-based discrete element model is one of the asphalt mixture simulation methods, which has the potential to not only predict mixture performance but also simulate particle movement during compaction, transporting, and other situations. However, modelling of asphalt sand mortar in this method remains to be a problem due to computing capacity. Larger-sized balls (generally 2.0–2.36 mm) were usually used to model the smaller particles and asphalt binder, but this replacement may result in the mixture’s unrealistic volumetric features. More specifically, replacing original elements with equal volume but larger size particles will increase in buck volume and then different particle contacting states. The major objective of this research is to provide a solution to the dilemma situation through an improved equivalent model of the smaller particles and asphalt binders. The key parameter of the equivalent model is the diameter reduction factor (DRF), which was proposed in this research to minimize the effects of asphalt mortar’s particle replacement modelling. To determine DRF, the DEM-based analysis was conducted to evaluate several mixture features, including element overlap ratio, ball-wall contact number, and the average wall stress. Through this study, it was observed that when the original glued ball diameters are ranging from 2.00 mm and 2.36 mm, the diameter reduction factor changes from 0.82 to 0.86 for AC mixtures and 0.80 to 0.84 for SMA mixtures. The modelling method presented in this research is suitable not only for asphalt mixtures but also for the other particulate mix with multisize particles.

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