Determining the Specific Gravity of Soil - Soil Properties: Testing, Measurement, and Evaluation - page 57

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CHAPTER SIX

CHAPTER SIX

Determining the
Specific Gravity of Soil

Determining the
Specific Gravity of Soil

(Referenced Document: ASTM D 854)

In general, the term specific gravity is defined as the ratio of the mass
of a given volume of material to the mass of an equal volume of water.
In effect, it tells how much heavier (or lighter) the material is than
water. The particular geotechnical term specific gravity of soil actually
denotes the specific gravity of the solid matter of the soil and refers,
therefore, to the ratio of the mass of solid matter of a given soil sample
to the mass of an equal volume (i.e., equal to the volume of the solid mat-
ter) of water. Alternatively, specific gravity of soil may be defined as the
ratio of the unit mass of solids (mass of solids divided by volume of
solids) in the soil to the unit mass of water. In equation form,

INTRODUCTION

M s V s

r w

> M s

V s r w

G s (6-1)

where:
G s specific gravity of soil (dimensionless)
M s mass of solids, g
V s volume of solids, cm 3
r w unit mass (mass density) of water (1 g/cm 3 )
The method given in this chapter covers determination of specific
gravity of soils that pass the 4.75-mm (No. 4) sieve, using a pycnometer.

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