Determining the Specific Gravity of Soil - Soil Properties: Testing, Measurement, and Evaluation - page 66

Equation (6-2) can be used to determine the calibrated volume of
the pycnometer, V p

M pw , c - M p
r w , c

V p (6-2)

656.43 158.68
0.99730

V p

499.10 mL

(Note that the density value, r w, c was determined from Table 6-1 for a
value of T c equal to 24°C.)
The mass of the solids, M s , can be computed by subtracting the
mass of the evaporating dish, M d , from the mass of the dish plus oven-
dried soil, M ds :

M s 387.15 289.14 98.01 g

The mass of the pycnometer and water at the test temperature ( T t )
can be calculated by Eq. (6-3).

M pw , t M p V p r w , t (6-3)

1 2

M pw , t 158.68 1 499.10 21 0.99777 2 656.67 g

(Note that the density value, r w,t was determined from Table 6-1 for
a value of T t = 22°C.)
From Eq. (6-4),

M s

G t (6-4)

M pw , t M pws , t M s

1 2

98.01

G t 2.71

656.67 718.52 98.01

1 2

From Eq. (6-5),

G 20 ° C K G t (6-5)

G 20 ° C 0.99957 2.71 2.71

1 21 2

(Note that the value of K was determined from Table 6-1 for a value of
T t equal to 22°C .)
These results, together with the initial data, are summarized in the
form on page 68. At the end of the chapter, two blank copies of this form
are included for the reader's use.

The single value determined (and therefore reported) in this test proce-
dure is the specific gravity of soil, G s . For most soils, the value of G s falls
within the range 2.65 to 2.80. Table 6-3 gives some typical values of G s
for different types of soil.

SUMMARY