检索结果-内蒙古大学图书馆

Experimental Testing and Finite-Element Modeling to Evaluate the Effects of aggregate angularity on Bituminous Mixture Performance

引用

JOURNAL OF MATERIALS IN CIVIL ENGINEERING 2012年第3期24卷 249-258页

作者： Souza, Leonardo T. Kim, Yong-Rak Souza, Flavio V. Castro, Leandro S. Kyung Hee Univ Dept Civil Engn Yongin Gyeonggi Do South Korea Univ Nebraska Dept Civil Engn Lincoln NE 68588 USA Univ Nebraska Dept Engn Mech Lincoln NE USA

This study evaluates the effects of aggregate angularity in bituminous mixtures. Previous studies have predominantly focused on the effects of aggregate angularity on the resistance to permanent deformation, while little work has investigated the role of aggregate angularity related to mixture volumetrics and fatigue fracture performance. To investigate the effect of aggregate angularity on mixture performance and characteristics, five mixes with different combinations of coarse and fine aggregate angularity are evaluated by performing the uniaxial static creep test and the indirect tensile fracture energy test. The asphalt pavement analyzer test is also performed with five-year field project mixtures. Fracture energy test results are then incorporated with finite-element simulations of virtual specimens produced to explore the detailed mechanisms of cracking related to the aggregate angularity. Rutting performance test results indicate that higher angularity in the mixture improves rut resistance due to better aggregate interlocking. The overall effect of angularity on the mixtures' resistance to fracture damage is positive because aggregate blends with higher angularity require more binder to meet mix design criteria, which mitigates cracking due to increased viscoelastic energy dissipation from the binder, while angular particles produce a higher stress concentration that results in potential cracks. Finite-element simulations of mixture microstructure support findings from experimental tests. DOI: 10.1061/(ASCE)MT.1943-5533.0000386. (C) 2012 American Society of Civil Engineers.

关键词： aggregate angularity Bituminous mixture Performance Finite-element method Cohesive zone

来源：评论

学校读者我要写书评

暂无评论

Innovation of aggregate angularity characterization using gradient approach based upon the traditional and modified Sobel operation

引用

CONSTRUCTION AND BUILDING MATERIALS 2016年 120卷 442-449页

作者： Chen, Siyu Yang, Xu You, Zhanping Wang, Min Michigan Technol Univ Dept Civil & Environm Engn Houghton MI 49931 USA Michigan Technol Univ Dept Math Sci Houghton MI 49931 USA

This study aims to employ the modified Sobel-Feldman operation to quantify aggregate angularity using the gradient approach, which has been used in previous studies. In detail, the modified Sobel-Feldman operation lies in expanding the conventional kernel size of the operation from 3 x 3 to 5 x 5, and up to 13 x 13 using the average gradient vectors of two neighboring pixels (2-pixel) instead of one single pixel (1-pixel) to calculate the angularity index. To achieve this goal, image processing was conducted to obtain the outlines of aggregate images. The gradient vectors of the surface pixels were obtained using the conventional and modified Sobel-Feldman operation. Then the angularity index (Al) of aggregates were calculated based on the change in gradient vectors of neighboring pixels with a rotational angle of 10 degrees. The angularity index calculated using the conventional and modified Sobel-Feldman operations were compared. The sensitivity of the approach to image resolution was also discussed in this study. The profile images of both real aggregates and computer generated aggregate models were used for this investigation. The results show that the conventional Sobel-Feldman operation results have a higher angularity Index than that of larger sized kernels. The Al values calculated from the 2-pixel method were more stable compared to those using the 1-pixel method. The modified Sobel-Feldman operation has lower sensitivity to image resolution than the conventional operation. Overall, the gradient approach using the 7 x 7 sized Sobel-Feldman operation with the 2-pixel method is the best way to calculate the angularity index. The findings of this study can potentially be adopted by commercial angularity index measurement apparatuses such as the aggregate imaging system (AIMS). (C) 2016 Elsevier Ltd. All rights reserved.

关键词： aggregate angularity angularity index Sobel-Feldman operation Image processing Gradient approach Sensitivity to resolution

来源：评论

学校读者我要写书评

暂无评论

Innovation for evaluating aggregate angularity based upon 3D convolutional neural network

引用

CONSTRUCTION AND BUILDING MATERIALS 2017年 155卷 919-929页

作者： Tong, Zheng Gao, Jie Zhang, Haitao Changan Univ Sch Highway Xian 710061 Shaanxi Peoples R China Northeast Forestry Univ Coll Civil Engn Harbin 150040 Heilongjiang Peoples R China

The performance of asphalt pavement is significantly influenced by the morphological characteristics of its aggregates, especially on its angularity. Evaluation of aggregate angularity is considered to be challenging because aggregates often have various shapes. Therefore, utilization of digital images in the evaluation of angularity has gained significant research interest in recent years. However, conventional manually processed images for evaluating the angularity of aggregates have the disadvantages of low efficiency and insufficient accuracy. This paper presents a novel application of convolutional neural networks (CNN) using digital images for evaluating aggregate angularity automatically. The research procedure is as follows: (a) develop a self-developed device for the acquisition of aggregate images;(b) establish an evaluation criterion for the angularity index (AI);(c) design a localization CNN and five AI CNNs;and (d) conduct a sensitivity analysis of the CNNs. First, a self-developed device is established based on the view-based approach to extract the 3D information of aggregates. Then, an evaluation criterion that is suitable for 3D images from aggregates is presented. Based on the 3D images and evaluation criterion, one localization CNN and five Al CNNs are jointly used to evaluate the Al of each aggregate. Finally, statistical analysis is performed to seek the optimal parameters for Al CNN, especially the kernel size, and to verify the sensitivity of Al CNN. The analysis includes the sensitivity to kernels size, image resolution, light, texture and aggregate size. The results indicate that the localization CNN is able to locate and abstract each aggregate from the images. The best size of the kernels is 6 x 6, and an AI CNN with a kernel size of 6 x 6 has a 0.0938 relative error for evaluating the AI using 300 PPI images. Moreover, Al CNN with a kernel size of 6 x 6 shows remarkable robustness under different light conditions, sizes and textures of ag

关键词： aggregate angularity aggregate index Convolutional neural network Image processing Sensitivity analysis

来源：评论

学校读者我要写书评

暂无评论

Influence of coarse aggregate angularity on the mechanical performance of cement-based materials

引用

CONSTRUCTION AND BUILDING MATERIALS 2019年 204卷 184-192页

作者： Lee, Seung Jae Lee, Chang Hoon Shin, Moochul Bhattacharya, Sumana Su, Yu Feng Florida Int Univ Dept Civil & Environm Engn Miami FL 33199 USA Western New England Univ Dept Civil & Environm Engn Springfield MA 01119 USA

This study aims to fundamentally understand the influence of angularity of coarse aggregate on the mechanical performance of cement-based materials. Three hypotheses are postulated to address the influence of aggregate angularity that negatively impacts the small-strain performances, while positively influences the property in the ultimate state at a large strain level. The morphology of two types of coarse aggregates is systemically quantified using an image-based analysis. This study experimentally corroborates the efficacy of the postulated hypotheses through a set of laboratory tests on cement-based cylinders. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Morphology aggregate angularity Coarse aggregate Cement-based materials Sphericity Roundness Image-based morphology analysis

来源：评论

学校读者我要写书评

暂无评论

Gene expression programming for evaluation of aggregate angularity effects on permanent deformation of asphalt mixtures

引用

CONSTRUCTION AND BUILDING MATERIALS 2019年 211卷 470-478页

作者： Leon, Lee P. Gay, Derek UWI Dept Civil & Environm Engn St Augustine Trinidad Tobago

The shape of the aggregate influences the particle interlocking capabilities, thus influencing the deformation behaviour of mixes. The research paper explores the use of gene-expression programming (GEP) as an unconventional approach to predict permanent deformation of asphalt concrete with the inclusion of aggregate angularity. Data for prediction of permanent deformation of dense graded asphalt concrete was obtained through laboratory experiments. The development and analysis of the proposed GEP technique was completed by using laboratory data. The new technique for the assessment of permanent deformation strain with additional angularity factor was developed. The GEP approach concluded satisfactory outcomes of the estimation of permanent deformation when compared to regression analysis. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： aggregate angularity Permanent deformation Asphalt concrete Gene expression programming

来源：评论

学校读者我要写书评

暂无评论

Image-Based Coarse-aggregate angularity Analysis and Evaluation

引用

JOURNAL OF MATERIALS IN CIVIL ENGINEERING 2020年第6期32卷

作者： Huyan, Ju Li, Wei Tighe, Susan Zhang, Yingjie Yue, Baofeng Univ Waterloo Dept Civil & Environm Engn Ctr Pavement & Transportat Technol Waterloo ON N2L 3G1 Canada Changan Univ Dept Informat Engn Middle Sect NanerHuan Rd Xian 710064 Peoples R China

The angularity of coarse aggregates significantly influences the performance of asphalt pavement. However, the research remains in the qualitative stage, and no universal evaluation standard has been proposed. This research proposes image-based methods to quantitatively analyze the angularity of coarse aggregates, thereby providing corresponding evaluation standards. First, aggregate levels of 4.75-9.5, 9.5-13.2, and 13.2-16 mm were obtained by sieving experiments, which were then abraded 0, 400, 800, and 1,200 times using a Los Angeles abrasion machine. Subsequently, the aggregate particle angularity parameters, including circumference, area, convex hull circumference, convex hull area, and total number of corner points, were calculated. Meanwhile, the aggregate imaging system (AIMS) gradient, skeleton extraction, convex hull, and uncompacted void content (UVC) methods were used to evaluate the angularities of the aggregates. Thereafter, the AC-13C-type mixture test specimens were formed using different angularity aggregates. On this basis, the angularity-related pavement skid resistance and rut resistance tests were conducted. The results show that the skeleton extraction method performs excellently for evaluating all aggregate levels, while the convex hull method is suitable for 9.5- and 13.2-mm aggregates, the AIMS gradient method is suitable for assessing 4.75- and 9.5-mm aggregates, and the UVC method is suitable for assessing 9.5- and 13.2-mm aggregates.

关键词： aggregate angularity Skeleton Convex hull Skid resistance Rut resistance

来源：评论

学校读者我要写书评

暂无评论

Precision of ASTM D 5821 standard test method for determining the percentage of fractured particles in coarse aggregate

引用

JOURNAL OF TESTING AND EVALUATION 2000年第2期28卷 67-76页

作者： Hand, AJ Epps, JA Sebaaly, PE Purdue Univ Sch Civil Engn W Lafayette IN 47907 USA Univ Nevada Dept Civil Engn Reno NV 89557 USA

An interlaboratory study was conducted to develop a precision statement for ASTM D 5821-95, Standard Test Method for Determining the Percentage of Fractured Particles in Coarse aggregate. The experimental design included ten laboratories, four materials, and three replicates per material per laboratory, resulting in 54 degrees of freedom. Outlier detection was given careful consideration due to the subjective nature of the method, and resulted in exclusion of one laboratory's data, reducing the degrees of freedom to 48. The materials included three partially crushed gravel blends and one quarry stone blend. As expected, multilaboratory variability was greater than single-operator variability. There was also a greater level of variability associated with two or more fractured face determinations than with one or more fractured face determinations. Surprisingly, the great est variability was observed for the quarry stone rather than for the crushed gravels. The results of the analysis were compared with other available data. The level of variability associated with this study was less than that observed in other studies, due most likely to the highly fractured nature of the materials used in the study.

关键词： HMA aggregate aggregate angularity fractured faces Superpave WesTrack

来源：评论

学校读者我要写书评

暂无评论

Modelling and evaluation of aggregate morphology on asphalt compression behavior

引用

CONSTRUCTION AND BUILDING MATERIALS 2017年 133卷 196-208页

作者： Liu, Pengfei Hu, Jing Wang, Dawei Oeser, Markus Alber, Stefan Ressel, Wolfram Falla, Gustavo Canon Rhein Westfal TH Aachen Inst Highway Engn Mies van der Rohe St 1 D-52074 Aachen Germany Univ Siegen Inst Highway Engn Paul Bonatz St 9-11 D-57076 Siegen Germany Univ Stuttgart Inst Rd & Transport Sci Pfaffenwaldring 7 D-70569 Stuttgart Germany Tech Univ Dresden Inst Urban & Pavement Engn Georg Schumann St 7 D-01187 Dresden Germany

Asphalt mixtures are widely used in the construction of high-grade highways and airport pavements. With regard to numerical simulations it was considered as homogeneous due to limitations of low computational capacity. In fact, it is a typical heterogeneous composite material consisting of aggregate with irregular shape and random distribution, asphalt binder and air voids. The heterogeneous numerical model is more consistent with reality and thus yields more reliable results. Experimental investigations have implied that morphological properties of aggregate have a great impact on the performance of asphalt mixtures. Unfortunately, it is extremely difficult to suppress the interferences from other features of the asphalt mixture in experiments, such as aggregate orientations, the spatial distribution of aggregates and air voids. In this study, the microstructural model of asphalt mixture used for uniaxial compression test was reconstructed based on X-ray CT scans, thus maintaining the original morphology of the aggregate. Then the angularity of the aggregate was decreased artificially while the other features of the asphalt mixture remained constant. Based on these microstructures three dimensional finite element models with different aggregate angularities were created followed by a simulation of a uniaxial compression test. The relationship between aggregate angularity and mechanical responses of the asphalt mixture, such as load-carrying capacity, creep deformation of the asphalt mastic, damage behavior and energy dissipation were investigated. The computational results indicate that the aggregate angularity significantly affects the mechanical responses of the asphalt mixture;some initial relationships were set up with high degrees of determination. The quantitative correlation is suggested to be analyzed based on extensive experimental and numerical studies in future research. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Asphalt mixture aggregate angularity Microstructure X-ray computed tomography Finite element method Damage behavior Energy dissipation

来源：评论

学校读者我要写书评

暂无评论

aggregate contributions to the performance of hot mix asphalt at WesTrack

Aggregate contributions to the performance of hot mix asphal...

引用

Symposium on aggregate Contribution to Hot Mix Asphalt (HMA) Performance

作者： Epps, AL Hand, AJ Epps, JA Sebaaly, PE Texas A&M Univ Dept Civil Engn College Stn TX 77843 USA

ISBN: (纸本)0803128924

Unexpected performance of coarse-graded and crushed stone mixtures when compared to fine-graded and partially crushed gravel mixtures at WesTrack led to an examination of consensus aggregate properties for all mixtures used. These properties did not explain the differences in performance, but an analysis of mixture sensitivity to asphalt content and percent passing the 0.075 mm sieve did highlight the potential for substantial changes in volumetrics in terms of air voids for coarse-graded Superpave mixtures. The rutting performance of both coarse and fine-graded mixtures was sensitive to asphalt content, with coarse-graded mixtures highly sensitive to decreases in asphalt content and both types of mixtures sensitive to increases in asphalt content. Increased variability in aggregate gradation for the coarse-graded mixture coupled with this sensitivity may explain the unexpected performance. Based on these results, a sensitivity analysis was recommended for inclusion in the Superpave mix design process. Rutting performance models also indicated that volumetrics and aggregate properties related to gradation significantly contribute to performance.

关键词： gradation Superpave restricted zone aggregate angularity fines volumetrics rutting and fatigue performance

来源：评论

学校读者我要写书评

暂无评论

Generation and evaluation of aggregate section using the fractal dimension

引用

CASE STUDIES IN CONSTRUCTION MATERIALS 2019年 11卷

作者： Ye, Sheng Han, Ding Li, Yang Anhui Commun Vocat & Tech Coll Dept Civil Engn Hefei 230051 Peoples R China Hefei Univ Technol Sch Civil Engn Hefei 230009 Peoples R China Anhui Sanlian Univ Sch Transportat Engn Hefei 230601 Peoples R China

A fractal dimension index for aggregate shape and an area index for aggregate size were used in this paper to construct fractal aggregate cross-sections which could characterize real aggregate contours. Firstly, images of the real section of asphalt concrete specimens were processed for the extraction of independent aggregate contours and the recognition of their fractal dimensions. Secondly, with square as the datum figure, the midpoint displacement method and the fractal dimensions were used to generate fractal aggregate cross-sections. Thirdly, numerical specimens were individually generated by square, circular and fractal aggregate cross-sections under three load conditions of uni-axial compression, uni-axial stretch and horizontal shear. Research results show that: 1) based on roundness, SP value and girth indices, fractal aggregate cross-section is closer to the real aggregate cross-section in terms of angularity when compared with the circular or square cross-section;2) shapes of aggregate cross-sections have obvious influences on the mechanical properties of asphalt concrete specimens. With the randomness and statistical features of aggregate cross-sections taken into account, the method of generating fractal aggregate cross-sections in the paper can construct reasonable numerical aggregates. (C) 2019 The Authors. Published by Elsevier Ltd.

关键词： Concrete aggregate section Fractal dimension aggregate angularity Image processing Microstructure model

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：