The document discusses various soil classification systems including engineering, agronomic, and geological classifications. It covers concepts such as particle size distribution curves, coefficients of uniformity and curvature, Atterberg limits, and classification charts used in systems like AASHTO and USCS to classify soils based on grain size and plasticity. The document also provides examples of classifying soils based on laboratory test results like sieve analyses, liquid limit, plastic limit, and natural water content.

1. 1

2.  Purpose of Soil Classification Test
 Principles of Soil Classification Test
 Types of Soil Classification (Argonomic
Classification, Geological classification,
Engineering Classification)
 Engineering Soil Classification Test ,
organic(peat, humus, muck etc)
 AASHTO Soil Classification System
 USCS
 Sieve Analysis (Well Graded, poorly graded,
Gap graded)
 Atterberg Limits (Liquid Limit , Plastic
Limit, ) 2

3.  Coarse Grained Soils (G & S)
 Fine Grained Soils M, C ,O
 Gradation Symbols W, P
 Liquid Limit & Plasticity Symbols H, L
 Composite Symbols
 GW, SW, GP, SP, GC, GM, SC, SM, ML, MH, CL,
CH, OL, OH

4. System/
Soil
Type
Boulder
s
Cobbles Gravel Sand Silt Clay Colloids
Coarse Medium Fine
ASTM
D422
300˃ 300 -75 75 –
4.75
4.75 –
2.0
2 -.425 .425 –
0.075
.075 - .
005
.005 - .
001
0.001˂

5. System/
Soil Type
Boulders Gravel Sand Silt Clay Colloids
Coarse Fine
AASHTO
T88
75˃ 75 – 2.0 2.0 –
0.425
.425 –
0.075
.075 - .005 .005 - .001 0.001˂

6. System
/ Soil
Type
Boulde
rs
Cobble
s
Gravel
Coarse
Fine Sand Fines (Silt, Clay)
Coarse Mediu
m
Fine
USCS 300˃ 300 -75 75 – 19 19 –
4.75
4.75 –
2.0
2 -.425 .425 –
0.075
0.075˂

7.  Sieve Analysis (Mechanical, Hydrometer)
 Well graded
 Gap Graded
 Poorly Graded
 Coefficient of Uniformity
 Coefficient of Curvature

8. 10
openings
per inch
# 10 sieve
1-
inch
Smaller sieves are
numbered
according to the
number of openings
per inch

9. Sieves larger
than the #4
sieve are
designated by
the size of the
openings in
the sieve

10. 0.0001 0.001 0.01 0.1 1 10 100
0
20
40
60
80
100
Particle size (mm)
%Finer
W Well graded

11. 0.0001 0.001 0.01 0.1 1 10 100
0
20
40
60
80
100
Particle size (mm)
%Finer
W Well graded
U Uniform

12. Grading curves
0.0001 0.001 0.01 0.1 1 10 100
0
20
40
60
80
100
Particle size (mm)
%Finer
W Well graded
U Uniform
P Poorly graded

13. Grading curves
0.0001 0.001 0.01 0.1 1 10 100
0
20
40
60
80
100
Particle size (mm)
%Finer
W Well graded
U Uniform
P Poorly graded
C Well graded with some clay

14. Grading curves
0.0001 0.001 0.01 0.1 1 10 100
0
20
40
60
80
100
Particle size (mm)
%Finer
W Well graded
U Uniform
P Poorly graded
C Well graded with some clay
F Well graded with an excess of fines

15. Prepare paste
of soil finer
than # 40 sieve
Place Soil in
Cup

16. Cut groove in
soil paste with
standard
grooving tool

17. Rotate cam
and count
number of
blows of cup
required to
close groove by
1/2”

18. 18
Das, 1998

19. 19
Das, 1998
Note:
The first group from the left to fit the test data is the
correct AASHTO classification.

20. 20
Passing No.200 86%
LL=70, PI=32
LL-30=40 > PI=32
[ ]
3347.33
)10PI)(15F(01.0
)40LL(005.02.0)35F(GI
200
200
≅=
−−+
−+−=
Round off A-7-5(33)
Passing No.200 86%
LL=70, PI=32
LL-30=40 > PI=32

21. 21
(Holtz and Kovacs, 1981)
LL
PI
HL
•The A-line generally
separates the more
claylike materials
from silty materials,
and the organics
from the inorganics.
•The U-line indicates
the upper bound for
general soils.
Note: If the measured
limits of soils are on
the left of U-line,
they should be
rechecked.

22. Unified Soil Classification System Plasticity Chart
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100
LIQUID LIMIT
PLASTICITYINDEX
CH
CL
ML
MH
CL-ML

23.  A sample of dry coarse grained material of mass
500gm was shaken through a nest of sieves and the
following results were obtained
Sieve # Diameter (mm) Mass Retained
(gm)
4 4.75 0
10 2 14.8
20 0.85 98
40 0.425 90.1
100 0.15 181.9
200 0.75 108.8
pan 6.1

24.  Plot the particle size distribution curve
 Determine the a) effective size b) average particle
size c) uniformity coefficient d) coefficient of
curvature
 Determine the textural composition of soil i.e the
amount of gravel, sand etc.

25.  Following are the GSD results of soil A & B.
Sieve # %age Finer
SOIL A SOIL B
4 99 23
10 96 18
40 89 09
100 79 05
200 70 04
LL (%) 49 _
PL (%) 24 _
PI 25 NP

26.  Determine the Group Index
 Determine the textural composition of
soil
 Classify the soil according to AASHTO

28.  The grain size Analysis for a soil is given as
Sieve # %age Passing
4 94
10 63
20 21
40 10
60 7
100 5
200 3

29.  Given that the soil is nonplastic, classify the
soil by using the unified soil classification
system.

30.  A sample of soil was tested in the laboratory and
results of the laboratory tests were as follows
 Liquid Limit = 42% , Plastic Limit = 16%
 Sieve Analysis Shows
Sieve # %age Passing
4 100
10 93
40 81
200 60

31. Classify the Soil Sample By
 The AASHTO CLASSIFICATION SYSTEM
 USCS

32.  A liquid test is conducted on a soil sample in the cup
device gave the following results
Number of
Blows
10 19 23 27 40
Water
Content
(%)
60 45.2 39.8 36.5 25.2

33.  Two determinations for the plastic limit gave water
contents of 20.30% and 20.8%. Determine
 Liquid Limit & Plastic Limit
 Plasticity index
 Liquidity index if the natural water content is
27.4%
 Void ratio at the liquid limit if Gs = 2.7
 If the soil were to be loaded to failure, would you
expect a brittle failure?