Question

Confirm the ASHTO classification and USCS classification

Soil A:
AASHTO
A-2-7
USCS
The soil is SM (silty sand)
Soil B:
AASHTO
A-1-a
USCS
soil is poorly graded
Soil C:
AASHTO
Coarse grained A-1-b
USCS
soil is SC-sm
Soil D:
AASHTO
Slity Clay - A-7-6
USCS
soil is CH
Soil E:
AASHTO
Slity Clay - A-4
USCS
soil is CL-ML

Sieve	%Passing
	A	B	C	D	E
37.5			100
26.5	100		94
19	89	100	82
9.5	76	78	69
4.75	59	62	59
2.36	50	48	52	100
1.18	41	35	41	94
0.425	33	27	38	79	100
0.15	25	10	34	68	80
0.075	20	2	20	55	55
Atterberg Limits
LL WI	48	24	20	58	26
PL Wp	35	24	17	24	22

Answer 1

All the above AASHTO Classification are correct but there is slight different classification according to USCS Classification as follows:

Soil A - {AASHTO - A-2-7} and {USCS - GM} Silty Gravel

Soil B - {AASHTO - A-1-a} and {USCS - SP} Poorly Graded Sand

Soil C - {AASHTO - A-1-b} and {USCS - GM} Silty Gravel

Soil D - {AASHTO - A-7-6} and {USCS - CH} Highly compressible clay

Soil E - {AASHTO - A-4} and {USCS - ML} Low compressible silt.

You can find the explanation below for different USCS Classifications...