What is Uniformity Coefficient(Cu) And Coefficient of Curvature(Cc) of Soil

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.

cable ampacity or current carrying ...
cable ampacity or current carrying capacity

Thus, Cu = D60/D10

Where,

  • D60 = Size of the particle corresponding to 60% finer and,
  • 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 well-graded soil. Cu is greater than 6 for sands.

Read Also:

Pipette Method

Atterberg Limits

Sieve and Sedimentation Analysis