Grain Size Distribution of Non-Cohesive Soils

The following particle size distinctions are made when grading non-cohesive types of soil:

Well-graded particle size distribution: The continuous grading curve traverses several particle size ranges. All particle sizes involved are partially present (see Image, e. g. curves 3 and 4).

Poorly-graded particle size distribution (uniformly graded): The grading curve runs steeply and, in the extreme case, it remains in just one particle size range (see Image, e. g. curves 5, 6 and 8).

Intermittently graded particle size distribution (gasp graded): The grading curve is staircase-shaped, as one or more fraction(s) is/are missing.