Ballast practice exam #6
6. what type of soil would be best for slab-on-grade construction?
A. Clayey sand
B. organic silt
C. poorly graded gravel
D. lean clay
Correct answer C. This confuses me bec per my attachment from Ching section 3.18, the base course of a slab on grade is gravel but then the soil beneath it can be anything else. Wiki says "Slab-on-grade foundations are commonly used in areas with expansive clay soil, particularly in California and Texas." (http://en.wikipedia.org/wiki/Shallow_foundation) so i am not sure if the question is asking which is the best base course or which is the best soil below the base course.
any ideas?