Particle size distribution curve

Particle size distribution

1. Particle size distribution curve

2. Curve A- well graded soil (good representations of all type particle) Curve B- uniformly graded soil (most of the particle are in same size) Curve c- well graded sand Curve E - gap graded soil (some intermediate particle are missing)

3. Uniformity coefficient (Cu): Uniformity coefficient is a measure of particle-size range and is given by the ratio of D 60 and D 10 sizes: Cu = D 60 /D 10 Uniformly grade soil, Cu is nearly unity. For well graded soil , cu > 4 for gravel. cu = 6 for sand .

4. COEFFICIENT OF CURVATURE ( cc): The shape of particle-size curve is represented by the Coefficient of curvature cc, given by Cc = (D 30 ) 2 /(D 10 x D 60 ) For well graded soil , cc must between 1 to 3.

5. F or coarse grained soil, certain particle size such as D 10 ,D 30 and D 60 . D 10 – Represents a size, in mm such that 10%of particles are finer than this size . It is called as effective diameter or effective size. D 30 – Represents a size, in mm such that 30%of particles are finer than this size. D 60 – Represents a size, in mm such that 60%of particles are finer than this size.