Specific gravity determination of marine sediments

Abstract

Accurate specific gravity measurements are required for the analysis of physical properties of marine sediments. Application of the bottle pycnometer technique, the standard determination method, is time consuming, tedious, and perhaps subject to inaccuracies in the case of fine particulate matter. A review of methods currently in use was conducted to ascertain the present state of the art and reveal any new developments in this field. Specific gravity values for three operating modes of the air comparison pycnometer, two of which use helium, were compared with bottle pycnometer values for four test materials. The air comparison pycnometer determinations, regardless of operating mode, resulted in higher specific gravities than their counterpart bottle pycnometer values for kaolinite, montmorillonite, and marine sediment samples. The use of helium as the comparison medium in the air comparison pycnometer appears to reduce the surface active characteristics of the colloidal material. Specific gravity determinations by all four test methods agreed very well for powdered quartz samples with a known specific gravity.