COMPARATIVE STUDY OF THE SHRINKAGE CHARACTERISTICS OF

PEAT AT SOUTH EAST JOHORE

NURSYAHIDAH BINTI SAEDON

A thesis submitted for partial fulfilment of the requirement for the award of

Masters in Civil Engineering

Faculty of Civil and Environmental Engineering

Universiti Tun Hussein Onn Malaysia

JUNE 2016

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

STATUS CONFIRMATION FOR MASTER PROJECT THESIS

COMPARATIVE STUDY OF THE SHRINKAGE CHARACTERISTICS OF

PEAT AT SOUTH EAST JOHORE

ACADEMIC SESSION: 2016/2017

I, NURSYAHIDAH BINTI SAEDON, agree to allow this Master Project Thesis to

be kept at the Library under the following terms:

1. This Master Project Report is the property of the Universiti Tun Hussein Onn Malaysia .

2. The library has the right to make copies for educational purposes only.

3. The library is allowed to make copies of this report for educational exchange between their

higher educational institutions.

4. ** Please mark (√)

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importance to Malaysia as STIPULATED under

the OFFICIAL SECRET ACT 1972)

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NOTE :** If this Undergraduate Project Report is classified as CONFIDENTIAL or

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NURSYAHIDAH BINTI SAEDON

48, JALAN GELAM 2,

TAMAN RINTING,

81750 JOHOR BAHRU,

JOHOR

Date :

Approved by,

ASSOC. PROF. DR. ADNAN BIN

ZAINORABIDIN

Date :

√

iii

DECLARATION

I hereby declare that the work in this thesis is my own except for quotations and

summaries which have been duly acknowledged

Student : …………………………………………..

NURSYAHIDAH BINTI SAEDON

Date : JUNE 2016

Supervisor : …………………………………………….

ASSOCIATE PROFESSOR DR. ADNAN BIN

ZAINORABIDIN

iv

DEDICATION

I wish to dedicated and thankful to Almighty Allah though whose grace and mercy, I

have survived till the end.

For my beloved Ayah, Emak and Ibu

Mr. Saedon B. Majid, Mdm. Halijah Bt. Salleh and Mdm. Mastura Bt. Ismail

My Supervisor

Associate Professor Engr. Dr. Adnan bin Zainorabidin

My Siblings

Nurhana, Nurhuda, Muhamad Nur Safwan, Muhammad Nur Hakimi and Mohammad

Nur Syahmi

My Special Friends

Daing Abdul Razzaq bin Mohd Nasir

My Friends

Siti Nooraiin, Nurul Nadia, Amira, Siti Noor Aini, Nor Amalina, Hawa Haidar

v

ACKNOWLEDGEMENT

In the name of Allah, the Most Gracious and the Most Merciful,

Alhamdulillah, all praises to Allah for the strengths and His blessing in completing

this thesis. Special appreciation goes to my supervisor, Assoc. Prof. Dr. Adnan bin

Zainorabidin, for his supervision, enthusiastic guidance, and encouragement in all

aspects during completing this project. His invaluable help of constructive comments

and suggestions throughout the experimental and thesis works have contributed to the

success of this research.

I would like to express my appreciation to the staff of Research Centre of Soft

Soil (RECESS), UTHM, Mrs. Salina, Mr. Amir and Mr. Muzaffar Syah for their

support and assisting in my laboratory work. Not forgotten to RECESS postgraduate

students for their support, co-operations and help towards my master project affairs.

My deepest gratitude to my beloved parents and also to my siblings for their

love, prayers, support and encouragement. Last but not least, sincere thanks to all my

friend for their kindness and moral support during my study. For those who directly or

indirectly contributed in this study, thank you very much.

vi

ABSTRACT

This study is to review the behaviour of peat under reconstituted sample and

undisturbed soil and to investigate shrinkage behaviour using modified techniques.

Three different locations have been selected which are Parit Nipah, Batu Pahat and

Integrated Peat Research Station (IPRS), Pontian for peat soil, while clay soil is

collected from the Research Centre of Soft Soil (RECESS), UTHM. For modified

techniques of measuring shrinkage, peat samples were prepared in different diameter

sizes (50mm, 70mm and 100mm) and temperatures (air-dried, 60C and 105C).

Undisturbed samples were compared with reconstituted sample that had been obtained

by wet sieve and dry sieve procedures (particles that passing 0.300mm and 0.425mm).

Reconstituted sample was also dried with two different temperatures. It is significant

in comparing the shrinkage characteristics by using a modified techniques with the

British standard method. In Von post classification system, Parit Nipah and Pontian

peat soil had been classified as H5 and H4. The results of the index properties tests of

Parit Nipah, Pontian peat soil and RECESS clay soil had been analysed. Most of the

shrinkage values show that reconstituted samples that had been prepared in wet

condition with particle sizes passing 0.300mm is nearly same with undisturbed

samples. It is also shows that particle sizes with passing 0.300mm sieve has higher

absorption rather than 0.425mm. Thus, it shows that, smaller particle sizes give higher

results of volumetric/linear shrinkage and loss of water. It was found that higher

temperature was not necessarily in the volume changes of the soil sample. It also can

be concluded that the shrinkage of peat soil that had been prepared in wet condition is

more compatible with undisturbed peat soil and natural state condition on field site.

Fibre of peat sample gives huge factors of the effect to the volume changes and

shrinkage measurement.

vii

ABSTRAK

Kajian ini adalah untuk mengkaji kelakuan tanah gambut bagi sampel tanah yang

terganggu dan tanah tidak terganggu. Ia juga bagi menyiasat pengecutan tanah gambut

menggunakan teknik baru yang telah diubah suai. Tiga lokasi yang berbeza telah

dipilih iaitu Parit Nipah dan Stesen Penyelidikan Tanah Gambut (IPRS), Pontian untuk

tanah gambut, manakala tanah liat diambil dari Pusat Penyelidikan Tanah Lembut

(RECESS), UTHM. Untuk teknik baru yang diubah suai dalam pengukuran

pengecutan tanah, sampel tanah gambut disediakan dalam berbeza saiz diameter

(50mm, 70mm dan 100mm) dan suhu (suhu bilik, 60°C dan 105°C). Sampel tidak

terganggu dibandingkan dengan sampel semula yang telah disediakan dengan prosedur

ayak basah dan kering (partikel yang melepasi 0.300mm dan 0.425mm).Sampel yang

terganggu telah dikeringkan melalui dua suhu yang berbeza. Ia penting dalam

mengukur pengecutan tanah dengan menggunakan kaedah baru yang diubah suai

berbanding dengan kaedah Standard British. Merujuk kepada sistem klasifikasi Von

Post, sampel di Parit Nipah dan Pontian dikelaskan sebagai H5 dan H4. Sifat asas ujian

Parit Nipah, Pontian tanah gambut dan tanah liat RECESS telah dianalisis. Sebahagian

besar pengecutan tanah gambut menunjukkan bahawa sampel semula yang disediakan

dalam keadaan basah dengan saiz partikel 0.300mm seakan selari dengan sampel tidak

terganggu. Ia juga menunjukkan saiz zarah 0.300mm menyerap lebih cepat daripada

0.425mm. Oleh itu, ia menunjukkan bahawa, saiz partikel yang lebih kecil

memberikan nilai yang tinggi bagi isipadu pengecutan dan kehilangan air. Didapati

bahawa suhu yang tinggi tidak semestinya menjadi faktor utama dalam perubahan

isipadu sampel tanah. Ia juga boleh disimpulkan bahawa pengecutan tanah yang telah

disediakan dalam keadaan basah lebih serasi dengan tanah gambut terganggu dan

keadaan semula jadi di tapak lapangan. Kandungan serat sampel tanah gambut akan

memberikan kesan yang tinggi kepada perubahan isipadu dan pengukuran pengecutan.

viii

TABLE OF CONTENTS

TITLE i

STATUS OF CONFIRMATION ii

DECLARATION iii

DEDICATION iv

ACKNOWLEDGEMENT v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES xii

LIST OF FIGURES xiv

LIST OF EQUATIONS xvii

LIST OF ABBREVIATIONS xviii

LIST OF APPENDIXES xix

CHAPTER TITLE PAGES

CHAPTER 1 INTRODUCTION

1.1 Background of thesis 1

1.2 Problem Statement 3

1.3 Objectives of study 6

1.4 Aim of study 6

1.5 Scope of study 7

1.6 Outline of thesis 8

ix

CHAPTER 2 LITERATURE REVIEW

2.1 Peat

2.1.1 Peat in the Malaysia 10

2.1.2 Properties of peat soil 12

2.2 Clay soil in Malaysia 16

2.3 Shrinkage Characteristics

2.3.1 Definition of Shrinkage Measurement 21

2.3.2 Shrinkage Process 23

2.3.3 Shrinkage of Peat Soil 24

2.3.4 Shrinkage of an Inorganic Soil 27

2.4 Methods of soil sampling 30

2.5 Summary of chapter 34

CHAPTER 3 RESEARCH METHODOLOOGY

3.1 Introduction 35

3.2 Sampling Method 38

3.2.1 Disturbed sampling 38

3.2.2 Undisturbed sampling 38

3.3 Laboratory testing method 41

3.3.1 Moisture Content by Standard Procedure 42

3.3.2 Moisture Content (different temperature - 60°C) 43

3.3.3 Specific Gravity 43

3.3.4 Liquid limit 45

3.3.5 Rolling hand (Plastic Limit for clay) 47

3.3.6 Organic Content 48

3.3.7 Fibre Content 48

3.4 Sampling Preparation of Shrinkage Measurement

3.4.1 Standard Linear Shrinkage 50

3.4.2 Modified Linear Shrinkage 52

3.5 Summary of chapter 54

x

CHAPTER 4 RESULTS AND CRITICAL ANALYSIS

4.1 Introduction 55

4.2 Physical Characteristic 56

4.3 Index Properties Test Result 57

4.3.1 Moisture Content 59

4.3.2 Specific Gravity 60

4.3.3 Organic Content 61

4.3.4 Fibre content 61

4.3.5 Liquid Limit 62

4.4 Shrinkage Analysis

4.4.1 Bar Linear Shrinkage Method 66

(BS1377: Part 2: 1990: 6.5)

4.4.2 Modified Linear Shrinkage

4.4.2.1 Undisturbed sample preparation 68

(different sizes and different temperature)

4.4.2.1.1 Relationship of volume changes 68

of sample to the temperature effect

4.4.2.1.2 Relationship of water loss to the 73

temperature effect

4.4.2.1.3 Relationship of shrinkage measurement 75

(horizontal) to the temperature effect

4.4.2.2 Reconstituted sample preparation 79

4.4.2.2.1 Relationship of volume changes of 80

sample to the temperature effect

4.4.2.2.2 Relationship of water loss to the 86

temperature effect

4.4.2.2.3 Relationship of shrinkage measurement 92

to the temperature effect

4.4.3 Other research contributions

4.4.3.1 Different compositions in 50mm diameter 102

of undisturbed samples

4.4.3.2 Further Investigation of Soil Volume Changes 104

xi

at Four Dimensional Points for Undisturbed

Samples of Parit Nipah and Pontian peat

4.4.4 Detailing shrinkage measurements

4.4.4.1 Undisturbed samples 106

4.4.4.1.1 Parit Nipah peat sample 106

4.4.4.1.2 Pontian peat sample 107

4.4.4.2 Reconstituted samples 109

4.4.4.2.1 Parit Nipah peat sample 109

4.4.4.2.2 Pontian peat sample 111

CHAPTER 5 CONCLUSION AND RECOMMENDATION

5.1 Introduction 115

5.2 Discussions 115

5.2.1 Objective 1: The behaviour of peat under 117

reconstituted and undisturbed samples condition

5.2.2 Objective 2: An investigation the characterization 120

shrinkage behaviour by modified techniques in

preparing samples and shrinkage measurement

techniques

5.2.3 Objective 3: Established the shrinkage behaviour of 123

peat by comparing reconstituted (samples with passing

sieve 0.300mm and 0.425mm) and undisturbed sample

that has variable particle sizes

5.3 Conclusion 124

5.4 Further recommendation 127

REFERENCES

xii

LIST OF TABLES

NO. TITLE PAGES

1.1 Outline of the study 8

2.1 The distribution of peat land and organic soil in Malaysia 11

(Hashim and Islam, 2008)

2.2 Properties of peat soil based on types of peat 13

2.3 The Von Post Scale of Humidification (source Ekono, 1981) 14

2.4 Properties of peat soil of some areas in Malaysia 16

2.5 Classification of clay soil in Malaysia (Balasubramaniam et al, 1985) 17

2.6 Thickness of clay soil in Peninsular Malaysia (Abdullah and 17

Chandra, 1987)

2.7 Characteristics of clay soil classification in Peninsular Malaysia 19

(Tajuddin, 2004)

2.8 Average annual subsidence of peat at different locations in the 27

Waikato Region

2.9 Probable Expansion as Estimated from Classification Test Data 29

(Holtz and Kovacs, 1981)

3.1 Type of tube sampling and related tests for each location 41

3.2 Summary of testing parameter and conditions (Zainorabidin, 2011) 41

3.3 USDA classification of peat 49

3.4 Numbers of the sample for reconstituted sample that was prepared by 53

wet sieving method

3.5 Numbers of the sample for reconstituted sample that was prepared by 53

dry sieving method

3.6 Numbers of the undisturbed sample for this testing 54

4.1 Typical results of index properties of peat soil 58

4.2 Typical results of index properties of clay soil 58

4.3 Specific gravity of peat and clay soil 60

xiii

4.4 Organic content of peat soil 61

4.5 Fibre content of peat soil 62

4.6 Liquid limit of Parit Nipah peat soil 63

4.7 Liquid limit of Pontian peat soil 64

4.8 Liquid limit of RECESS clay soil 65

4.9 Linear shrinkage of Parit Nipah peat soil 67

4.10 Linear shrinkage of Pontian peat soil 67

4.11 Linear shrinkage of RECESS clay soil 67

4.12 Volumetric shrinkage of Parit Nipah and Pontian peat due to temperature 71

4.13 Loss of water on Parit Nipah and Pontian peat sample due to temperature 73

4.14 Linear shrinkage of Parit Nipah and Pontian peat due to temperature 79

effect

4.15 Volumetric shrinkage on Parit Nipah and Pontian peat sample due to 86

temperature effect

4.16 Loss of water on Parit Nipah and Pontian peat sample due to temperature 91

effect

4.17 Linear shrinkage of Parit Nipah reconstituted peat sample 92

4.18 Linear shrinkage of Pontian reconstituted peat sample 98

4.19 Shrinkage observation that contains different compositions 102

4.20 Detailing shrinkage measurements of Parit Nipah undisturbed samples 106

4.21 Detailing shrinkage measurements of Pontian undisturbed samples 107

4.22 Detailing shrinkage measurements of Parit Nipah reconstituted samples 109

4.23 Detailing shrinkage measurements of Pontian reconstituted samples 111

5.1 Volumetric shrinkage on reconstituted samples of Parit Nipah and 121

Pontian peat soil

5.2 Volumetric shrinkage of undisturbed sample of Parit Nipah and 121

Pontian peat due to temperature effect

5.3 Different structure of reconstituted samples between 0.300mm and 123

0.425mm in dry condition

5.4 Index properties of peat and clay soil 124

5.5 Linear shrinkage of undisturbed peat sample due to temperature effect 125

5.6 Linear shrinkage of reconstituted peat sample due to temperature effect 125

xiv

LIST OF FIGURES

NO. TITLE PAGES

1.1 The Holme Post, today and in the past (Waltham, 2000) 2

1.2 Land subsidence on one of the houses in Kampung Parit Nipah, 4

Batu Pahat

1.3 Poor road conditions in Kampung Parit Nipah, Batu Pahat as a 5

result of subsidence caused by shrink-swell behaviour.

1.4 Longitudinal cracking on a rural road in Lincolnshire as a result of 5

clay-related subsidence. Credit photo: O. Pritchard. (Pritchard, 2015)

2.1 Peat land distribution in Semenanjung Malaysia (642,857 ha) 11

(Hashim and Islam, 2008)

2.2 Definition of shrinkage limit of clay soil (Holtz and Kovacs, 1981) 21

2.3 Shrinking Soil Mechanism 24

2.4 The record of ground subsidence on the peat within 150 years at 25

the Holme Post which is correlated with water table (Waltham, 2000)

2.5 Conceptual model describing the development of primary, secondary 28

and tertiary cracks, resulting from the build-up of tensile stresses

on drying (Taboada, 2003)

3.1 Actual work procedure in this study 36

3.2 Method of collecting undisturbed sample 40

3.3 Specific gravity testing procedure 44

3.4 Apparatus for cone penetrometer liquid test 45

3.5 Peat soil preparation of bar linear shrinkage 51

3.6 Procedure of modified shrinkage measurement of undisturbed sample 53

4.1 Illustration of peat and clay soil composition (a) Parit Nipah peat 57

soil; (b) Pontian peat soil; and (c) RECESS clay soil

4.2 Graph of penetration against moisture content for Parit Nipah 64

peat soil

xv

4.3 Graph of penetration against moisture content for Pontian 65

peat soil

4.4 Graph of penetration against moisture content for RECESS 66

clay soil

4.5 Volume changes with various temperature for Parit Nipah peat soil 68

(50mm, 75mm and 100mm diameter of samples)

4.6 Volume changes with various temperature for Pontian peat soil 69

(50mm, 75mm and 100mm diameter of samples)

4.7 Volume changes of 50mm diameter of sample with different 71

temperature for Parit Nipah (PPN) and Pontian (PN) peat soil

4.8 Volume changes of 75mm diameter of sample with different 72

temperature for Parit Nipah (PPN) and Pontian (PN) peat soil

4.9 Volume changes of 100mm diameter of sample with different 72

temperature for Parit Nipah (PPN) and Pontian (PN) peat soil

4.10 Water loss of Parit Nipah (PPN) and Pontian (PP) peat soil 73

with different temperature (50mm diameter size)

4.11 Water loss of Parit Nipah (PPN) and Pontian (PP) peat soil 74

with different temperature (75mm diameter size)

4.12 Water loss of Parit Nipah (PPN) and Pontian (PP) peat soil 74

with different temperature (100mm diameter size)

4.13 Linear shrinkage of Parit Nipah peat soil with different temperature 76

(a) 50mm diameter of samples; (b) 75mm diameter of samples; and

(c) 100mm diameter of samples

4.14 Linear shrinkage of Pontian peat soil with different temperature 77

(a) 50mm diameter of samples; (b) 75mm diameter of samples; and

(c) 100mm diameter of samples

4.15 Schematic drawing in dry and saturated conditions; 80

(i) sand; (ii) clay; and (iii) peat soil (Zainorabidin, 2010)

4.16 Volume changes for Parit Nipah reconstituted peat sample with 81

different drying temperature (a) air-dried; (b) 60°C; and (c) 105°C

4.17 Comparison of volumetric shrinkage for Parit Nipah reconstituted peat 83

sample with different drying temperature

4.18 Volume changes for Pontian reconstituted peat sample with different 84

drying temperature (a) air-dried; (b) 60°C; and (c) 105°C

xvi

4.19 Comparison of volumetric shrinkage for Pontian reconstituted 85

peat sample with different drying temperature

4.20 Moisture loss for Parit Nipah reconstituted peat sample with different 87

drying temperature (a) air-dried; (b) 60°C; and (c) 105°C

4.21 Comparison of moisture loss for Parit Nipah reconstituted peat 88

sample with different drying temperature

4.22 Moisture loss for Pontian reconstituted peat sample with drying 89

temperature (a) air-dried; (b) 60°C; and (c) 105°C

4.23 Comparison of water loss for Pontian reconstituted peat sample 90

with different drying temperature

4.24 Linear shrinkage for Parit Nipah reconstituted peat sample with 93

different drying temperature (a) air-dried; (b) 60°C; and (c) 105°C

4.25 Comparison of linear shrinkage for Parit Nipah reconstituted peat 95

sample with different drying temperature

4.26 Horizontal and vertical shrinkage for Parit Nipah reconstituted sample 96

4.27 Linear shrinkage for Pontian reconstituted peat sample with different 97

drying temperature (a) air-dried; (b) 60°C; and (c) 105°C

4.28 Comparison of linear shrinkage for Pontian reconstituted peat 100

sample with different drying temperature

4.29 Horizontal and vertical shrinkage for Pontian reconstituted sample 101

4.30 Changes in density for 50mm diameter size of PP sample 103

4.31 Changes in loss of moisture for 50mm diameter size of PP sample 103

4.32 Shrinkage measurement by point A, B, C and D 104

4.33 Diameter of Parit Nipah peat sample in 105⁰C for 24 hours 105

4.34 Diameter of Pontian peat sample in 105⁰C for 24 hours 105

5.1 Comparison between undisturbed and reconstituted samples for 118

Parit Nipah (PN) peat soil; (a) air-dried; (b) 60°C; and (c) 105°C

5.2 Comparison between undisturbed and reconstituted samples for 120

Pontian (PO) peat soil; (a) air-dried; (b) 60°C; and (c) 105°C

xvii

LIST OF EQUATIONS

NO. TITLE PAGES

2.1 Linear Shrinkage 22

2.2 Inside Clearance Ratio (ICR) 33

2.3 Area Ratio (AR) 33

3.1 Moisture Content 42

3.2 Specific Gravity 43

3.3 Plastic Limit 47

3.4 Ignition Loss 48

3.5 Fibre Content 49

3.6 Linear Shrinkage 52

xviii

LIST OF ABBREVIATIONS

AD Air-dried

AR Area Ratio

ASTM American Society for Testing and Materials Standard

AW Absorbed Water

BS British Standard Institution

CR Clay RECESS

FC Fibre Content (%)

GS Specific Gravity

ICR Inside Clearance Ratio

ICW Intercellular Water

IPRS Integrated Peat Research Station

IPW Interparticle Water

ISA Ideal Sampling Approach

LL Liquid Limit (%)

LOI Loss of Ignition (%)

LS Linear Shrinkage (%)

OC Organic Content (%)

PIV Particle Image Velocimetry

PL Plastic Limit (%)

PP Pontian Peat

PPN Parit Nipah Peat

PVC Polymerized Vinyl Chloride

RECESS Research Centre of Soft Soils

SL Shrinkage Limit (%)

USA United States of America

UTHM Universiti Tun Hussein Onn Malaysia

w Moisture Content (%)

xix

LIST OF APPENDICES

Appendix A

Appendix B

Appendix C

Appendix D

Appendix E

Appendix F

1

CHAPTER 1

INTRODUCTION

1.1 Background of thesis

Urbanisation leads to the utilization of very soft soil such as peat ground conditions,

especially in extensive peat areas such as Kampung Parit Nipah and Integrated Peat

Research Station (IPRS), Pontian. The behaviour and composition of peats are

accentuating the need for useful geotechnical design purposes and engineering

geological classification and assessment of the ground conditions (Zainorabidin and

Bakar, 2003; Zainorabidin et al.,2007).

Peat soil area is categorized as very unstable ground (Alwi, 2008; Deboucha et

al., 2008; Hashim and Islam, 2008; Duraisamy et al., 2008; Huat et al., 2011 and

Atemin, 2012). It is highly compressible and characterized to have very low shear

strengths and poor drainage characteristics (Duraisamy et al., 2008; Huat et al., 2011;

and Atemin, 2012).

The characterization and composition of peat that are not homogenous and high

fibrous content have a significant effect on behaviour as well as the strength of soil.

The physical characteristics such as high moisture content and organic content more

than 75% are the causes of stability problems (Masawi, 2010). It creates very

challenging construction problems, such as excessive time-dependent foundation

settlements, as well as bearing capacity and foundation failures (Fuleihan, 2015).

In many parts of the world, most of the countries that experienced seasonal

changes every year such as United Kingdom, USA and Japan are considered as

important and have potential economic significance with a shrink swell characteristics

of fine-grained soil. It can cause excessive damage to structure and road constructions

2

by shrinking swell characteristics which happen repetitively every year. This situation

is also called as the subsidence of soil.

For countries with no seasonal changes such as Malaysia, rainfall and hot

weather occur frequently significantly in shrink swell soil. It can cause cracking to the

building and heaving the roadways. For the property owners of buildings and roadways

who do construction on representative soil, they will face financial lost to repair the

affected houses.

According to Figure 1.1, it shows the emergence of the Holme Post from the

wasting peat, and there was subsidence from 1850’s to 2000’s even without any

loading. Waltham (2000) mentioned that it subsided about 4m and gave an impressive

record of the ground subsidence. Throughout the time, it was then slowed to a rate that

only recognisable over a decade or more; where the observations were clearly recorded

the ground movement since the peat was more drained which caused subsidence.

Figure 1.1: The Holme Post, today and in the past (Waltham, 2000)

However, sampling of the soil is also significant in obtaining more accurate

results by minimizing the degree of disturbance before the sampling is tested in the

laboratory. Further study and ground information were gathered as the most desired

research based on the appreciation of the type and the extent of challenging ground

3

conditions, especially subsidence by the shrinkage effect that exists on the test sites. It

gives difficulty to the construction of peat soils due to the fibre origin, temperature and

humidity. Apart of shrinkage effect, ground subsidence is also due to a combination of

consolidation and wastage, and it will cause a settlement to the soils.

1.2 Problem Statement

Peat as organic soil that is known as soft soil is widely distributed in Malaysia. It is

difficult to collect samples of peat soil due to the high fibre and groundwater level

especially an undisturbed sample.

For peat, shrinkage effect and some other important parts are important in

determining the strength and moisture content. It is a common cause to foundation

problems; especially in road construction. It is also contributed to the cause of

settlement of soil. The changes of moisture content may also due to periods of unusual

rain, changes in humidity or unusual drought. By referring to British Standard, oven

dried temperature for a soil is 105 ± 5 C. However, it will be a problem to the peat

soil because of its composition with high fibre content that consists of root and wood

decayed.

It is significant to observe the shrinkage effect especially when a property

subsides it can cause significant cracking and damage to the property. For affected

areas such as Parit Nipah, buildings that were constructed with piling were floated

while buildings without piling were cracked. However, shrinkage which taking into

account on climate change is likely to result in more frequent occurrence of

subsidence.

4

Figure 1.2: Land subsidence in one of the houses in Kampung Parit Nipah, Batu

Pahat

Infrastructure such as roadways was also affected by clay-related subsidence

that was caused by shrinkage effect. Road networks were also susceptible to

subsidence. As in Figure 1.3 and 1.4, it can result in severe longitudinal cracking of

pavements and making poor driving conditions. Since the roadways were constructed

using piling methods, the pile can emerge from the road when it was subsidised.

5

Figure 1.3: Poor road conditions at Kampung Parit Nipah, Batu Pahat as a result of

subsidence that possibly caused by shrink-swell behaviour

Figure 1.4: Longitudinal cracking on a rural road in Lincolnshire as a result of clay-

related subsidence. Credit photo: O. Pritchard. (Pritchard, 2015)

6

1.3 Objectives of Study

The objectives of this study are:

1. To review the behaviour of Parit Nipah and Pontian peat under

reconstituted and undisturbed conditions.

2. To investigate the characterization of shrinkage behaviour by modified

techniques in preparing samples and shrinkage measurement techniques.

3. To establish the shrinkage behaviour of peat by comparing reconstituted

(samples that passing sieve at 0.300mm and 0.425mm) and undisturbed

samples.

1.4 Aim of the study

The purpose of the study is to review the shrinkage behaviour of peat under

reconstituted sample and undisturbed sample with different techniques and

temperatures. A modified method of using two different grain sizes was compared with

undisturbed sample. According to the British Standard, the sample preparation for

linear shrinkage testing used particle sizes that passing 0.425mm. However, in real

condition of peat soils, it was composed to various particle sizes and most of the peat

soil particles were formed by decayed plants that are larger than 0.425mm. Moreover,

the shrinkage characteristics were observed by two different techniques which are in

accordance to British standard which is bar linear shrinkage method and modified

shrinkage techniques. Modified shrinkage techniques were conducted directly on

undisturbed samples of the tube sampler in order to retain their conditions,

compositions and soil moisture.

7

1.5 Scope of the study

In this study, two different types of soil were collected which are peat and clay soil.

Peat samples were collected from Kampung Parit Nipah and Institute Peat Research

Station (IPRS), Pontian, while clay samples were collected from the Research Centre

of Soft Soil (RECESS), UTHM. This study is also focused on the sampling method of

undisturbed sample especially for soft soil due to no proper method of collecting

samples. Clay soil was conducted to compare with peat soil based on a standard

method. It is also focused on behaviour of soft soil such as peat and clay soil. By

establishing the engineering properties of soft soil; it involves field and laboratory

testing.

For the laboratory test, it is significant in measuring the physical test like

measuring shrinkage characteristics for different types of soil, diameter of samples,

different grain sizes, temperature and duration of testing. A physical test also includes

Particle Size Distribution, Degree of Decomposition, Specific Gravity, Moisture

Content, Loss of Ignition, Liquid Limit, Fibre Content, Organic Content and pH test.

All tests were conducted according to BS1377:1990 and ASTM: D4427.

Shrinkage effect was evaluated by different techniques then the samples were

compared with a standard method with three different diameter sample sizes (50mm,

70mm and 100mm). For sample preparations, reconstituted sample was prepared by

using wet and dry sieve methods with two different grain sizes (0.300mm and

0.425mm). Meanwhile, undisturbed sample was prepared directly by using a PVC tube

that had been collected from field sites. Reconstituted and undisturbed samples were

placed into oven-dried with three different temperatures, which are air-dried, 60C and

105C to observe the shrinkage effect. Two different types of sample which are peat

and clay were used in order to establish and review the shrinkage behaviour of peat

soils to be compared with inorganic soil.

8

1.6 Outline of the thesis

An outline of the thesis during this study is listed as below:

Table 1.1: Outline of the study

Chapter Titles Description

01 Introduction

The background of this study, including the

objectives of the project, aims, scopes of study and

problem statement.

02

Literature

review of past

research

Critical reviews from the past researches that

related to this study, which include soil

properties/characteristics (peat soil), laboratory

testing techniques and theories and shrinkage

characteristics.

03 Research

Methodology

Materials and experimental works in terms of

sample preparation, site investigation, test

equipment and procedure of the laboratory and field

testing. This section discusses on laboratory and

field testing techniques. It also proposes a modified

method of observation on shrinkage measurement

with different methods.

04 Results and

analysis

This chapter presents the test results include the

analysation of volume changes, loss of water and

linear shrinkage of soil with different techniques

that are reconstituted sample and undisturbed soil in

terms of swelling and shrinkage properties. It also

conducts basic properties. Correlations between the

various parameters are established and compared

with results from previous researchers.

9

05 Conclusion and

recommendation

Summary of study and detail recommendation for

future work based on current research experience

and literature review. It helps to establish a

modified method for further practice and long term

applications.

Reference A complete list of references is included

Appendices Appendices on relevant topics can be found at the

end of the thesis.

10

CHAPTER 2

LITERATURE REVIEW

2.1 Peat

2.1.1 Peat in Malaysia

Peat is found in all parts of the world except in deserts and the arctic regions which are

estimated to have about 1 billion acres of peat land in the world or about 4.5% of total

land areas (Deboucha et al., 2008). Distribution of peat soil is predominantly in a

tropical area. Meanwhile, Huat et al. (2011) reviewed that peat area consists of 300

million hectares and 2/3 of South East Asia. As in Indonesia, it is covered by 26 million

hectares, then, for Japan, the peat area consists of approximately 2000 km2, 170 million

hectares of peat in Canada, 150 million hectares of peat soil in Rusia and U.S. consists

of 30 million hectares of peat. He concluded that Canada has the largest area of peat

in the world.

Peat has also been identified as one of the major types of soil that found in

Malaysia. According to Zainorabidin and Bakar (2003), almost 13% or 16,500 km2 of

areas in Sarawak is covered by peat and it is the most extensive peat lands in Malaysia.

90% of the area has more than 1 m thickness of peat. They also mentioned that in

Peninsular Malaysia, peat soils are found in the coastal areas, especially in the west

area which are Pontian, Batu Pahat, Kuantan and Pekan districts, West Selangor and

Perak.

Hashim and Islam (2008) tabulated the distribution of peat land and organic

soil in Malaysia as in Table 2.1 and Figure 2.1. It is stated that Sarawak has the largest

area covered by peat in Malaysia.

11

Table 2.1: The distribution of peat land and organic soil in Malaysia (Hashim and

Islam, 2008)

State Peat (ha) Organic Clay

Johor 228, 960 69, 540

Negeri Sembilan 6, 300 -

Selangor 194, 300 -

Perak 107, 500 -

Pahang 219, 561 62, 939

Terengganu 81, 245 6, 755

Kelantan 7, 400 -

Sarawak 1, 657, 600 -

Sabah 86, 000 -

Total for Malaysia 2, 588, 866 139, 234

Figure 2.1: Peat land distribution in Semenanjung Malaysia (642,857 ha) (Hashim

and Islam, 2008)

12

Generally, most of the peat areas have a problem with road construction and

foundation. The development process will be more difficult to be carried out because

of the nature of soft soil, loam, high organic content and a very low shear force because

it consists of fibre. These unfavourable characteristics of peat soil deposits make them

unsuitable for supporting most engineering projects or infrastructure development.

Furthermore, such ground presents failure due to ground instability such as localised

sinking and extreme settlement over extended time periods when subjected to an

increment in loading (Jarret, 1995; Huat et al., 2004). Most of the areas that

predominantly covered by peat cannot be developed by any infrastructure and most of

the buildings have lower than four-storey.

2.1.2 Properties of Peat soil

There are differences between organic soil, inorganic soils, and peat soil. For

soil that contains less than 20% of organic matter can be classified as inorganic soil.

Meanwhile soil that contains organic matter more than 20% can be considered as

organic soil and soft soil. As peat, it must have more than 65% of organic matter. Peat

soil is also known to have high content of fibre and mineral which is less than 35%.

Composition of peat for every location is different due to its origin fibre, climate,

humidity, water level and temperature. Huat et al. (2004) discussed that properties of

peat are divided into three which are physical, chemical and physico-chemical

properties. The physical structure changes in chemical state that is loss of organic

matter either in gas or solution by involving the decomposition and humidification of

soil.

Peat is divided into three groups of layers which are fibric, hemic and sapric.

Fibric is the peat soil with least decomposition with 67% of fibre content. Meanwhile,

hemic is known as semifibrous with a moderate decomposed plant which consist of

33% to 66% of fibre content and sapric with less than 33% of fibre content can be

called as sapric [Duraisamy et al. (2008); Huat et al. (2011); Tang et al. (2011)]. Peat

profile can be categorized into three distinguish degrees of decomposition which are

sapric, hemic and fibric. In general, sapric layer is located in the upper layer underlain

by hemic and fibric.

13

In Malaysia, classification of peat and organic soils is based on the British

Standard 5930:1981. However, this classification has been modified and improved by

Public Work Malaysia to make this system works better with the Malaysia

environment (Jarret, 1995). Table 2.2 presents the properties of peat soils and the Von

Post Scale of Humidification (Ekono, 1981) is shown in Table 2.3.

Table 2.2: Properties of peat soil based on types of peat

Properties Fibric peat Hemic peat Sapric peat

Bulk density (γb) 1.260 Mg/m3 1.170 Mg/m3 0.996 – 1.019

Mg/m3

Dry density (γd) - 0.180 Mg/m3 0.243 Mg/m3

Moisture content (w) 630 – 670% 791 % 140 – 300%

Void ration (e) 8.36 10.48 – 15.98 4.12 – 4.84

Fibre content 90.00% 65% 31 – 32%

Specific gravity (Gs) 1.24-1.64 1.88 1.49 – 1.56

Classification/Von Post H3 H4 H8

Linear Shrinkage 12% 7 – 29% -

Liquid Limit 380% 119% 240 – 330%

pH 3 – 4 3.6 -

Loss on ignition 97 – 99% 78.76% 70 – 80%

Location Pontian Parit Nipah West Malaysia

References Tang (2011) Atemin (2012)

Huat et al.

(2004);

Duraisamy

(2007)

14

Table 2.3: The Von Post Scale of Humidification (Ekono, 1981)

Symbol Description

H1

Completely undecomposed peat which, when squeezed, releases

almost clear water. Plant remains easily identifiable. No amorphous

material presents.

H2

Almost entirely undecomposed peat which, when squeezed, releases

clear or yellowish water. Plant remains easily identifiable. No

amorphous material presents.

H3

Very slightly decomposed peat which, when squeezed, releases

muddy brown water, but no peat passes between the fingers. Plant

remains identifiable and no amorphous material presents.

H4

Slightly decomposed peat which, when squeezed, releases very

muddy dark water. No peat is passed between the fingers but the plant

remains slightly pasty and lost some of its identifiable features.

H5

Moderately decomposed peat which, when squeezed, releases very

“muddy” water with a very small amount of amorphous granular peat

escaping between the fingers. The structure of the plant remains quite

indistinct although it is still possible to recognize certain features.

The residue is very pasty.

H6

Moderately highly decomposed peat with a very indistict plant

structure. When squeezed, about one-third of the peat escapes

between the fingers. The residue is very pasty but shows the plant

structure more distinctly than before squeezing.

H7

Highly decomposed peat. Contains a lot of amorphous material with

very faintly recognizable plant structure. When squeezed, about one-

half of the peat escapes between the fingers. The water, if any is

released, is very dark and almost pasty.

H8

Very highly decomposed peat with a large quantity of amorphous

materials and has a very indistinct plant structure. When squeezed,

about two-thirds of the peat escapes between the fingers. A small

quantity of pasty water may be released. The plant material remains

in hand and consists of residues such as roots and fibres that resist

decomposition.

H9

Practically fully decomposed peat in which there is hardly any

recognizable plant structure. When squeezed, it is a fairly uniform

paste.

H10 Completely decomposed peat with no discernible plant structure.

When squeezed, all the wet peats escape between the fingers.

B1 Dry peat

B2 Low moisture content

B3 Moderate moisture content

B4 High moisture content

B5 Very high moisture content

*Note: The moisture of each peat sample is estimated using the above scale of 1-5

and symbol “B” (derived from Swedish blӧthet = wetness)

15

By referring to the properties of In-situ peat soil that was obtained by Alwi

(2008), moisture content and fibre content have value in the range of 700 – 850 % and

84.99%. Peat soil is classified by conducting Von Post Scale of Humidification (source

Ekono, 1981). It was shown that the soil is slightly decomposed peat which, when

squeezes, it releases very muddy dark water. Moreover, no peat is passed between the

fingers but the plant remains slightly pasty and lost some of its identifiable features.

Soil sample is classified as H4.

Basic parameters such as water content, fibre content, organic content, specific

gravity and linear shrinkage are included in this study as shown in Table 2.4. One of

basic parameters is water content. The values depend on its origin, degree of

decomposition and chemical composition of peat. Naturally, peat has very high natural

water content due to its natural water-holding capacity (Huat et al., 2011). The water

content is in the range between 414 to 850%. Past researchers conducted water content

testing according to BS 1377: Part 1: 1990 which requirements for oven-drying

method.

Specific gravity of peat is greatly affected by its composition and percentage

of the inorganic component. It is related to the degree of decomposition and mineral

content of peat. Higher specific gravity indicates higher degree of decomposition and

higher mineral content. The determination of the specific gravity of the peat soil

sample uses small pycnometer method according to BS 1377: Part 2: 1990. Specific

gravity lies in the range from 0.9 to 1.88.

Organic matter influences many of the physical, chemical and biological

properties of soils. Some of the properties are influenced by organic matter including

soil structure, soil compressibility and shear strength. According to BS 1377: Part 3:

1990, the organic content will determine the mass loss on ignition.

As mentioned previously, there are differences between organic soil, inorganic

soils, and peat soil. For soil that contains less than 20% of organic matter can be

classified as inorganic soil while soil that contains organic matter more than 20% can

be considered as organic soil and soft soil. As peat, it must have more than 65% of

organic matter. Table 2.4 shows that organic content that is valued between 78.76 to

99% while fibre content is from 58 to 90%, which is in the range to classify the soil as

peat soil.

16

Table 2.4: Properties of peat soil of some areas in Malaysia

Location Klang, Selangor Matang,

Sarawak

Pontian,

Johor

Parit Nipah,

Batu Pahat

Water Content (%) 414 – 850 700 – 850 600 791 630-670

Fibre Content (%) 85 – 90 84.99 79 58 -

Organic Content

(%) 89 – 98 98.46 91 78.76 97 – 99

Specific Gravity 0.9 – 1.4 1.343 1.2 1.88 1.24 – 1.64

Linear Shrinkage

(%) 5.6 5.58 5 7 to 29 12

References Wong et

al. (2008)

Deboucha

and

Hashim

(2009)

Kolay et

al. (2011)

Atemin,

H.H.

(2012)

Tang, B.L.

(2011)

2.2 Clay soil in Malaysia

According to Guggenheim and Martin (1995), clay can be defined as a combination of

one or more clay minerals with traces of metal oxides and organic matter. Brand and

Brenner (1981) claimed that clayey soil has a compression strength between 25kPa to

50kPa. Clay is a natural substance which is called as a fine-grained soil that has

plasticity behaviour when mixed with water. Clay can be distinguished from other

fine-grained soils by the differences in size and mineralogy and it is formed by

sedimentary deposition process. Table 2.5 shows the classification of clay soil in

Malaysia (Balasubramaniam et al., 1985).

17

Table 2.5: Classification of clay soil in Malaysia (Balasubramaniam et al, 1985)

Types of soil Thickness (m) Colour Description

1 2-6 Light grey/ light

brown

Sand black with sea shells/ upper

layer

2 10-32 Greenish grey /

greyish

Loose sand at 2-3 m layer thickness,

multiple amount of shells and

organic materials

3 3-11 Light brown/

greyish brown Fine grained soil

4 4-25 Light grey/

yellowish grey

Non homogenous, with moderately

hard clay soil layer

5 - Light brown/ grey Peat soil group to sandy gravel soil

It also can be distinguished from other soils by Geotechnical testing based on

plasticity index of the soil on conducting the Atterberg Limits since clayey soil can

expand and shrink due to moisture content. By referring to the ASTM standard, clay

particles are smaller than 2 μm. Clay is also considered as the earliest to be used in

building materials. For a thousand years, it has the high qualities in this natural

product.

In Peninsular Malaysia, clayey soil is commonly found in coastal areas of the

east and west Malaysia, especially in the coastal areas of Johor, Melaka, Selangor and

several areas in East Malaysia which are Kelantan and Terengganu (Abdullah and

Chandra, 1987). The thickness of the clayey soil layer in those locations is

approximately at 35 meters. Abdullah and Chandra (1987) found the thickness of the

clay soil in Peninsular Malaysia as shown in Table 2.6.

Table 2.6: Thickness of clay soil in Peninsular Malaysia (Abdullah and Chandra,

1987)

Location Thickness (m)

Perlis and Kedah 5-12

Sungai Kedah river dam 8-12

Alor Setar airport 12

Prai and Penang Bridge 12-25

Butterworth – Changkat Jering highway 5-15

Sungai Kerian basins 10

Bagan Datoh – Teluk Intan 5-11

Klang port 8-30

18

Kg. Acheh – Marine Harbour 3-7

Development project area in agricultural at Johor

Bahru 10-35

Kuantan 3-20

Sungai Kuantan bridge 5-12

Kuantan Port 3-15

Chukai 4-8

Semerak – Kemasin 3-10

Ting and Ooi (1977) conducted engineering characteristics of clay and found

that the sensitivity of clayey soil is a moderate sensitivity and a little loam. Table 2.7

below shows some characteristics of clay soil classification in Peninsular Malaysia by

Tajuddin (2004).

Chen and Tan (2003) studied properties of clay in Klang area, they found that

the thickness of the soil may vary from 20 to 40m. The liquid limit of this soil is high

which mostly about 50 to 150%. Plasticity index varies from 20 to 80% and the

compression ratio is in the range of 0.25 to 0.5. It is shown that there is a relationship

between the compression index and moisture content.

19

Table 2.7: Characteristics of clay soil classification in Peninsular Malaysia (Tajuddin, 2004)

Source Characteristics of clay classification

West Coast Moisture

Content (%)

Unit Weight

(kN/m3)

Specific

Gravity, Gs

Particle Size

Distribution (%) Activity

Liquid Limit

(%)

Plastic Limit

(%)

Liquidity

Index

Ting & Ooi

(1977) 20 - 140 - -

33-65 clay

24-62 silt

1-36 sand

- 40-155 10-45 -

Abdullah &

Chandra

(1987)

20-175 14.6-15 2.53-2.6

15-55 clay

38-70 silt

7-16 sand

Natural -

Active - - 0.5-1.2

Malaysian

Highway

Authority

(1989)

20-120 14-17 -

30-70 clay

25-55 silt

1-30 sand

- 40-100 20-40 0.4-2.3

Kobayashi, et

al. (1990) 40-125 14.5-17.5 2.45-2.7

25-85 clay

15-60 silt

0.45 sand

- 50-130 20-70 -

Aziz (1993) 15-130 14-15.5 2.6

27-59 clay

25-64 silt

2-28 sand

Non active –

active (0.77-4) 40-130 16-53 0.1-1.6

Ramli, et al.

(1994) 12-175 13-16.5 2.35-2.75

50-60 clay

40-50 silt

<5 sand

Natural –

Active (1.5-

1.8)

50-150 20-65 -

19

20

Hussein

(1995) 20-160 13-16 2.5-2.8

50-60 clay

20-40 silt

0-25 sand

Non active –

active (0.5-2) 40-125 10-40 0.1-2.1

East Coast Moisture

Content (%)

Unit Weight

(kN/m3)

Specific

Gravity, Gs

Particle Size

Distribution (%) Activity

Liquid Limit

(%)

Plastic Limit

(%)

Liquidity

Index

Abdullah &

Chandra

(1987)

21-107 16.3-17.1 2.5-2.57

31-56 clay

16-49 silt

6-28 sand

- - - -

Kobayashi et

al (1990) 70-100 14.5-15.5 2.65-2.7 - - - - -

Ramli et al

(1994) - - - -

Non active -

active (0.6-

1.2)

- - -

20

21

2.3 Shrinkage Characteristics

2.3.1 Definition of Shrinkage Measurement

The shrinkage limit (SL) is the water content where further loss of moisture will not

result in any more volume reduction (United States Army Corps of Engineers,

1970). The test to determine the shrinkage limit is ASTM International D4943. The

shrinkage limit is much less commonly used than the liquid and plastic limits.

Shrinkage limit of a soil is defined as soil where reduction in water content will

not cause a decrease in the volume of the soil mass, but an increase in water content

will cause an increase in the volume of soil mass (McGraw-Hill Dictionary, 2003).

Haines (1923) and Strik (1954) also defined soil shrinkage as the specific

volume change of soil relative to its water content and mainly due to clay swelling

properties. It can be measured in most soils with more than 10% of clay content

(Boivin et al., 2006). This process is reversible with changes in water content and the

reverse to shrinkage is swelling.

The Shrinkage Limit of a soil is defined as the water content at which no further

volume decrease occurs, but where the degree of saturation is still essentially 100 %

(Holtz and Kovacs, 1981) (Figure 2.2).

Figure 2.2: Definition of shrinkage limit of clay soil (Holtz and Kovacs, 1981)

22

In terms of linear shrinkage, it has been introduced by the Texas Highway

Department in 1932 (Heidema, 1957) and it is currently described as a standard test

procedure of bar linear shrinkage test in British Standard (1990). It was found to be

the most reliable soil constant in road construction (Netterberg, 1978) and most

significant indicator of cohesion for gravel wearing course material (Paige-Green,

1989). Haupt (1980) and Emery (1985) performed studies to determine subgrade

moisture prediction models and indicated that the bar linear shrinkage produced good

result than any other Atterberg Limit results. Paige-Green and Ventura (1999)

concluded that the bar linear shrinkage test is a more effective test to indicate material

performance than the traditional Atterberg limits.

Cerato and Lutenegger (2006) performed linear shrinkage test by conducting

liquid limit test with Casagrande cup. A third of the soil was placed in a greased brass

mould approximately 140 mm long and 25 mm in diameter. The soil was placed in the

mould in three layers and tapped against a flat surface in between the layering to

remove air bubbles from the soil. The sample was allowed to air dry for four hours.

Then the soil sample was placed in an oven at 105°C for 18 hours.

After the soil was dry, the mould was removed from the oven and allowed to

cool. The length of the soil sample was measured three times with digital callipers and

the average was used to calculate linear shrinkage using the equation:

𝐿𝑆 = (1 − 𝐿𝑎𝑣𝑔

𝐿𝑜) 𝑥 100 (2.1)

Where:

LS = Linear Shrinkage (%)

Lavg

= Average Length (mm)

Lo = Original Length of Brass mould (mm)

Cerato and Lutenegger (2006) mentioned that Linear Shrinkage test potentially has

a number of advantages over other tests, including:

1. The test is simple to perform

2. The test is essentially independent of operator and therefore may be subject to

less variability.

3. The equipment is simple and inexpensive.

4. The test does not require the use of toxic materials.

23

5. The test can be used for soils of low plasticity, such as silts, as well as for clays.

6. The test directly measures the desired behaviour; i.e., shrinkage.

There are two laboratory test methods of measuring the shrinkage properties of

fine-grained soil which are Shrinkage Limit (Head (1994) and Linear Shrinkage (BS-

1377:90). Shrinkage Limit test calculates the volumetric shrinkage while Linear

Shrinkage test is used to calculate one-dimensional shrinkage, although the volumetric

shrinkage may be calculated. The linear shrinkage is a measurement of the average

oven dry length of the sample after shrinkage of the original length, which occurs at

initial water content at or above the Liquid Limit.

2.3.2 Shrinkage Process

In a dry season, as the moisture content decreases, capillary stress in the void spaces

increases due to the increment of surface tension. This increased surface tension tends

to pull adjacent soil particles closer together, resulting in an overall soil volume to

decrease. As moisture content continues to decrease, capillary stress continues to

increase which continues to reduce overall volume. However, the shrunken soils will

tend to swell when access to water due to unusual rain (Pavement Interactive, 2008).

Soil shrinkage is generally confined to the upper portions of soil. Chegenizadeh

and Nikraz (2011) mentioned that it is caused by a reduction in soil moisture content

through (i) evaporation from the soil surface in dry climates, (ii) lowering of the

groundwater table and (iii) desiccation of soil by trees during the dry season in humid

climates as illustrated in Figure 2.3.

24

Figure 2.3: Shrinking Soils Mechanism

(http://www.pavementinteractive.org/article/shrinking-and-swelling-soils, 2008)

2.3.3 Shrinkage of Peat Soil

Waltham (2000) stated that the largest area of peat soils of Britain is located in the

fenlands along the East Midlands which is known as weak, highly compressible and

also high shrinkage when it is drained. The peat soil area will cause ground subsidence

even though without any loading due to a combination of consolidation and wastage.

The loss of water will allow the peat with porous particle, thereby it will increase the

density but reduce its volume. Holme Post peat area was drained to control the River

Ouse. They also realized that peat land area will be more useable and inhabitable when

it is drained but it will cause the ground surface to be subsided.

Figure 2.4 shows the record of ground subsidence in the peat soil area in the

Holme Post within 150 years. The subsidence of soil that had been observed over 150

years were related to the thickness of peat, water table and the ground surface which

is decreased compared to the original peat thickness which is 6.7 meters. In the first

50 years after its initial drainage (the water content of peat began to decrease), it shows

that its thickness of peat was subsided nearly 3.2 meters and it has lowered the water

table from its ground surface. Waltham (2000) observed that there was no subsidence

in the period 1890 to 1925 due to arable farmland replacement. It appeared with

smaller scale measurement of subsidence as it continued in 2000’s as the land absorbed

and lost water.