Influence of particle size and particle orientation on the shear strength parameters of unbound slate slag

Seth Knihtila, Adam F. Sevi, Brad Ruderman, John B. Stevens

In the proceedings of: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Transportation Geotechnics

ABSTRACT: The objective of this study is to determine if particle orientation and particle size have an influence on the angle of internal friction for unbound slate slag with an emphasis on low normal stresses. Slate slag samples were retrieved from the Paine Mountain slate tract, located in Northfield VT, USA, and sieved. Using parallel gradations and particle scalping techniques, four different gradation samples were produced for testing. In order to compare data between gradations, a relative density of 50% was used for all tested samples. In order to assess angle of repose of the slag under no confinement a Òpour testÓ was performed. Direct shear testing was also performed on all gradations to determine the angle of internal friction under normal stresses of 6.9, 14, 21, 69, 138, and 207 kPa (1, 3, 5, 10, 20, and 30-psi) normal loads. An additional direct shear test was performed using samples with particles carefully oriented perpendicular to the shear plane. The four random oriented granular gradation samples angle of internal friction ranged between 28-38 degrees while the vertically oriented sample found an apparent angle of internal friction of 75-degrees. The size of particles in the pour test was directly proportionate to the angle of repose found using this test. The smaller the grain sizes present in the sample, the steeper the angle of repose. The direct shear testing showed that as the particle size within the sample increased, the angle of internal friction also increased. The critical void ratio for all compiled slate samples was found to be between 14-21 kPa normal stresses. Most pronounced was the finding of the apparent angle of internal friction differing considerably with careful particle orientation. R…SUM… L'objectif de cette ”tude est de d”terminer si les orientation de particules et de la taille des particules ont une influence sur l'angle de frottement interne pour laitier ardoise mettant l'accent sur la basses des accouchements. Ardoise laitier ”chantillons r”cup”r”e par les voies de la montagne de Paine ardoise, situ” ‹ Northfield VT, USA, ont ”t” acquis et tamis”s. Ë l'aide des gradations parall‘les, quatre ”chantillons ont ”t” produites pour les tests. Afin de comparer les donn”es entre les gradations, une densit” relative de 50 % a ”t” test”e pour tous les ”chantillons. Afin d'”valuer ‹ angle de repos des scories sous aucune confinement un test pour a ”t” effectu”e. Diriger le cisaillement tests ont ”t” effectu”s sur tous les gradations pour d”terminer l'angle de frottement interne sous accouchements de 6.9, 13.79, 20.7, 68.9, 137.9, and 206.8 kPa (1, 3, 5, 10, 20, and 30-psi) charges normales. L'essai est ”galement r”alis” sur des ”chantillons avec particules soigneusement orient”s perpendiculairement au plan de cisaillement. La gradation granulaire quatre ”chantillons angle de frottement interne que se situait entre 28-38 degr”s, alors que l'”chantillon orient” verticalement a conclu avec un angle de 75 degr”s de frottement interne. La taille des particules, du test pour, est directement proportionnelle ‹ l'angle de repos ‹ aucune confinement. Plus la taille des grains pr”sente plus l'angle de repos. L'essai de cisaillement direct a montr” que plus les particules pr”sentes dans le cisaillement ”chantillon, plus l'angle de frottement interne. Le rapport de vide critique pour tous les ”chantillons ardoises compil”s s'est av”r” entre 3 et 5 psi. Aussi, l'angle de frottement interne diff‘re consid”rablement avec orientation de particules.

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Cite this article:
Seth Knihtila; Adam F. Sevi; Brad Ruderman; John B. Stevens (2011) Influence of particle size and particle orientation on the shear strength parameters of unbound slate slag in GEO2011. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GEO11Paper462,author = Seth Knihtila; Adam F. Sevi; Brad Ruderman; John B. Stevens ,title = Influence of particle size and particle orientation on the shear strength parameters of unbound slate slag,year = 2011}