Page 45 - ebook_soil engineering practical workbook_15112021

4.10 Note

1. Particle size, also called grain size, refers to the diameter of individual grains
of sediment. The size of particle of international standard are as follow:

Class Size Range (mm)

Gravel 2.0 - 63

Sand 0.063 – 2.0

Fines Less than 0.063

2. The uniformity coefficient is given by the relation,
D
C  60
u
D 10

Where D60 is the diameter corresponding to 60% finer in the particle-size
distribution and D10 = 0.093 mm (from curve).

3. The coefficient of gradation may he expressed as:

D  2
C  30
c
D 10  D 60

Where D30 is the diameter corresponding to 30% finer in the particle-size
distribution. (from curve)

4. Weight of soil passing = Wt of dry sample – Wt of soil retained.

37 | Soil Engineering Practical Workbook