What is Bulk, Submerged, Dry and Saturated Density of Solids of Soil


The density or unit weight of a soil mass is defined as its weight per unit volume.

a. What is Bulk Density (𝛾)

The bulk density or moist density 𝛾 is defined as the total weight (W) as a soil mass per unit of its total volume (V). 
Thus, 𝛾 =W/V

b. What is Submerged Density (𝛾sub)

The submerged density or buoyant unit weight is defined as the submerged weight (  W_{d} )sub of the soil solids per unit of total volume (V) of the soil mass. 
Thus,  \gamma_{sub} = \frac{(W_{d})_{sub} }{V}

It is also expressed as,  \gamma_{sub} = \gamma_{sat} - \gamma_{w}
Where  \gamma_{w} is the density of water and   \gamma_{sat}  is the saturated density of soil.

c. What is Dry Density

The dry density or dry unit weight 𝛾d is defined as the weight of solids (  W_{d} ) per unit of total volume (V) of the soil mass. 
Thus,  \gamma_{d} = \frac{W_{d} }{V}

d. What is Saturated Density

When the soil mass is saturated, its bulk density is called the saturated density. Thus saturated density is the ratio of the total weight of a saturated soil sample (  W_{sat} ) to its total volume (V). 
Thus,  \gamma_{sat} = \frac{W_{sat} }{V}

e. What is the Density of Solids

The density or unit weight of soil solids Is the weight of soil solids (  W_{d} ) per unit volume of the solids (  V_{s} ). 
Thus,  \gamma_{s} = \frac{W_{d} }{V_{s}}

Read also: 

Define Specific Gravity, Bulk Specific Gravity, Air Content and Percentage Air Voids 

What is Porosity, Void Ratio, Water or Moisture Content, And Degree of Saturation of Soil