# Curvature Coefficient

Written by Jerry Ratzlaff on . Posted in Geotechnical Engineering

Curvature coefficient, abbreviated as $$C_c$$, also called coefficient of curvature, 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

 $$\large{ C_c = \frac{ D_{30}^2 }{ D_{60} \; D_{10} } }$$

### Where:

 Units English Metric $$\large{ C_c }$$ = curvature coefficient $$\large{in}$$ $$\large{mm}$$ $$\large{ D_{10} }$$ = 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. $$\large{in}$$ $$\large{mm}$$