IMPROVEMENT OF S(" (TT 1D-k1ITTT4J( 1'T V AQfl AND BOTTOM ASH PERPUSTAKAAN UMP

1 IH IH I Ill II 1111 UIII I llI 0000092743

MOHD AZFAR IRFAN B MD NASIR

A thesis is submitted in partial fulfillment of the

requirements for the award of degree of

Bachelor of Civil Engineering

Faculty of Civil Engineering and Earth Resources

Universiti Malaysia Pahang

JANUARY 2013

ABSTRACT

The studies conducted is focused on stabilization of soil situated in Pekan

area which are chosen to be the investigation areas. The uses of fly ash and bottom

ash in soil stabilization are intended to improve the physical properties of soil

structural engineering. The amount of fly ash and bottom ash tried were 5%, 10%,

15%, 20%, and 25% by weight. Each testing was conducted five times to get the

average value. The specimens were determined by using the laboratory testing such

as particle size analysis, atterberg limits, standard proctor test, falling head

permeability test, and unconfined compression test. According to AASHTO, the soil

is classified by referred to the passing sieve No. 10, No. 40, and No. 200 which are

75.54%, 66.43% and 55.76% respectively. The average moisture content of plastic

limit for the control soil is 36.71%. When cone penetration is 20mm, the moisture

content of the soil is* 38.5% for liquid limit. From this data, the plasticity index of the

soil is 1.79%. From the giaph compaction curve of control soil, it shows that the

maximum dry density is 17.22 kN/m 3 and the optimum moisture content is 13.0%.

The control soil has the lowest averages ofthepermeability coefficient which is 2.12

x 10-4 cm/s. The value of unconfined compressive strength, qu is 1.132 X 10'° kN/m2.

From Mohr's circle, the cohesion value that obtained is 0.566 x 10'° kNim2. The

consistency of control soil can categorize as very soft clay where the q value are in

range 0 kN/m2 to 24 kN/m2 . By comparing the liquid limit, plastic index and

optimum water content for both fly ash and bottom ash, the additional of 25% bottom

ash gave the lowest values than others percentages which mean that the soil were

have the highest of maximum dry density. By comparing the values of unconfined

compressive strength for both fly ash and bottom ash, the additional of 25% bottom

ash give the highest value of compressive strength which is 1.465 x 10- '0 kN/m2 and

0.732 x 10.10 kN/m2 for the cohesion value than others percentages.

V

Kajian yang dijalankan tertumpu kepada penstabilan tanah yang terletak di

kawasan Pekan yang dipilih untuk menjadi kawasan siasatan. Penggunaan abu

terbang dan abu dasar dalam penstabilan tanah adalah bertujuan untuk meningkatkan

sifat-sifat struktur fizikal kejuruteraan tanah. Jumlah abu terbang dan abu dasar yang

digunakan adalah 5%, 10%, 15%, 20%, dan 25% mengikut berat. Ujian dilakiikan

sebanyak lima kali untuk meiidapatkan nilai purata. Spesimen yang telali ditentukan

akan menjalam ujian makmal seperti analisis saiz zarah, had Atterberg, pemadatan

Proctor Piawai, ujian keboiehtelapan, dan ujian mampatan tidak terkurung. Menurut

AASHTO, tanah dikelaskan dengan merujuk kepada ayak No. 10, No 40, dan No.

200 yang masing-masing bernilai 75.54%, 66.43% dan 55.76%. Purata kandungan

lembapan had plastik bagi tanah kawalan adalah 36,71%. Apabila kon penembusan

adalah 20mm, kandungan lembapan tanah adalah 38.5% bagi had cecair. Daripada

data liii, indeks kep1astikan tanah adalah 1.79%. Daripada graf lengkung pernadatan

tanah kawalan, ia menunjukkan bahawa ketumpatãn kering maksimum adalah 17.22

kN/m3 dan kandungan lembapan optimum ialak l3.O°/q. Tanah kawalan mempunyai

purata pekali kebolehtelapan terendah iaitu 2.12 x 10-4 cm/s. Nilai kekuatan

mampatan tak terkurung, qu adalah 1.132 x 10b0 /m2 Daripada bulatan Mohr,

nilai ricih yang diperolehi adalah 0.566 x 10.10 kN/m2. Tanah kawalan boleh

dikategorikan sebagai tanah hat yang sangat lembut di mana nilai qu berada dalam 0

kN/m2 hingga 24 kN/m2. Dengan membandingkan had cecair, indeks plastik dan

kandungan lembapan optimum untuk kedua-dua abu terbang dan abu dasar,

tambahan 25% abu dasar masing-masing memberikan nilai terendah berbanding

peratusan yang lam. Im bermakna tanah tersebut mempunyai ketumpatan kering

paling maksimum. Dengan membandingkan nilai kekuatan mampatan tak terkurung

untuk kedua-dua abu terbang dan abu dasar, tambahan 25% abu dasar memberi nilai

kekuatan mampatan tertinggi iaitu 1.465 x 10b0 kN/m2 dan 0.732 x 10' 0 kN/m2

untuk nilai ricihan berbanding peratusan yang lain.

vi

TABLE OF CONTENTS

CHAPTER TITLE PAGE

TITLE PAGE i

DECLARATION

DEDICATION

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS xiv

LIST OF APPENDICES xvi

1 INTRODUCTION

1.1 Research Background 1

1.2 Problem Statement 2

1.3 Objectives of Study 3

1.4 Scope of Study 3

1.5 Significant of Study 4

2 LITERATURE REVIEW

2.1 Introduction 5

2.2 Definition 5

2.2.1 Soil Stabilization 5

2.2.2 Additive Stabilization 6

2.2.3 Fly Ash 6

2.2.3.1 Physical Characteristics 7

vii

VII'

2.2.3.2 Fly Ash Classification 7

2.2.4 Bottom Ash 8

2.2.4.1 Physical Characteristics 8

2.2.5 Clay 9

2.3 Clay Formation 10

2.4 Mineral of Clay Fraction 10

2.5 Sampling 11

2.5.1 Sample Quality 13

2.5.2 Types of Sampling Method 13

2.6 Soil Classification 14

2.7 AASHTO Classification System 15

2.8 Unified Soil Classification System (USCS) 16

2.9 Sieve Analysis 17

2.10 Atterberg Limit 17

2.10.1 Liquid Limit 17

2.10.2 Plastic Limit 17

3 METHODOLOGY

3.1 Introduction 19

3.2 Sample Preparation 21

3.3 Testing Configuration 21

3.4 Particle Size Analysis 21

3.5 Atterbérg Limit 22

3.5.1 Liquid Limit 22

3.5.2 Plastic Limit and Plastic Index of soil 23

3.6 Standard Proctor Test 24

3.7 Falling Head Permeability Test 25

3.8 Unconfined Compression Test 26

4 RESULTS AND ANALYSIS

4.1 Introduction 28

4.2 Laboratory Test 28

4.2.1 Particle Size Analysis 28

x

4.2.2 Atterberg Limit 31

4.2.2.1 Liquid Limit 31

4.2.2.2 Plastic Limit 32

4.2.3 Standard Proctor Test 44

4.2.4 Falling Head Permeability Test 55

4.2.5 Unconfined Compression Test 59

5 CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions 76

5.1.1 Summary of conclusion 80

5.2 Recommendations 81

REFERENCES 83

APPENDICES 86

LIST OF TABLES

NO TITLE PAGE

2.1 Classification of fly ash according to Australian standard 8

2.2 Typical range of index properties of some common clay 11

2.3 Types of sample quality and suitable test 13

2.4 Types of sampler suitable for soft clay 14

2.5 AASHTO classification criteria 15

2.6 First and second letters of group symbols 16

4.1 Sieve analysis data 29

4.2 Classification of soil sample by AASHTO 30

4.3 Liquid limit data 31

4.4 Plastic limit data 32

4.5 Summary of liquid limit and plastic index data 40

4.6 Density determination data for control soil 44

4.7 Summary of dry density and moisture content data 51

4.8 Permeability data of control soil 55

4.9 Summary of permeability coefficient 57

4.10 Unconfined compression test data for control soil 60

4.11 The relative consistency 62

4.12 Summary of unconfined compressive strength 73

4.13 Summary of cohesion values 74

4.14 Summary of liquid limit 77

4.15 Summary of plastic index 77

4.16 Summary of maximum dry density 78

4.17 Summary of optimum moisture content 78

4.18 Summary of unconfined compressive strength 79

4.19 Summary of cohesion value 80

x

LIST OF FIGURES

NO TITLE PAGE

2.1 Engineering properties of fly ash 7

3.1 Flowchart of study 20

4.1 Particle size distribution curve (control soil) 30

4.2 Graph of cone penetration versus moisture content 33

(control soil)

4.3 Plasticity chart (USCS) 34

4.4 USCS and symbol chart 34

4.5 5% of fly ash 35

4.6 10%of fly ash 35

4.7 15%of fly ash 36

4.8 20% of fly ash 36

4.9 25% of fly ash 37

4.10 5% of bottom ash 37

4.11 10% of bottom ash 38

4.12 15% of bottom ash 38

4.13 20% of bottom ash 39

4.14 25% of bottom ash 39

4.15 Graph of liquid limit % (fly ash) 41

4.16 Graph of liquid limit % (bottom ash) 41

4.17 Graph of plastic index % (fly ash) 42

4.18 Graph of plastic index % (bottom ash) 42

4.19 Compaction curve of control soil 45

4.20 5% of fly ash 46

4.21 10% of fly ash 46

4.22 15% of fly ash 47

xi

4.23 20% of fly ash 47

4.24 25% of fly ash 48

4.25 5% of bottom ash 48

4.26 10% of bottom ash 49

4.27 15% of bottom ash 49

4.28 20% of bottom ash 50

4.29 25% of bottom ash 50

4.30 Graph of maximum dry density, kN/m 3 (fly ash) 52

4.31 Graph of maximum dry density, kN/m 3 (bottom ash) 52

4.32 Graph of optimum moisture content, % (fly ash) 53

4.33 Graph of optimum moisture content, % (bottom ash) 53

4.34 Hydraulic conductivity. 56

4.35a Graph of load per unit area versus unit strain 61

4.35b Mohr's circle 61

4.36a 5% of fly ash 63

4.36b Mohr's circle 63

4.37a 10% of fly ash 64

4.37b Mohr's circle 64

4.38a 15% of fly ash 65

4.38b Mohr's circle 65

4.39a 20% of fly ash 66

4.39b Mobr's circle 66

4.40a 25% of fly ash 67

4.40b Mohr's circle 67

4.41a 5% of bottom ash 68

4.41b Mohr's circle 68

4.42a 10% of bottom ash 69

4.42b Mohr's circle 69

4.43a 15% of bottom ash 70

4.43b Mohr's circle 70

4.44a 20% of bottom ash 71

4.44b Mohr's circle 71

4.45a 25% of bottom ash 72

xli

xlii

4.45b Mohr's circle 72

4.46 Graph value of qu (fly ash) 73

4.47 Graph value of qu (bottom ash)

73

4.48 Graph of cohesion (fly ash) 74

4.49 Graph of cohesion (bottom ash)

74

4.50 Effects of disturbance on stress-strain behavior 75

LIST OF ABBREVIATIONS

AASHTO American Association of State Highway and

Transportation Officials

kPa = Kilopascal

Si02 = Silica dioxide

CaO = Calcium Oxide

ASTM = American Society for Testing and Materials

Si = Silicon

Al = Aluminum

Fe = Iron

Ca Calcium

Na = Natrium

Mg Magnesium

USCS = Unified Soil Classification System

LL = Liquid limit

PL Plastic limit

P1 = Plastic index

BS British standard

g = Gram

M111 Millimeter

in Inch

kg = Kilogram

cm Centimeter

m/s = Meter per second

= Micrometer

kN/m3 = Kilo Newton per meter cube

cm2 = Centimeter square

cm/s = Centimeter per second

s = Second

xiv

xv

mm 2 Millimeter square

kN Kilo Newton

kN/mm2 = Kilo Newton per millimeter square

kN/m2 = Kilo Newton per meter square

c = Cohesion

qu Compressive strength

xvi

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Particle Size Analysis result 86

B Atterberg Limit Test result 87

C Standard Proctor Test result

109

D Falling Head Permeability Test result 132

E Unconfined Compression Test result 143

CHAPTER 1

INTRODUCTION

1.1 Research background

Soil is the base of any structures as building will stand firm on it. Normally, a

base must be strong, can resist failure and able to support huge load of a structure.

This is why, before any constructions work can be done, analysis and study must be

applied to the soil in order to know the status of the soil. The soil will give problems

and difficulties to engineers as soil can present in many types, properties and

strength. The variety of the soil is the factors that cause some soil to undergo

excessive settlement, collapse, and have distinct lack of strength. Different types of

soil could produce differéht soil characteristics as it is due to their nature of their

pore fluids and their mineralogy of their fabric.

Soil stabilization has become one of the useful solutions to treat the soil in

such areas to achieve the required engineering properties and specification. Soil

stabilization can be defined as the modification of the characteristics of soil in order

to enhance the engineering performance of the soil, for example improve the density

of soil, mixing the soil with additives to change the chemical and physical properties

such as stiffness, compressibility, permeability, and workability.

This study presents the determination of basic properties and effectiveness of

soft soil in Pekan, Pahang. The research were conducted several of contents of fly

ash and bottom ash mixed with soft soil as a samples. The samples set up by mixing

soil samples with several of fly ash and bottom ash at optimum water content. The

amount of fly ash and bottom ash tried were 5%, 10%, 15%, 20%, and 25% by

weight.

2

1.2 Problem statement

Structures are meant to stand firm for many years to come and more

importantly, could provide great strength to support loads within the structure. The

unstable properties of soft soil are believed to be the major circumstances for any

structure to be built on it. The major challenge of problems with soft soil are the

stability of the soil and settlement.

Foundation settlements are the most emergence problems happened in

building constructions. Many commercial and residential buildings have become

distressed due to settlement. This problem is often caused by weak or improperly

compacted soils. All buildings which are built on soft soil are compatible to be

constructed with weak foundation and having a high risk for structure failure.

The high compressibility properties of soft soil are one of the major factor

that couid lead to high settlement. This is happened from the fact that soft soil are

fitter in particles and being too cohesive with the presence of water. High settlement

are so dangerous as it could affects the movement of whole structure and would

ended up with structure failures and cracks.

Soft soil have the lower value of permeability where water are hard to get

through it particles and this is the reason why soft soil have a high moisture content.

The presence of water could have made the soil become more unstable. Water could

be the main agent that make the soil become unstable especially with the high ability

of the soft soil to trap huge amount water within its particles. The soil particles have

high tendency to bond closely with one another that make soft soil become easily

compressed when undergoing compaction activity. By the weak conditions of the

soil, the stiffness of the soil could easily be affected and this have made the soil

become weak in strength. Strength of soil are the most vital part of any soil

properties. Soil with weak strength could not sustain massive and high load on it. It

becomes more dangerous when structures are built on the soft soil without having

proper design and analysis to the soil. The structures are more subjected to fail rather

than safe to be used. The development of any construction works in this type of soil

perhaps the most challenging of all.

3

1.3 Objectives of study

The main objectives of this study are:

1. To investigate the engineering properties of Pekan soil.

2. To determine the effectiveness of soil stabilized by using fly ash and

bottom ash.

3. To determine the optimum content of stabilizer those give the

maximum strength.

1.4 Scope of study

The scopes of this research were focused on stabilization of soft soil situated

in Pekan area. The soil samples were collected from Jalan Kuantan, Pekan while fly

ash and bottom ash were obtained from Pahang Malaysian Rock Products. Sdn Bhd.,

Panching. The site investigation and analysis data were done to get engineering

properties and strength for original soft soil as well as soil that added with fly ash

and bottom ash.

The study focused on the fly ash and bottom ash to be used in soil

stabilization of soft soil. There are three types of specimens were prepared which is

soil as control specimen, soil added with fly ash and soil added with bottom ash. This

specimens were added with different propotion of fly ash and bottom ash which is

5%, 10%, 15%, 20%, and 25%. Each testing were conducted five times to get the

average value. The specimens were determined by using the laboratory testing such

as particle size analysis, atterberg limits, standard proctor test and falling head

permeability test, and unconfined compression test. The test result and analyzing

were followed the AASHTO or Malaysian specification and supported by computer.

4

1.5 Significant of study

Soft soil can be categorized as problematic soil. The low strength and high

compressibility characteristics the soil had, are the major reasons why a careful

design analysis could be taken for any structure built on it. Due to these problems,

soil investigation on the basic properties and shear strength of the soil must be

carried out.

This study presents the determination of basic properties and shear strength of

soft soil in Pekan, Pahang. Any construction works which have been constructed in

soft soil area are believed to face more problems compared to other types of soils.

Soft soil is believed to experience more failure through its characteristics due to

weak compressibility and problematic. Some of the significant problems happened to

soft soil are its failure to supports huge loads as a foundation and its nature of high

settlement.

Consequently, soil improvement is a very important study in geotechnical

engineering. Without this step, failures will occur which will cause losses of life,

money and effort. Hence, before any construction, site investigations should be

carried out to evaluate the kind of soil improvement in the site. Soil improvement can

be done either by soil stabilization or soil consolidation. The results data of the basic

soil properties and shear strength could also allow a quick and economic alternative

in order to design for construction on soft soil.

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

Most area in Malaysia have soft clay soil as the major soil distribution

percentage. This is happened from the fact that Malaysia has many parts of coastal

areas and also rivers that located in many state in Peninsular Malaysia. The

construction of building, roads, bridge and harbors on soft clays are facing the higher

risk for settlement and stability problem. This has become main geotechnical

problem in soft clay engineering (Brand & Brenner, 1981) stated that soft is defined

as clay that has the shear strength less than 25kPa. Soft clay cause many problem to

geotechnical engineers since it is highly compressible, high liquid limit and high

plasticity.

2.2 Definition

2.2.1 Soil Stabilization

Stabilization is the process of blending and mixing materials with a soil to

improve certain properties of the soil. The process may include the blending of soils

to achieve a desired gradation or the mixing of commercially available additives that

may alter the gradation, texture or plasticity, or act as a binder for cementation of the

soil (Erdem O.T et al., 2011). According to Armstrong (1961), soil stabilization has

been introduced during World War II to strengthen the weak soil so that it could bear

with heavy military five machines.

6

2.2.2 Additive Stabilization

Additive is manufactured commercial products when added to the soil in the

proper quantities which can improve some engineering characteristics of the soil

such as strength, texture, workability, and plasticity. Additive stabilization is

achieved by the addition of proper percentages such as cement, lime, fly ash and

bottom ash, bitumen, or combinations of these materials to the soil. The selection of

type and determination of the percentage of additive to be used is dependent upon the

soil classification and the degree of improvement in soil quality desired. Smaller

amounts of additives are required when it is simply to modify soil properties such as

gradation, workability, and plasticity. Larger quantities of additive are used when it

is to improve the strength and durqbility significantly. After the additive has been

mixed with the soil, spreading and compaction are achieved by conventional means

(McCarthy, 2005).

2.2.3 Fly Ash

Fly ashis one of the residues generated in the combustion of coal. Fly ash is

generally captured from the chimneys of coal-fired power plants. This material is

solidified while suspended in the exhaust gases and is collected from the exhaust two

gases by electrostatic precipitators. Since the particles solidify while suspended in

the exhaust gases, fly ash'particles are generally spherical in shape (Ferguson, 1993).

Depending upon the source and makeup of the coal being burned., the component of

fly ash vary considerable, but all fly ash includes substantial amounts of silicon

dioxide (Si02) (both amorphous and crystalline) and calcium oxide (CaO), both

being endemic ingredients in many coal bearing rock strata. Fly ash produced from

coal power stations is usually disposed of in landfills. But, nowdays fly ash can be

reused in construction sector. The reuse of fly ash as an engineering material

primarily stems from its pozzolanic nature, spherical shape, and relative uniformity.

Fly ash recycling, in descending frequency, includes usage in Portland cement and

grout, embankments and structural fills and road subbase.

7

2.2.3.1 Physical Characteristics

The physical, geotechnical and chemical parameters to characterize fly ash

are the same as those for natural soils, e.g., specific gravity, grain size, atterberg

limits, compaction characteristics, permeability coefficient, shear strength parameters

and consolidation parameters. The properties of ash are a function of several

variables such as coal source, degree of pulverization, design of boiler unit, loading

and firingconditions, handling and storage methods. A change in any of the above

factors can result in detectable changes in the properties of the ash produced

(Parisaramahiti, 2007). The procedures for determination of these parameters are also

similar to those for soils.

Specific gravity 11 .90-2.55 Plasticity 'Non Plastic Proctor compaction - Maximum dry density, 10.90-1.60 Optimum moisture content. (%) 38.0-18.0 Angle of internal friction'( 0) 13040° cohesion (kg/cm 2) lNegltgible compression index 10.05-0.4 Penneability (CM/SEC) - i05-103 Particle size distributlo4n Clay size fraction (%) Silt size fction (%) Sand size fraction (%)

ZI Gravel stze fraction (%)

1710 8-85

7-90

0-10

Coefficient of uniformity 13.1-10.7

Figure 2.1: Engineering properties of fly ash (Parisaramahiti, 2007)

2.2.3.2 Fly Ash Classification

This classification reflects the broad subdivision of US coals in bituminous

and higher rank coal of the eastern states and the lower rank western coals with

associated high calcium contents. Although widely used (Sloss et al., 1996, Smith,

2005), the ASTM classification may not be directly applicable to or adequately

reflect the variability found in Australian fly ashes both with respect to chemistry and

8

mineralogy. In Australia, three grades of fly ash are recognised (SAA, 1998) as

shown in Table 2.1.

Table 2.1 : Classification of fly ash according to Austalian standard (SAA, 1998)

Grade Fineness Loss on Moisture S03 content (% minimum ignition content (% maximum)

mass passing a (%maximum) (%maximum) 45um_sieve)

Fine 75 4.0 1.0 3.0 Medium 65 5.0 1.0 3.0 Coarse 55 1 6.0 1.0 3.0

Due to the variability of fly ash, doubts have been raised as to the suitability

of the current classification schemes which may be overly simplistic and fail to take

into account other important characteristics such as mineralogy (vide discussion in

Sloss et al., 1996). Also, many of the current classifications have been developed for

the use of fly ash in concrete and cement and thus may not be applicable for other

end uses. A need has been identified for an overall rating system which would be

useful for all potential end-users of fly ash (Sloss et al., 1996).

2.2.4 Bottom Ash

Bottom ash refers to the coal ash byproduct, formed in pulverized coal

furnaces, which are too large to be carried in the flue gases and therefore fall to the

bottom of the furnace into a dry bottom ash hopper. Bottom ash is produced in power

generation as a by-product from the burning of coal. It is usually treated as a waste

product which, in many instances, is required to be disposed of in the same manner

as municipal wastes (Kayabali and Bulus, 1999). As the bottom ash is removed from

the hopper, it is then passed through a grinder for size reduction, and resembles

coarse sand in size and shape. The major components of the bottom ash material are

silicon (Si), aluminum (Al), iron (Fe) and calcium (Ca). Bottom ash is well-graded

granular and highly compactable materials. The physical, chemical and engineering

properties, in particular, are important parameters affecting the behavior of bottom

ash in various engineering applications.

9

2.2.4.1 Physical Characteristics

Bottom ashes colour was dark black similar to coal. They have angular

particles with a very porous surface texture. Bottom ash particles range in size from a

fine gravel to a fine sand with very low percentages of silt-clay sized particles. The

ash is usually a well-graded material, although variations in particle size distribution

may be encountered in ash samples taken from the same power plant at different

times. Dry bottom ash is gray to black in colour, angular, irregular shape and has a

porous structure and rough surface texture while wet bottom ash is composed of hard

and angular to sub-angular particles with a shiny black colour and a smooth surface

texture much like crushed glass. According to Huang (1990), majority portion of

bottom ash formed in a dry condition and gray in colour with an irregular shape.

2.2.5 Clay

According to Whitlow (2001) clay is define as soils particles having sizes

below 2.tm which can be determine at site by its feel that is slightly abrasive but not

gritty and clay also feel greasy. Clays are flake shape microscopic particles of mica

clay minerals and other minerals (Heiwany, 2007). Clay is a common type of

cohesive soil (Liu & Evett, 2005) which has small particle that cannot be separated

by sieve analysis into size categorizes because there no practical sieve can be made

with the so small opening. Clay is said as a submicroscopic mineral particle size of

soil which has the fine texture when clay present in dominant proportions compare

with silt and sand the soil is described as having a fine or heavy texture. Fine

textured soils are plastic and sticky when wet but hard and massive when dry.

According to Tan et al., (2005) the heavy texture used because they are very heavy

and difficult to flow.

According to Singer & Munns (2006), clay is said to be surface active which

means that much happen on their surface. Clay minerals cohere to each other and

adhere to longer mineral particles. Their surface absorbs and holds water, organic

compounds, plant nutrients ion and toxic ions.

10

2.3 Clay Formation

Clay formation and translocation are processes that differentiate soils from

rocks. (Singer & Munns, 2006), started that feldspar, mica, amphibole and pyroxene

minerals are transformed into clays through process of hydrolysis, hydration and

oxidation. As an example, in bitite mica, FE2+ can oxidize, K-- leaves the structure to

maintain electrical neutrality and the structure is weakened. Next, soluble Ca2+, Mg2+

and Na-4- in the soil solution replace the remaining biotite K+ to form vermiculite or

montrimorillonite. All this may take place without any movement of mineral. Mica

and other aluminosilicates can slowly dissolve into individual silica molecules and

Al, Mg, K and Fe ions can recombine to form clay in the same location, where they

recombine to form clay.

According to Brand & Brenner (1981) usually clay minerals are the product

of rock weathering. The type and the amounts of clay minerals formed are affecting

by climate, parent material, drainage pattern (topography) and vegetation. The most

important affect is by the climate.

Young sediments such as soft clay must undergone little diagenese when it

became to isostatic upliftor marine regression, whereas the sediments which are

covered by big overburden, consolidate and dehydrate and make the particles

become cemented. Further increase in temperature and pressure would lead to

metamorphism, a process where the clay minerals are destroyed and new minerals

such as mica and feldspar are formed. Tectonic pressure or volcanic activity can

bring the metamorphism material back to the surface where the first diagenese occur

and by the weathering of the exposed rock 4 the formation of clay minerals start a new

(Brand & Brenner, 1981).

2.4 Mineral of Clay Fraction

Singer & Munns (2006) stated that clay minerals in Table 2.2 have some

comrrion properties and important difference that are:

11

a. Clay minerals tend to form microscopic to submicroscopic crystal

with large surface area. They are colloidal particle which are in range

of 1 qm to 1 gm in diameter.

b. Clays are platy or flaky microcrystal, reflecting their layered crystal

structure. The shape and size explain clays slipperiness and plasticity

when wet and tendency of clay particles to stack and stick together to

coat larger particles and to line pores. Plasticity describes the ability of

clay to be molded into forms that remain their shape.

C. All clays absorb or lose water on their surface when the water content

changes. Some clay allows water into interlayer of their molecule

structure. When water is absorbed, clays expand as the water leaves

the space.

Table 2.2: Typical Range of Index Properties of some Common Clay Minerals

(Shroff & Shah, 2003)

Clay Mineral Liquid Limit Range P1 range

Kaolinite 40-60 10-25

Illite 80-120 50-70

Sodium Montrimollite 700 650

Other montrimollite 300-650 200-250

Granular soils 20 or less 0

2.5 Sampling

Sampling can refer to the taking of soil or rock from bored holes (Liu &

Evett, 2005). Besides that, Brand & Brenner (1981) state that samplings are the

samples are used for soils identification and determination of soil properties and it is

required for almost every investigation. Depending of type of soils, the choice of the

sampler type and sampling techniques can be obtained and it necessary for obtaining

Undisturbed samples.