Curvature Coefficient
Curvature coefficient, abbreviated as \(C_c\), also called coefficient of curvature, a dimensionless number, classifies a soil as well graded or poorly graded. It is a measure of the fineness or coarseness of the soil particles. Particle size distribution curves are commonly used in geotechnical engineering to describe the distribution of different sizes of particles in a soil sample. These curves provide information about the proportion of various particle sizes within the soil.
Curvature coefficient categorizes fluids into different regimes
 Mildly Curved Flow (C < 1)  The curvature effects are relatively small, and the flow behaves similarly to that in a straight channel.
 Moderately Curved Flow (1 < C < 100)  The curvature starts to significantly influence the flow patterns, leading to secondary flow structures.
 Strongly Curved Flow (C > 100)  The curvature dominates the flow behavior, and the secondary flow patterns become even more pronounced.
Curvature Coefficient formula 

\( C_c \;=\; D_{30}^2 \;/\; D_{60} \; D_{10} \) (Curvature Coefficient) \( D_{30} \;=\; \sqrt{ D_{60} \; D_{10} } \) \( D_{60} \;=\; D_{30}^2 \;/\; C_c \; D_{10} \) \( D_{10} \;=\; D_{30}^2 \;/\; C_c \; D_{60} \) 

Solve for Cc
Solve for D30
Solve for D60
Solve for D10


Symbol  English  Metric 
\( C_c \) = curvature coefficient  \(dimensionless\)  
\( D_{30} \) = is the sieve diameter (grain size) which there are 30% of particles go through.  \(in\)  \(mm\) 
\( D_{60} \) = is the sieve diameter (grain size) which there are 60% of particles go through.  \(in\)  \(mm\) 
\( D_{10} \) = is the sieve diameter (grain size) which there are 10% of particles go through.  \(in\)  \(mm\) 
Tags: Coefficient Soil Surveying