A study on characterization of compressive strength. seminar pptx

“A STUDY ON CHARACTERIZATION OF COMPRESSIVE STRENGTH
AND LEACHING BEHAVIOR OF STABILIZED SOILS USING FLY ASH AND
GROUND GRANULATED BLAST FURNACE SLAG”
Visvesvaraya Technological University, Belgaum

Naveen Kumar.S
1BM10CEE07

Under the Guidance of Dr. MAYA NAIK
Professor, Dept. of Civil Engineering,
BMS College of Engineering, Bangalore -560019.

1

CONTENTS

 Introduction
 Objective
 Literature review
 Materials and Methods
 Results and Discussions
 Conclusions
 Scope for future work
 References

2

INTRODUCTION
• Soil stabilization is the permanent physical and chemical alteration
of soils to enhance their physical properties.
• Stabilization increases the shear strength and controls the shrink-
swell properties of a soil, and it increase the load-bearing capacity of
a sub-grade to support pavements and foundations.
• Stabilization can be achieved with a variety of chemical additives
including lime, cement, fly ash and GGBS mixtures as well as by-
products of industrial wastes.
• Stabilization of expansive soils with admixtures controls the
potential of soils for a change in volume behavior.
• Proper design and testing is an important component of any
stabilization project.
• Fly ash and GGBS mixtures have been utilized in bulk in
Geotechnical Engineering applications such as construction of
Embankments, as a Backfill material, etc
3

GRADATION OF SOIL, COMPACTION OF
SOIL FLY ASH MIXTURES
• Soil gradation is an important aspect of soil
mechanics and Geotechnical engineering.
• Soil gradation is a classification of a coarse-grained soils based on
the different particle sizes.
• The compaction of soil with fly ash, GGBS and lime is an
important parameter since it controls the Strength, Compressibility
and Permeability behavior of stabilized mixture.
• The compacted unit weight of the material depends on the amount
and method of energy application, grain size distribution, plasticity
characteristics and moisture content.
• In the present work gradation of fly ash and GGBS mixtures has
been carried out in order to bring the effect of gradation on
stabilization of black cotton soil.

4

PRINCIPLES AND NEED FOR SOIL
STABILIZATION
• Selecting Effective and economical method of soil stabilization and
designing the stabilized soil mix for intended stability and durability
values.
• An attempt has been made for utilization of locally available soils
and other suitable stabilizing agents and encourage the use of
industrial fly ash and other wastes in construction activities.
TYPES OF SOIL STABILIZATION
• Mechanical stabilization
• Soil-lime stabilization
• Soil-Fly ash stabilization
• Soil-cement stabilization
• Soil-bitumen stabilization
5

MECHANICAL STABILIZATION
• The basic principles of mechanical stabilization are mechanical
strength of coarse mixtures, gradation, properties of the soil, ease of
compaction.
• This method is suitable for low volume i.e. Village roads in low
rainfall areas.
• This method involves the correct proportioning of coarse mixtures
and soil, adequately compacted to get mechanically stable layer.
SOIL-LIME STABILIZATION
• Soil lime imparts some binding action even in granular soils
and increase in lime content causes slight change in liquid limit
and considerable increase in plasticity index.
• The strength of soil-lime increases with curing period up to
certain time. The rate of increase is rapid during initial period.
The humidity of the surroundings also affects the strength.
• Soil- Lime Stabilization has been widely used as a modifier or a
binder 6

SOIL-FLY ASH STABILIZATION
• Soil- fly ash Stabilization reduces its plasticity index, and swell
potential owing to a cat ion exchange process that results in an
agglomeration of the fine clay particles into coarse particles.
• The stable exchangeable cat ions provided by fly ash, such as
Ca2+, Al3+, and Fe3+ promote flocculation of the clay particles.
• Formation of cemented compounds characterized by their high
shear strength and low volume change. In addition to fly ash
stabilization, lime is widely used to reduce swell and increase shear
strength of expansive soils.
• The improvement is due to the following two basic reactions, short-
term reaction including cation exchange and flocculation and long-
term reaction including pozzolanic reaction.

7

SOIL- CEMENT STABILIZATION

• Cement stabilization is generally the best type of admixture to be
used with soil. It is also commonly available but it is often
expensive.
• Mixing cement with expansive soils reduces swell potential.
• Generally, the amount of cement required to stabilize expansive
soils ranges from 2 to 6% by weight.
• When the pore water in soil encounters the cement, hydration of the
cement occurs rapidly and the major hydration products are
hydrated calcium silicates, hydrated calcium aluminates, and
hydrated lime.
• The hydration of cement leads to a rise in pH value of the pore
water, which is caused by the dissociation of the hydrated lime.

8

OBJECTIVES OF THE PRESENT STUDY
In the light of extensive literature survey carried out for the
stabilization of soil fly ash and GGBS mixtures, the following are the
major objectives of the present study.
 To determine the compaction and unconfined compressive strength
of stabilized black cotton soil using fine and coarse fly ash mixtures.
 To determine the compaction and unconfined compressive strength
of stabilized black cotton soil using fine and coarse GGBS mixtures.
 To determine the optimum lime content required for stabilizing
black cotton soil by performing unconfined compressive strength
test.
 To study the leaching behavior of heavy metal ions from stabilized
black cotton soil for various types of admixtures used.

9

LITERATURE REVIEW

Chen 1975; Liao 1984; Locat et al.1990
• The relationship between the plasticity index and swell-shrinkage
properties for pre-treated and post-treated soils was brought out.
• The test results show that the plasticity index, activity, free
swell, swell potential, swelling pressure, and axial shrinkage percent
decreased with an increase in fly ash or fly ash-lime content.
• With the increase of the curing time for the treated soil, the swell
potential and swelling pressure decreased.
• Soils immediately treated with fly ash shows a consecutive change
in the unconfined compressive strength.
• However, after 7 days curing of the fly ash treated soils, the
unconfined compressive strength increased significantly.

10

Contd…
Phanikumar and Sharma (2004)
• A study was carried out on the effect of fly ash on engineering
properties of expansive soil and the effect on parameters like free
swell index (FSI), swell potential, swelling
pressure, plasticity, compaction, unconfined compressive strength and
hydraulic conductivity of expansive soil was studied.
• The ash blended expansive soil with fly ash contents of 0, 5, 10, 15
and 20% on a dry weight basis and they inferred that increase in fly
ash content reduces plasticity characteristics and the free swell index
(FSI) was reduced by about 50% by the addition of 20% fly ash.
• The hydraulic conductivity of expansive soils mixed with fly ash
decreases with an increase in fly ash content, due to the increase in
maximum dry unit weight with an increase in fly ash content.
• When the fly ash content increases there is a decrease in the optimum
moisture content and the maximum dry unit weight increases.

11

Contd…

P.V. Sivapullaiah (2000)
• Fly ashes with high pozzolanic reactivity are widely used but those
with less pozzolanic reactivity are greatly inhibited.
• As the strength development in natural expansive soil considered in
this investigation is very less with different percentages of fine fly
ash, an attempt is made to increase the same by addition of lime along
with fly ash.
• Based on several tests conducted, the optimum lime contents for soft
soil studied is about 8% as indicated by pH and unconfined
compressive strength tests.
• The strength of compacted soil with different fly ash mixtures has
attained more strength which is determined after curing for different
periods.
• The strength improvement for any soil mixture, which is substantial
with percentage increase of lime, is further improves the strength.
12

Contd…
Pandian et.al. (2002)
• Studied the effect of two types of fly ashes Raichur fly ash (Class F)
and Neyveli fly ash (Class C) on Strength characteristics of the
black cotton soil. The fly ash content was increased from 0 to 100%.
• The low percentage of BC soil is attributed to the inherent low
strength, which is due to the dominance of clay fraction. The
addition of fly ash to BC soil increases the compaction of the mix up
to the first optimum level due to the frictional resistance from fly
ash in addition to the cohesion from BC soil.
• The variation of strength of fly ash black cotton soil mixes can be
attributed to the relative contribution of frictional or cohesive
resistance from fly ash or BC soil, respectively.
• In Neyveli fly ash also there is an increase of strength with the
increase in the fly ash content, here there will be additional
pozzolanic reaction forming cementitious compounds resulting in
good binding between BC soil and fly ash particles.
13

Contd…
Dhananjay bhaskar sarode, Sanjay baliram attarde(2009)
• A study was carried out on the leach ability of heavy metals from fly ash,
bottom ash, dumping site ash, Samples admixture with fly ash in the area of a
thermal power plant were compared.
• During these studies, extraction and leaching of various heavy metals like Zn,
Ni, Cu, Fe, Mn and Mg was carried out by applying batch leach test and
toxicity characteristic leaching procedure (TCLP) to check the possibility of
ground water contamination.
• The ground water samples in the vicinity of ash dumping sites were analyzed
for heavy metal concentrations and results obtained were compared WHO
permissible limits.
• Mg, Mn, and Fe were leached to a larger extent Zn, and Cu to moderate and Ni
to a smaller extent, from the ash and admixture samples. The concentrations of
Zn, Fe, Mn, and Mg in groundwater samples were below the permissible limits
of Indian standards.
• The concentration of Cu was within the permissible limits but slightly higher
than Indian Standards. The admixture of thermal power plant fly ash in fine
and coarse seems to be an ecofriendly practice as far as leaching of heavy
metals in groundwater is concerned. 14

MATERIALS AND METHODS
In the present study stabilization of black cotton soil has been carried out
by using the following materials.
• Black cotton soil
• Ground granulated blast slag (Fine and Coarse)
• Fly ash (Fine and Coarse) and lime.
BLACK COTTON SOIL:
• Natural black cotton soil was obtained from Gadag district in
Karnataka State. The soil was excavated from a depth of 2.0 m from
the natural ground level.
• The soil is dark grey to black in color with high clay content. The
obtained soil was air dried and pulverized manually and soil passing
through 425 µ IS sieved was used in the present study.

15

Contd…
• This soil has a property of high moisture retentively and develops
cracks in summer. This soil predominantly consists of expansive
montmorillonite as the principal clay mineral. Physical properties of
black cotton soil is as shown below.
Table1 Physical properties of black cotton soil

Natural Grain size distribution Atterberg’s Limit
Specific
Water Gravel Silt and Liquid Plastic Plasticity Shrinkage
gravity Sand (%)
content (%) clay (%) limit limit Index limit
38.22 and
8.95% 2.68 00 10.06 66% 37.12% 28.88% 11.63%
51.72

Plate 1 Black cotton soil sample Plate2 Grain size distribution by hydrometer Analysis
16

GRAIN SIZE DISTRIBUTION BY HYDROMETER ANALYSIS

This test is done according to IS 2720(part 3/ section 1) - 1980
Grain size distribution of Black Cotton Soil from Gadag
100

% Sand=10.06
80
%Silt=38.22
Percentage fines

% Clay=51.72
60

40

20

0
0.001 0.01 0.1 1 10

Particle size, mm
17

LIQUID LIMIT GRAPH FOR BLACK COTTON SOIL

80

70
Flow Curve
WL
60

50
% of Water

40

30 % of water

20

10

0
0 10 20 N =25 30 40 50 60 70

No of Blows

18

Contd..

Table 2 Mini compaction and compressive strength of Black cotton soil
optimum moisture content Compressive Strength in
Max dry density in g/cc
in % Kpa
1.48 21 112.3

Plate 3 Compaction test and Compressive strength of Black Cotton Soil

19

COMPACTION RESULTS FOR SOIL ALONE

Water content Dry density
Sl No
(%) Γd g/cc
Trial1 6 1.22
Trial2 10 1.29
Trial3 12.3 1.35
Trial4 16.1 1.42
Trial5 18 1.45
Trial6 20 1.48
Trial7 26 1.44
Trial8 37.5 1.28

20

COMPACTION CURVE FOR SOIL ALONE
1.6

1.5 γ d max
dry density gm/cc

1.4

1.3

Series1
1.2

1.1

1 OMC
0 5 10 15 20 25 30 35 40

water content in %

21

GROUND GRANULATED BLAST SLAG (GGBS)
• About10 million tons of blast furnace slag is produced in India annually
as a byproduct of Iron and Steel Industry.
• Blast furnace slag is composed of silicates and alumino silicates of lime
and other bases. It is a latent hydraulic product which can be activated
with anyone- lime, alkalis or Portland cement.
• GGBS procured from Hubli Steel plant has been used in the present
Fine and coarse GGBS sample is as shown in Plate 5

Plate5 Fine and coarse GGBS sample
22

Contd….

Physical and chemical properties are presented in Table 3 and Table4
Table 3 Physical properties of Ground granulated blast slag
Atterberg’s limit Mini compaction

Specific Maximum dry Optimum
Color Liquid limit Plastic limit
gravity density in moisture
(%) (%)
g/cc content in %

Off -white 2.81 32 Non plastic 1.38 20

Table 4 Chemical properties of Ground granulated blast slag
Constituent SiO2 CaO AI2O3 MgO Fe2O3 SO3 L.O.I

Percentage 40% 39.2% 13.5 % 3.6% 1.8 1.7% 0.2

Source UK cementitious slag maker association (CSMA) by Dr. D.D Higgins
Soil stabilization with ground granulated blast furnace slag (GGBS) 23

FLY ASH
• Fly ash is a fine residue collected from the burning of pulverized
coal in thermal power plants. The disposal of the fly ash is a serious
hazard to the environment that consumes millions of rupees towards
the cost of its disposal.
• Fly ash has been used in a variety of construction applications, such
as compacted fills, concretes, bricks, liners, construction of
embankments in many countries including India.
• In the present study, fly ash of class “F” Category procured from
Raichur thermal power station (RTPS), in Karnataka, India, called
Raichur Fly ash (RFA), has been used. The fly ash used was grey in
color. Fine and coarse fly ash sample is as shown in Plate 6.

24
Plate 6 Fine and coarse fly ash sample

TYPES OF FLY ASH
Fly ash is categorized into two broad classes
Class C Fly ash Class F Fly ash
• Class C Fly ash
 This class of fly ash has a high CaO content and used as a stand-
alone stabilizing agent.
 The strength characteristics of Class C fly ash having a CaO less
than 25 percent can be improved by adding lime.
• Class F Fly ash
 This class of fly ash has a low CaO content.
 Class F fly ash has an insufficient CaO content for the pozzolanic
reaction to occur.
 It is not effective as a stabilizing agent by itself however, when
mixed with either lime or lime and cement, the fly ash mixture
becomes an effective agent.
25

Contd…
Physical and chemical properties are presented in Table 5 and Table 6

Table 5 Physical properties of Fly ash
Specific Grain size distribution Atterberg’s limit
gravity

Silt and Liquid Plastic Shrinkage
Gravel (%) Sand (%)
2.13 clay (%) limit limit limit
00 58 42 35% Non plastic 18.50%

Table 6 Chemical properties of Fly ash

Constituent SiO2 Al2O3 TiO2 Fe2O3 MnO MgO CaO K2O Na2O L.O.I

Percentage 61.1 28 1.3 4.2 0.15 0.8 1.7 0.18 0.18 1.4

Source:P.V. Sivapullaiah, et al- IISc, Bangalore.
Enhancement of strength of soft soils with fly ash and lime.
26

CHEMISTRY OF FLY ASH
• Formation of cementitious material by the reaction of lime with the
pozzolans (Al2O3, SiO2, Fe2O3)in the presence of water is known as
hydration of fly ash.

• In the presence of moisture, react with calcium hydroxide at ordinary
temperature to form compounds possessing cementitious properties
like calcium silicate hydrates and calcium aluminate hydrates.
27

HYDRATED LIME
• This is a type of lime most commonly available in dry powder.
Often lime is added as a supplement to enhance the properties of
mixture of soil and fly ash to reduce settlement and increased
bearing capacity.
• Commercially available pure hydrated lime Ca(OH) 2 was used in
the study. Hydrated lime, known as slaked lime. Typical hydrated
lime sample is shown in Plate 6.

Plate 6 Hydrated lime sample 28

PREPARATION OF SYNTHETIC SOURCE SOLUTION
The chemicals used are Copper sulphate, Ferrous Ammonium Sulphate (FAS)
Crystals, and Nickel Nitrate crystals for determination of copper, iron and nickel.

• The nickel nitrate [Ni(NO3)26H2O] is used as source of nickel[Ni(II)]. A stock
solution of 1000mg/l of Ni (II) is prepared by dissolving 4.96g of nickel
nitrate in 1000ml distilled water. The solution is diluted as required to obtain
standard solutions containing 100mg/l of Ni (II).
• The copper sulphate is used as source of copper. A stock solution of 1000mg/l
is prepared by dissolving 2.51g of copper sulphate in 1000ml distilled water.
The solution is diluted as required to obtain standard solutions containing
100mg/l of Cu2+
• The Ferrous ammonium sulphate is used as source of iron. A stock solution of
1000mg/l is prepared by dissolving 5.08g of ferrous ammonium sulphate in
1000ml distilled water. The solution is diluted as required to obtain standard
solutions containing 100mg/l of iron.

29

METHODOLGY
COMPACTION TEST
• Compaction test were carried out by using Mini compaction test apparatus
accordance with IS 2720 (part7)-1980.Compaction involves an expulsion
of air without a significant change in the amount of water in the soil mass.
• About 250 grams soil is used for each trial. The soil is mixed with
consistent quantity of water and is transferred on to the mould of diameter
3.8 cms and height of 10 cms in three layers, each layer is compacted by 36
blows.
• The compaction characteristics of soil fly ash mixtures specimens were
prepared to include optimum water content range for soil fly ash, and soil
GGBS mixtures The Compaction test were carried out for different
proportions of fine and coarse combination of fly ash, and soil GGBS
mixtures.
• For trial mixes the value of Maximum Dry Density and corresponding
Optimum Moisture content was obtained from Compaction curves.

30

Contd…

Plate 8 Compaction test for different soil mixtures and placing of soil mixtures in desiccators for curing.

31

UNCONFINED COMPRESSIVE STRENGTH TEST
IS2720(PART 10)-1973
• The soil samples were prepared by using steel split mould having a diameter
of 3.8 cm and a height of 7.6 cm was used.
• The weight of the soil to be taken and the volume of water to be added are
calculated by knowing the volume of mould and Maximum Dry Density and
Optimum Moisture content of the soil.
• Once the trial mix is prepared, the mould is oiled thoroughly. The mix is
transferred to the mould compacted and then extracted from the mould.
• Three identical samples were prepared for their Maximum Dry Density and
Optimum Moisture content based on the compaction curves obtained.
• The sample was subjected to various curing periods (1, 7, 14, 28 days)
according to their trial combination chosen. Samples intended for long term
testing were kept in desiccators to maintain 100% humidity and to prevent
loss of moisture from samples. Water was sprinkled at regular intervals and
was cured in the desiccators. All the samples intended for immediate testing
were tested immediately.
32

CHARACTERISTIC LEACHING TEST
• After the Unconfined compressive strength test, has been carried out for the
combination of fine and coarse soil mixtures the representative sample is
taken for batch leaching test. according to standard test method (ASTM
4646-87 reapproved 2001).
• A sample with Solid to liquid ratio of 1:10 is maintained. The soil mixture
is kept in a shaker for 24 hrs. at a speed of 30 rpm. After that mixture is
allowed to settle for 5 min, and then aqueous solution is filtered through a
0.45µm pore size membrane filter. The filtrate is analyzed using Atomic
absorption spectrophotometer. (AAS)

Plate 6 Unconfined compressive strength for soil mixtures and batch leaching tests for different soil mixtures.

33

Contd…

• Atomic absorption spectrophotometer (AAS) A203 Version -04 was used to
measure the nickel concentration. The, fuel used was acetylene (C2H2) and
the oxidant used was air or Nitrous oxide for strong flames. Calibration of
the AAS was done according to the equipment manual using certified
standards and the analysis of calibrated standards was attained to ensure the
accuracy of results. Rotary flask shaker used for experiment work

Plate7 Rotary flask shaker used and atomic absorption spectrophotometer used for analysis of heavy metal ions.

34

RESULTS AND DISCUSSIONS
COMPACTION CHARACTERISTICS OF STABILIZED BLACK COTTON
SOIL WITH DIFFERENT PROPORTIONS OF FINE FLY ASH

The results of stabilized black cotton soil for various percentages of fine fly
ash mixtures along with optimum water content and corresponding dry
density has been presented below.it can be observed that with increase in fly
ash content the OMC increases and the dry density decreases.

Optimum Water Content (%) Max Dry density(g/cc)
Soil+ Fine fly ash
95%+5% 22.5 1.35
90%+10% 23.8 1.20
85%+15% 25.0 0.90
80%+20% 26.0 0.80
75%+25% 28.0 0.65
70%+30% 30.0 0.60

35

Compaction with Soil and fine Fly ash

Black cotton soil + Fine Fly Ash
1.4

5%Fly Ash
1.2
Max. Dry density in g/cc

1
10% Fly Ash

0.8 15%Fly Ash

0.6 20% Fly Ash

0.4
25%Fly Ash

0.2
30%Fly Ash
0
0 5 10 15 20 25 30 35 40

Water content in %

36

COMPACTION CHARACTERISTICS OF STABILIZED
BLACK COTTON SOIL WITH DIFFERENT PROPORTIONS
OF COARSE FLY ASH
ash mixtures along with optimum water content and corresponding dry
density has been presented below. it can be observed that with increase in fly
ash content the OMC increases and the dry density decreases.

Soil+ Fly ash(Coarse) Optimum Water Content (%) Max Dry density (g/cc)

95%+5% 10.5 1.35

90%+10% 14.5 1.30

85%+15% 16.0 1.22

80%+20% 18.5 1.19

75%+25% 20.0 1.10

70%+30% 21.0 1.00

37

Compaction with Soil and coarse Fly ash

Black cotton Soil+ Coarse Fly ash

1.6
5% Coarse Fly ash
1.4

1.2 10%Coarse Fly ash
1
15%Coarse Fly ash
0.8
20%Coarse Fly ash
0.6


0
0 5 10 15 20 25 30 35

Water content in %

38

COMPACTION CHARACTERISTICS OF STABILIZED
BLACK COTTON SOIL WITH DIFFERENT PROPORTIONS
OF FINE GGBS

ash mixtures along with optimum water content and corresponding dry density
has been presented below. it can be observed that with increase in GGBS
content the OMC decreases and the dry density increases.

Soil+ Fine GGBS Optimum Water Content (%) Max Dry density(g/cc)

95%+5% 18.5 1.42

90%+10% 18.0 1.45

85%+15% 17.5 1.55

80%+20% 17.0 1.65

75%+25% 16.5 1.68

70%+30% 16.0 1.72

39

Compaction with Soil and Fine GGBS

Black cotton Soil+ Fine GGBS

2 5% Fine ggbs

10%Fine ggbs

1.6
15%Fine ggbs
1.2 20%Fine ggbs

25%Fineggbs
0.8
30%Fine ggbs
0.4

0
0 5 10 15 20 25 30 35

Water Content in %

40

COMPACTION CHARACTERISTICS OF STABILIZED BLACK
COTTON SOIL WITH DIFFERENT PROPORTIONS OF COARSE
GGBS

The results of stabilized black cotton soil for various percentages of fine fly ash
mixtures along with optimum water content and corresponding dry density has
been presented below. it can be observed that with increase in GGBS content
the OMC decreases and the dry density increases.

Soil+ Coarse GGBS Optimum Water Content (%) Max Dry density (g/cc)

95%+5% 18.0 1.30

90%+10% 17.5 1.38

85%+15% 17.0 1.42

80%+20% 16.5 1.45

75%+25% 16.0 1.50

70%+30% 15.0 1.55

41

Compaction with Soil and Coarse GGBS

Black cotton Soil+ Coarse GGBS

1.8
5%coarse ggbs
1.6
10%Coarse ggbs

1.4

1.2
15%Coarse ggbs
1

0.8 20%Coarse ggbs

0.6
25%Coarse ggbs
0.4

0.2 30%Coarse ggbs
0
0 5 10 15 20 25 30 35

Water Content in %

42

CHARACTERISTIC UNCONFINED COMPRESSIVE
STRENGTH OF SOIL FLY ASH MIXTURES

The results of unconfined compressive strength of soil fly ash mixtures for
varying percentage of fine and coarse fly ash mixtures have been presented in
the table below.it can be observed that with increase in percentage of fine and
coarse fly ash the UCC strength increases for both the mixtures, however the
increase is more pronounced with fine fly ash content

Sl No Parameter UCC in Kpa (fine) UCC in Kpa(Coarse)
1. 95%+ 5% Fly Ash 140.704 152.61
2. 90%+ 10% Fly Ash 249.727 158.336
3. 85%+ 15% Fly Ash 320.217 164.057
4. 80%+ 20% Fly Ash 330.098 168.964
5. 75%+ 25% Fly Ash 209.62 147.871
6. 70%+ 30% Fly Ash 89.143 118.302
7. 65%+ 35% Fly Ash 78.238 101.285
43

Effect of fly ash content on the strength of soil

characteristic strength of Fly ash
400

350

300
UCC strength in kpa

250

200
fine fly ash coarse fly ash
150

100

50

0
0 5 10 15 20 25 30 35 40

% varying of Fly ash

44

CHARACTERISTIC UNCONFINED COMPRESSIVE
STRENGTH OF SOIL GGBS MIXTURES
The results of unconfined compressive strength of soil GGBS mixtures for
varying percentage of fine and coarse GGBS mixtures have been presented in
the table below. it can be observed that with increase in percentage of fine and
coarse GGBS the UCC strength increases for both the mixtures, however the
increase is more pronounced with fine GGBS content.

SLNo Parameter UCC in Kpa (fine) UCC in Kpa (Coarse)
1. 95%+ 5% GGBS 255.073 55.797
2. 90%+ 10% GGBS 265.742 88.135
3. 85%+ 15% GGBS 316.451 120.473
4. 80%+ 20% GGBS 325.587 122.453
5. 75%+ 25% GGBS 216.856 124.434
6. 70%+ 30% GGBS 108.125 98.668
7. 65%+ 35% GGBS 68.265 72.902

45

Effect of GGBS content on the strength of soil

Characteristic strength of GGBS
350

300
UCC strength in kpa

250

200 fine GGBS coarse GGBS

150

100

50
0 5 10 15 20 25 30 35 40

% varying of Ground Granulated Blast Slag

46

CHARACTERISTIC COMPRESSIVE STRENGTH
OF BOTH FLY ASH AND GGBS MIXTURES
The results of unconfined compressive strength of soil fly ash mixtures for
varying percentage of fine and coarse combination mixtures have been
presented in the table below. it can be observed that with increase in
percentage of fine and coarse combination of mixtures the UCC strength
increases for both the mixtures, however the increase is more pronounced with
fine mixture content.

Combination of soil, Fly Ash and 5% Ground granulated slag (Fine and Coarse)

Sl no Parameter UCC in Kpa (fine) UCC in Kpa (Coarse)

1. Soil+ 0% Fly Ash 255.073 55.797

2. Soil+ 5% Fly Ash 265.682 173.481

3. Soil+ 10% Fly Ash 272.292 180.845

4. Soil+ 15% Fly Ash 300.101 190.488

5. Soil+ 20% Fly Ash 329.910 103.25

6. Soil+ 25% Fly Ash 300.25 44.25

47

Effect of fine and coarse mixtures on the strength of soil

Comparison of fine and coarse Combination

350

300 Fine Combination
UCC Strength in Kpa

250

200 Coarse Combination

150

100

50

0
0 5 10 15 20 25 30

% varying fly ash

48

CHARACTERISTIC COMPRESSIVE STRENGTH
OF BOTH FLY ASH AND GGBS MIXTURES
The results of unconfined compressive strength of soil GGBS mixtures for
varying percentage of fine and coarse combination mixtures have been
presented in the table below. it can be observed that with increase in percentage
of fine and coarse combination of mixtures the UCC strength increases for both
the mixtures, however the increase is more pronounced with fine mixture
content.
Combination of soil, 5%Fly Ash and Ground granulated slag (Fine and Coarse)
Sl no Parameter UCC in Kpa (fine) UCC in Kpa (Coarse)

1. Soil+0% GGBS 140.704 152.61

2. Soil+ 5% GGBS 265.682 173.481

3. Soil+ 10% GGBS 165.065 136.818

4. Soil+ 15% GGBS 141.665 127.331

5. Soil+ 20% GGBS 119.266 117.845

6. Soil+ 25% GGBS 98.625 90.25

49

Effect of fine and coarse mixtures on the strength of soil

Comparison of fine and coarse combination

300

Fine combination
250
UCC Strength in Kpa

200

Coarse combination
150

100

50

0
0 5 10 15 20 25 30

% Varying ground granulated slag

50

VARIATION OF STRENGTH OF BLACK COTTON
SOIL WITH ADDITION OF LIME
The results of variation of strength of stabilized black cotton soil for
different percentage of lime has been presented in the table below.
From the table it can be observed the characteristic compressive
strength of black cotton soil increases with increase in lime content
and also with different curing period.

Soil, lime in% Compressive strength in Kpa

1 day curing 7 day curing 14day curing 28 day curing

2 55.228 60.215 108.188 162.161

4 68.495 72.625 166.373 248.128

6 170.708 258.589 350.234 480.453

8 228.924 312.368 286.581 546.43

10 186.285 496.325 225.865 404.594
51

Variation of unconfined compressive strength with lime
for different periods of curing soil sample.
Variation of UCC with lime on Curing

600

500 1day curing
UCC Strength in Kpa

400
7day curing
300

14day curing
200

100
28day curing

0
0 2 4 6 8 10 12

Lime in percentage

52

LEACHING OF HEAVY METAL IONS FROM
STABILIZED SOIL MIXTURES
The leaching behavior of stabilized soil mixtures for heavy metal
ions has been studied for 5% of admixtures used and remaining 95%
of black cotton soil the results of leaching concentration of above
mixtures has been presented in the table below.
For 5% Soil Leaching Concentration in mg/l
mixtures

Heavy metal Ions Nickel Copper Iron

Fine fly ash 1.0 0.98 1.0

Coarse fly ash 2.25 5.8 0.89

Fine ggbs 0.95 0.55 2.85

Coarse ggbs 2.5 0.82 0.98

Fine combination 1.98 2.2 2.5

Coarse combination 2.2 2.65 2.8
53

95% soil+5% admixtures

5% Soil mixture

6
Fine fly ash

5
Coarse fly ash
Concentration in mg/l

4
Fine ggbs
3

Coarse ggbs
2

1 Fine combination

0 Coarse combination
nickel copper iron

54

Contd…

ions has been studied for 10% of admixtures used and remaining
90% of black cotton soil the results of leaching concentration of
above mixtures has been presented in the table below.

mixtures




Fine ggbs 1.1 0.88 5.24

Coarse ggbs 2.39 0.87 1.06



55


10% Soil mixture

Fine fly ash
6

5 Coarse fly ash

4 Fine ggbs

3
Coarse ggbs
2
Fine combination
1

Coarse combination
0

nickel copper iron

56

Contd…


mixtures




Fine ggbs 1.2 0.95 5.25

Coarse ggbs 2.5 1.0 1.22



57

15% Soil mixture
6
Fine fly ash
5
Coarse fly ash

4
Fine ggbs

3
Coarse ggbs

2
Fine combination

1
Coarse combination

0
nickel copper iron

58

Contd…

mixtures
1.4 1.25 1.2
Fine fly ash
2.45 6.64 3.1
Coarse fly ash
1.28 1.2 6.24
Fine ggbs
2.58 1.8 1.02
Coarse ggbs
2.95 3.5 4.25
Fine combination
2.42 4.5 3.95
Coarse combination
59

8
20% Soil mixture
Fine fly ash
7

6 Coarse fly ash

5
Fine ggbs

4
Coarse ggbs

3

Fine combination
2

Coarse
1
combination

0

nickel copper iron
60

CONCLUSIONS
I. VARIATION OF MAXIMUM DRY DENSITY AND OPTIMUM
MOISTURE CONTENT FOR FINE AND COARSE FLY ASH MIXTURE
• It was observed that with the increase in water content the dry density decreases
up to 20-30% moisture content and with further increase in water content the
dry density decreases gradually.
• The maximum dry density was observed to be about 1.35 g/cc for 95% soil and
5% fly ash mixture and lowest density was about 0.6g/cc for 70% soil and 30%
fly ash mixture.
II VARIATION OF MAXIMUM DRY DENSITY AND OPTIMUM
MOISTURE CONTENT FOR FINE AND COARSE GGBS MIXTURE
• It was found that with the increase in water content the dry density also
increases up to 20-30% moisture content and with further increase in water
content the dry density increases gradually.
• The lowest dry density was observed to be about 1.42g/cc for 95% soil and 5%
GGBS mixture and maximum density was about 1.72 g/cc for 70% soil and
30% GGBS mixture.
61

Contd..
III VARIATION OF UNCONFINED COMPRESSIVE STRENGTH FOR FINE
AND COARSE FLY ASH MIXTURES
• It was found that percentage variation of strength was maximum for 20-30%
of fine and coarse combination of fly ash content.
• It was found that percentage variation of strength was maximum for 15-20%
of fine and coarse combination of GGBS mixture
• It was found that 8% of lime was optimum for stabilization of soil and
mixture at the end of 28 days of curing period and the corresponding
maximum strength attained was 500 Kpa.
IV LEACHING BEHAVIOR OF HEAVY METAL IONS FROM STABILIZED
SOIL MIXTURES (5 TO 20% OF FLY ASH AND GGBS MIXTURES)
• It was observed that Ni ion concentration was relatively low in the extracted
solution when compared to copper and iron from the stabilized soil mixtures
for all the combinations.
• The analysis of heavy metal ions reveals that the concentration of all the
heavy metal ions were invariably well below the permissible limits except
for copper and iron as per BIS.
62

SCOPE FOR FUTURE WORK
• The amount of fly ash and GGBS mixtures to be mixed for
stabilization of soil may depend on the constituents of soil besides
the environmental conditions. Hence the effect of the mixtures on
different types of soil having different characteristics might be
studied as future research works.
• Scanning electron microscope/ X-ray diffraction studies should be
carried out primarily to identify the mineral phases for different
combinations of soil mixtures.
• Further studies are required so as to ascertain the properties of
absorption behavior for all soil mixtures of heavy metals like
lead, cadmium, mercury, zinc, magnesium, etc.
• Adsorption processes and its effects on their properties for different
combination of soil mixtures need to be studied for different heavy
metals considered.

63

REFERENCES
• KanirajS R, Havanagi V.G Geo technical characteristics of fly- ash soil
mixtures. Geo technical Engineering journal, 1999, 30 (2):129-147
• Bardet, J P and Young, J (1997) Grain size analysis by Buoyancy
method, Geotechnical testing Journal, Vol20, No-4, 1997, pg 481-485
• Sivapullaiah P.V Prashanth J. P Reactive silica and strength of fly
ash, Geotechnical and Geological Engineering Vol.16, 1998, pp239-
250
• D.D. Higgins, J.M. Kinuthia and S. Wild “Soil Stabilization using
Lime-Activated Ground Granulated Blast Furnace Slag” volume
178, pp.1057-1074June 1, 1998
• Joan E Mclean., Bert E,. Behavior of metals in soils, report no 540 S-
92-018, Environmental protection agency, USA,1992.

64

Contd…

• Arif Ali Baig, Sivapullaiah.P.V, Heavy metal leachability of low
lime fly ashes, in Indian Geotechnical Conference-2008, Advances
in geotechnical Engineering Vol II, 2008, PP470-473.
• Joris.J.Dijkstra, R.N.J Comans, W.HW Van Riemsdijk, Development
of a consistent geochemical modeling approach for leaching and
reactive transport processes in contaminated materials,. Wageningen
University, Netherlands, 2007.
• Zhou,C.,Yin, J. H. and Ming,J.P. (2002) Bearing capacity and
settlement of weak fly ash Ground improved using Lime Fly ash
Canadian Geotechnical Journal, 39: 585-596.
• ASTM, Standard test method for 24-h batch –type measurement of
Contaminant by soils and sediments, International American
Standard testing method D4646-87(reapproved 2001., USA,2001.

65

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