A soil mass contains 40% gravel, 50% sand and 10% silt.

A soil mass contains 40% gravel, 50% sand and 10% silt. This soil can be classified as

1. silty sandy gravel having coefficient of uniformity less than 60.
2. silty gravelly sand having coefficient of uniformity equal to 10.
3. gravelly silty sand having coefficient of uniformity greater than 60.
4. gravelly silty sand and coefficient of uniformity cannot be determined.

Gravel: 40%; Size = 4.75 mm
∴ D₆₀ = 4.75 mm
S_and = 75mm
S_and + gravel = 50 + 40 = 90%
∴ D₁₀ = 75 mm = 0.075 mm

C_u =	D₆₀
	D₁₀

=	4.75
	0.075

= 63.33 > 60
∴ Soil is gravelly silty sand with C_u > 60.