Density

Definition

Density is a property dependent upon the compactness of matter, defined as the mass contained within a volume. With units of grams per cubic centimeter (g/cm³, in the CGS system) or kilograms per cubic meter (kg/m³, in the MKS system), the density of soil and rock depends on the volume of the mineral particles, and the volume of water and air contained within the voids between the particles and within the particles (Fig. 1). Wet density and dry density are calculated to indicate the in situ material condition relative to the solid components. Density of a material can also be expressed as the specific gravity, a dimensionless parameter, by relating the material density to that of water at 4 °C.

Density, Fig. 1

Schematic diagram representing three phases of material in a volume of earth materials: solid, liquid, and gas. (a) Angular particles with relatively small void volume (pore space). (b) Uniform rounded particles with a small range of sizes and relatively large void...