###
**Uniformity coefficient(Cu)**

The uniformity coefficient is a measure of particle size range and given by
the ratio of D60
and D10
size of particles.It
is denoted by Cu .**Thus, Cu=D60/D10**

**Where,D60 =Size of the particle corresponding to 60% finer**

D10=Size of the particle corresponding to 10% finer.

###
**Coefficient of curvature(Cc)**

The coefficient of curvature is a measure of
gradation of particles and given by the following expression:**Cc=(D30)2/D60.D10**

Where,D60 =Size of the particle corresponding to 60% finer.

D30=Size of particle corresponding to 30% finer.

D10=Size of the particle corresponding to 10% finer.

The size D10 is some times called effective size.The value of Cu is nearly equal to unity for a uniformly of poorly graded soil.The value of Cc is more than 1.0 but less than 3.0 for a well graded soil.Cu is greater than 6 for sands.