The document describes procedures for determining the liquid limit and plastic limit of soil samples. The liquid limit test involves adding water to soil and determining the moisture content at which a groove closes after 25 blows. The plastic limit is the moisture content at which a soil ball crumbles after rolling out to 3mm diameter. These limits are used to classify soils and predict properties like strength and compressibility. The plasticity index, defined as the liquid limit minus the plastic limit, provides further information on soil type and reactivity. Proper determination of the Atterberg limits is important for building foundations to ensure suitable shear strength and volume change with moisture fluctuations.

1. Objective
Student should be able to:Determine the liquid and plastic limit of soil samples for identification
and classification of dried soil.
Knowing that the determination of these limits is also used to predict
the shear strength and sedimentof soil.

2. Theory
The Atterberg limits can be used to distinguish between silt and clay, and it can
distinguish between different types of silts and clays. These limits were created
by Albert Atterberg, a Swedish chemist. They were later refined by Arthur
Casagrande. These distinctions in soil are used in picking the soils to build
structures on top. Soils when wet retain water and expand in volume. The
amount of expansion is related to the ability of the soil to take in water and its
structural make up (the type of atoms present). These tests are mainly used on
clay or silty soils since these are the soils that expand and shrink due to
moisture content. Clays and silts react with the water and thus change sizes
and have varying shear strengths. Thus these tests are used widely in the
preliminary stages of building any structure to insure that the soil will have the
correct amount of shear strength and not too much change in volume as it
expands and shrinks with different moisture contents.
Plasticity index
The plasticity index (PI) is a measure of the plasticity of a soil. The plasticity
index is the size of the range of water contents where the soil exhibits plastic
properties. The PI is the difference between the liquid limit and the plastic limit
(PI = LL-PL). Soils with a high PI tend to be clay, those with a lower PI tend to be
silt, and those with a PI of 0 (non-plastic) tend to have little or no silt or clay.
PI and their meanings
0 – Non-plastic
(1-5)- Slightly plastic
(5-10) - Low plasticity
(10-20)- Medium plasticity
(20-40)- High plasticity
 40 Very high plasticity

3. EQUIPMENT
equipment
Apparatus Casagrande
Can
Sieve # 36 (0425 mm)
Porcelain bowl
Spatula
picture

4. Distilled Water
Glass plate
Pan Balance – sensitive to 0.1 gram

5. PROCEDURE
A. Determination of liquid limit
Description
Prepare about 250 grams of ground 0425 mm sieve
transparent.
Check drop tray (bowl casagrade) using a calibration
block size of 10 mm thick.
3) Mix the soil with distilled water earlier in the
porcelain bowl until smooth with a spatula. Alliance
mixture (paste) occurs when it looks creamy and
uniform colour. Separate the mixture about 30
grams of mixture and place in sealed containers for
plastic limit test.
Fill in the earlier part of the soil mixture into the
porcelain bowl until smooth the soil surface
casagrade with a spatula. By using the tools for
creating grooves, one groove are lined along the
centre line axis through the centre of the bowl.
Groove maker to be held upright to the surface of
the bowl
The spin being spun at a rate of 2 cycles per second
and number of blows to close the groove along the
13 mm was recorded.
Picture

6. Take 10 grams of soil in the valleys which are closed
to determine moisture content. More land is
brought out and put in bowl porcelain again. Wash
and dry the bowl casagrade
The excess land in the bowl of porcelain mixed with
a small increase distilled water. Repeat steps 3 to 6
at least 5 times for a total impact of between 50 and
10. Plot a graph of a straight line for moisture
content versus number of blows on semi-log graph
paper and determine the liquid limit the impact of
land 25 times
B. Determination of plastic limit
Description
Divide the land which has been separated
from the first program to the same three
examples make it spherical.
Soil ball then rolled up with a finger on a glass
plate until it forms a cylinder diameter of 3
mm. If the land has not been split, fold and
roll the land ceases to be a cylinder 3mm. This
is repeated until the land is split on the
cylinder diameter of 3mm. Keep the Soil in a
covered container for moisture content.
Repeat step 2 remaining soil example
Picture

7. Data and analysis
Liquid limits
No of Can
Number of
Impact
Can + Wet Soil
Weight (g)
Can + dry soil
weight (g)
Water weight (g)
Can Empty
Weight (g)
Dry soil weight
(g)
Moisture
content (%)
1
49
2
41
3
23
4
18
5
15
0.067
0.061
0.064
0.060
0.063
0.063
0.058
0.062
0.059
0.062
0.004
0.050
0.003
0.48
0.002
0.050
0.001
0.049
0.001
0.051
0.066
0.057
0.059
0.057
0.059
30.1
30
16.67
10
10
Example :
= 0.31
Mass of water
Moisture content % = -------------------Total weight of Solid mass
Example :
= 0.31
0.31 x 100 = 30.1 %
x 100

8. Plastic limits
No. of Can
Can + Wet Soil Weight
(g)
Can + dry soil weight
(g)
Water weight (g)
Can Empty Weight (g)
Dry soil weight (g)
Moisture content (%)
Average Moisture
content (%)
1
0.049
2
0.049
3
0.053
0.048
0.048
0.052
0.001
0.047
0.048
1
0.001
0.047
0.048
1
0.001
0.051
0.052
1
1
Example:
=1
Mass of water
Moisture content % = -------------------Total weight of Solid mass
Example:
=1
1 x 100 = 100 %
Plasticity index = (LL – PL)
=17-1
=16 %
x 100

9. Discussion
The importance of the liquid limit test is to classify soils. Different
soils have varying liquid limits. Also to find the plasticity index of a
soil you need to know the liquid limit and the plastic limit.
The values of these limits are used in a number of ways. There is also
a close relationship between the limits and properties of a soil such
as compressibility, permeability, and strength. This is thought to be
very useful because as limit determination is relatively simple, it is
more difficult to determine these other properties. Thus the
Atterberg limits are not only used to identify the soil's classification,
but it allows for the use of empirical correlations for some other
engineering properties.
Different types of clays have different specific surface areas which
controls how much wetting is required to move a soil from one
phase to another such as across the liquid limit or the plastic limit.
From this activity, it can predict the dominant clay type present in a
soil sample. High activity signifies large volume change when wetted
and large shrinkage when dried. Soils with high activity are very
reactive chemically. Normally the activity of clay is between 0.75 and
1.25, and in this range clay is called normal. It is assumed that the
plasticity index is approximately equal to the clay fraction (A = 1).
When A is less than 0.75, it is considered inactive. When it is greater
than 1.25, it is considered active.

10. Conclusion
The conclusion is, another method for measuring the liquid limit is
the fall cone test. It is based on the measurement of penetration
into the soil of a standardized cone of specific mass. Although the
Casagrande test is widely used across North America, the fall cone
test is much more prevalent in Europe due to being less
dependent on the operator in determining the Liquid Limit.
The importance of the liquid limit test is to classify soils. Different
soils have varying liquid limits. Also to find the plasticity index of a
soil you need to know the liquid limit and the plastic limit.

11. Reference
University of Washington lecture notes
Soil Physical Properties--Mechanics
Seed, H.B. (1967). "Fundamental Aspects of the Atterberg
Limits". Journal of Soil Mechanics and Foundations Div.,
92(SM4),
Das, B. M. (2006). Principles of geotechnical engineering.
Stamford, CT: Thomson Learning College.
Geotechnical engineering from
http://trid.trb.org/view.aspx?id=38900

12. Atterberg
limits
Test

13. Content
no
Title
page
1
Objective
3
2
Theory
4
3
Equipment
5
4
Procedure
7
5
Data and analysis
9
6
Discussion
11
7
Conclusion
12
8
Reference
13