Test: Soil Classification & Soil Structure - Civil Engineering (CE) MCQ

GW is well graded gravel for which coefficient of uniformity (C_u) > 4.
SW is well graded sand for which coefficient of uniformity (C_u) > 6
ML is silt with low plasticity (< 35%)
CL is clay with low plasticity (< 35%). It also possess low compressibility.

∴ D₆₀ = 4.75 mm
D₁₀ = 0.075 mm

So correct answer is ‘c’.

In ML;
M represents inorganic soil,
L represents low compressibility, 
MH. Inorganic soil of high compressibility,
SL: Sand of low compressibility,
CH: Clay with high compressibility,

Total mass of dry sample = 1000 g
Soil passing through 4.75 mm sieve = 980 g
=9801000×100=98 %
Soil passing through 0.075 mm sieve
= 270 g = 27%
Liquid limit, wL=40%
Plastic limit, wp=18%
Plasticity Index, Ip=wL−wP
= 40 - 18 = 22%
Since less than 50% passes through 0.075 mm sieve, soil is coarse grained
More than 50% of coarser fraction passes through 4.75 mm sieve, so it is sand.
Since fines(< .075 mm) are more than 12%
so using A line chart
IPC=0.73(wL−20)
= 0.73 (40 - 20) = 14.6
Ip>IPC, So point lies above A line (clayey type)
Hence, soil is classified as SC.

As 50% of soil is clay. So it will be classified as clay.

980 gm of soil passes through 4.75 mm sieve
270 gm of soil passes through 0.075 mm sieve
Liquid limit of the soil,
Plastic limit of the soil,
Formula of plasticity index is given by,

More than 50% of the material passes through 4.75 mm sieve therefore it is sand. Percentage finer is 27%. It is clayey sand, SC.

Lower the shrinkage limit greater is the volume change.
For coarse grained soil with fines < 5% classification will be GP, GW, SP, and SW, for fines > 12% classification will be based on plasticity chart as GM, GC, SM and SC. For fines 5 -12% dual classification like GP - GM; GP - GC etc., will be used.
At liquid limit the soils possess a certain shear strength which is the smallest value that can be measured in a standard procedure. From direct shear tests on different types of clays it is found that liquid limit corresponds to a shearing strength of about 2.7 kN/m².

If shrinkage limit Is less the volume change with change in water content will be more.