Uniformity Coefficient

Written by Jerry Ratzlaff on . Posted in Geotechnical Engineering

Uniformity coefficient, abbreviated as \(C_u\), also called coefficient of uniformity, 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 greater than 4 to 6.  If less than 4 it is classified as poorly graded.

 

Uniformity Coefficient formula

\(\large{ C_u =  \frac{ D_{60} }{ D_{10} }     }\)   

Where:

 Units English Metric
\(\large{ C_u } \) = uniformity coefficient \(\large{dimensionless}\)
\(\large{ D_{10} } \) = is the sieve diameter (grain size) which there are 10% of particles go through. \(\large{in}\) \(\large{mm}\)
\(\large{ D_{60} } \) = is the sieve diameter (grain size) which there are 60% of particles go through. \(\large{in}\) \(\large{mm}\)

 

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Tags: Coefficient Equations Soil Equations Geotechnical Equations