Question

In a particle size distribution curve, the coefficient of curvature ($C_c$) for a soil having particle size $D_{10}$, $D_{30}$, $D_{60}$ corresponding to percentage finer value (N) 10%, 30%, and 60%, respectively, can be calculated as:

• A. $C_c = \frac{(D_{30})^2}{D_{10}D_{60}}$
• B. $C_c = \frac{D_{30}}{D_{60}}$
• C. $C_c = \frac{(D_{60})^2}{D_{10}}$
• D. $C_c = \frac{(D_{30})^3 \cdot D_{10}}{D_{60}}$

Hint:

Remember: Use $C_c = \frac{(D_{30})^2}{D_{10} \cdot D_{60}}$ for gradation analysis. A well-graded soil typically has $1 \leq C_c \leq 3$.

Answer 1

The Correct Option is A

The coefficient of curvature ($C_c$) is defined as:
\[C_c = \frac{(D_{30})^2}{D_{10} \cdot D_{60}}\]
where:
$D_{10}$: Particle size at 10% finer.
$D_{30}$: Particle size at 30% finer.
$D_{60}$: Particle size at 60% finer.
This formula is essential in evaluating the uniformity and gradation of soil particles.