The graphical representation of sieve analysis is also knows as Grade curve.

1.      Readings recorded from sieve analysis is plotted in graph shown below (take particle size on X-axis and percent finer on Y-axis). This graph is also known as Grading Curve.

2.      With respect to this graph 10%, 30% and 60% finer, and dimeter from graph is also designated as D10, D30 and D60

3.      Calculate the Coefficient of uniformity (Cu)and Coefficient of curvature (Cc) by using following equations,

Cu = D60/ D10

Cc = D230/ (D60 x D10)

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## Uniformity Coefficient (Cu):

• ·        The Uniformity coefficient is express as the ratio of D60 to D10.
• ·        Where D60 is the value where the particle size of aggregates are 60% finer and 40%  are coarser.
• ·        And D10 is the value where the particle size of aggregates are 10% finer and 90%  are coarser.
• ·             And Cu is calculated as, Cu = D60/ D10
• ·        If Cu is greater than 4: Soil is classified as well graded
• ·        If Cu is less than 4: Soil is classified as poorly/unifromly graded

## Coefficient of Curvature (Cc):

• ·        The coefficient of curvature is express of D30, D60  and D10.
• ·        Where D30 is the value where the particle size of aggregates are 30% finer and 70%  are coarser.
• ·        D60 is the value where the particle size of aggregates are 60% finer and 40%  are coarser.
• ·        And D10 is the value where the particle size of aggregates are 10% finer and 90%  are coarser.
• ·        And Cc is calculated as,
• ·        If Cc is between 1 to 3: Soil is classified as well graded
• ·        If Cu and Cc is equal to 1: Soil is classified as single sized soil mass.