Artificial sand production for laboratory uses

Abstract

Natural sands, like standards sands, are used for geotechnical purposes in laboratory experiments. However, they have some certain drawbacks such as variability even in the same deposit, high cost of collecting samples or becoming unavailable over the time. So, they are not suitable for parametric study concerning geotechnical laboratory experiments. The objective of this M.S. thesis is producing artificial sand in order to use in geotechnical laboratory experiments for parametric studies and examining its geotechnical properties. The usability of the pellets as artificial sand for laboratory uses can be decided by evaluating and comparing the parameters such as mineralogy, roundness, sphericity, specific gravity, water absorption, grain size distribution and internal friction angle with those of the natural or standard sands. In order to evaluate the performance of artificial sand; natural sand samples, crushed sand samples and artificial sand samples produced from cement and fly ash, alternatively, were prepared. Constrained modulus tests are conducted to specify the strain-stress behavior of the samples at rest, in K0 condition and to find crushability values. Internal friction angles of pellets, produced both from fly ash and cement, are close to the internal friction angle values of crushed sand. Crushed sand and Sakarya sand have internal friction angle values ranging between 33.6o and 41o. Whereas pellets produced from fly ash and cement have internal friction angle values between 32.8o to 42o. Lastly, stress path tests and cyclic triaxial tests were conducted. The samples produced from fly ash and cement reaches to the failure after 25 and 23 cycles, whereas Sakarya sand and crushed sand reaches to the failure after 19 and 21 cycles with amplitude of 50 kPa and 2 Hz cyclic sinusoidal loading. It is seen that pellets have similar or better performance than the performance of natural and crushed sands under the condition of cyclic loading.