Lesson 2/Learning Event 2
the classification is the primary letter of the symbol. The second letter is always M and the fourth letter
is always C. Figure 14 covers coarse-grained soils with less than 5 percent fines and greater than 12
percent fines.
FIGURE 14. SOIL CLASSIFICATION CHART
Coarse-grained Soil with Fines from 5 to 12 Percent
Soils with 5 percent or more fines but with less than or equal to 12 percent fines can be well-graded (W)
or poorly-graded (P) but, the amount of fines are enough to be significant when considering the soil for
use as a construction material. Therefore, when a soil has 5 - 12 percent fines we use a dual
classification to reflect both the gradation and type of fines.
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