Grading and classification of soil

Well graded soil:- It shows good representation of diameter of each particles.

Poorly graded soil / Uniformly graded soil:- Single diameter of particle exceed in a soil. eg. Aeoline soil.

Gap graded soil :- Sum particles are more in quantity, where sum particles missing in soil. 

Grain Soil Distribution Curve

 

Classification of soil
 Diameter / size                                      Soil type 

1) <2u                                                           clay
2) 2u - 75u                                                    Silt
3) 75u - 425u                                    Fine sand 
4) 425u - 2mm                                   Mid sand
5) 2mm - 4.75 mm                        Fine Gravel
6) 4.75 mm - 20 mm                    Fine Gravel
7) 20mm - 80mm                     Coarse Gravel
8) 80mm - 300mm                               Cobble
9) >300mm                                         Boulder


Symbols

         Sr.                   Symbol                   Group Name
            1                       SC                          Clayey Sand
         2                       SM                         Silty Sand
              3                       SG                          Gravel Sand
                  4                       GC                         Clayely Gravel
              5                       GM                         Silty Gravel
                  6                       GS                           Sandy Gravel
               7                       CS                           Sandy Clay
             8                      CM                           Silty Clay
                 9                      CG                            Gravel Clay
              10                     MC                           Clayey Silt
               11                     MS                             Sandy Silt
                12                     MG                            Gravel Silt

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