The grain size of a soil indicated that D10 = 0.75 mm, D30 = 1.5 mm and D60 = 3 mm. The uniformity co-efficient of this soil is
- A0.5
- B1.0
- C2.0
- D4.0Correct
Solution
Concept
Uniformity coefficient
Formula
Cu = D60 / D10
Step-by-step solution
1. Cu = D60 / D10 = 3 / 0.75 = 4.
Explanation
The uniformity coefficient measures the range of particle sizes. Cu = D60/D10; the coefficient of curvature Cc = D30² / (D10 × D60) = 1.5² / (0.75 × 3) = 1.0.
Shortcut
Cu = D60/D10; Cc = D30²/(D10·D60).
Common mistake
Giving Cc (=1.0) instead of Cu.
Correct answer: D) 4.0