Physical and Statistical Models for Bulking of Sand
Four physical models and one statistical model are proposed to provide quantitative estimates of the extent of the contribution of water film, entrapped water vapor, and particle aggregates to the process of bulking of sand. The limiting conditions of each model are also discussed. A new concept of void-to-aggregate-volume-index (VAVI) is proposed. The experimental study, performed on two fractions of Narmada sand, suggests that VAVI is larger for finer sand. The dependence of VAVI on moisture is complex. It is confirmed that the porosity of sand is maximum when the moisture content is 5 to 7%. This observation is duly explained on the basis of a new concept of moisture per contact per particle due to the disappearance of apparent cohesive forces. The models and concepts developed in this study may be extended to other granular media.