Minimum and Maximum Densities of Granular Materials

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Abstract
Laboratory tests were conducted to determine minimum and maximum densities of arroyo sand, concrete sand, Ottawa sand, and glass beads. Minimum densities were determined by six different methods using two different molds. Maximum density tests were performed using an electromagnetic vibrator producing vertical simple harmonic motion. The vibration parameters investigated were frequency, acceleration, displacement, and the duration of vibrations. The minimum densities obtained by using the ASTM Test for Relative Density of Cohesionless Soils (D 2049-69) were considerably higher than those obtained by using several other simple procedures. Acceleration appeared to be the most important vibration parameter, and accelerations greater than the optimum acceleration (the acceleration at which the maximum density of a soil was obtained) caused a decrease in the maximum density. We recommend that these tests be performed at different amplitudes of acceleration and that the acceleration be continuously monitored during the test. A simple harmonic motion of the soil container gave results which were highly reproducible. We recommend that the soil container be directly attached to the moving core of the electromagnetic vibrator and that the vibrating table be eliminated.

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