Impact of the coarse aggregate shape parameters on compaction characteristics of asphalt mixtures

The aggregate shape properties produced from the different crushing techniques influence the performance properties of the asphalt mixtures. The objective of this study was to classify the aggregates into spherical, flat, elongated and flat, and elongated shapes, collected from impact crusher and jaw crusher of two sources, and to calculate the shape parameters, such as aspect ratio, shape factor, form factor, sphericity, roundness, and angularity index. In addition, this study also investigated the effects of this classification on the Marshall stability and volumetric properties of asphalt mixtures prepared from the respective shape of aggregates. The results showed that the aggregate of different fractions (passing 37.5 mm and retained on 4.75 mm) produced from the jaw crusher of Margalla quarry showed better shape parameters. The spherical aggregates collected from all crushers showed 20–30% higher Marshall stability of the blends by improving the mechanical and volumetric properties of the asphalt mixtures.

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Quantification of Coarse Aggregate Shape and Its Effect on Engineering Properties of Hot-Mix Asphalt Mixtures

Journal of Testing and Evaluation ◽

10.1520/jte12396j ◽

2001 ◽

Vol 29 (6) ◽

pp. 513 ◽

Cited By ~ 28

Author(s):

RE Petersen ◽

RE Link ◽

J-S Chen ◽

M-S Shiah ◽

H-J Chen

Keyword(s):

Hot Mix Asphalt ◽

Coarse Aggregate ◽

Asphalt Mixtures ◽

Engineering Properties ◽

Aggregate Shape

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The impact of coarse aggregate shape on the behavior of self-compacting high-performance concrete

E3S Web of Conferences ◽

10.1051/e3sconf/20184900079 ◽

2018 ◽

Vol 49 ◽

pp. 00079

Author(s):

Krzysztof Ostrowski

Keyword(s):

High Performance ◽

Coarse Aggregate ◽

High Performance Concrete ◽

Significant Proportion ◽

Rheological Parameters ◽

Concrete Technology ◽

Binder Ratio ◽

Strength And Stiffness ◽

Aggregate Shape ◽

The Impact

Self-Compacting High Performance Concrete (SCHPC) presents a crucial step in the development of concrete technology. The most important features of self-consolidating concrete are flowability, segregation resistance and passing ability. Generally, the rheological properties are modified by effective superplasticisers and water to binder ratio. The aim of this study is to focus on the important aspect of the impact of shape of the coarse aggregate on fresh concrete mixture properties, strength and deformability of SCHPC. Coarse aggregate is a significant proportion of the concrete volume and therefore has a meaningful influence on its quality. By appropriate selection of the shape of the grain aggregate, it is possible to affect the rheological parameters of concrete. The results presented in this study indicated that the shape of the grains of coarse aggregate has an impact on the strength and stiffness of SCHPC. Moreover, the occurrence of irregular grains of coarse aggregate causes lower slump flow and higher plastic viscosity in comparison to concrete mixtures with regular grains only. The research presented in this article is part of the author's wider research devoted to this issue.

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Effect of Coarse Aggregate Morphology on the Resilient Modulus of Hot-Mix Asphalt

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198105192900101 ◽

2005 ◽

Vol 1929 (1) ◽

pp. 1-9 ◽

Cited By ~ 9

Author(s):

Tongyan Pan ◽

Erol Tutumluer ◽

Samuel H. Carpenter

Keyword(s):

Surface Texture ◽

Coarse Aggregate ◽

Resilient Modulus ◽

Asphalt Binder ◽

Aggregate Size ◽

Asphalt Mixtures ◽

Maximum Aggregate Size ◽

Asphalt Mixes ◽

Aggregate Morphology ◽

The Relationship

The resilient modulus measured in the indirect tensile mode according to ASTM D 4123 reflects effectively the elastic properties of asphalt mixtures under repeated load. The coarse aggregate morphology quantified by angularity and surface texture properties affects resilient modulus of asphalt mixes; however, the relationship is not yet well understood because of the lack of quantitative measurement of coarse aggregate morphology. This paper presents findings of a laboratory study aimed at investigating the effects of the material properties of the major component on the resilient modulus of asphalt mixes, with the coarse aggregate morphology considered as the principal factor. With modulus tests performed at a temperature of 25°C, using coarse aggregates with more irregular morphologies substantially improved the resilient modulus of asphalt mixtures. An imaging-based angularity index was found to be more closely related to the resilient modulus than an imaging-based surface texture index, as indicated by a higher value of the correlation coefficient. The stiffness of the asphalt binder also had a strong influence on modulus. When the resilient modulus data were grouped on the basis of binder stiffnesses, the agreement between the coarse aggregate morphology and the resilient modulus was significantly improved in each group. Although the changes in aggregate gradation did not significantly affect the relationship between the coarse aggregate morphology and the resilient modulus, decreasing the nominal maximum aggregate size from 19 mm to 9.5 mm indicated an increasing positive influence of aggregate morphology on the resilient modulus of asphalt mixes.

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Analysis and optimization of mechanical properties of recycled concrete based on aggregate characteristics

Science and Engineering of Composite Materials ◽

10.1515/secm-2021-0050 ◽

2021 ◽

Vol 28 (1) ◽

pp. 516-527

Author(s):

Jiangwei Bian ◽

Wenbing Zhang ◽

Zhenzhong Shen ◽

Song Li ◽

Zhanglan Chen

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Coarse Aggregate ◽

Aggregate Size ◽

Peak Stress ◽

Recycled Concrete ◽

Maximum Aggregate Size ◽

Coarse Aggregates ◽

Aggregate Content ◽

Aggregate Shape

Abstract The most significant difference between recycled and natural concretes lies in aggregates. The performance of recycled coarse aggregates directly affects the characteristics of recycled concrete. Therefore, an in-depth study of aggregate characteristics is of great significance for improving the quality of recycled concrete. Based on the coarse aggregate content, maximum aggregate size, and aggregate shape, this study uses experiments, theoretical analysis, and numerical simulation to reveal the impact of aggregate characteristics on the mechanical properties of recycled concrete. In this study, we selected the coarse aggregate content, maximum aggregate size, and the aggregate shape as design variables to establish the regression equations of the peak stress and elastic modulus of recycled concrete using the response surface methodology. The results showed that the peak stress and elastic modulus of recycled concrete reach the best when the coarse aggregate content is 45%, the maximum coarse aggregate size is 16 mm, and the regular round coarse aggregates occupy 75%. Such results provide a theoretical basis for the resource utilization and engineering design of recycled aggregates.

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