Index properties

AMANPREET TANGRI
Assistant Professor
Chandigarh University

Index properties are sometimes divided into two categories-
1. Properties of individual particles
2. Properties of soil mass ,also known as aggregate properties
The properties of individual particles can determined from a
remolded , disturbed sample
Whereas aggregate properties should be determined from
undisturbed samples

a) Water content
b) Specific gravity
c) In-situ density
d) Particle size
e) Consistency
f) Relative Density

a) Sand bath method
b) Alcohol method
c) Oven drying method
d) Calcium carbide method
e) Radiation method

This is a field method for the determination of water content .
This method is rapid but not accurate. The container with the
soil is placed on a sand bath. Heated over a kerosene stove.
The soil become dry within ½ to 1 hrs.

Where, M1= mass of empty container
M2= mass of container + wet soil
M3= mass of container + dry soil
100%*
13
32
MM
MM
w




 The soil sample is taken in a evaporating dish. Sample is
then mixed with methylated spirit.
 Quantity of methylated spirit required is one millilitre for
every gram of soil.
 The methylated spirit is then ignited. The mixture is then
stirred with spatula.
 After the methylated spirit has burnt away completely
dish is allowed to be cooled and mass of dry soil is
obtained .
DISADVANTAGES-
 Cannot be used if soil contain large proportion of clay,
organic matter.
 Methylated spirit is volatile so extra care is required.
 Not accurate.

Equipments:-
a) Containers
b) Desiccator with any suitable desiccating agent
c) Thermostatically controlled oven
d) Weighing balance with accuracy of 0.01 gm

1. Clean the container, dry it and weight it with the lid. (M1)
2. Take the required quantity of the wet soil specimen in the
container & weight it with the lid.(M2)
3. Place the container with its lid removed, in the oven till its
weight become constant.
4. When the soil has dried, remove the container from the oven
using tongs.
5. Find the weight M3 of the container with the lid and the dry
soil sample.

%100*
13
32
MM
MM
w




This method of the determination of water content makes use
of fact that when water reacts with calcium carbide, acetylene
gas is produced.
PROCEDURE:-
 Wet sample is placed in a sealed container containing calcium
carbide. The test require about 6 g of soil.
 The pressure of acetylene produced acts on the diaphragm of
moister tester.
 The quantity of gas is indicated on a pressure gauge. From the
calibrated scale of pressure gauge the water content is
determined.

1. Radioactive isotopes are used in determination of water
content.
2. A device containing a radio active isotopes material such as
cobalt 60 is placed in a capsule. which is lowered in a steel
casing. Steel casing has an opening from where rays come
out.
3. Another casing consist of detector which is placed in
opening. Neutrons are emitted from radioactive material.
4. Hydrogen atoms in water cause scattering of neutrons. As
neutrons strike with hydrogen atoms they loose energy.
5. The loss of energy released is proportional to the water
content.

The specific gravity of solids is frequently required for
computation of several soil properties such as void ratio,
degree of saturation, unit weight of solids, fine soil particle
size, etc.
Methods used for determination are:-
1. Pycnometer bottle method
2. Density bottle method
3. Measuring flask method
4. Gas jar method
5. Shrinkage limit method

1. Clean and dry the pycnometer . Find its mass with cap as
W1.
2. Place about 200 gm of oven dried soil passing through 4.75
mm sieve.
3. Determine mass of pycnometer with dry soil as W2.
4. Add sufficient amount of de-aired water to the soil in the
pycnometer. Thoroughly mix it. Determine mass of
pycnometer with soil and water as W3.
5. Empty the pycnometer, clean it and wipe it dry.
6. Fill the pycnometer with distilled water and find its mass as
W4.
7. Now, calculate the specific gravity of soil solids as under :
G=[(W2-W1)/{(W2-W1)- (W3-W4)}]

A density bottle of 50 ml capacity is used. Bottle is dried and
cleaned at temperature of 105 -110o C. Mass of bottle including
stopper is taken. About 5-10g of soil is taken in the bottle and
weighted. Distilled water is added to cover sample. The soil is
allowed to soak water for about 2 hours. Air entrapped is expelled
by applying a vacuum pressure of 55 cm of mercury. The stopper is
inserted in bottle and mass is taken . The bottle is emptied, washed
and refilled with distilled water. The mass of bottle filled with water
is taken.
Let W1= mass of empty container
W2= mass of container + dry soil
W3= mass of container + wet soil
W4=mass of bottle filled with water
G=[(W2-W1)/{(W2-W1)- (W3-W4)}]
DENSITY BOTTLE METHOD

A measuring flask of 250 ml capacity, with a graduation
marked at that level .It is fitted with an adaptor for connecting
it to a vacuum line for removing entrapped air. This method is
similar to density bottle method. About 80-100 g of oven
drying sample is taken.
Advantage-
Suitable for fine grained and medium grained soil.

1. Measure the inside dimensions of the core cutter
2. Determine empty weight of core cutter ( W1)
3. Level the surface, about 300 mm square in area.
3. Place the dolly over the top of the core cutter and press the core
cutter into the soil mass using the rammer.
4. Stop the process of pressing when about 15 mm of the dolly
protrudes above the soil surface.
5. Remove the soil surrounding the core cutter and take out the core
cutter.
6. Remove the dolly. Trim the top and bottom surface of the core
cutter carefully using a straight edge.
7. Weight the core cutter filled with the soil (W2).
8. Remove the core of the soil from the cutter. Determine the water
content

DETERMINATION OF FIELD DRY-DENSITY

Bulk density,
Dry density,
Where, w is the water content
DETERMINATION OF FIELD DRY-DENSITY
M1
M2

 Determination of
◦ Mass density of sand
◦ Volume of excavated
hole
◦ Mass density of soil

Mass density of sand
 Where, M1 initial mass of cylinder with sand
 M2 mass of sand in cone only
 M3 mass of cylinder after pouring sand into
the cone and the container
 Vc volume of the container
C
s
V
MMM 321 


Volume of the hole
 Where, M1 initial mass of cylinder with sand
 M2 mass of sand in cone only
 M4 mass of cylinder after pouring sand into
the hole
 s mass density of sand
s
h
MMM
V

421 


Bulk density,
Dry density,
Where, w is the water content
hole
soil
V
M


Particle size analysis is a method of separation of soils
into different fractions based on particle size.
Particle analysis is done in 2 stages:-
1. Sieve Analysis
2. Sedimentation Analysis
The first analysis is meant for coarse grained soil
(particle size > 75 micron). Whereas sedimentation
analysis is for fine grained soils. ( particle size < 75
micron).
Particle size smaller than 0.2 micron can be determined
by an electron microscope or by X-ray technique.

PROCEDURE
a) The test sample is dried to a constant weight at a temperature of
110 + 5oC and weighed.
b) The sample is sieved by using a set of IS Sieves.
c) On completion of sieving, the material on each sieve is weighed.
d) Cumulative weight passing through each sieve is calculated as a
percentage of the total sample weight.
e) Fineness modulus is obtained by adding cumulative percentage of
aggregates retained on each sieve and dividing the sum by 100.

Particle size, D (mm)
Percentagefiner,N%
100
90
80
70
60
50
40
30
20
10
0
D10 D30 D60
D10 – Effective size
Uniformity coefficient,
Coefficient of curvature,
10
60
D
D
Cu 
1060
2
30 )(
DD
D
Cc



32
Log scale
Effective size D10: 0.02
mm

 The consistency of a fine grained soil is the physical state in
which it exists.
 The water content at which the soil changes from one state to
other are known as consistency limits or ATTERBERG limits.
 At the same water content one soil may be relatively soft,
whereas another soil may be hard.
 Thus consistency limits are very important properties of fine
grained soil.

34
Purpose:
This is performed to determine the plastic and liquid limits of a fine
grained soil. The Atterberg limits are based on the moisture content
of the soil.
The plastic limit: is the moisture content that defines where the
soil changes from a semi-solid to a plastic (flexible) state.
The liquid limit: is the moisture content that defines where the soil
changes from a plastic to a viscous fluid state.

1) The liquid limit device is adjusted to have a free fall of cup of 1cm this is
done with the help of adjusting screw provided near the cup hinge.
2) Take 100gm of soil sample after passing from 425µ IS sieve.
3) Add 15% water in soil by weight of soil.
4) Mix it thoroughly to make uniform paste.
5) Put wet soil in cup and leveled it at lowest spot and squeezed down with
spatula to have a uniform space.
6) Then with the help of casegrande’s tool , divided into two parts by
grooving up to bottom surface of cup.
7) Rotate handle at the rate of 2 no. per second and cup will start process of
up and down.
8) Count the rotation of handle until the bottom surface of groove is
connected .
9) Then add water as 3% of soil and mix thoroughly and repeat process.
10) The process of adding water is contained until connecting of groove is
completely in 25 blows.
11) Then get the result of Liquid limit.

 The minimum water content at which a soil will just begin to
crumble when it is rolled into a thread of approximately 3 mm
in diameter.
 When point is reached where thread is cracking and cannot be
re-rolled to 3 mm diameter, collect at least 6 grams and
measure water content.
 The test is repeated taking a fresh sample each time. Plastic
limit is taken as average of three values.

Plasticity Index is the numerical difference between the Liquid
Limit w% and the Plastic Limit w%
Plasticity Index= Liquid Limit - Plastic Limit
TYPE LIQUID LIMIT
Low plasticity < 35%
Intermediate plasticity 35 - 50%
High plasticity 50 - 70%
Very high plasticity 70 - 90%
Extremely high plasticity > 90%

situ.inforratiovoide
statedensestin thesoiltheofratiovoide
stateloosestinsoiltheofratiovoidewhere,
min
max
minmax
max






ee
ee
Dr
The relative density is generally used to indicate the in situ
(on site) denseness or looseness of soil. It is defined by:-

The relative density of a soil give more clear idea of denseness
than does the void ratio. Two types of sand having same void ratio
may have entirely different state of denseness. However if two
sands have same relative density, they usually behave in identical
manner.
The Relative Density of soil indicates how it would behave
under the loads . If the deposit is dense it can take heavy loads
with very little settlement. Depending upon the relative density,
soils are generally divided into 5 categories:-
RELATIVE DENSITY (%) DENSENESS
<15 Very loose
15-35 Loose
35-65 Medium Dense
65-85 Dense
85-100 Very Dense

Index properties

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