If uniformity coefficient (Cu) is 9 and coefficient of curvature (Cc) is 1 for a soil, then D30/D10 for the soil is
- A1
- B2
- C3Correct
- D4
Solution
Concept
Relation between Cu, Cc and D30/D10
Formula
Cu = D60/D10; Cc = D30² / (D10 D60) ⇒ (D30/D10)² = Cc · Cu
Step-by-step solution
1. (D30/D10)² = Cc × Cu = 1 × 9 = 9. 2. D30/D10 = 3.
Explanation
Writing Cc = (D30/D10)² × (D10/D60) = (D30/D10)²/Cu, and rearranging, we get (D30/D10)² = Cc·Cu. With Cc = 1 and Cu = 9, D30/D10 = 3.
Shortcut
(D30/D10)² = Cc × Cu.
Common mistake
Taking the ratio as Cu/Cc = 9.
Correct answer: C) 3