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

Following are the definition and equation of porosity, void ratio, water content, and degree of saturation:

1. What is Porosity (n)

The porosity of a given soil sample is the ratio of the Volume of voids (Vv) to the total volume (V)of the given soil mass. It is generally expressed as a percentage and denoted by ‘n‘ It is also termed as percentage voids.

Thus, n = Vv/V

2. What is Void Ratio (e)

The void ratio of a given soil sample is the ratio of the volume of voids (Vv) to the volume of soil solids (Vs) in the given soil mass. It is generally expressed as a fraction and denoted by ‘e’.

Thus, e = Vv/Vs

3.Water Content or Moisture Content (w)

The water content or moisture content (w) is defined as the ratio of the weight of water (Ww) to the weight of solids (Wd) in a given soil mass. It is denoted by m or w. It is generally expressed as a percentage.

Thus,  w = (Ww/Wd ) * 100 %

4. What is the Degree of Saturation (Sr)

The degree of saturation is defined as the ratio of the volume of water (Vw) present in a given soil mass to the total volume of voids (Vv) in it. It is denoted by (Sr). It is generally expressed as a percentage and is also known as per cent saturation.

Thus, Sr = Vw / Vv