Specific Gravity of Soil

Soil specific gravity is the ratio of the density of void-less material to the density of distilled water at a certain temperature, say 270c. The specific gravity of soils is a useful data when it comes to the evaluation of volume in the soil. The differ

How to do specific gravity test

We require four different weights in order to simplify this test namely;

         i.            The weight of pycnometer or gas jar

       ii.            The weight of pycnometer or jar filled with the soil

      iii.            The weight of pycnometer, void-less material and water

     iv.            The weight of pycnometer filled with water

Specific gravity test soil

a)      Oven dry the sample in the oven with temperature ranging  between 1050c to 1100c

b)      Record the weight of the pycnometer or gas jar as M1

c)       The next step is to record the weight of either pycnometer or the jar filled with enough materials as M2

d)      Then fill the pycnometer or jar with the soil and water

e)      Shake the mixture thoroughly at least for 25 minutes and fill the remaining space with water to the brim M3

f)       Weigh the pycnometer or jar filled with water M4

How to calculate specific gravity

Specific gravity of soil= (m2-m1)/ (m4-m1)-(m3-m2)

Example of how to calculate specific gravity

Test #



Weight of empty pycnometer-M1

455.6 g

455.0 g

Weight of pycnometer and material-M2

903.3 g

901.9 g

Weight of pycnometer, material and water-M3

1140.1 g

1141.6 g

Weight of pycnometer with water-M4

861.6 g

859.2 g

Specific gravity

2.646 g

2.717 g



Specific gravity units can be expressed in grams per cubic centimeters (g/cm3) or kilograms per cubic meters (Kg/m3)


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