I a CRITICAL PERFORMANCE STUDY of INNOVATIVE

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A CRITICAL PERFORMANCE STUDY OF INNOVATIVE LIGHTWEIGHT FILL TO MITIGATE SETTLEMENT OF EMBANKMENT CONSTRUCTED ON PEAT SOIL

TUAN NOOR HASANAH BINTI TUAN ISMAIL

A thesis submitted in fulfillment of the requirements for the award of the Doctoral of Philosophy

Faculty of Civil and Environmental Engineering Universiti Tun Hussein Onn Malaysia

March 2017 iii

Specially Dedicated to

My beloved husband and family

Thanks for all the love and support

Sincerely, Tuan Noor Hasanah binti Tuan Ismail iv

ACKNOWLEDGEMENT

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

Syukur Alhamdulillah and all thanks are due to Allah for gave me strength and ability to complete my research successfully. First and foremost, I would like to express my deepest gratitude to my project supervisor, Prof. Dr. Devapriya Chitral Wijeyesekera for his supervision and guidance, invaluable assistance and his constant confidence in me. Without his continued guidance and support, this thesis would not have been a success. Forever I appreciate his patience and availability for any help whenever needed despite his heavy workload. I would like to express my sincere appreciation to Prof. Dato’ Dr. Ismail Hj. Bakar as my co supervisor for their helpful suggestions, assistance, and encouragement. His absolute support is greatly appreciated. I also gratefully acknowledge all the academic staffs and support staffs especially Mr As-Shar bin Kasalan and Mdm. Salina binti Sani for assisting and give the guidance to me during conducting the laboratory and field works. I am also very thankful to all my colleagues and other researchers I have met for their help, encouragement, motivation and friendship on my research work. Financial support from MTUN-COE grant and MyPhD scholarship are also gratefully acknowledged Heartfelt acknowledgements are expressed to my beloved husband and parents for their sacrifices, support and encouragement. Without them, I may never have overcome this long journey in my studies. Not forgetting my siblings for their friendship and support during the difficult times of my study. May Allah reward all of you. Thank you…

ABSTRACT

Infrastructure construction now demands the development on soft ground such as peat. Discomfort of road users such as bumpy road need to be addressed with the use of appropriate lightweight and stiff backfill materials. Alternative lightweight fills used in current highway construction is critically reviewed in this research prior to the conceptual development of a stiff lightweight mat (Geocomposite Cellular Mat, GCM). The GCM concept is somewhat similar to the EPS concept by virtue of the mat form. However, the EPS is lighter than GCM, but the GCM is much stronger, stiffer, more porous and permeable. The performance of the GCM on hemic peat ground at the test site in Parit Nipah, Johor was compared with that from conventional backfill (sand fill). The typical geotechnical properties of Parit Nipah peat were high in organic content (85.3 %), high in moisture content (> 600 %) and low in undrained shear strength (< 15 kPa). The consolidation characteristics of Parit Nipah peat was obtained from both laboratory and field tests using Terzaghi’s, and hyperbolic methods. The settlement predicted by hyperbolic method gave a better agreement with the field data. The field tests were environmentally monitored and innovative field instrumentation for the settlement monitoring was specially designed for this research. The research effectively demonstrates potential for the use of GCM to mitigate settlement of highway embankment built on peat ground. The field observation showed that the maximum settlements were reduced up to 84 % with the adoption of GCM fills. Furthermore, 70 % differential settlement was reduced with GCM fill compared with sand fill. GCM fills not only reduces excessive settlement but also reduces the differential settlement. However, they also effectively accelerate the consolidation settlement within the sub-grade through the ease of dissipation of the excess pore water pressure through the open-porous cellular structure of the GCM fills. vi

ABSTRAK Pembinaan infrastruktur di atas tanah lembut contohnya tanah gambut kini mendapat permintaan yang tinggi. Namun yang demikian, pembinaan jalan raya diatas tanah gambut memberi ketidakselesaan kepada pengguna jalan raya disebabkan oleh jalan yang beralun dan ini perlu ditangani dengan pendekatan yang sesuai seperti penggunaan bahan tambak yang ringan dan kuat. Melalui penyelidikan ini, kajian secara kritikal terhadap bahan alternatif tambak ringan yang digunakan dalam pembinaan jalan raya masa kini telah dilakukan sebelum pembangunan konseptual bahan tambak berbentuk tikar yang ringan dan keras (Geocomposite Celular Mat, GCM). GCM mempunyai konsep yang hampir sama dengan EPS iaitu berbentuk tikar. Namun yang demikian, EPS adalah lebih ringan berbanding GCM, tetapi GCM lebih kuat, keras, poros dan telap jika dibandingkan dengan EPS. Hasil ujikaji terhadap prestasi GCM ke atas tanah gambut hemik yang dilakukan di tapak ujikaji terletak di Parit Nipah, Johor dibandingkan dengan tambak konvensional berbentuk pasir. Ciri geoteknikal tanah gambut di Parit Nipah yang tipikal mempunyai kandungan organik yang tinggi (85.3%), kandungan kelembapan yang tinggi (> 600 %) dan kekuatan ricih yang rendah (< 15 kPa). Ciri-ciri pengukuhan tanah gambut ini diperoleh melalui ujikaji makmal dan lapangan dengan menggunakan kaedah Terzaghi dan hiperbolik. Kaedah hiperbolik menunjukkan ramalan pemendapan lapangan yang lebih baik berbanding dengan kaedah lain. Pemantauan terhadap persekitaran kawasan lapangan telah dilakukan dan penggunaan peralatan tapak telah direka khas dalam kajian ini untuk memantau pemendapan. Hasil kajian menunjukkan potensi penggunaan GCM bagi mengurangkan pemendapan penambakan jalan raya yang dibina diatas tanah gambut adalah sangat efektif. Kajian lapangan menunjukkan penggurangan sehingga 84% terhadap pemendapan maksimum berjaya dicapai dengan menggunakan GCM. Selain itu, perbezaan pemendapan juga berjaya dikurangkan sebanyak 70 % dengan penggunaan GCM. GCM bukan saja dapat mengurangkan jumlah dan perbezaan pemendapan, ianya juga mampu mempercepatkan pemendapan subgred secara efektif dengan memudahkan penyerapan lebihan tekanan air liang melalui struktur sel liang terbuka GCM. vii

TABLE OF CONTENTS

TITLE i DECLARATION ii DEDICATION iii ACKNOWLEDGMENT iv ABSTRACT v TABLE OF CONTENTS vii LIST OF TABLES xv LIST OF FIGURES xix LIST OF SYMBOLS AND ABBREVIATIONS xxviii LIST OF APPENDICES xxxiv

CHAPTER 1 - INTRODUCTION 1.1 Preamble 1 1.2 Problem identification 3 1.3 Research hypothesis 5 1.4 Research aim and objectives 5 1.4.1 Aim of the research 5 1.4.2 Objectives of the research 5 1.5 Scope (boundary) of research 6 1.6 Research programme 8 1.7 Thesis outline 9

CHAPTER 2 – LITERATURE REVIEW 2.1 Introduction 10 2.2 Settlement induced failure of highways and infrastructures on soft 10 soil

viii

2.3 Problematic soils in Malaysia 13 2.3.1 Definition of peat soil 13 2.3.2 Peatland in Malaysia 15 2.3.2.1 Peat morphology 17 2.3.2.2 Structural arrangement of peat soil 18 2.3.2.3 Classification of peat soil (engineering) 19 2.3.2.4 Characteristic properties of peat soils 21 2.3.2.5 Critical review of characteristic properties of peat 24 soils at Parit Nipah, Johor 2.4 Ground improvement methods 25 2.4.1 Alternative construction technologies using lightweight fill 29 materials particularly for road construction 2.4.1.1 Expanded polystyrene (EPS) geofoam 30 2.4.1.2 Shredded tires and tire bale fills 32 2.4.1.3 Foamed concrete (blocks/panel) 34 2.4.1.4 Bamboo grid frame 35 2.4.1.5 Other lightweight fill materials (mixed or added to 36 the soils) 2.4.2 Critical design properties of feasible lightweight fill blocks 39 used in embankment construction 2.4.3 Review of past literature on road embankments constructed 42 using lightweight fill material 2.5 Plastic (synthetic and semi-synthetic polymer) as an alternative 48 lightweight construction materials 2.5.1 Why recycled plastics? 50 2.5.2 Engineering and thermal properties of plastic 53 2.5.2.1 Properties of virgin plastic 53 2.5.2.2 Critical review of mechanical properties of 55 recycled plastic blends 2.5.3 Use of plastic in engineering field 58 2.6 Contributory advantages from cellular structure 61 2.6.1 Characteristic properties of cellular solids 65 2.6.2 Engineering applications of cellular structure 67 ix

2.7 Field monitoring instrumentation 70 2.7.1 Survey method for measuring vertical movement 72 2.7.2 Comparisons of field instrumentation 78 2.7.3 Appropriate field instrumentation for embankment over soft 79 ground 2.8 Consolidation settlement of soils 83 2.8.1 Consolidation model for peat soils 84

2.8.1.1 Cα/Cc concept (1977) 84 2.8.1.2 Rheological model for peat soil (1961) 86 2.8.1.3 Summary of rheological model 90 2.8.2 Consolidation behaviour of peat 90 2.8.3 One-dimensional consolidation test 94 2.8.4 Settlement prediction based on one-dimensional 96 consolidation test 2.8.5 Applicability of Terzaghi’s theory to predict settlement over 102 peat 2.8.6 Comparative overview of classical One-dimensional (1D), 104 three-dimensional (3D) and large strain consolidation theories 2.8.7 Settlement prediction during construction period 110 2.9 Alternative methods of settlement analysis 112 2.9.1 Hyperbolic method 112 2.9.2 Asaoka method 116 2.10 Guideline and standard for road embankment construction 118 2.10.1 Critical overview of JKR Malaysia standard (ATJ 5/85) for 118 road construction 2.10.2 Critical overview of guideline for the construction on peat 121 and organic soil by CREAM and CIDB 2.10.3 Critical overview of geotechnical design standard for road 125 embankment 2.10.4 Critical overview of design guidelines for lightweight fill 125 embankment system 2.10.4.1 Basic of the load bearing analysis design 127 procedure x

2.10.4.2 Design guideline and design procedure for 129 embankment construction

CHAPTER 3 – RESEARCH METHODOLOGY 3.1 Introduction 132 3.2 Material and site selection 132 3.2.1 Geocomposite Cellular Mat (GCM) 132 3.2.1.1 Quality assessment of the GCM tube 135 3.2.1.2 Structures of GCM 137 3.2.1.3 Brief outline of GCM production 138 3.2.2 Site selection – field soil sample and field test 140 3.2.2.1 Visual observation of Parit Nipah peat 141 3.2.2.2 Peat sampling 142 3.3 Laboratory tests 144 3.3.1 Testing on peat soil 146 3.3.2 One-dimensional consolidation test on undisturbed peat soil 146 3.3.3 General index property tests on GCM material 148 3.3.2.1 Determination of density and specific gravity of 148 vPP and rPP particle (solid block form) 3.3.2.2 Properties of GCM block 153 3.3.2.3 Water absorption 157 3.3.4 Thermal analysis of polypropylene 159 3.3.4.1 Thermogravimetric analyses (TGA) testing 159 3.3.4.2 Differential scanning calorimetry (DSC) testing 161 3.3.5 Engineering characteristic of GCM block 166 3.3.5.1 Compression test 166 3.3.5.2 Loading and unloading evaluation 171 3.3.5.3 Interface shearing strength 172

CHAPTER 4 – FIELD INSTRUMENTATION, TESTING AND OBSERVATIONS AT PARIT NIPAH 4.1 Introduction 176 4.2 Site location (Research Peat Station at Parit Nipah) 176 xi

4.2.1 Temporary Bench Mark (TBM) at the test site 177 4.2.2 Other relevant site information 180 4.3 Field instrumentation 181 4.3.1 Instrumentation for environmental observation 181 4.3.2 Instrumentation for settlement observation 183 4.3.2.1 Instrument setup 185 4.3.2.2 Checking the level accuracy 185 4.3.3 Appropriately design instrumentation for settlement 186 observation (settlement plate gauge) 4.4 Observation of site environmental conditions 189 4.4.1 Temperature and humidity observation 189 4.4.2 Rainfall data 190 4.4.3 Groundwater level variation 191 4.4.4 Heave and settlement of ground due to changes in 192 groundwater level 4.5 Field test description 195

4.5.1 Outline of the field test group 1 (F11-GCM1 and F21-CF) and 199

group 2 (F32-GCM2 and F42-CF) – uniform loading 4.5.1.1 Quality controls for field test groups 1 and 2 199 4.5.1.2 Field test preparation for field test groups 1 and 2 203 4.5.1.3 Site instrumentation setup for field test groups 1 203 and 2 4.5.1.4 Construction stages for testing (groups 1 and 2) – 203 uniform loading

4.5.2 Outline of the field test group 3 (F53-GCM3,4,5 and F63-CF) – 210 trial embankment loading 4.5.2.1 Quality controls in field testing (group 3) 210 4.5.2.2 Field test preparation for field test group 3 211 4.5.2.3 Arrangement of GCM fill in trial embankment 211

(F53-GCM3,4,5) 4.5.2.4 Site instrumentation setup for field test group 3 213 4.5.2.5 Construction stages for testing group 3 – trial 213 embankment loading xii

4.5.3 Data collection 216 4.5.4 Monitoring interval 217 4.6 Observation results and analysis 218 4.6.1 Settlement during construction loading (for test groups 1, 2 219 and 3)

4.6.2 Long term settlement observation for field test group 1: F11- 225

GCM1 (GCM fill – uniform loading) and F21-CF (sand fill – non-uniform loading)

4.6.3 Long term settlement observation for field test group 2: F32- 232

GCM2 (GCM fill – uniform loading) and F42-CF (sand fill – non-uniform loading)

4.6.4 Long term settlement observation for field test group 3: F53- 234

GCM3,4,5 (GCM fill – uniform embankment loading) and

F63-CF (sand fill – non-uniform embankment loading) 4.6.5 Summary of observation results 237

CHAPTER 5 – CRITICAL ANALYSIS OF RESEARCH OBSERVATIONS AND PREDICTIONS 5.1 Introduction 239 5.2 Performance of GCM fill 240 5.2.1 Engineering characteristic of the GCM – compression test 240 5.2.1.1 Observation of the axial compressive strength and 242 stiffness of vPP and rPP material 5.2.1.2 Observation on the influence of single and 243 multiple polypropylene (PP) tube arrangements and specimen heights on axial compressive strength and stiffness 5.2.1.3 Observation on the influence of diameter of open- 247 cell on the axial compressive strength and stiffness 5.2.1.4 Observation on the influence of wall thickness on 348 the axial compressive strength and stiffness

xiii

5.2.1.5 Observation on the influence of temperature on 249 axial compressive strength and stiffness of the specimens 5.2.1.6 Transverse compressive stress and stiffness of 252 specimens 5.2.1.7 Summary of strength and stiffness of GCM and 253 compared with other alternative lightweight fill materials 5.2.2 Engineering characteristic of the GCM – loading unloading 255 evaluation 5.2.3 Engineering characteristic of the GCM – interface shearing 256 strength 5.2.3.1 Shear strength of GCM block alone (in material) 259 5.2.3.2 Shear strength between GCM-GCM blocks 261 (within embankment) 5.2.3.3 Comparison of shear strength parameter of GCM 263 fill with other alternative lightweight fill materials 5.3 Consolidation behaviour Parit Nipah peat 264 5.3.1 Analysis of settlement curves from one-dimensional 264 consolidation tests 5.3.2 Determination consolidation characteristics of Parit Nipah 266 peat 5.3.3 Effect of secondary settlement on rate of consolidation 271 5.4 Critical analysis of field observation 273

5.4.1 Test F21-CF – Settlement due to a flexible foundation 274

5.4.2 Test F11-GCM1 – Settlement due to a rigid foundation 279

5.4.3 Test F42-CF – Settlement due to a flexible foundation (repeat 280

test F21-CF)

5.4.4 Test F32-GCM2 – Settlement due to a rigid foundation 283

(repeat test F11-GCM1)

5.4.5 Test F63-CF – Settlement due to a flexible foundation (trial 284 embankment) xiv

5.4.6 Test F53-GCM3,4,5 – Settlement due to a rigid foundation 287 5.4.7 Performance compatibility with design standards and 290 guidelines 5.5 Theoretical prediction 5.5.1 Prediction of settlements using Terzaghi’s one-dimensional consolidation theory 5.5.2 Prediction of settlement based on field consolidation data using hyperbolic method

CHAPTER 6 – CONCLUSION AND RECOMMENDATION 6.1 Introduction 305 6.2 Conclusions obtained for objectives 305 6.2.1 The engineering and geotechnical properties of GCM fill 306 material 6.2.2 Consolidation characteristic of Parit Nipah peat 307 6.2.3 The field settlement performance of GCM fill compared 308 with conventional sand fill 6.2.4 Theoretical predicted laboratory and field settlement 310 performance 6.3 Contributions to knowledge and industry 311 6.4 Recommendations for further research 311

REFERENCES 313 APPENDICES 336

LIST OF TABLES

1.1 Thesis outline 9 2.1 Definition of peat soil by various fields 14 2.2 Organic content based on ASTM D4427-1992 14 2.3 Definition of soils based on organic content in the soil 14 2.4 von Post degree of humification 20 2.5 Classification of peat 20 2.6 Classification of peat based on fiber content 21 2.7 General properties of peat soils in Malaysia by various 22 researchers 2.8 Strength terms according to laboratory test and hand 23 identification 2.9 List of soil improvement methods are practiced to stabilize the 26 soil 2.10 General properties of various lightweight materials and problem 28 associated with them 2.11 Comparison of typical properties of EPS geofoam, tire bales and 40 earth fill materials 2.12 Types and classification of plastics by Plastics Industry 49 Association 2.13 Typical properties of various types of plastic for engineering 54 application 2.14 Mechanical properties of rPP/vHDPE blends 56 2.15 Mechanical properties of vPP/rPP blends 57 2.16 Uses of plastic in civil engineering field 60 2.17 Typical relative densities of some cellular material 65 2.18 General applications of cellular structure 68 xvi

2.19 Uncertainty of instrument performance 71 2.20 Causes and remedies of errors in measurement 72 2.21 General match between monitoring needs and instruments 73 2.22 Surveying methods 77 2.23 Instruments for monitoring progress of consolidation 80 2.24 Summary of selected case histories of embankment on soft 81 ground 2.25 Comparison between consolidation and compaction process 84

2.26 Values of natural moisture content (wc) and Cα/Cc for peat 85 deposit 2.27 Rheological model for various types of soil 91 2.28 Definition of notation and consolidation parameters of soil 100 ′ 2.29 Typical values of Cα/Cc ratio for different types of soils 101 2.30 Prediction of magnitude of the settlement based on Terzaghi’s 102 one-dimensional consolidation theory 2.31 Comparative overview of one-dimensional (1D), three- 108 dimensional (3D) and large strain consolidation 2.32 Comparison of observed and predicted settlement 115 2.33 Material properties for each layer 120 2.34 Methodology and criteria for road design 121 2.35 Correlation between basic properties and parameters for 122 estimating consolidation settlement 2.36 Minimum geotechnical requirements in design of the road 124 embankment 2.37 Design parameter considered for EPS application 127 2.38 Summary of EPS design guideline for the use in highway 129 embankment by NCHRP 3.1 Typical properties of particle virgin PP and recycled PP 134 3.2 Geometry of cell and the GCM blocks used 135 3.3 Range of tube geometry and density for vPPB 136 3.4 A summary from the visual observation on the GCM tubes 136 3.5 Outlined of the laboratory tests on Parit Nipah Peat and the test 145 results on the general properties of peat in comparison to xvii

published data 3.6 Outlined of the laboratory tests were conducted on plastic 150 particle and GCM block 3.7 Density and specific gravity of vPP and rPP particles based on 151 Method A 3.8 Average specific gravity of vPP and rPP particles 153 3.9 Measured weight of the GCM block 156 3.10 Water absorption of vPP and rPP compared with EPS 158 3.11 Important thermal properties observed in this study 162 3.12 Total samples were tested through TGA and DSC tests 165 3.13 Summary of thermal characteristics 165 3.14 Schedule of specimens tested under axial compression loading 168 3.15 Test specimens were used for load and unloading evaluation 171 3.16 Test specimens were tested through direct shear test 174 3.17 Summary of important shear test parameter by past researchers 175 4.1 The instrument used to evaluate environment condition on site 182 4.2 National vertical control accuracy standard 183 4.3 Standpipe head elevation and water table under various 191 environmental conditions 4.4 Details of field test groups 196 4.5 Materials used and setup on test site (for field test groups 1 and 204 2) 4.6 Schematic view of model tests and settlement points were 205

evaluated for tests F11-GCM1, F21-CF, F32-GCM2 and F42-CF 4.7 Materials used and setup on test site (for field test group 3) 210 4.8 Schematic view of field test group 3 and settlement points were 212 evaluated 4.9 Summary of field test observation in this research 210 4.10 Embankment height and schedule of staged construction 220 practices adopted by previous researchers 5.1 Summary of the transverse compressive strength and stiffness of 253 tube at different temperature stages 5.2 Average strength and stiffness of GCM for temperature of 30 oC 254 xviii

5.3 Average strength and stiffness of GCM for temperature of 50 oC 255 5.4 Average peak shear strength at different normal stresses for 259 shearing resistance in GCM alone/itself 5.5 Average peak shear strength at different normal stresses for 263 shearing resistance between GCM-GCM blocks 5.6 Comparison of shear strength parameter of various lightweight 264 fill alternatives 5.7 Summary of one-dimensional consolidation parameters 268

5.8 The comparisons of coefficient of consolidation (cv) value for 270 single drainage obtained from different methods

5.9 The comparisons of coefficient of consolidation (cv) value for 271 double drainage obtained from different methods 5.10 Comparison of consolidation characteristics of Parit Nipah peat 272 5.11 Summary of the relevant information for the critical analysis 275 5.12 Summary of settlement analysis of this research and comparison 287 with previous researches 5.13 Research output in the contact of performance standard and 291 guideline for road embankment 5.14 Unit weight of the sample from point A and C 293 5.15 Summary of stress increment at the middle of each sublayer of 293 peat 5.16 Determination of time to reach 90 % consolidation 294 5.17 Primary and secondary consolidation settlement predicted based 295 on laboratory one-dimensional consolidation data 5.18 Determination of β and α for hyperbolic method using field 299 consolidation data

5.19 Comparison of ultimate primary settlement (∆Hp) estimates using 302 hyperbolic method and settlement observed in this research 6.1 Comparison of typical properties of GCM fill, EPS geofoam and 307 conventional earth fill 6.2 Comparison of consolidation characteristics of Parit Nipah peat 308 and typical inorganic clay

xix

LIST OF FIGURES

1.1 Ground subsidence in Sibu, Sarawak, Malaysia (a) failure of 4 structure and (b) road settlement 1.2 Peat settlement occurring at Parit Nipah, Johor 4 1.3 Research elements studies within the boundary of in investigation 6 1.4 General detail of field location and soil sampling 7 1.5 Flow for the research 9 2.1 Typical section of a structure on peat; (a) immediately after 11 completion of construction, (b) several years after completion of construction 2.2 Settlement condition in shallow flexible and rigid foundation 12 2.3 Tropical peatland of Southeast Asia 15 2.4 Peatland of Johor area 16 2.5 Typical cross section of a basin peat 17 2.6 Profile morphology of organic soil 18 2.7 Schematic diagram; (a) multi-phase system of peat, and (b) peat 19 arrangement 2.8 Variation of soil properties with depths; (a) natural moisture 25 content profile, (b) specific gravity, (c) undrained strength profile 2.9 Road construction using EPS block 30 2.10 Tire shreds into 50 to 300 mm in length 32 2.11 Tire bales for lightweight embankment fill 33 2.12 SEM images of foamed concrete 34 2.13 Ground improvement using bamboo grid frame technology 35

2.14 (a) wood chip coarse fibre, (b) sawdust coarse fibre 36 2.15 Expended shale 37 2.16 Clam shells 38 xx

2.17 Typical road embankment constructed by EPS geofoam 43 2.18 View of Athens-Thessaloniki highway failure 45 2.19 Road embankment constructed by shredded tire 45 2.20 Road embankment constructed by application of tire bales 46 2.21 Application of tire bales in embankment construction 47 2.22 Construction of road embankment using tire bales as subgrade 48 2.23 Solid wastes composition generated: (a) volume percentage in 51 Malaysia, (b) volume percentage United State 2.24 Percentage components of plastic waste available in Europe and 51 USA 2.25 Waste management practice in Malaysia 53 2.26 A chart showing the correlation of density and Young’s modulus 55 2.27 Example of cellular and foam structure: (a) two-dimensional 62 honeycomb structure, (b) three-dimensional open-cell foam, (c) three-dimensional closed-cell foam 2.28 Mechanics of material: (a) cell structure, (b) individual soil 63 particles structure 2.29 Some examples of nature cellular structure: (a) wood, (b) 63 cancellous bone, (c) skull, (d) plant stems 2.30 (a) Schematic of sandwich panel structure, (b) sandwich panel 64 structure with honeycomb core 2.31 The range of properties available to the engineer through 66 foaming; (a) density, (b) thermal conductivity, (c) Young’s modulus, (d) compressive strength 2.32 Aircraft component with cellular structure 67 2.33 Construction of the flexible pavement using polymer geocell 69 2.34 Accuracy and precision 71 2.35 Benchmark installation in rock 78 2.36 Embankment on soft ground 79 2.37 Possible layout of instrumentations beneath a test embankment 80 when vertical drain have been installed 2.38 Calculation of Cα/Cc ratio value 85 2.39 Rheological model by Gibson and Lo (1961) 87 xxi

2.40 Theoretical log strain (∆휀/∆푡) against time curve 87 2.41 Correction for b parameter for field condition 88 2.42 Rheological model based on Berry & Poskitt (1972) theory for 89 fibrous peat 2.43 Types of time-compression curved from consolidation test 92 2.44 Time-settlement behavious of peat Type II 92 2.45 Time-settlement relationship 93 2.46 Settlement-time curve at the center of Middleton test fill 94 2.47 Schematic diagram of an consolidation cell 95 2.48 Void ratio – log effective stress curve to determined consolidation 97 parameters; (a) for normally consolidated curve and (b) for overconsolidated curve ′ ′ 2.49 Determining preconsolidation pressure (𝜎푐) from e-log 𝜎 curve 98 by Casagrande method 2.50 Void ratio versus incremental stress curve for determining 98 coefficient of compressibility 2.51 Determination of the coefficient of secondary consolidation 99 2.52 Relationship between degree of consolidation (U) and time factor 101

(Tv) curve 2.53 (a) A soil layer infinite lateral extent and (b) a soil element with 104 boundaries fixed in space 2.54 One, two- and three-dimensional conditions 105 2.55 Domain of a soil layer under consolidation using Lagrangian 107 coordinate system; (a) before and (b) after consolidation

2.56 Settlement coefficient (휇푐) for pore pressures set up under a 110 foundation proposed by Skempton & Bjerrum, 1957 2.57 Correction of graphical settlement curve during construction 111 period 2.58 Settlement prediction by hyperbolic method 112 2.59 Hyperbolic plot Terzaghi’s one-dimensional consolidation theory 113 2.60 Hyperbolic plot of field settlements 114 2.61 Comparison of measured and predicted settlement 116 2.62 Graphical method of settlement prediction 117 xxii

2.63 Typical flexible pavement cross-section in Malaysia by JKR 118 2.64 Flexible pavement cross section with the certain thickness of 119 layers 2.65 Thickness design by nomograph 120

2.66 Correlation of bulk density (훾푏) and dry density (훾푑) with natural 122

moisture content (wo)

2.67 Correlation of specific gravity (Gs) with ignition loss 122

2.68 Correlation of initial void ratio (eo) with natural moisture content 123

(wo) 2.69 Correlation of void ratio (e) with coefficient of permeability (k) 123

2.70 Correlation of compressibility index (Cc) with natural moisture 123

content (wo)

2.71 Correlation of compressibility index (Cc) with secondary 124

compression index (C훼) 2.72 Important Components of an EPS block embankment 126 2.73 Load bearing failure of the EPS block resulting in excessive 128 settlement 2.74 Compression stress-strain behaviour on EPS block specimen 128 through unconfined compression test 2.75 Stress-strain relationship of EPS block specimen based on 128 unconfined compression creep test 2.76 Cyclic load behaviour for EPS block specimen 129 3.1 Flow plan for the research 133 3.2 Geocomposite cellular mat (GCM) block (with dimension of 0.5 134 x 0.5 m by 0.2 m height); (a) by rPP and (b) by vPP 3.3 Determination of outer diameter, inner diameter and wall 136 thickness of the GCM tube cell 3.4 Various geometry and density observed along the 1000 mm tube; 137 (a) outer diameter of cell, (b) inner diameter of cell, (c) wall thickness of cell, (d) solid density 3.5 GCM structure 138 3.6 Phase involved in producing of GCM 138 3.7 Typical layout of soil sampling and field site 139 xxiii

3.8 The soil is squeezed in the palm of hand 140 3.9 Classification of soil profile at Parit Nipah using peat sampler 141 3.10 Decayed tree stump removed from test site 142 3.11 Peatland Parit Nipah (test site); (a) pineapple roots in the peat (b) 142 hemic peat 3.12 Standard consolidation test; (a) test setup, (b) Consolidation cell 147 3.13 Mettler Toledo balance used to measure weight and density of 149 solid material 3.14 Test specimens for specific gravity test 152 3.15 Test specimen in pycnometer for specific gravity test 153 3.16 Measure weight of GCM block using digital hook scale 155 3.17 (a) TGA testing machine, and (b) test setup 159 3.18 Typical TGA and DTG thermograms on (a) vPP and (b) rPP 160 3.19 Typical DSC thermogram for plastic 162 3.20 TA DSC Instrument 163 3.21 Apparatus to prepare DSC sample; (a) aluminum hermatic pans 163 and lid, (b) encapsulating press, and (c) die set 3.22 The platform to hold both the sample and reference pans 164 3.23 Axial compression test equipment 167 3.24 Universal Testing Machine with a temperature chamber 167 3.25 The different tubes arrangements (single and multiple tubes 169 arrangement) to be tested 3.26 Compression loading on tube; (a) axial loading and (b) transverse 169 loading. 3.27 Strength and stiffness parameters as measured in compression test 170 3.28 Geocomp Shear Trac II direct shear apparatus used in this testing 172 3.29 Schematic diagram of direct shear test setup 173 3.30 Test specimen; (a) GCM block alone, (b) between GCM-GCM 173 block interfaces 4.1 Research Peat Station (REPEATS) office at Parit Nipah 177 4.2 TBMs on Parit Nipah site 178 4.3 Observations of TBM1, 2, 3 and 4 during testing period (14th 180 April to 1st December 2015) xxiv

4.4 Location of rainfall data stations 181 4.5 Levelling instrumentation used in the study 184 4.6 Important functions of digital automatic level 185 4.7 Method for checking the level accuracy 186 4.8 Settlement plate gauge was used for field tests 187 4.9 Calibration of developed settlement plate gauge 189 4.10 Variation of temperature and humidity observed (from 14th April 189 to 28th December 2015) 4.11 Temperature profile for 1 year 190 4.12 Rainfall observed at the two closest stations to the field site 190 4.13 Variation of groundwater level and rainfall with time at the test 192 site 4.14 Schematic diagram of test setup on site 193 4.15 Ground movement in relation to groundwater level 194 4.16 Field test outline and setup at Parit Nipah, Johor 198 4.17 Load test setup on site 200 4.18 Loading with concrete cube (7.74 kg each) arrangement 201 4.19 Ground settlement profile with preliminary load test on peat 201 4.20 Soil box system compensation setup on site for field test groups 1 202 and 2 4.21 Stage 1 - preparation of platform for test groups 1 and 2 207 4.22 Stage 2 - level the ground surface for test groups 1 and 2 207 4.23 Stage 3 - (a) Transfer soil box to test area and (b) level the soil 208 box 4.24 Stage 4 – (a) setup instrumentation for field test group 1 and (b) 208 setup instrumentation for field test group 2 4.25 Stage 6 – view of the barcode staff of the settlement plate gauges 209 4.26 Isometric of trial embankment 213 4.27 Stage 1 - preparation of platform for test group 3 214 4.28 Stage 2 - level the ground surface 214 4.29 Stage 4 - settlement plate gauges fixed on site for F6 215 4.30 Stage 5 - construction process for test group 3 215 4.31 Trial embankment constructed with GCM fill 219 xxv

4.32 Settlement curve during construction due to step loading 221 4.33 Loading pattern and settlement during construction period 222

4.34 Measured settlement of the ground surface at the center of the 225

field loading for tests F11-GCM1 and F21-CF 4.35 Zoom out of the ground movement over GCM fill compared with 226 the sand fill 4.36 Ground movement at center in relation to groundwater level 227

4.37 Ground movement at various points beneath fill loading (F11-GCM1 228

and F21-CF) 4.38 Settlement measurement taken at distance of 0.25B, 0.5B, 0.75B 229

and 1.0B from the GCM fill loading (F11-GCM1) 4.39 Settlement measurement taken at distance of 0.25B, 0.5B, 0.75B 231

and 1.0B from the sand fill loading (F21-CF) 4.40 Measured settlement of the ground surface at the center of the 232

field loading for tests F32-GCM2 and F42-CF

4.41 Ground movements at various points beneath GCM fill (F32-GCM2) 233

4.42 Ground movements at various points beneath sand fill (F42-CF) 233 4.43 Measured settlement of the ground surface at the center of the 234

field loading for tests F53-GCM3,4,5 and F63-CF

4.44 Ground movements at various points; (a) beneath GCM fill (F53- 235

GCM3,4,5) and (b) beneath sand fill (F63-CF) 4.45 The ground movement at centerline of all fill loading 236 4.46 Typical settlement-log time curve of field settlement observed on 237 peat ground 5.1 Stress area on single and multiple arrangements of tubes 241 5.2 Example calculation of material stress and average mat stress 241 5.3 Stress-strain response on rPPC and vPPD tubes 243 5.4 Stress-strain curve influenced by single and multiples tubes 244 arrangements at temperature stage of 30 oC 5.5 Stress-strain curve influenced by specimen height 246 5.6 Stress-strain curve influenced by different diameters of open-cell 248 tube xxvi

5.7 Stress-strain curve influenced by different wall thickness 249 5.8 Stress-strain behaviour of multiple tube arrangements under axial 250 compression loading at temperature stage of 50 oC 5.9 Comparison of maximum axial compressive strength at 251 temperatures of 30 oC and 50 oC 5.10 Comparison of initial stiffness at temperatures of 30 oC and 50 oC 252 5.11 Stress-strain behaviour of tube under transverse loading 253 5.12 Comparison of the initial stiffness of GCM and EPS geofoam 254 5.13 Stress-strain relationship of cyclic loading from axial 255 compression tests 5.14 Shear stress-displacement curve of GCM block at two speed rate 257 (0.2 and 0.5 mm/min) 5.15 Variation of shear stress versus horizontal displacement behavior 258 of GCM block at different times (15 min, 30 min and 60 min) 5.16 Shear stress-displacement behaviour at different normal stress 260 (25, 40 and 50 kPa) 5.17 Shear strength envelope for rPP-GCM and vPP-GCM interface 261 5.18 Shear stress-displacement behaviour at different normal stress for 262 two GCM block 5.19 Shear strength envelope from GCM-GCM block interface 263 5.20 Typical settlement-log time curve from one-dimensional 265 consolidation tests. 5.21 Variation of the end of primary consolidation or beginning of 266 secondary consolidation with increasing of effective stress. 5.22 Relationship of void ratio versus effective pressure 267 5.23 Time-settlement plotted from one-dimensional consolidation test 269 results at both, (a) Casagrande’s method, and (b) Taylor’s method 5.24 Hyperbolic plots based on laboratory consolidation data 270

5.25 Variation of coefficient of consolidation (cv) analysed for the peat 271 sample A1 using different method

5.26 Variation of coefficient of volume compressibility (mv) as a 272 function of effective stress 5.27 Variation of coefficient of secondary consolidation with 273 xxvii

increasing of effective stress. 5.28 Settlement behaviour over flexible foundation represented by test 277

F21-CF 5.29 Settlement behaviour over rigid foundation represented by test 278

F11-GCM1 5.30 Settlement behaviour over flexible foundation represented by test 281

F42-CF 5.31 Settlement behaviour over rigid foundation represented by test 282

F32-GCM2 5.32 Settlement behaviour over flexible foundation represented by test 284

F63-CF 5.33 Case studies 286 5.34 Settlement behaviour over rigid foundation represented by test 288

F53-GCM3,4,5 5.35 Percentage improvement using GCM fills 290 5.36 Layout of soil sampling 293 5.37 Profile of the soil layers for settlement prediction 294 5.38 Comparison of the settlement prediction with observed field 295 settlements 5.39 Methodology scheduling for settlement prediction 298

5.40 Predicted settlements using field data in test F11-GCM1 299

5.41 Predicted settlements using field data in test F21-CF 300

5.42 Predicted settlements using field data in test F32-GCM2 300

5.43 Predicted settlements using field data in test F42-CF 301 5.44 Long-term settlements predicted using hyperbolic method based 302 on field data 5.45 Post construction settlements predicted using hyperbolic method 303 based on field data 6.1 Visual observation of settlement profile for field test group 3; (a) 309

flexible settlements observed in test F53-GCM3,4,5, and (b) rigid

settlements observed in test F63-CF

xxviii

LIST OF SYMBOLS AND ABBREVIATIONS

av – Coefficient of compressibility AASTHO – American Association of State Highway and Transportation Official ASTM – American Standard Testing Method ATJ – Arahan Teknik Jalan B – Buoyancy Factor B – Width of loaded area B – Foundation width/ BM – Benchmark BS – British Standard c – Cohesion

Cc – Compression index

Cr – Recompression index

Cs – swelling index

Cα – Coefficient of secondary consolidation ′ Cα – secondary consolidation cv – Coefficient of consolidation CIDB – Construction Industry Development Board cm – Centimeter CO – carbon monoxide

CO2 – carbon dioxide CREAM – Construction Research Institute of Malaysia D – Diameter D – Depth of foundation DSC – Differential Scanning Calorimetry e – Void ratio ′ eo – Void ratio intercept of virgin consolidation line at 𝜎 = 1 kPa xxix

ep – Void ratio at the end of primary consolidation E – East

Ei – Initial stiffness

Ese – Secant stiffness

Es – Modulus of elasticity

Et – Tangent modulus EDM – Electronic distance measurement EOP – End of primary consolidation EPS – Expanded Polystyrene FKAAS – Faculty of Civil and Environmental Engineering FS – Factor safety ft – feet ft2 – Square feet G – Shear modulus

Gs – Specific gravity GCM – Geocomposite Cellular Mat g – Gram g/cm3 – Gram per cubic centimeter g/m2 – Gram square meter GPS – Global Positioning System GPa – Gigapascal H – Height of embankment H – Height of specimen/mat

H푖 – Initial height HDPE – High density polyethylene hr, hrs – Hour ID – Inner diameter in – Inches JKR – Jabatan Kerja Raya (Public Work Department) J/m – Joule per meter k – Thermal Conductivity k – Coefficient of permeability (or hydraulic conductivity) kh – Horizontal hydraulic conductivity xxx

kv – Vertical hydraulic conductivity kg – Kilogram kg/m3 – Kilogram per cubic meter km – Kilometer kN/m3 – Kilonewton per cubic meter kN/m2 – Kilonewton per square meter kN/mm2 – Kilonewton per square millimeter kPa – Kilopascal L – Length L – Foundation length LDPE – Light density polyethylene LL – Liquid limit M – Mass m – Meter m3 – Cubic meter mv – volume compressibility MFI – Melt Flow Index mg – Milligram Mg/m3 – Milligram per cubic meter min – Minimum mm – Millimeter mm/min – Millimeter per minutes m2/MN Square meter per meganewton MPa – Megapascal N – Newton N – North N – Number of tube NCHRP – National Cooperative Highway Research Board OC – Organic content OCR – overconsolidation ratio OD – Outer diameter OPKIM – Operasi Khidmat Masyarakat P – Point load xxxi

PE – Polyethylene PET – Polyethylene terephthalate PFA – Pulverised Fuel Ash pH – Potential Hydrogen PL – Plastic limit PM – Member of Parliament POFA – Palm Oil Fuel Ash PP – polypropylene PS – Polystyrene PVC – Polyvinyl chloride q – Uniformly distribution load Q – Applied load R – Thermal Resistance RECESS – Research Centre for Soft Soil REPEATS – Research Peat stations RM – Ringgit Malaysia rHDPE – Recycled high density polyethylene rPP – Recycled Polystyrene

Su – Undrained shear strength SCDOT – South Carolina Department of Transportation SP – Poorly graded sand t – time t – Rate of consolidation settlement tp – Time at the end of primary settlement t – Thickness T – Temperature

Tamb – Ambient temperature

Td – Degradation Temperature

Tg – Glass Transition Temperature

Tm – Melting Temperature

Tv – time factor TBM – Temporary Bench Mark TGA – Thermal Gravimetric Analysis xxxii

TP – thermoplastics TS – thermoset

U, Uv – degree of consolidation U.S. – United States USA – United States of America USCS – United Soil Classification System USDA – United States Department of Agriculture UTHM – Universiti Tun Husein Onn Malaysia UTM – Universal Testing Machine V – Volume

Vs – Volume of solid material

Vv – Volume of void VCL – Virgin consolidation line vPP – Virgin Polystyrene w – Moisture content wo – Natural moisture content W – Weight WA – Water absorption WSDOT – Washington State Department of Transportation WT – Water level z – Depth below load ∆H, S – Settlement

∆Hp, Sp – Primary settlement

∆Hs, Ss – Secondary settlement oC – Degree Celsius oC/min – Degree Celsius per minute oF – Fahrenheit 휀 – Strain 𝜎 – Stress 𝜎′ – Effective stress ′ 𝜎v – Vertical effective stress ′ σc – Preconsolidation pressure , 𝜎푖 – Initial effective stress xxxiii

σmax – Maximum stress

𝜎퐶퐸퐿퐿 – Material stress

𝜎푀퐴푇 – Mat stress ∆𝜎′ – increase of effective stress ′ σc – Preconsolidation pressure 휙 – Friction angle 𝜌 – Density 𝜌∗ – Density of cellular material

𝜌푠 – Solid density

𝜌푠푎푡 – Saturated density

𝜌푤 – Density of water

훾푏 – Bulk unit weight

훾푑 – Dry unit weight

훾푤 – Unit weight of water o – Degree % – Percentage

휇푠 – Poisson’s ratio

휇푐 – Settlement coefficient

xxxiv

LIST OF APPENDICES

A Method to Determine Coefficient of Consolidation (cv) 336 B1 Soil Profile 340 B2 Undisturbed Peat Sampling 345 C Index properties and classification 346 D1 Calibration curve (compression test) 350 D2 Calibration curve (direct shear box test) 351 E Data Temperature 352 F1 The Arrangement of GCM structure 356 F2 Arrangement of Number of GCM Fills Block in Embankment 358 G1 Engineering properties – compression test data 360 G2 Engineering properties – direct shear strength test data 368 H Consolidation data 370 I Regression analysis 381 J1 Theoretical calculation of vertical stress distribution 385 J2 Settlement prediction 389

CHAPTER 1

INTRODUCTION

CHAPTER 1

INTRODUCTION

1.1 Preamble

Infrastructure constructions on compressible soil have had many post construction problems in the past. The most critical geoenvironment challenges are associated with excessive settlement and differential settlement leading to hazard and discomfort in road usage. Nearly, 28.6 % of the road user complaints received in 2011 referred to poor condition of road due to differential consolidation settlement (Unit Komunikasi Korporat, 2011). Within the Medium term National Infrastructure Development Plans there are proposals being mooted for the construction of the new East Coast Highway and Dual Track Rail Road extensions from Kluang to Seremban. Such projects will necessarily meet challenging peat ground conditions. Some authorities frequently consider construction of roads on peat to be a ‘black art’. Consequently many engineers opt for conservative but unsustainable construction technology such as excavation and replacement with alternative natural resources. Furthermore, this technology also leads to uneconomic designs because it will increase the cost of construction and delay the period to completion (Kadir, 2009). Various alternative construction and stabilisation methods such as surface reinforcement, preloading, chemical stabilisation, sand or stone column, pre-fabricated vertical drains, and piles have been suggested and adopted in the past to support structures over soft yielding ground (Huat, Maail & Mohamed, 2005; Kadir, 2009; Construction Research Institute of Malaysia, 2015). However these technologies are constrained by 2 technical feasibility, space and time limitations and expensive process. Even after these procedures, problems of differential settlement are not uncommon. Innovative use of lightweight fill material can meet the geotechnical challenges posed by soft yielding ground, because it offers an attractive solution to reduce settlement. The stress on the subsoil can be reduced so that the settlement is reduced or eliminated, if the road embankment is constructed out of fill material lighter than that of soil. In this respect, various types of lightweight materials (sawdust, fly ash, slag, cinders, cellular concrete, lightweight aggregates, expanded polystyrene (EPS, shredded tires, and sea shells) have been proposed for road embankment construction. Application of lightweight fill materials such as EPS (also known as “geofoam”) has been used for more than 40 years around the world for roadwork construction projects (Frydenlund & Aaboe, 2001; Buksowics & Culpan, 2014). However, the first application of this technology in Malaysia was in 1992 for the remedy of settlement of bridge abutments (Gan & Tan, 2003). Others are as below: ▪ Remedial of bridge abutment settlements at Kota Bridge II, Klang, Selangor, 1992. ▪ Construction of lightweight road embankment at Teluk Kalung Bypass, Kemaman, Terengganu, 1994. ▪ Construction of approach embankment to overpass bridge at Sungai Tengi, Kuala Selangor, Selangor, 1995. ▪ Remedial of differential settlement problem for a bus terminal platform, 1996. ▪ Transition treatment between the approach embankment and a major bridge at the main entrance of Tanjung Pelepas Port, Johor, 1997. ▪ Remedial of platform settlement at Sungai Dua Toll Canopy, Penang, 1997 ▪ Strengthening of bridge abutments on both sides of a bridge, 1999. ▪ Transition treatment of a railway bridge abutment founded on the reclamation fills at Tanjung Pelepas Port, Johor, 2001. ▪ Mitigate platform settlement at Sungai Dua Toll Canopy Extension Works, Penang, 2002.

1.2 Problem identification

The recent dramatic growth of population in Malaysia and many other parts of the world has been a cause for rapid pace of infrastructure development to meet the demands of society and transformation of the economy (Department of Statistic Malaysia, 2012). Due to the limited availability of ‘suitable’ ground, construction activities are now forced to consider the development on soft yielding ground. Such soils are geotechnically problematic, which comprise of high compressibility, high moisture content (>200 %), low bearing capacity (<8 kN/m2) and low shear strength (<20 kPa) as reported by Zainorabidin & Wijeyesekera (2007). These usually are subjected to localised sinking and slip failure, and massive primary and long-term consolidation settlement even when subjected to a moderate load (Huat et al., 2005; Duraisamy et al., 2008). Roller coaster scenarios in different settling highways have proved uncomfortable to the driver and passenger. Figure 1.1(a) shows a house in Sibu which was badly damaged just one year after completion of the construction, due to differential settlement in peat soil (Huat, 2004). Figure 1.1(b) shows the poor condition of a road in Sibu town, Malaysia caused by ground settlement (Kolay, Sii & Taib, 2011). Huat (2004) and Kolay et al. (2011) state that the ground subsidence on peat land in Sibu town is due to poor groundwater flow, which has resulted in negative gradients to drainage. Figure 1.2 (taken by author) shows another example of settlement failure occurring in a structure constructed on peat at Parit Nipah, Johor. Here the peat has settled from the original level causing the structure of the house to become unsupported. This case clearly shows the peat soil settlements not only depend on its magnitude but also on its degree of non-uniformity and the nature’s effects such as dewatering and drying of the peat. This was also reported by Nurhana (2010). Any construction activity below the groundwater table must also carefully consider the buoyancy forces in the design especially for the lightweight fill material. Three failures associated with buoyancy forces on EPS and water fluctuations have been reported. Two different failures occurred at Northern Europe in 1987 and Thailand (Asia) were reported by Frydenlund & Aaboe (2001) and failure at Carousel Mall in Syracuse New York was reported by Horvath (1999).

(a) (b)

Figure 1.1: Ground subsidence in Sibu, Sarawak, Malaysia (a) failure of structure and (b) road settlement.

Unsupported structure

Figure 1.2: Peat settlement occurring at Parit Nipah, Johor.

The alternative technology of the lightweight cellular mat structure is developed in Universiti Tun Hussein Onn Malaysia (UTHM) and is being used in this research. The idealised cellular structure in this technology allows water to flow freely and vertically, reduces the probability of floating, minimising the settlement and help accelerate the consolidation settlement within the sub-grade through rapid dissipation of the excess pore water pressure developed. Furthermore, the mat structure will even out any local differential settlement. The performance of this technology constructed on peat soil is critically studied in this research. 5

1.3 Research hypothesis

This research is backed by the following hypothesis. The adoption of the Geocomposite Cellular Mat (GCM) as a lightweight fill embankment will: a) Reduce the embankment settlement that occurs due by reducing self-weight of embankment. b) Minimise the differential settlement that may occur through the use of a stiff and contiguous mat structure and the consequent load sharing mechanism of the mosaic style laying of the mats. c) Accelerate the consolidation settlement within the sub-grade through the dissipation of the excess pore water pressure via the very open porous cellular structure of the GCM. d) Reduce the probability of floatation. Buoyancy forces arise when submerged in water. Relatively low densities are prone to create greater buoyancy, and the open-porous cell structure becomes effective to accommodate the high permeability characteristic for unhindered flow.

1.4 Research aim and objectives

1.4.1 Aim of the research

The aim of this research is to study the performance of the GCM as a fill material to mitigate settlement of embankment construction on peat soil.

1.4.2 Objectives of the research

In pursuit of the above aim, the following objectives will necessarily be done: 1) To evaluate the engineering characteristics of GCM fill through laboratory test. 2) To evaluate the consolidation properties of Parit Nipah peat based on results obtained from one-dimensional consolidation test. 3) To critically evaluate the field performance of settlement behaviour of GCM over soft ground compared with sand fill. 4) Assessment of observed and predicted settlement 6

1.5 Scope (boundary) of research

The focus of this research is to critically investigate the GCM performance in particular the use as a fill embankment for soft ground especially peat soil. The boundary of research activity is shown in Figure 1.3. Within the embankment construction only the application of it on problematic ground condition is studied particularly in excessive and differential settlement. Considerable attempt is given to investigate the appropriateness of using this lightweight fill (rather than soil stabilisation), and the economic and logistics of the use of this material.

CONSTRUCTION

Embankment Fill

SOIL CHALLENGING

Differential Differential

excessive &

LIGHTWEIGHT settlement

FILL TO MITIGATE SETTLEMENT OF

EMBANKMENT

Materials

CONSTRUCTED ON

Lightweight Fill PEAT SOIL

the problematicthe soils

TECHNIQUE to overcome Plastic

MATERIALS USED

Figure 1.3: Research elements studies within the boundary of in investigation.

The research includes series of both laboratory and field testing as well as theoretical evaluation of predicted settlement. The necessary GCM produced at Research Centre for Soft Soil (RECESS), UTHM are used for both laboratory and field tests. Laboratory testing is primarily done at RECESS and Polymeric and Ceramic Laboratory, UTHM. The aim is to determine characteristic properties of the GCM. Results of strength and stiffness obtained through laboratory testing are compared with past literature values for different fill materials. This research also considered the variation of three geometrical parameter of the tube associated with 7 the weight being (1) thickness of tube, (2) external diameter of tube and (3) height of cellular mat form from the tubes.

Parit Nipah Universiti Tun Test Site Hussein Onn Malaysia (UTHM) Scale: 2 km Scale: 2 km

Field test area at Parit Nipah Grid reference: Latitude: 1o 50’ 07.1” N o Longitude: 103 11’ 04.6” E

Distance: 17.1 km (28 min from UTHM by car)

Figure 1.4: General details of field location and soil sampling.

The field testing was conducted using prototype testing setups on a site to investigate performance of GCM under fill loading only and compared the response from conventional natural fill material. Furthermore, this research scope for field testing comprised of: ▪ Evaluation of the magnitude of independent settlement in vertical direction only. 8

▪ Monitoring of the field settlement was using an improvised digital automatic level. ▪ Evaluation of environmental condition at the site (groundwater table fluctuation, soil surface movement, air temperature, humidity and rainfall). Figure 1.4 shows detail of the field test site at Parit Nipah, Johore. More information of the site is discussed in Chapter 3.

1.6 Research programme

Figure 1.5 shows the planned flow of the research programme in order to achieve the aim and objectives of this study.

Research Programme

Literature Review Chapter 2

Selection Material and Testing Site Chapter 3

Laboratory Properties and Objectives 1 & 2 Implementation Results

Field Instrumentation, Testing Objective 3 Chapter 4 and Observation at Parit Nipah

Critical Analysis of Research Objective 4 Chapter 5 Observations and Predicted

Chapter 6 Conclusion and Recommendation

Figure 1.5: Flow for the research.

1.7 Thesis outline

This thesis consists of five chapters, a brief summary of each chapter is as presented in Table 1.1.

Table 1.1: Thesis outline Chapter Description 1 Introduction This chapter presents general information regarding this study; includes a preamble, problem identification, aim and objectives, boundaries or focus of the study, hypothesis and flow to achieve the aim and objectives of this study. 2 Literature This chapter presents a critical review of the past literature Review on the geo-environmental challenge facing highway design and construction, and current technologies used to construct highway embankment on soft ground. Furthermore, in this chapter, literature reviews associated with the use of plastic products in civil engineering, contributory advantages from cellular structure, theoretical predictions of settlement, field measurement devices and methods used to observe settlement are also presented. It further discusses the outlines of the design guideline for lightweight fill material application and other topics that are relevant to this research work. 3 Research This chapter gives guidance for this study to ensure that the Methodology process of the research is carried out systematically. Brief descriptions on the materials used throughout the research are covered in this chapter. All methods involved and how the method was done in order to achieve the aim and objectives of the study are also described in this chapter. In this chapter, it also briefly discusses the general laboratory test results. 4 Field This chapter discusses in detail the field testing, including Instrumentation, description and implementation of the GCM on test site, Testing and field instrumentation setup, environmental condition on Observation at site, field site preparation and construction, data collection Parit Nipah and field observation. Moreover, the development of settlement plate gauge as well as calibration results using this instrument is also presented in this chapter. 5 Critical Analysis This chapter presents a comprehensive analysis of the of Research result from laboratory and field performance as well as Observation and theoretical evaluation of predicted settlement. Predicted 6 Conclusion and This chapter presents the summary and conclusions from Recommendation this research, significance findings from laboratory and field studies, brief of preliminary design guideline adopted for GCM application and recommendation for future work on the topic related to the present study. 10

CHAPTER 2

LITERATURE REVIEW

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

This chapter presents an overview of the current geoenvironmental problems relevant to this research. Past research and the research drivers leading to design and construction of infrastructure, particularly in highway constructions on difficult ground condition are also presented in this chapter. Furthermore, in this chapter a comprehensive literature associated with current lightweight technologies used to construct highway embankment on soft yielding ground, advantage and application of plastics product (basis of new alternative) in civil engineering, contributory advantages from cellular structure, field measurement devices to observe settlement (vertical movement), consolidation behaviour of peat soil, applicability of Terzaghi’s theory on peat soil and theoretical predictions of settlement are also presented. It further discusses the outlines of the standard and design guideline for lightweight fill material application and other topics that are relevant to this research work. The supportive information presented in this chapter was comprehensively and critically compared with the results obtained from this research as presented and discussed in Chapter 4 and 5.

2.2 Settlement induced failure of highways and infrastructures on soft soil

Soil stiffness of a road sub-grade/base helps define the potential to prevent indiscriminate road settlement leading to uneven road surfaces. Settlement is the downward movement of foundations to a point below its original position. 11

Settlement of highway embankments over soft soils (silty, clayey or excessive organic soils) is a prime problem encountered in maintaining structure facilities. Such soils tend to lack both the requisite shear strength and consolidation or long term creep. These soils also have poor drainage properties (low permeability) and tend to retain moisture (high moisture content). These types of soils tend to initially consolidate (short term settlement) much more than comparable soils with less water.

(a)

(b)

Figure 2.1: Typical section of a structure on peat; (a) immediately after completion of construction, (b) several years after completion of construction (Huat et al., 2005).

Figure 2.1 presents the typical section of a road and housing on peat soils (organic content greater than 75 %). This figure shows the structure resulting in settlement several years after completion of construction due to consolidation of the soft soil. Additional failures have been reported by Kolay et al. (2011), Adon et al. (2012) and Razali (2013). This is a challenge to civil engineers in the design and construct road and highway embankment on this soil because they are extremely soft, wet, unconsolidated surficial occurring in wetland systems. Designing of roads and buildings foundation must consider the factor that causes settlement. The settlement may occur due to the following reasons: ▪ Elastic compression of the structure and underlying soil (also called immediate settlement). ▪ Plastic or inelastic compression of the underlying soil. ▪ Groundwater lowering is another major cause of settlement. Repeated rising and lowering of groundwater, particularly in granular soils, tend to reduce the void volume and cause the surface settlement. ▪ Pumping of water or draining of water without proper filter material also can cause settlement. ▪ Other cause of settlement includes volume change of soil, ground movement and excavation for adjacent structures, mining subsidence, etc.

Figure 2.2: Settlement condition in shallow flexible and rigid foundation (Das, 2011) 13

In additional, the interaction between soil and foundation also plays an important role in the distribution of settlements. This study identifies two types of settlement as shown in Figure 2.2. This figure shows the uniform settlement that occurs with a rigid foundation while the non-uniform settlement is a result of the flexibility of the foundation structures as portrayed by the effect of the particulate material in the conventional fill. This will be closely observed in this research.

2.3 Problematic soils in Malaysia

Organic materials are formed by biochemical processes, whereas the process of organic material accumulation is mainly a direct function of environmental conditions, the climate, and the ecosystems (peat swamps, bogs or mires) in which the peat is formed. Organic materials only accumulate to form peat under certain conditions. It is essential that the production of biomass (organic materials) is greater than its chemical breakdown to form peat (Andriesse, 1988; Zulkifley et al., 2013).

2.3.1 Definition of peat soil

Peat deposits are superficial soils with high organic matter content, usually occurring as integral parts of wetland systems, where they form extremely soft, wet, unconsolidated superficial deposits. Peat deposits sometimes occur as underlying strata or layers under other superficial deposits. Huat (2004) defines peats as naturally occurring highly organic substances that are derived primarily from plant materials and are formed when the accumulation of plant organic matter occurs more quickly than it humifies, usually when organic matter is preserved below high water tables, as in swamps or wetlands (Huat, 2004). The definition of peat soil in soil science, agriculture and engineering fields is defined in a different way as stated in Table 2.1. Soil scientists define peat as a soil with organic content greater than 35 %. In agriculture field, peat soils consist of organic content more than 20 % (refer to reference in Zolkefle, 2015). In geotechnical engineering, organic soil with organic content is greater than 75 %, it is called a ‘peat’ soil. Soils are termed organic soil when their organic content is between of 25 to 75 %. However, when the organic content is lower than 20 %, the soils will become clay, silt or sand soils (Huat, 2004). These variations in definition 14 are due to the mechanical properties of the soil, which change when the organic content of the soil is greater than 20 %. The classifications of peat according to ASTM D4427-92 and according to Jarrett, based on laboratory testing, are shown in Tables 2.2 and 2.3 (ASTM D4427 1992; Jarrett 1995; Huat 2004).

Table 2.1: Definition of peat soil by various fields (adopted from Zolkefle, 2015)

Field Description Standard All soils with organic content greater than 75 Geotechnical % are known as peat. Soils that have an ASTM D4427-1992 Engineering organic content below 75 % are known as organic soils. All soils with organic content greater than 35 Soil Science USDA (Soil Taxonomy) % are categorized as peat. Peat is classified if the organic content is Agriculture USDA (Soil Taxonomy) more than 20 %

Table 2.2: Organic content based on ASTM D4427-1992 (adopted from Huat, 2004) Soil Groups Description Organic Content (%) Clay or Silt or Sand Slightly organic 2 – 20 Organic Soil - 25 – 75 Peat Soil - > 75

Table 2.3: Definition of soils based on organic content in the soil (Jarret, 1995; Huat, 2004) Soil Groups Description Symbol Organic Content (%) Clay or Silt or Sand Slightly organic O 2 – 20 Organic Soil - O 25 – 75 Peat Soil - Pt > 75

Nevertheless, the Malaysian Soil Classification System for Engineering Purposes based on BS5930 defined that the soils that have organic contents from 3 to 20 % are classified as slightly organic soils, soils with organic contents in the range of 20 to 75 % are classified as organic soils, and soils with organic contents greater than 75 % are classified as peats (adopted from Zulkifley et al., 2013). The amount of the organic content in soil significantly affects engineering properties of soils include hydraulic conductivity and compressibility. Zulkifley et al. (2013) claimed that the ignition test is a most common practice for the determination of organic content (ASTM D2974). When used in conjunction with the Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System) (ASTM D2487), the ignition test provides a quick and 15 inexpensive means of determining the organic content of a soil and is usually the only laboratory test needed for the classification of organic soil (Engineering Geology Working Group, 2007; Zulkifley et al., 2013).

Malaysia Sabah Brunei

Kalimantan

Distribution of Peat Land in Sumatra Perlis Peninsular Malaysia Kedah Java

P. Pinang Kelantan Peatland Pera Terengganu k

Pahang

Selangor

N. Sembilan Melaka Johor

Organic Clay and Muck

Peat

Figure 2.3: Tropical peatland of Southeast Asia (modified from Hassan, 2006 and Huat et al., 2005).

2.3.2 Peatland in Malaysia

Peat soil is formed by the decomposition or breakdown of plant and other organic materials. Peat has been identified as a major group of problem soils found in many 16 countries including Malaysia. Peat covers more than 4 million km2 of the planet’s surface which represents 50 to 70 % of the total wetlands on the earth (Abdullah et al., 2007). About 3.0 million hectares or 8 % of the land area in Malaysia is covered with tropical peat as shown in Figure 2.3 (Huat, 2004; Huat et al., 2005; Kadir, 2009). Among these lands, 6,300 hectares of the peatlands are found in Pontian, Batu Pahat and Muar at West Johore area (Gofar, 2005; Huat at el., 2011). Figure 2.4 shows the distribution of peatlands in Johor (Hassan, 2006). This was the main driver in conducting this research. Furthermore, peatland is also found in Pahang (such as Endau Rompin, Kuantan and Pekan district), northwest Selangor and Perak (such as Perat Tengah and Hilir Perak district) (Kadir, 2009). Sarawak has the largest coverage of tropical peat in Malaysia as peat covers up to 1.66 million hectares (Huat et al., 2011).

Area of field performance study for this research Segamat

Muar Mersing

Kluang

Batu Pahat Kota Tinggi Parit Raja Pontian Johor Baharu

Figure 2.4: Peatland of Johor area.

In the tropical area, peat occurs mainly between the lower stretches of the main river course (basin peat) and in poorly drained interior valleys (valley peats) (Kadir, 2009). According to Huat (2004), basin peat is found on the inward edge of mangrove swamps along the coast while valley peat is flat or interlayered with river 17 deposits. Figure 2.5 shows a typical cross section of a basin peat. The depth of the peat is generally shallower near the coast and increases inwardly, locally exceeding more than 20 m. Gofar (2005) claims that the peat deposits in the west coast of Malaysia are mainly formed in depressions consisting predominantly of marine clay deposits or a mixture of marine and river deposits especially in area along river courses.

Nipah and Mangrove Padang Forest Nipah and Mangrove

LEGEND Sapric Peat Hemic-Fibric Peat Clayey Peat Sand Clay Bedrock

Figure 2.5: Typical cross section of a basin peat (Huat, 2004).

2.3.2.1 Peat morphology

Generally, peat deposits consist of the elements that are not uniform in nature with large variations occurring over very small distances (Zolkefle, 2015). It depends on the accumulated plant material, the state of decay and the access to oxygen (Zolkefle, 2015). The morphological characteristics of lowland organic soils are quite similar throughout the region. The convexity of coastal and deltaic peat swamps surfaces is increasingly pronounced with distance from the sea (Mohamed et al., 2002). Nevertheless, in drained areas, where the organic soils are transformed to a compact mass consisting of partially and well-decomposed plant remains with large wood fragments and tree trunks embedded in it (Mohamed et al., 2002). This led to the formation of various elements in the peat deposits. According to Mohamed et al. (2002), the profile morphology in drained organic soils consists of three distinct 18 layers as illustrated in Figure 2.6. The upper layer consisting of well-decomposed organic materials of the sapric type, a middle layer consisting of semi-decomposed organic materials of the hemic type and a lower layer of fibric materials which is mainly large wood fragments and branches and tree trunks (Mohamed et al., 2002).

Sapric (20-30 cm thick)

Hemic (30-40 cm thick)

Fibric

Figure 2.6: Profile morphology of peat soil (Mohamed et al., 2002).

2.3.2.2 Structural arrangement of peat soil

The structural arrangement of peat highly influences its engineering properties. They are dependent on the forming plant, the conditions on which the peat accumulated and deposited, and the degree of decomposition (Yulindasari, 2006). The presence of fiber content has been affecting the consolidation behaviour of peat (it is further discussed in Section 2.8). Dhowian & Edil (1980) also reported that fiber arrangement to be a major compositional factor in determining the way in which peat soils behave. The structure of fibrous peat is coarser than clay. This condition gives a significant effect to the geotechnical properties of peat related to the particle size and compressibility behavior of peat. Moreover, physical properties of fibrous peat differ markedly from other mineral soils. The fibrous peat has many void spaces existing between the solid grains. Due to the irregular shape of individual particles, fibrous peat deposits are porous and the soil is considered as a permeable material (Yulindasari, 2006). Kogure, Yamaguchi & Shogari (2003) have developed a multi-phase system of peat as presented in Figure 2.7(a). It was divided into two categories which are 19 organic bodies and organic spaces. Figure 2.7(b) shows a simple schematic diagram of cross section of deposition in order to give a clear picture of the peat soil arrangement (Wong, Hashim & Ali, 2009). It can be seen that organic particles consist of solid organic matter and inner voids. The solid organic matter is flexible with the inner voids, which is filled with water and it can be drained under consolidation pressure. The spaces between the organic bodies are known as outer voids, which is filled with solid particles (solids), fiber and water.

Organic particle Solid organic Organic Particles matter Inner void (Solids) Solid particle Fiber

Water (Inner voids) Organic Bodies

Soil Particles (Solids) Outer void

Water (outer voids) Organic Spaces

(a) (b)

Figure 2.7: Schematic diagram; (a) multi-phase system of peat (Kogure et al., 2003), (b) peat arrangement (Wong et al., 2009).

2.3.2.3 Classification of peat soil (engineering)

In geotechnical engineering, the classification of peat soil is defined based on decomposition of fiber, the vegetation forming the organic content and fiber content.

(a) Classification of peat soil based on degree of humification

The classification of peat based on the degree of humification test (von Post classification system) was developed in the early 1920s in Sweden and is related to the fiber content of the peat (Zulkifley et al., 2013). This reflects the amount on soil water and peat soil that is expelled between the fingers when the soil is squeezed in the palm of hand, and it was classified as belonging to one of ten (H1 – H10) degree 20 of humidification scale as shown in Table 2.4. However, for geotechnical purposes, these 10 degrees of humification has been divided in three (3) classes namely fibric (fibrous), hemic (semi-fibrous) and sapric (amorphous) peat as shown in Table 2.5

(Huat, 2004). Fibrous peats are in the humification range of H1 to H4. Hemic peats are in the range of H5 to H7. Sapric peats are in humification range of H8 to H10.

Table 2.4: von Post degree of humification (Huat, 2004) von Post Description Scale Completely undercomposed peat which, when squeezed, releases almost clear water. H1 Plant remains easily identifiable. No amorphous material present. Almost entirely undecomposed peat, when squeezed, releases, clear or yellowish water. H2 Plant remains still easily identifiable. No amorphous material present. Very slightly decomposed peat which, when squeezed, releases muddy brown water H3 but for which no peat passes between the fingers. Plant remains still identifiable and no amorphous material present. Slightly decomposed peat which, when squeezed, releases very muddy dark water. No H4 peat is passed between the fingers but the plant remains are slightly pasty and have lost some of their identifiable features. Moderately decomposed peat which, when squeezed, releases very “muddy” water with a very small amount of amorphous granular peat escaping between the fingers. H5 The structure of the plant remains is quite indistinct although it is still possible to recognize certain features. The residue is very pasty. Moderately decomposed peat which a very indistinct plant structure. When squeezed, H6 about one-third of the peat escapes between the fingers. The structure more distinctly than before squeezing. Highly decomposed peat which contains a lot of amorphous material with very faintly H7 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. Very highly decomposed peat with a large quantity of amorphous material with very indistinct plant structure. When squeezed, about two thirds of the peat escapes between H8 the fingers. A small quantity of pasty water may be released. The plant material remaining in the hand consists of residues such as roots and fibers that resist decomposition. Practically fully decomposed peat in which there is hardly any recognizable plant H9 structure. When squeezed it is fairly uniform paste. Completely decomposed peat with no discernible plant structure. When squeezed, all H10 the wet peat escapes between the fingers.

Table 2.5: Classification of peat (Huat, 2004) Type of Peat von Post Scale Description Low humified Fibric peat H1 – H4 Easy recognized plant structure, primarily of white masses Intermediate humified Hemic peat H5 – H7 Recognizable plant structure Highly humified Sapric peat H8 – H10 No visible plant structure 21

(b) Classification of peat soil based on fiber content

Peat is further classified based on fiber content due to the presence of fiber which alters the consolidation process of peat from that of inorganic soil (Gofar, 2005). Boelter (1968) claims that the fiber content gives a high impact to the physical properties of peat soil especially in compressibility characteristic. Table 2.6 shows the classification of peat based on fiber content. Peat soil with fiber content less than 33 % can be classified as sapric peat. It contains mostly particles of colloidal size (less than 2 microns), and the pore water is absorbed around the particle surface (Gofar, 2006). The behaviour of sapric peat is almost similar to the clay soil. The fiber content of between 33 to 67 % was classified as hemic peat while fibric peat consists of fiber content more than 67 % and possess two types of pore which are macro-pores (pores between the fiber) and micro-pores (pores inside the fiber itself) (Gofar, 2006). The behavious of fibric peat is very contradictory to the clay soil due to fiber in the soil. Moreover, fibric peat differs from sapric peat in that it has a low degree of decomposition, fibrous structure, and easily recognizable plant structure (Gofar, 2005). In addition, the compressibility of fibrous peat is very high.

Table 2.6: Classification of peat based on fiber content (Huat, 2004; Gofar, 2005) Classification of peat based on ASTM standards Fibric peat Peat with greater than 67 % fibers Fiber Content (ASTM Hemic peat Peat with between 33 % and 67 % fibers D1997) Sapric peat Peat with less than 33 % fibers

2.3.2.4 Characteristic properties of peat soils

Peat soil possesses a variety of physical properties such as texture, water content, density and specific gravity. This has an implication on the geotechnical properties of peat related to the compressibility behaviour of peat. Thus, the geotechnical properties and behaviour of the soil is necessary in order to choose the best practical design and material for foundations. The basic index properties of Malaysia peat soil observed by past researchers are given in Table 2.7. As noted in the table, peat is classified as a problematic soil due to the high moisture content, low bearing capacity and large settlement characteristics. These properties which are summarised from the table are given as follows: 22

Table 2.7: General properties of peat soils in Malaysia by various researchers Characteristic Properties Degree of Fiber References Standard Location 훾 Su Humification w (%) OC (%) Content G 푏 e LL (%) pH C s (kN/m3) c (kPa) (%) Deboucha & West 700 – 88.61 - 3.68 – Hashim, 2009 BS - 84.99 1.34 15.60 10.99 173.75 - Malaysia 850 99.06 4.6 and 2010 Kolay et al., Sarawak, ASTM H4 598.5 90.47 79.33 1.21 - - 200.2 3.75 - 2011 Malaysia Kazemian & BS Malaysia 504 88.23 - 1.21 10.04 - 159.6 4.9 - Huat, 2009 West 200 – 190 – 1.0 – 65 – 97 - 1.38 – 1.7 - - - Malaysia 700 360 2.6 Huat, 2004 BS East 200 – 210 – 0.5 – 76 - 98 - 1.07 – 1.63 - - - Malaysia 2207 550 2.5 Islam & West 414 – 88.61 – 90.25 – 10.16 – 2.43 – BS H4 0.95 – 1.34 9.33 208.39 3.51 Hashim, 2010a,b Malaysia 674 99.06 90.49 10.20 2.84 Zainorabidin, & 220- 0.9- 7 – 11 - Johore (hemic peat) 230-500 80-96 - 1.48 –1.8 - - - Bakar, 2003 250 1.5 Duraisamy et West 140 – 7.95 – 4.13- 240 - 1.88 – BS (fibrous peat) 70 -88 - 1.42 – 1.56 - - al., 2008 Malaysia 350 10.01 10.48 398 3.63 Parit Nipah 3.76 – 5 – 15 Atemin, 2012 - (hemic peat) 791.00 78.76 - 1.88 - 119 3.6 Peat 5.30 Parit Nipah Saedon, 2012 BS H5 546.43 86.24 - 1.56 - - 417 - - - Peat Johari et al., BS & Parit Nipah - 640.00 83.1 61.42 1.36 10.54 8.36 322 - 2.68 - 2015 ASTM Peat Parit Nipah Yusoff, 2015 BS - 480.61 - - 1.51 - - 162.50 3.76 - - Peat Parit Nipah Zolkefle, 2015 BS H6 710.44 78.77 40.97 1.34 - - 318 3.69 0.79 -

Peat

▪ Water content greater (w) than 100 % (when natural and wet) ▪ Organic content in range 65 ~ 100 % (note: peat is defined when organic content >75 %, see Table 2.2 and 2.3)

▪ Specific gravity (Gs) in range 0.95 ~ 1.88 3 ▪ Bulk density (훾푏) in range 7.95 ~ 11.5 kN/m ▪ Liquid limit (LL) and plastic limit (PL) more than 100 % (when natural and wet) ▪ Acidity (pH) in range 3.5 ~ 4.9 (very acidic)

▪ Compression index (Cc) in range 0.13 ~ 5.30

▪ Undrained shear strength (Su) in range 5 ~ 15 kPa (very soft soil as classified in Table 2.8) The determination of undrained shear strength is also important when considering that peat soil is always below the groundwater table. Due to this, sampling of undisturbed peat for laboratory evaluation of undrained shear strength is almost impossible, so it is suggested that the test to be done via in-situ test. Gofar (2006) lists some approaches to in-situ testing in peat deposits such as vane shear test, cone penetration test, pressure-meter test, dilatometer test, plate load test and screw plate load tests. Amongst them, the vane shear test is the most frequently used in practices (Gofar, 2006; Atemin, 2012; Tong, 2015). Gofar (2006) found that the Su value of peat soil obtained by vane shear test ranged from 3 to 15 kPa.

Table 2.8: Strength terms according to laboratory test and hand identification (Barnes, 2000)

Term Su (kPa) Field Identification Very Soft <20 Exudes between fingers when squeezed in hand Soft 20 – 40 Moulded easily by finger pressure Soft to Firm 40 – 50 - Firm 50 – 75 Can be moulded by strong finger pressure Firm to Stiff 75 – 100 - Cannot be moulded by fingers but can be indented with Stiff 100 – 150 thumb Very Stiff 150 – 300 Cannot be indented by thumb nail Hard >300 Broken with difficulty

In addition, peat soil is also considered as a frictional and/or non-cohesive material due to having high fiber content. Thus, the shear strength of peat is usually determined in drained condition (Gofar, 2006). The friction is typically due to the fiber, but fiber is not always solid because it is usually filled with water. Gofar 24

(2006) stated that the high friction angle does not actually reflect the high shear strength of the soil. Direct shear box is the frequently test used to determining the drained shear strength of peat and triaxial test is the most common test for determining shear strength of peat under consolidated-undrained condition (Noto, 1991). Edil & Dhowian (1981) investigated that the effective internal friction angle

(휙) of peat is generally higher than inorganic soil which are 50 o for amorphous granular peat and in the range of 53 o to 57 o for fibrous peat. According to Landva & La Rochelle (1983), the friction angle of peat under a normal stress of 30 to 50 kPa in the range of 27 o to 32 o. Huat (2004) reported that the range of internal friction angle of peat in West Malaysia was in the range of 3 o to 25 o. However, studies done by Mansor & Zainorabidin (2014) on direct shear box reported that the hemic peat at Parit Nipah, Johore (West Malaysia) had a 39.35 o friction angle (휙). Consolidation behaviour is one of most important properties related to the peat soil which is generally controlled by the fiber content. Consolidation behaviour and determination of consolidation parameters of peat are further discussed in Section 2.8.

2.3.2.5 Critical review of characteristic properties of peat soils at Parit Nipah, Johor

The characteristic properties of peat soil at Parit Nipah by past research are critically discussed in this section. This is the site area chosen for field performance study for this research. The average index properties of peat at Parit Nipah is given and highlighted in Table 2.7. In this section, moisture content (w), specific gravity and undrained shear strength (Su) parameter were determined at various depths as shown in Figures 2.8(a), (b) and (c), respectively (Tong, 2015). All of these parameters varied with depth in Parit Nipah peat and generally: ▪ Moisture content (w) in range 450 to 1200 %

▪ Specific gravity (Gs) in range 1.25 to 1.65

▪ Undrained shear strength (Su) in range 5 to 16 kPa The geotechnical properties presented in Sections 2.3.2.4 and 2.3.2.5 show difficulties for construction on the peat deposit. The loads of heavy traffic and the road embankment weight imposed on the subsoil results in settlement due to the subsoil which lacks the capability of supporting the weight or bearing pressure 313

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