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

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.

Contd…

14

MATERIALS AND METHODSIn 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

• 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

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

Contd…

Natural

Water

content

Specific

gravity

Grain size distribution Atterberg’s Limit

Gravel

(%)Sand (%)

Silt and

clay (%)

Liquid

limit

Plastic

limit

Plasticity

Index

Shrinkage

limit

8.95% 2.68 00 10.0638.22 and

51.7266% 37.12% 28.88% 11.63%

16

GRAIN SIZE DISTRIBUTION BY HYDROMETER ANALYSIS

This test is done according to IS 2720(part 3/ section 1) - 1980

0.001 0.01 0.1 1 100

20

40

60

80

100

Grain size distribution of Black Cotton Soil from Gadag

Particle size, mm

Per

cen

tage

fin

es

% Sand=10.06

%Silt=38.22

% Clay=51.72

17

LIQUID LIMIT GRAPH FOR BLACK COTTON SOIL

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70

% o

f Wat

er

No of Blows

% of water

Flow CurveWL

N =25

18

Contd..

Table 2 Mini compaction and compressive strength of Black cotton soil

Max dry density in g/ccoptimum moisture content

in %

Compressive Strength in

Kpa

1.48 21 112.3

Plate 3 Compaction test and Compressive strength of Black Cotton Soil

19

COMPACTION RESULTS FOR SOIL ALONE

Sl NoWater content

(%)Dry density

Γd g/cc

Trial1 6 1.22Trial2 10 1.29Trial3 12.3 1.35Trial4 16.1 1.42Trial5 18 1.45Trial6 20 1.48Trial7 26 1.44Trial8 37.5 1.28

20

COMPACTION CURVE FOR SOIL ALONE

1

1.1

1.2

1.3

1.4

1.5

1.6

0 5 10 15 20 25 30 35 40

dry

dens

ity

gm/c

c

water content in %

Series1

γd max

OMC

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 sample22

Contd….

Physical and chemical properties are presented in Table 3 and Table4 Table 3 Physical properties of Ground granulated blast slag

ColorSpecific

gravity

Atterberg’s limitMini compaction

Liquid limit

(%)

Plastic limit

(%)

Maximum dry

density in

g/cc

Optimum

moisture

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 HigginsSoil 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.

Plate 6 Fine and coarse fly ash sample 24

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

Table 6 Chemical properties of Fly ash

Specific gravity

Grain size distribution Atterberg’s limit

2.13Gravel (%) Sand (%)

Silt and clay (%)

Liquid limit

Plastic limit

Shrinkage limit

00 58 42 35% Non plastic 18.50%

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

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

Contd…

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

• 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.

Contd…

34

RESULTS AND DISCUSSIONSCOMPACTION 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.

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

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

0 5 10 15 20 25 30 35 400

0.2

0.4

0.6

0.8

1

1.2

1.4

Black cotton soil + Fine Fly Ash

5%Fly Ash

10% Fly Ash

15%Fly Ash

20% Fly Ash

25%Fly Ash

30%Fly Ash

Water content in %

Max

. Dry

den

sity

in g

/cc

36

COMPACTION CHARACTERISTICS OF STABILIZED BLACK COTTON SOIL WITH DIFFERENT PROPORTIONS

OF COARSE 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.

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

0 5 10 15 20 25 30 350

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Black cotton Soil+ Coarse Fly ash

5% Coarse Fly ash

10%Coarse Fly ash

15%Coarse Fly ash

20%Coarse Fly ash

25%Coarse Fly ash

30%Coarse Fly ash

Water content in %

Max

. Dry

den

sity

in g

/cc

38

COMPACTION CHARACTERISTICS OF STABILIZED BLACK COTTON SOIL WITH DIFFERENT PROPORTIONS

OF FINE GGBS

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

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.

39

Compaction with Soil and Fine GGBS

0 5 10 15 20 25 30 350

0.4

0.8

1.2

1.6

2

Black cotton Soil+ Fine GGBS

5% Fine ggbs

10%Fine ggbs

15%Fine ggbs

20%Fine ggbs

25%Fineggbs

30%Fine ggbs

Water Content in %

Max

. Dry

den

sity

in g

/cc

40

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

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

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.

41

Compaction with Soil and Coarse GGBS

0 5 10 15 20 25 30 350

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Black cotton Soil+ Coarse GGBS

5%coarse ggbs

10%Coarse ggbs

15%Coarse ggbs

20%Coarse ggbs

25%Coarse ggbs

30%Coarse ggbs

Water Content in %

Max

. Dry

den

sity

in g

/cc

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

0 5 10 15 20 25 30 35 400

50

100

150

200

250

300

350

characteristic strength of Fly ash

fine fly ash coarse fly ash

% varying of Fly ash

UC

C s

tren

gth

in k

pa

44

CHARACTERISTIC UNCONFINED COMPRESSIVE STRENGTH OF SOIL GGBS MIXTURES

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

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.

45

Effect of GGBS content on the strength of soil

0 5 10 15 20 25 30 35 4050

100

150

200

250

300

350

Characteristic strength of GGBS

fine GGBS coarse GGBS

% varying of Ground Granulated Blast Slag

UC

C s

tren

gth

in

kp

a

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

0 5 10 15 20 25 300

50

100

150

200

250

300

350

Comparison of fine and coarse Combination

Fine Combination

Coarse Combination

% varying fly ash

UC

C S

tren

gth

in K

pa

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

0 5 10 15 20 25 300

50

100

150

200

250

300

Comparison of fine and coarse combination

Fine combination

Coarse combination

% Varying ground granulated slag

UC

C S

tren

gth

in K

pa

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.

1 2 3 4 5 6 7 8 9 10 110

100

200

300

400

500

600

Variation of UCC with lime on Curing

1day curing

7day curing

14day curing

28day curing

Lime in percentage

UC

C S

tren

gth

in K

pa

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 mixtures

Leaching Concentration in mg/l

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

nickel copper iron0

1

2

3

4

5

6

5% Soil mixture

Fine fly ash

Coarse fly ash

Fine ggbs

Coarse ggbs

Fine combination

Coarse combination

Con

cen

trat

ion

in m

g/l

54






Fine ggbs 1.1 0.88 5.24

Coarse ggbs 2.39 0.87 1.06




Contd…

55


nickel copper iron0

1

2

3

4

5

6

10% Soil mixture

Fine fly ash

Coarse fly ash

Fine ggbs

Coarse ggbs

Fine combination

Coarse combination

Con

cen

trat

ion

in m

g/l

56






Fine ggbs 1.2 0.95 5.25

Coarse ggbs 2.5 1.0 1.22




Contd…

57


nickel copper iron0

1

2

3

4

5

6

15% Soil mixture

Fine fly ash

Coarse fly ash

Fine ggbs

Coarse ggbs

Fine combination

Coarse combination

Con

cen

trat

ion

in m

g/l

58




Fine fly ash1.4 1.25 1.2

Coarse fly ash2.45 6.64 3.1

Fine ggbs1.28 1.2 6.24

Coarse ggbs2.58 1.8 1.02

Fine combination2.95 3.5 4.25

Coarse combination2.42 4.5 3.95


Contd…

59


nickel copper iron0

1

2

3

4

5

6

7

8

20% Soil mixture

Fine fly ash

Coarse fly ash

Fine ggbs

Coarse ggbs

Fine combination

Coarse combina-tion

Con

cen

trat

ion

in m

g/l

60

CONCLUSIONSI. 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

THANK YOU

66

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