Group index of soils

The group index of soils (GI) indirectly expresses the bearing capacity of soil material. The values obtained are higher than zero (0). Low values from 0 to 4 indicate a soil material with good bearing capacity, whereas values 8 indicate a soil material with bearing capacity varying from low to bad. 

Under no circumstances does the determination of group index exempt the engineer from not determining the bearing capacity of the soil material by other laboratory or in situ tests. 

General classification Coarse soil material, percentage passing through the 0.075 mm sieve 35% Fine soil material (silt-clayey), percentage passing through the 0.075 mm sieve 35%  

Typical types of soils Gravels, sand and Fine sand Silty or clayey sand gravels Sihy soils Clayey soils  

Suitability as subgrade sand gravels Excellent to good Fair to poor  

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