Effect of the quasi rate of loading in Particle Crushing and Engineering Properties of Black Tough Sand

of tough black sand will be studied experimentally. The Black tuff
sand was obtained from the Al-Hala area (Al Tafila) in southern
Jordan. Sand chemical composition is composed mainly of SiO2
with a considerable amount of Fe2O3, Al2O3, and CaO oxides. The
experimental works will be conducted at different normal stresses
(136 kPa, 245 kPa, 463 kPa, and 899 kPa), different relative
densities (20%, 40%, 60%, and 80%), and different rates of loading
(0.50 mm/minute, 1.00 mm/minute and 2.00 mm/minute) using the
direct shear tests. All test specimens were prepared with uniformly
graded sand, passing United States standard sieve #4, and retained
United States standard sieve #8.
The results of direct shear tests were analyzed to examine the stressstrain response to different shearing rates and to obtain the shear
strength parameters from the Mohr-Coulomb envelope to
investigate the factors influencing shear strength parameters,
especially the friction angles. After shearing each specimen, sieve
analysis was performed to determine the extent of the percentage of
particle breakage. Results showed that the rate of loading in direct
shear tests plays a significant role in the amount of crushing and in
the internal friction angles. The amount of crushing as well as shear
strength was increased with the increased rate of loading. Moreover,
the microstructural analysis used scanning electron microscopy
(SEM) analysis showed that the crushing from granular has
primarily resulted from disintegration, grinding, and abrasion of
particles.