Modeling of the maximum and minimum void ratios for binary-sized granular materials

Maximum and minimum void ratios are two fundamental parameters for evaluating the packing efficiency of granular materials. For binary-sized granular materials composed of two size classes (coarse and fine), many packing models has been proposed for predicting their packing density (relating to void ratio). However, analytical packing models directly based on maximum and minimum void ratios are very limited in the field of geotechnical engineering. In this study, using a concept of dominant size class, a nonlinear packing model was developed for predicting the maximum and minimum void ratios with respect to fines content. Only two parameters (filling coefficient and embedment coefficient) were required in the proposed model and they were found to be closely related to the particle size ratios between the two size classes. The applicability and accuracy of the developed model were verified by experimental results of the crushed pellets of GMZ bentonite in this work and that of several other granular materials from literature. Furthermore, the relationship between the maximum and minimum void ratios was investigated. It appeared that the maximum void ratios were linearly related to the minimum void ratios with the same slope, regardless of the particle size ratio between the two size classes.