Sieve Analysis Identify what problem occurs when calculating

Sieve Analysis Identify what problem occurs when calculating Cc and Cu for soils having more than 10% passing the No.200 sieve. Discuss possible options to resolve the problem

Solution

since only 10% of the soils are passing through the 200 no sieve so the remainig soils are the soils which includes the fine and coarse grained soils. The coeffcient of unifomity and the coefficient of gradation or curvature,where:

Cu=D60/D10 and Ck=D30^2/d60Xd10

for a single grained soils both Cu & Cc will be equal to unity,

Cu>5 Well graded soil Cu<3 uniformy graded soil

the value of Ck should be between 0.5-2.

For a sol which is having high plasticity which show high amount of expansion and contraction, just like clayey soils, for those soils sieving process will be difficult and thus the calculation of the Cu & Cc. so to overcome this the soil can be mixed with the soil having less plasticity or oven dried sils with the same characteristics of the highly plastic soils. After mixing the soils the plasticity of the soil reduces and can be fit for further operations.