Classification of soil on the basis of grain size

Classification of soil on the basis of grain size:

While taking into account the engineering behavior of the soil, the size of the soil grains and the distribution of the soil grain in the soil mass have the same effect.  On the basis of the grain size can be divided into two major categories

1. Coarse grained soils.
2. Fine grained soils.

• Coarse grained soils:

They are also called as cohesion less soils or the non cohesive soils. The forces between the particles of such soil are very less. The size of the particles in non cohesive soils is > or = to 0.075 mm due to their large size they are usually visible to the naked eye. This category of soils includes cobbles, boulders, sands and gravels.

• Fine grained soils:

Those soils in which particle size < or = to 0.075 mm are known as fine grained soils. Examples are clays. The particles do have sufficient cohesion because in these soils the forces between these particles are strong. The particle size is very small therefore they cannot be seen with naked eye and not even with powerful microscope.