When vibration is given to binary mixture of coarse and fine granules, the coarser granules are gradually collected in the upper layer and so the finer granules are in the lower layer. To find the amount of such segregation, the coefficient of the segregation was defined, and the experimental formula was proposed to relate this coefficient to the vibration time.
In our experiments, spherical glass beads were used for samples, and the vessel used for the experiments was a plastic cylinder. Ten plastic rings, each with inside diameter of 3cm and height of 1.7cm, were piled together to form a cylinder. Coarse granules were first poured into this cylinder, and then fine granules were poured over the coarse. After that, vibration was given the cylinder vertically.
The higher the weight ratio of the coarse granules to that of the fine rose, the more easily their segregation took place. Depending on the difference of granular size and the vibrating condition, the state of segregation varied considerably.