Determination of average grain sphericity in granular porous media

Natural granular porous media are composed of particles of varying grain shapes and grain volumes. The average grain sphericity of a finite number of grains with varying grain sphericity and grain volume is of much practical value and utility. Average grain sphericity is shown to be a function of fractional porosity and specific surface of the natural porous media as well as of specific spherical surface per unit solid volume if the natural irregular grains are replaced by fictitious spheres of equal volume as those of natural grains. These three variables can be easily measured by thin section or by thin section cum loose grain methods but the thin section method is preferred because of its greater accuracy in the whole range of size of interest, its ease and quickness, and its applicability to consolidated as well as unconsolidated granular media.