# Curvature Coefficient

Written by Jerry Ratzlaff on . Posted in Geotechnical Engineering

Curvature coefficient, abbreviated as $$C_c$$, also called coefficient of curvature, a dimensionless number, classifies a soil as well graded or poorly graded.  For the soil to be well graded for a given sample, the range must be between 1 and 3.

## Curvature Coefficient formula

$$\large{ C_c = \frac{ D_{30}^2 }{ D_{60} \; D_{10} } }$$
Symbol English Metric
$$\large{ C_c }$$ = curvature coefficient $$\large{dimensionless}$$
$$\large{ D_{10} }$$ = is the sieve diameter (grain size) which there are 10% of particles go through. $$\large{in}$$ $$\large{mm}$$
$$\large{ D_{30} }$$ = is the sieve diameter (grain size) which there are 30% of particles go through. $$\large{in}$$ $$\large{mm}$$
$$\large{ D_{60} }$$ = is the sieve diameter (grain size) which there are 60% of particles go through. $$\large{in}$$ $$\large{mm}$$