Soil Mechanics Lab: Classifying Soil Using the USCS Method

This practical assignment focuses on classifying a coarse-grained soil sample using the Unified Soil Classification System (USCS). The methodology involves conducting a sieve analysis and sedimentation test to determine the particle size distribution. The assignment details the procedure, including weighing the soil sample, sieving it through a series of sieves with decreasing aperture sizes, and recording the mass retained on each sieve. Calculations are performed to determine the percentage of soil retained on sieve no. 200 and sieve no. 4, leading to the conclusion that the soil is sandy. The assignment references established handbooks for soil classification, emphasizing the importance of accurate soil characterization for construction and engineering purposes. Desklib provides access to similar solved assignments and past papers for students.

Excetutive summary
Soil are grouped into fine – graided soil, coarse – grained soils and natural soil, on the
perspective of classifying the soil based to texture, the coarsed – grained soils have 50 percent
for evey amount or less of the soil material passing the sieve number 200, whereas the fine –
grained soil have more than 50 percent for amount of material passing sieve number 200. The
coarse grained soils are further divided into gravel and rock soils, sans and sandy soil. Fine
grained soils are further divided based on water cutoff of 50 percent and less, soil having more
than 50 percent of water breaking.
Gravel and sandy soils have no limit that can be used to differentiate them, therefore it is
impractable if conducting their division. For proof coarse grained soil are classified as rock if the
coarse division is larger than sieve number 4 and sand if the coarse division is better than sieve
number 4.

Introduction
Soils are identified based on their characteristic texture and versatility and their gathering
conducts. Soil exist in natural state independently as rock, sand or in single segment, however,
they are generally found mixed on different particle sizes, where each constituent contributes to
the quality of the natural state of soil, the soil classification will depend on the quality of the soil
characterization, this characterization quality will be used to specify the right soil that will be
used for building.
The properties based on this qualities have been discovered and used in various categories of
fields, they can also be detected using wi-h test experience which will give out its accuracy on
the type of sample the soil is used
a. Rocks, sand and fine soils that will pass sieve number 20
b. Grain measure circulation mixture
c. Compressibility state which is based on how the soil particles are arranged .
Objectives
To classify the soil and describe the procedure of the unified soil classification field method
which used for soil identification

Methodology
Procedure
1. Weigh a sample of approximately 200 gm of soil provided
2. Assemble a series of sieves, with aperture size in descending order: 4.75 mm, 2.36 mm,
1.18 mm, 600 μm, 425 μm, 300 μm, 150 μm and 75 μm.
3. Sieve the soil sample through the series of sieves, record the mass of soil retained on each
sieve, and the mass passing the finest mesh (i.e. soil retained in the pan).
4. A sedimentation test of the fine material in the pan will be performed following the
procedure described in the Australian Standard
Data
AS sieve
Siz
e
Weig
ht
Sieve +
sample
g
(2)
Mass
retained
g
(2) – (1)
Cumulative
mass retained
, g
% cumulative
Mass retained
% mass
passing
4.750 427.23 427.52 0.29 0.29 0.139309 99.86069
2.360 432.31 454.53 22.22 22.51 10.81328 89.18672
1.180 382.85 417.01 34.16 56.67 27.22294 72.77706
0.600 345.43 384.57 39.14 95.81 46.02488 53.97512
0.425 336.53 368.28 31.75 127.56 61.27684 38.72316
0.300 342.32 365.24 22.92 150.48 72.28707 27.71293
0.150 303.09 325.23 22.14 172.62 82.92261 17.07739
0.075 289.93 298.67 8.74 181.36 87.1211 12.8789
pan 252.21 278.66 26.45 207.81 99.82706 0.172936

Graph
0.010.1110
0
10
20
30
40
50
60
70
80
90
100
Particle Diameter (mm)
% Passing
GRAVEL Coarse
SAND
Medium
SAND
Fine
SAND SILT/CLAY
Calculations
Calculation of the percentage of soil retained on sieve no. 200 sieve.
R200=100−F200=100−12.8789=87.1211
Since R200 > 50, the soil under investigation is a coarse-grained soil.
Next we calculate the percentage of soil retained on no. 4 sieve
R4 =100− percent passing on no . 4 sieve
¿ 100−99.86069=0.13931
R4 = 10< 0.5R200 = 43.56, the soil is sandy.

Conclusion
In conclusion, it is observed that the percentage of soil retained in sieve number 200 is 87.1211%
and because R200is greater than 50% the soil sample retained here will be coarse grained, and this
will continue until the sample of soil that will be retained at sieve number 4 which is 0.139331%
and since R40 =1< 0.5 R200=43.56, the soil will be classified as sandy.

References
Howard, A. K., & Engineering and Research Center (U.S.). (1986). Soil classification handbook:
Unified soil classification system. Denver, CO: Geotechnical Branch, Division of Research and
Laboratory Services, Engineering and Research Center, Bureau of Reclamation.
Michalyna, W. (2000). Soil landscapes of Canada-Manitoba: Unified soil classification system
for engineering applications. Winnipeg: Land Resource Unit, Brandon Research Centre,
Agriculture and Agri-Food Canada, Research Branch.