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Geomechanics and Engineering
  Volume 1, Number 4, December 2009, pages 323-335
DOI: http://dx.doi.org/10.12989/gae.2009.1.4.323
 


Fractal and laboratory analyses of the crushing and abrasion of granular materials
Luis E. Vallejo and Zamri Chik

 
Abstract
    Gravels forming part of the base of flexible pavements experience abrasion and crushing as a result of static and dynamic loads. Abrasion takes place when the sharp corners of the particles of gravel are removed as a result of compressive and shear loads. As a result of abrasion, the particles change in shape. Crushing is caused by the fragmentation of the particles into a mixture of many small particles of varying sizes. In this study, the abrasion and crushing of gravels are evaluated experimentally and analytically. The laboratory component of this study involves gravels that were subjected to abrasion and dynamic compression tests. The evaluation of the abrasion and crushing experienced by the gravel was carried out using fractals. In this study, the fractal dimension concept from fractal theory is used to evaluate: (a) the changes in shape, and (b) the crushing (fragmentation) of the original particles of gravel. It was determined that the fractal dimension of the profile of the particles decreased as a result of abrasion. With respect to crushing, the fragmentation fractal dimension was found to increase with the degree of breakage of the gravel. To understand the influence of crushing on the permeability of the gravels, the hydraulic conductivity of the gravels was measured before and after crushing. The hydraulic conductivity of the gravels was found to decrease with an increase in their level of crushing. Also, changes in the angle of friction of the granular materials as a result of abrasion was calculated using the Krumbein
 
Key Words
    crushing; abrasion; granular materials; laboratory analysis; fractals.
 
Address
Luis E. Vallejo: Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
Zamri Chik: Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
 

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