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FACULTY OF Engineering
Civil Engineering Department
Soil lab - ENCE 311
Experiment NO. 6
Group D
Partners Names and IDs:
Mahmoud Sehweil 1110744
Islam Assi 1122300
Rouya Arnaout 1121852
Mohammed Jubran 1122148
Instructor: Dr. Sahem Murshed
Eng. Montaser AlWarasna
Date of Conducting the Experiment 14 .Mar.2015
Date of Submitting the Report 23.Feb.2015
FALL CONE METHOD
FA
LL
CO
NE
ME
TH
OD
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TABLE OF CONTENTS.
Index __ 2
Introduction __ 3
Objectives __ 3
Background (Theory) __ 4
Instruments __ 5
Procedure __ 5
Measurements and Calculation __ 5
Conclusion __ 7
Engineering Use __ 8
References __ 8
Copy of Data signed __ 9
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INTRODUCTION
At 1900, Atterberg developed a method to describe consistency of
fine grained soil. Depending on the
water content (w%), he divided soil into four basic states:
1. Solid state.
2. Semisolid state.
3. Plastic state.
4. Liquid state.
Through these states he determined three limits:
1. Shrinkage limit: is the water content at the minimum volume
of the soil.
2. Plastic limit: which turns soil from plastic into semisolid
state.
3. Liquid limit: the water content at which the behavior of a
clayey soil changes
from plastic to liquid.
These limits determined experimentally at the lab, for our
experiment we will determine both plastic and
liquid limits.
To apply this description for a certain soil, several method are
used, such as Casagrande apparatus for
liquid limit, and rolling method for plastic limit, in this
experiment we used to apply fall cone method, which
stands over penetration principle using cone at 30 degrees with
80 g for liquid limit, and 240 g for plastic limit.
According to this test, liquid limit defined as the w%
corresponding to penetration of 20mm after 5
seconds. While plastic limit depend on a formula as will be
pointed to it in theory.
This test considered as more accuracy than other tests, because
human error is less, and it is portable
and easy to use.
AIMS AND OBJECTIVES.
Determine plastic limit and liquid limit, in order to describe
the consistency of fine-grained soil.
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THEORY.
Liquid Limit (LL): The water content at which the soil will
transformed from plastic state to liquid state. &
(LL) is the moisture content at which a standard cone of apex
angle 30 and weight of 0.78N will penetrate a
distance d=20 mm in 5 seconds when allowed to drop from a
position of point contact with the soil surface.
The Determination of the water content can be by the
equation:
W (%) = (weight of can and moist soil- weight of can and dry
soil)/ weight of can and moist soil
The relation between the penetration (x-axis) and the moisture
content (w %) (Y-axis)
Should be drawn after many trials, from this graph we determine
the value of liquid limit (L.L.).
All the consistency limits depends on the type and amount of
clay mineral so the liquid limit of the soil will
change from clay to another as shown in the following table.
L.L Clay mineral
35-100 Kaolinite
55-120 IIlite
100-800 Montmorillonite
Flow index: is the slop of the flow line.
= 1 2
1 2
D is the penetration.
Plastic limit test:
Plastic limit: The moisture content at the point of transition
from semisolid to plastic state. & it is the moisture
content at which a cone of apex angle 30 and weight of 2.35N
will penetrate a distance d=20mm in 5 seconds
when allowed to drop from a position of point contact with the
soil surface.
Plastic limit (P.L)=Liquid limit(L.L) -4.2*w
W: is the difference in w% at penetration equal to 20mm between
the two lines from L.L test and P.L test.
Plasticity index: is a number giving an indication about the
degree of plasticity of the soil. And we can use it to
determine if the soil is good or bad to the structural projects,
as the value of plasticity index increase this means
that the soil particles become finer so the soil become bad for
the structural projects.
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PI=Liquid limit (L.L) - plastic Limit (P.L)
INSTRUMENTS.
o Balance sensitive to 0.01 gm .
o Sample of soil passed sieve #200.
o Oven.
o knife to mix soil with water.
o Fall cone device with timer.
o 6 water cans.
o Plastic squeeze bottle
PROCEDURE. o Taking the sample of passing sieve No.40 , we smash
using hammer to obtain a fine soil passes
through No. 20.
o Bring cans moisture, and weight this cans was taken. o Sample
was mixed with water until the paste is uniform. o After that, the
weight of moist soil was taken(W2). o The soil sample was taken to
the fall cone device , the cone was just touching the soil surface,
here
we measure the initial reading then , the penetration test was
done, by releasing the cone for just 5
sec, finally the final penetration was known.
o The penetration during the 5 seconds is d = d2 d1.
o The soil sample was placed on the oven for 24 hours, to
calculate the percent of water. o The test was done 3 times for P.L
samples, and other 3 for the L.L.
DATA AND CALCULATIONS. TABLE 1-2. PLASTIC LIMIT DATA.
Test
No.
Can
No.
Mass Of Can ,
W1 (g)
Mass Of Can
+ Moist Soil
,W2 (g)
Mass Of Can
+ Dry Soil ,
W3 (g)
Initial
Penetration
Final
Penetration
Penetration
1 99 28.3 291.8 207.7 43 300 25.7
2 23 25.6 272.1 195.9 11 191 18.0
3 98 27.2 286.9 209.7 45 174 12.9
Description PI
Nonplastic 0
Slightly plastic 1-5
Low plasticity 5-10
Medium plasticity 10-20
High plasticity 20-40
Very high plasticity >40
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o Sample Calculations Plastic limit.
Trail No. 1, Can No.99
Water content is determined by W(%) = 2331
100%
W(%) = 291.8 207.7
207.7 28.3 100% = 46.87%
Penetration = (Final reading First reading)
10 =
(300 43)
10 = 25.7
Trail No. 2, Can No.23
W(%)2 = 44.74
Penetration =18.0 %
Trail No. 3, Can No.98
W(%)2 = 42.30 %
Penetration =12.9
TABLE 2-2. LIQUID LIMIT DATA.
Test
No.
Can
No.
Mass Of Can
, W1 (g)
Mass Of Can
+ Moist Soil,
W2 (g)
Mass Of Can
+ Dry Soil ,
W3 (g)
Initial
Penetration
Final
Penetration
Penetration
1 16 26.8 317.2 223.8 113 336 22.3
2 54 28.2 297.7 218.8 117 235 11.8
3 4 32.6 324.4 234.0 107 282 17.5
o Sample Calculations Liquid limit.
Trail No. 1, Can No.16
Water content is determined by W(%) = 2331
100%
W(%) = 317.2 223.8
223.8 26.8 100% = 47.41%
Penetration = (Final reading First reading)
10 =
(336 113)
10 = 22.3
Trail No. 2, Can No.54
W(%)2 = 41.40 Penetration = 11.8
Trail No. 3, Can No.4
W(%)2 = 44.90 Penetration = 17.5
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Liquid limit = (w %) corresponding to penetration of 20mm after
5 seconds
Liquid limit (L.L) Form the graph = .46 2 % Plastic limit (P.L)
Form the graph = 45.0 %
(. ) = = % %
FI = 47.4141.41
22.311.8= 45.14
Plasticity Index (P.I) = L.L P.L = 46.2 45.0 = 1.2 %
ANALYSIS AND CONCLUSION.
Knowing the Atterberg limits of the soil (P.L & L.L) is
important because it is used for classification of
the soil, by finding L.L, P.L, and to calculate some necessary
values such that plasticity index.
By looking at our data above and our curves we can notice some
important things.
o This method is more accurate than the last one used to find
P.L and L.L , because the human error was
less than the first one.
o The slop of the liquid curve is the Flow Index (F.I) = 45.14
%
41
42
43
44
45
46
47
48
0 5 10 15 20 25 30
W(%
)
PENETRATION
Liquid Limit & Plastic Limit
Plastic Limit
Liquid Limit
Liquid limit
Plastic Limit
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o The Plasticity Index in our experiment equals 1.2 which give
an idea about soil description and here our soil sample is Slightly
Plastic.
o L.L and P.L are used in USCS (Unified Soil Classification
System) to classify the soil into silt or clay.
o Since L.L for our soil = 46.2 % , we can conclude that
Kaolinite is the main component of our soil.
The A-line Equation
. = 0.73 (. 20) P.I = 0.73 (46.220) = 19.126 % and our P.I = 1.2
% so our P.I lies above the A Line , there for our soil sample is
In Organic Silt with High Plasticity or Organic Silt with High
Plasticity .
The U Line Equation P.I = 0.9 (LL 8 ) P.I = 0.9 (46.2 8 ) =
34.38 and our P.I = 1.2 % so our P.I lies below the U Line ,
therefor our results are accepted.
There are some sources of errors that should be discussed.
o The soil paste was not mixing uniformly with water. o
Balancing errors. o Not looking vertically at fall cone method
device may cause positive error or negative one.
ENGINEERING USE.
Fall cone method is another method to find L.L & P.L, which
used in USCS classification, for fine-grained
fractions and this helps us as engineers to know the properties
of soils and its behavior with water. And used for
knowing soil shear strength, permeability and other soil
parameters and properties.
The values discussed ultimately help us to evaluate soils to be
used in various construction applications
such as structural fill for dams, embankments and landfills
REFERENCES:
Braja M.Das, Principles of geotechnical engineering ,7th
edition
Das, Braja M. (2002) Soil Mechanics Laboratory Manual, 6th
Ed.
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