Comparison and Evaluation of Tests for Coarse Aggregate Particle Shape, Angularity, and Surface Texture

2000 ◽  
Vol 28 (2) ◽  
pp. 77 ◽  
Author(s):  
DR Petersen ◽  
RE Link ◽  
MS Hossain ◽  
F Parker ◽  
PS Kandhal
Keyword(s):  
Surface Texture ◽  
Particle Shape ◽  
Coarse Aggregate ◽  
Aggregate Particle

Uncompacted Voids and Particle Index Tests for Evaluating Coarse Aggregate

2000 ◽  
Vol 1721 (1) ◽  
pp. 100-105 ◽  
Author(s):  
M. Shabbir Hossain ◽  
Frazier Parker ◽  
Prithvi S. Kandhal
Keyword(s):  
Surface Texture ◽  
Particle Shape ◽  
Coarse Aggregate ◽  
Weighted Average ◽  
Mix Design ◽  
Design System ◽  
Test Results ◽  
Aggregate Particle ◽  
Index Tests ◽  
Individual Size

Coarse-aggregate angularity and surface texture are properties specified under the SuperpaveTM mix design system. To control specification requirements, the fractured-face count test is suggested. The use of a more objective test was investigated. Uncompacted voids and index of aggregate particle shape and texture tests were studied to measure coarse-aggregate angularity. The gradation of the sample has an obvious influence on both test results. Ways to separate the effect of gradation from aggregate angularity were studied. Viable options include testing a standard graded sample and computing a weighted average from tests of individual size fractions based on the gradation of the blend. When comparing aggregate sources, either option produces a comparable evaluation, but testing standard graded samples saves time. On the other hand, the weighted average is more appropriate for evaluating an aggregate blend. The index of aggregate particle shape and texture test and the uncompacted voids test provide comparable measures of coarse aggregate angularity and surface texture.

Study on Coarse Aggregate Gradation Analysis of Cement Treated Base Course Based on Core Sample Image

2011 ◽  
Vol 320 ◽  
pp. 445-449
Author(s):  
Li Qun Hu ◽  
Chao Fan Wang
Keyword(s):  
Coarse Aggregate ◽  
Core Sample ◽  
Morphological Operations ◽  
Threshold Method ◽  
Aggregate Gradation ◽  
Aggregate Particle ◽  
Sample Rotation ◽  
Passing Rate ◽  
Base Course ◽  
Good Quality Image

In order to get the coarse aggregate particle gradation of cement treated base course core sample dilled form the pavement, an image acquisition system is designed. The system mainly contains an Aviiva ® M2 CL line scan camera, a core sample rotation platform and a LED light source. The software are designed and implemented by using the Matrox Mil controls in the Visual Studio VB.NET. Test results show that when the camera exposure time is set to 800μs, good quality image of core sample can be obtained. In the study, the original core sample images of cement treated aggregate were improved by rescaling of each pixel, then were binarized by using adaptive threshold method. After getting the binary image, morphological operations were carried out to deal with the conglutinations of the particles. Next, characteristics of each particle, such as area, perimeter, fitting ellipse and minFeret were extracted to calculate the area passing rate of aggregate with different size. Results shows that, in this way, the gradation of coarse aggregate (>2.36mm) can be got and the method helps to get the coarse aggregate particle distribution of cement treated aggregate core sample quickly.

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

2005 ◽  
Vol 1929 (1) ◽  
pp. 1-9 ◽  
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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