The document discusses various index properties that are used to identify and classify soils and determine their engineering behavior. Some key index properties discussed include moisture content, specific gravity, density, particle size distribution from sieve and sedimentation analysis, consistency limits of liquid limit, plastic limit and shrinkage limit, and density index. Methods for measuring these properties such as oven drying method, pycnometer method, core cutter method, and sand replacement method are also summarized. The index properties are useful for understanding properties like strength, compressibility, swelling potential of soils that influence engineering design.

2. INDEX PROPERTIES OF SOILS
Used for the identification and classification
of soils and determining the engineering
behavior of soils.
Engineering behavior such as: Strength,
Load bearing capacity, Swelling & shrinkage,
Settlement etc.

3. Index properties of soil are:-
 Moisture content / Water content
 Specific Gravity
 In-situ density / Field density
 Particle size distribution / Grain size analysis
 Consistency Limits
 Relative density / Density index

4.  Oven Drying Method
 Pycnometer Method
 Sand Bath Method
 Rapid moisture Method
Moisture Content/Water
content:-

5. Pycnometer Method
The water content of the soil can be given by using the
formula:-

6. 2.Specific Gravity:-

7. DENSITY BOTTLE METHOD
 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.
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)}]

8. 3.In-situ density/Field density:-
 Core cutter
method

9.  Core cutter method
Bulk density,
Dry density,
Where, w is the water content

10.  SAND REPLACEMENT METHOD
⦁ Determination of
◦ Mass density of sand
◦ Volume of excavated
hole
◦ Mass density of soil

11. SAND
REPLACEMEN
T METHOD

12. 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
V
M  M  M3
  1 2

14. 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
V 

M  M  M4
1 2

15. Bulk density,
Vhole
Dry density,
Where, w is the water content
Msoil
 

16. 3.Grain SizeAnalysis:-
 Soil in nature exists in different sizes,shapes and appearance.
 Depending on these attributes, the soil at the site can be
packed either densely or loosely
.
 Hence it is important to determinethe percentage of various
sized particles in a soil mass.
 This process iscalled as Grain size analysis or particle size
distribution analysis.
 Grain SizeAnalysis
SieveAnalysis
(For Coarse grained soils)
Sedimentation analysis
(For fine grained soils)
Gravel(80 Mm – 4.75 Mm), Sand(4.75 Mm – 0.075 Mm) Silt
(0.075 Mm – 0.002 Mm), Clay (Less Than 0.002 Mm)

17. ⚫ This test is meant for coarse
grained soils (particle size > 75µ) which can
easily pass through set of sieves.
⚫ The sieves used are 80 mm, 40 mm, 20 mm, 10
mm , 4.75 mm, 2.36 mm, 2 mm, 1 mm, 600µ,
425µ, 212µ,150µ,75µ.
⚫ The selection of the required number of sieves
is done to obtain a good particle size
distribution curve.

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

20. SedimentationAnalysis:-
 It is also called as wet analysis and is applicable
for fine grained soils (particle size<75µ)
 The analysis is based on stokes law, which states
that the velocity at which soil particles settles in a
suspension depend on shape, size and weight of
particles.

23. Curve-1:-Well graded
soil: good
representation of grain
sizes over a wide
range and its gradation
curve is smooth.
Curve-2:-Poorly graded
soil / uniform gradation:
it is either an excess
or a deficiency of
certain particle sizes or
has most of the
particles about the
same size.
Curve-3:-Gap graded
soil: In this case some
of the particle sizes are
missing.

24. 4.Consistency Limits & Indices:-
The consistency is meant the relative ease with which soil can
be deformed.
The consistency of a fine-grained soil refers to its firmness,
and it varies with the water content of the soil.
A gradual increase in water content causes the soil to change
from solid to semi-solid to plastic to liquid states.
The water contents at which the consistency changes from one
state to the other are called consistency limits (or Atterberg
limits).
The three consistency limits/Atterberg limits are:-
1. Liquid limit
2. Plastic limit
3. Shrinkage limit

25. Liquid Limit (LL or wL ):- It is the water content at which soil
changes from a plastic to a liquid state .(O R)
It is defined as the minimum water content at which a part of a soil
is cut by a groove of standard dimensions, will flow together for a
distance of 12 mm under an impact of 25 blows in the device.

27. TYPE LIQUID LIMIT
Low plasticity < 35%
Intermediate plasticity 35 - 50%
High plasticity 50 - 70%
Very high plasticity 70 - 90%
Extremely high plasticity > 90%

28. Plastic Limit (PL or wP):- It is the water content at which soil
changes from a semi solid state to plastic state .(OR)
It is defined as the minimum water content at which the soil will just
begin to crumble when rolled into a thread of approximately 3 mm
in diameter
.
Shrinkage Limit (SL or wS):- It is defined as the water content at
which the soil changes from a solid state to a semi-solid state.(OR)
It is the maximum water content at which a reduction in water
content will not cause a decrease in the volume of a soil mass.
Plastic limit

29. DETERMINATION OF SHRINKAGE
LIMIT
 Procedure:
 Take about 30 g of air dried soil after passing through
425μ sieve in an evaporating dish.
 Soil is mixed with sufficient quantity of water so that it
may flow.
 Fill the soil mix in dish and take the weight of dish.
 The soil pat is allowed to dry in air till the colour of pat
changes from dark to light.
 The dish is then placed in oven at 110oc till it attains
constant weight.
 The shrinkage dish is weighed with the dry soil and dry
weight of soil is determined.
 The volume of dry soil pat is determined by mercury
displacement method.

31.  V1 = Volume of container in which
plastic phase soil is filled initially.
 W1 =Weight of wet soil sample along
with container.
 V2 = Volume of soil at shrinkage limit.
 W2 =Weight of soil sample at
shrinkage limit.
 Vs=Weight of dry soil pat
 γw= Unit weight of water

33. Consistency Indices:-
Plasticity index(PI or IP):-
It is the range of water with in which the soil exhibits plastic
properties. Hence it is the difference between liquid limit and plastic
limit.
PI or IP = (LL-PL) or (wL - wP)
Shrinkage index(SI or IS):-
It is the difference between the plastic limit and shrinkage limit of a
soil.
SI or IS = (PL-SL) or (wP - wS)

34. Liquidity index(LI or IL):-
It is the ratio of the difference between the natural water content
and the plastic limit to the plasticity index.
LI or IL = (w-PL)/PI or (w- wP)/IP
Flow index(IF):-
It is the slope of the flow curve obtained between the number of
blows and the water content in the casagrande test for the
determination of liquid limit.
Flow curve gives an idea of shear strength variation with water
content of the soil.

35. Consistency index(IC) or Relative consistency:-
It is defined as the ratio of the difference between the liquid limit
and natural water content of a soil to its plasticity index.
IC = (wL - w)/ IP
T
oughness index(IT):-
It is defined as the ratio of plasticity index to the flow index.
IT = IP/IF
It gives an idea about the shear strength of a soil at plastic limit.

36. Shrinkage
ratio(SR):-
It is defined as the ratio of a given volume change in a soil
expressed as percentage of its dry volume to the
corresponding change in water content above shrinkage limit.
V1=volume of soil mass at water content w1
V2=volume of soil mass at water content w2
Vd=volume of dry soil mass
At shrinkage limit,V2=Vd and w2=ws ,hence

37. The change in water content,
Hence,
Volumetric Shrinkage (VS):-
It is defined as the decrease in the volume of a soil mass expressed
as percentage of its dry volume when the water content is reduced
from a given percentage to the shrinkage limit.

38. Other soil aggregate
properties
 Permeability
 Unconfined compressive strength
 Sensitivity and thixotropy
 Void ratio, porosity and unit weight
 Relative density and density index
 Activity

39. Porosity
 Since bulk density relates to the
combined volume of the solids and pore
spaces, soils with high proportion of pore
space to solids have lower bulk densities
than those that are more compact and
have less pore space.
 Consequently, any factor that influences
soil pore space will affect bulk density

40. Activity of clays(AC):-
It is defined as the ratio of plasticity index to the percentage of clay
size particles by weight less than 2µ.
AC = IP/% C(by weight finer than 2µ)
shrinkage
It is a measure of the water holding capacity of clayey soils.
It is used as an index for identifying swelling and
characteristics.
CLAY MINERAL ACTIVITY
Kaolinite 0.38 (not have any
shrinkage)
Illite 0.98
Montmorillonite >4 (have more shrinkage)

41. Sensitivity of clays(St):-
It is defined as the ratio of unconfined compressive strength of
undisturbed specimen of the soil to the unconfined compressive
strength of remoulded specimen of the same soil.
Sensitivity Classification
1 Insensitive
1-2 Little or low sensitive
2-4 Moderate or medium
sensitive
4-8 Sensitive
8-16 Extra sensitive
>16 Quick sensitive

42. Thixotropy
 Thixotropy of clay is the process of strength loss and gain
with no alteration in volume or water content.
 This can also be defined as “a softening process caused by
remoulding, followed by a time-dependent return to the original
harder state.”
 ‘Thixis’ means ‘tough,’ and ‘tropo’ means ‘to transform,’ or ‘to
alter.’ Thixotropy literally means “to alter by contact or touch,”
but it can also be described as a reversible gel-sol-gel
transformation in some colloidal systems caused by a
mechanical disruption followed by a period of rest.
 The loss of strength during remoulding is due to the in-situ
permanent destruction of the structure, as well as the
reorientation of molecules in the adsorbed layers. The
restoration of the soil’s molecular structure is responsible for
the increase in strength. The resilience lost as a result of the
structure’s collapse is irreversible.
 he degree of strength gain over time depends on the form of
clay minerals involved; in general, clay minerals that absorb
significant amounts of water into their lattice frameworks, such
as montmorillonites, experience greater thixotropic effects
than more stable clay minerals.

44. 5.Relative Density or Density Index(Dr or ID):-
Relative density is defined as the ratio of difference of void ratios of
cohesion less soil in its loosest state and the natural state (emax –
e) to the difference between void ratio in its loosest and densest
states (emax – emin).

45.  Index properties:
 https://www.youtube.com/watch?v=KoM5EGCbuKI&t=8s
 Grain size distribution
 https://www.youtube.com/watch?v=uIXeo5W5jzE
 Sand replacement
 https://www.youtube.com/watch?v=f5Z2l9RFumo&list=RDCM
UC1A_poM_ksoafQJLc3Iu_Bg&index=9
 sensitivity
 https://www.youtube.com/watch?v=6mAKxLuTD3M&list=RDC
MUC1A_poM_ksoafQJLc3Iu_Bg&index=10
 thixotropy
 https://www.youtube.com/watch?v=izn9-
LVBqVA&list=RDCMUC1A_poM_ksoafQJLc3Iu_Bg&index=15
 Liquid limit
 https://www.youtube.com/watch?v=OvrqyFYhhxQ&list=RDCM
UC1A_poM_ksoafQJLc3Iu_Bg&index=37