Geotechnical and Micro-Structural Behaviour of Chemically Stabilized Tropical Residual Soil

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GEOTECHNICAL AND MICRO-STRUCTURAL BEHAVIOUR OF CHEMICALLY STABILIZED TROPICAL RESIDUAL SOIL

NIMA LATIFI

A thesis submitted in fulfilment of the requirements for the award of the degree of Doctor of Philosophy (Civil Engineering)

Faculty of Civil Engineering Universiti Teknologi Malaysia

JUNE 2014

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Specially dedicated to my beloved parents and my adorable wife

ACKNOWLEDGEMENT

Acknowledgments for the completion of this thesis must be extended to many people who provided me with precious time and invaluable advice. My gratitude to the Almighty God, due to all His blessings and grace, this thesis finally came to an end.

I wish to express my sincerest appreciations to Prof. Dr. Aminaton Marto for her invaluable comments, genuine encouragement, constructive advice, and professional guidance during the formulation of this thesis. Thank you for the opportunity you granted to me. I am also very thankful to my co-supervisor Dr. Amin Eisazadeh for his permanent support, continuing feedback, patient guidance, and motivation.

My sincere gratitude also goes to all laboratory technicians in the Geotechnical Engineering and Structures and Materials laboratories for their genuine help in carrying out the laboratory tests and physical modeling works throughout the study.

Last but not least, my utmost appreciations go to my beloved parents for their eternal support, unconditional love, sacrifice, and encouragement. I am nothing without you both. My special thanks go to my adorable wife, Nazanin for all her support and tolerance throughout this research journey. Words really fail to appreciate her for everything.

ABSTRACT

The stabilization of soils with additives is a chemically modified method that can be used to improve soils with weak engineering properties. Non-traditional additives such as ionic, enzymes, salts, polymers, and tree resins are widely used for treating problematic soils. The effects of non-traditional additives on the geotechnical properties of soils have been the issue of investigation in recent years. The publications on macro-structural, micro-structural, and molecular characteristics of tropical residual soil stabilized by non-traditional stabilizers are limited. This research aimed at determining the stabilization mechanism and performance of the tropical residual (laterite) soil mixed with two types of non-traditional stabilizer; namely the calcium based powder stabilizer (SH-85) and sodium silicate based liquid stabilizer (TX-85). Macro-structural study including the compaction, unconfined compression strength, direct shear, and consolidation tests were used to assess the engineering properties of the stabilized soil. The physico-chemical bonding mechanisms contributed to the stabilization process were discussed based on the results of micro-structural study from different spectroscopic and microscopic techniques such as X-ray Diffractometry, Energy-Dispersive X-ray Spectrometry, Field Emission Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Surface Area Analysis and Thermal Gravimetric Analysis. In addition, the performance of treated laterite backfill stabilized with the selected additives was evaluated using series of physical model tests. The model tests consisted of strip footing placed on stabilized backfill behind sheet pile wall. The numerical simulation using PLAXIS finite element (FE) software was carried out to compare and evaluate the results obtained from the physical models. The laboratory tests showed that the addition of 9 % (as the optimum amount) of both additives increased more than 80% of compressive strength after 7 days of curing periods while the consolidation settlement had been effectively reduced. The micro-structural study revealed that the stabilization process modified the porous network of laterite soil. The pores of the soil had been filled by the newly formed compounds known as calcium aluminate hydrate cementitious material for SH-85 treated samples and sodium aluminosilicate hydrate gel-like product for TX-85 treated samples. Hence, the stabilization mechanism of two selected non-traditional additives was by cationic exchange and physical bonding. The numerical simulation and physical modelling showed identical trends. Therefore the finite element method using elasto-plastic Mohr-Coulomb model is suitable to be used in evaluating and predicting the behaviour of chemically stabilized backfill. The results from the physical model tests showed that the ultimate capacity of the footing placed on the stabilized backfill soil increased greatly while the settlement reduced compared to untreated backfill laterite soil, after just 7 days of curing. It can be concluded that the quick reaction of the selected stabilizers with laterite soils is very advantageous and cost-effective for geotechnical engineering projects.

ABSTRAK

Penstabilan tanah menggunakan bahan tambah merupakan suatu kaedah pengubahsuaian kimia yang boleh digunakan untuk memperbaiki sifat tanah yang mempunyai sifat-sifat kejuruteraan yang lemah. Bahan tambah bukan konvensional seperti ionik, enzim, garam, polimer dan resin pokok digunakan secara meluas untuk rawatan tanah bermasalah. Kesan bahan tambah bukan konvensional kepada sifat geoteknikal tanah telah menjadi isu penyelidikan dalam tahun-tahun kebelakangan ini. Penerbitan mengenai makrostruktur, mikrostruktur dan sifat-sifat molekul tanah baki tropika yang distabilkan dengan bahan penstabil bukan konvensional adalah terhad. Penyelidikan ini bertujuan untuk menentukan mekanisme penstabilan dan prestasi tanah baki (laterit) tropika yang dicampur dengan dua jenis penstabil bukan konvensional, iaitu penstabil serbuk berasaskan kalsium (SH-85) dan bahan penstabil cecair berasaskan sodium silikat (TX-85). Kajian makrostruktur termasuk ujian pemadatan, ujian kekuatan mampatan tak terkurung, ujian ricih, dan ujian pengukuhan telah dijalankan untuk menilai sifat kejuruteraan tanah laterit yang distabilkan. Mekanisme ikatan fizikokimia yang menyebabkan proses penstabilan dibincangkan berdasarkan hasil kajian mikrostruktur melalui kaedah spektroskopik dan mikroskopik seperti X-ray Diffractometry, Energy-Dispersive X-ray Spectrometry, Field Emission Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Analisis Luas Permukaan dan Thermal Gravity Analysis. Prestasi tanah laterit yang distabilkan dengan bahan tambah yang digunakan sebagai tanah kambus balik telah dinilai melalui satu siri ujian model fizikal. Ujian model terdiri daripada asas jalur di atas kambus balik yang distabilkan dan terletak di belakang dinding cerucuk turap. Simulasi berangka dengan perisian unsur terhingga PLAXIS telah dijalankan untuk membandingkan dan menilai hasil ujian model fizikal. Ujian makmal menunjukkan bahawa penggunaan bahan tambah sebanyak 9% (nilai optimum) bagi kedua-dua bahan tambah meningkatkan kekuatan mampat tanah laterit sebanyak 80% selepas tempoh pengawetan selama 7 hari, dan mampu mengurangkan enapan pengukuhan secara efektif. Berdasarkan kajian mikrostruktur, didapati bahawa proses penstabilan telah mengubahsuai rangkaian liang tanah laterit. Liang-liang tanah diisi dengan kompaun yang baru terbentuk, iaitu kompaun bersimen kalsium aluminat hidrat bagi sampel yang distabilkan dengan SH-85, dan sodium aluminosilikat hidrat berbentuk gel bagi sampel yang distabilk dengan TX- 85. Mekanisme penstabilan bagi kedua-dua bahan tambah bukan konvensional disebabkan oleh pertukaran kation dan ikatan fizikal. Simulasi berangka dan pemodelan fizikal menunjukkan tren yang serupa. Oleh itu, kaedah unsur terhingga yang menggunakan model elasto-plastik Mohr-Coulomb didapati sesuai digunakan untuk menilai dan meramal perilaku kambus balik yang distabilkan menggunakan bahan kimia. Hasil ujian model fizikal menunjukkan bahawa kapasiti muktamad asas di atas tanah kambus balik yang distabilkan mengalami peningkatan yang banyak dan mengurangkan enapan tanah selepas 7 hari tempoh pengawetan berbanding dengan tanah kambus balik yang tidak dirawat. Kesimpulannya, reaksi pantas bahan penstabil untuk menstabilkan tanah laterit adalah sangat berfaedah dan kos-berkesan bagi projek-projek kejuruteraan geoteknik.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii DEDICATION iii ACKNOWLEDGEMENT iv ABSTRACT v ABSTRAK vi TABLE OF CONTENTS vii LIST OF TABLES xiv LIST OF FIGURES xvi LIST OF ABBREVIATIONS AND SYMBOLS xxiii LIST OF APPENDICES xxvii

1 INTRODUCTION 1 1.1 Background 1 1.2 Problem Statement 3 1.3 Objectives of Study 4 1.4 Scope and Limitation of Study 5 1.5 Significance of Study 6 1.6 Thesis Organization 7

2 LITERATURE REVIEW 9 2.1 Introduction 9 2.2 Soil Improvement using Stabilizers 9 2.2.1 Traditional Additives 12 2.2.2 Non-Traditional Additives 15 2.3 Tropical Residual Soils 30 2.3.1 Origin and Chemical Composition 32

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2.3.2 Clay Minerals 35 2.3.3 Engineering Properties 42 2.4 Macro-Structural Characterizations and Engineering Analysis of Stabilized Soil 44 2.4.1 Compaction Characteristics 45 2.4.2 Compressive Strength 48 2.4.3 Shear Strength 52 2.4.4 Compressibility 56 2.5 Micro-Structural Characterization and Chemical Analysis of Stabilized Soils 60 2.5.1 X-ray Diffraction Studies 60 2.5.2 Microscopic Studies 64 2.5.3 Thermal Studies 69 2.5.4 Surface Area, Pore Size and Particle Size Distribution 72 2.5.5 Molecular Characterization 77 2.6 Modelling the Retaining Wall with Stabilized Backfill 81

3 RESEARCH METHODOLOGY 94 3.1 Introduction 94 3.2 Selection, Collection and Preparation of Materials 97 3.2.1 Soil Sample 97 3.2.2 Additives 98 3.3 Determination of Physical and Chemical Properties of Laterite Soil 99 3.3.1 Soil Classification 99 3.3.2 Specific Gravity 101 3.3.3 Loss on Ignition 102 3.3.4 Organic Content 102 3.3.5 pH Measurement 103 3.4 Determination of Chemical Component of Additives 104 3.5 Determinations of Engineering Properties 105 3.5.1 Compaction 105

3.5.2 Unconfined Compressive Strength 107 3.5.3 Direct Shear 109 3.5.4 Consolidation 110 3.6 Micro-Structural and Molecular Characterization of Samples 112 3.6.1 X-ray Diffraction 113 3.6.2 Scanning Electron Microscopy and X-ray Spectrometry 115 3.6.3 Fourier Transform Infrared Spectroscopy 117 3.6.4 Thermal Gravimetric Analysis 119 3.6.5 Surface Area Value 120 3.6.6 Particle Size Analysis 121 3.7 Physical Model Tests 123 3.7.1 Introduction 123 3.7.2 Materials 124 3.7.3 Test box 124 3.7.4 Wall and Footing 129 3.7.5 Instruments 130 3.7.6 Testing Programme 132 3.7.7 Model Preparation and Test Procedure 132 3.8 Numerical Simulation 134 3.8.1 Introduction 134 3.8.2 Simulation Process 135 3.9 Summary 138

4 PHYSICO-CHEMICAL, MACRO AND MICRO STRUCTURAL STUDIES OF MATERIALS 139 4.1 Introduction 139 4.2 Physical Properties of Laterite Soil 140 4.3 Geochemistry Characteristics of Materials 145 4.3.1 Soil 145 4.3.2 Additives 147 4.4 Macro-Structural Characterization 149 4.4.1 Compaction 149

4.4.2 Unconfined Compressive Strength 154 4.4.3 Consolidation 160 4.4.4 Shear Strength 165 4.5 Micro-Structural Characterization 171 4.5.1 X-ray Diffraction 172 4.5.2 X-ray Spectrometry 174 4.5.3 Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) 180 4.5.4 Molecular Characteristics 187 4.5.5 Thermal Gravimetric Analysis 189 4.5.6 Surface Area Analysis 192 4.5.7 Particle Size Analysis 195 4.5.8 pH 198 4.6 Summary 200

5 PERFORMANCE OF TREATED SOILS THROUGH PHYSICAL MODELLING AND NUMERICAL SIMULATION 203 5.1 Introduction 203 5.2 Physical Model Tests 203 5.2.1 Series 1 : Loading Placed at 5 cm 205 5.2.2 Series 2 : Loading Placed at 10 cm 210 5.2.3 Series 3 : Loading Placed at 15 cm 215 5.3 Summary of Physical Modelling Tests 220 5.4 Numerical Simulation 224 5.4.1 Numerical Simulation of Series 1 225 5.4.2 Numerical Simulation of Series 2 228 5.4.3 Numerical Simulation of Series 3 231 5.5 Summary of Numerical Simulation 234

6 CONCLUSION AND RECOMMENDATIONS 237 6.1 Introduction 237 6.2 Conclusion 237 6.3 Macro-Structural Study 238

6.3.1 Micro-Structural Study 239 6.3.2 Physical Modelling and Numerical Simulation 240 6.3.3 Recommendations for Further Research 241

REFERENCES 243 Appendices A-G 270-301

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LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Proposed stabilization mechanisms and suitability for stabilization applications (Tingle et al., 2007) 24 2.2 Summary of compressive strength changes due to the soil-additive reaction 51 2.3 Effect of soils mixed with different concentration of fly ash on cohesion and angle of internal friction (Prabakar et al., 2004) 53 2.4 TGA, DTG, and DTA analysis for more commonly available clay minerals (Guggenheim and van Groos, 2001) 71 2.5 IR bands of kaolinite (KGa) and montmorillonite (SWy) clay along with their assignments (Madejova and Komadel, 2001) 78 3.1 Laboratory testing programme with standards or methods used 96 3.2 Testing programme in physical model tests 132 4.1 Values of physical indices of granitic residual soils from various places in the Peninsular Malaysia 140 4.2 Percentages of soil components based on particle size 143 4.3 Amount of major elements (%), organic contents and pH in some granitic residual soils 146 4.4 Oxides and chemical components of SH-85 and some of traditional stabilizers 148 4.5 Chemical components of TX-85 149 4.6 Maximum dry density and optimum moisture content of some granitic residual soil in the Peninsular of Malaysia 150

4.7 pdmax and wopt of treated and untreated soils obtained from standard compaction tests 151

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4.8 Unconfined compressive strength of untreated and treated laterite soils with SH-85 and TX-85 at various curing time 154 4.9 Unconfined compressive strength of granitic residual soils from various places in the Peninsular Malaysia mixed with different type of stabilizers 156 4.10 Shear values for the granitic residual soil in Malaysia 166 4.11 Al:Si, and Ca:Si ratios of untreated and treated soil with 9% SH- 85 obtained from EDAX analysis 178 4.12 Al:Si, and Na:Si ratios of untreated and treated soil with of 9% TX-85 obtained from EDAX analysis 180

4.13 Surface area obtained from N2-BET for the untreated and treated laterite soils at various curing time 193 4.14 Particle Size Distribution of Untreated and Treated samples with SH-85 197 4.15 Particle Size Distribution of Untreated and Treated samples with TX-85 197 4.16 pH obtained for the untreated and treated laterite soils at various curing time 199 5.1 Summary results of physical model tests at failure 204 5.2 Parameters for backfill, sheet pile wall and footing in PLAXIS modelling 224 5.3 Summary results obtained from numerical simulation at failure 225

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Process of surface stabilization by liquid additive 10 2.2 Deep mixing process in field 11 2.3 Proposed stabilization mechanisms for ionic additives (Tingle et al., 2007) 17 2.4 Proposed stabilization mechanisms for enzymes additives (Tingle et al., 2007) 19 2.5 Proposed stabilization mechanisms for Lignosulfonate additives (Tingle et al., 2007) 20 2.6 Typical profile of residual soil (Little, 1969) 31 2.7 Basic sheet arrangements of silica tetrahedral and aluminum octahedral and synthesis pattern of clay minerals (Mitchell and Soga, 2005) 36 2.8 Morphology of kaolinite (McBride, 1994) 37 2.9 Morphology of montmorillonite (McBride, 1994) 38 2.10 Structure and morphology of illite (McBride, 1994) 39 2.11 Some possible mechanisms of water adsorption by clay surfaces: (a) hydrogen bonding, (b) ion hydration, (c) attraction by osmosis, and (d) dipole attraction (Mitchell and Soga, 2005) 40 2.12 General distribution of cations held as exchangeable ions at different pH values (Brady and Weil, 1996) 41 2.13 Typical moisture-density curve (Ahmad, 2004) 45 2.14 Variation of dry density with moisture content (Hossain et al., 2007) 46

2.15 Plots of dry unit weight versus molding moisture content of clay and clay–FA geopolymer for FA/clay ratios of 0.3, 0.5, and 0.7 (Sukmak et al., 2013) 47 2.16 Relation between maximum dry density and optimum moisture content at different SBR%-MH soil (Ahmad et al., 2013) 48 2.17 Unconfined compressive strengths values for one day of curing (Newman and Tingle, 2004) 49 2.18 Strength gain for lime and phosphoric acid-treated laterite clay with different stabilizer content and curing time (Eisazadeh et al., 2011) 50 2.19 Effect of the fibre content on cohesion and angle of internal friction of fibre–lime treated soil specimens after 28-day curing (Cai et al., 2006) 54 2.20 Effect of soil stabilizer concentration on cohesion of samples of stabilized soil (Liu et al., 2011) 54 2.21 Effect of soil stabilizer concentration on friction angle of samples of stabilized soil (Liu et al., 2011) 55 2.22 Effect of fly ash, lime – fly ash, and curing time on the compression and rebound indices Cc and Cr (Nalbantoglu and Tuncer, 2001) 57 2.23 Strain versus pressure for Soil 1 and 2, treated with lime (de Brito Galvão et al., 2004) 58 2.24 Compressibility and SEM image of 30% cement-treated clay (Chew et al., 2004) 59 2.25 X-ray diffraction patterns for composite clay samples treated with the ionic stabilizer at different application mass ratios (Katz et al., 2001) 61 2.26 XRD of Arizona Montmorillonite before (red) and after (blue) TM treatment with EcSS 3000 soil stabilizer (Malek, 2006) 62 2.27 Comparison between X-ray diffraction patterns of natural, phosphoric acid, and lime treated Laterite Clay after 8 months curing period (Eisazadeh et al., 2011) 63

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2.28 SEM of untreated and 6% lime treated Tapah Kaolin after one year of curing (Kassim et al., 2005) 64 2.29 Scanning electron micrograph of cementation compounds formed in lime–soil reactions (Cai et al., 2006) 65 2.30 Cluster of elongated particles found in CKD-treated Na-m clay cured for 90 days (Peethamparan et al., 2009) 66 2.31 SEM image of untreated laterite clay from Malaysia (Eisazadeh et al., 2011) 67 2.32 SEM image of lime laterite clay from Malaysia (Eisazadeh et al., 2011) 67 2.33 SEM images (a) the FA geopolymer and (b) the clay–FA geopolymer specimens at L/FA ratio of 0.7 (Sukmak et al., 2013) 68 2.34 Various pores observed in micro-fabric of Tucson silty clay (Mitchell and Soga, 2005) 72 2.35 Adsorption of gas molecules on solid particles (Quantachrome manual, 2007) 74 2.36 Laser diffraction technique used in CILAS equipment 76 2.37 IR spectra of montmorillonite (SWy-2) and kaolinite (KGa-2) using (Potassium Bromide) KBr pellet (Madejova and Komadel, 2001) 79 2.38 FTIR of Arizona Montmorillonite before and after treatment with TM Ecss 3000 soil stabilizer (Malek, 2006) 80 2.39 FTIR spectrums for untreated and phosphoric acid and lime- treated lateritic soils at 8 months time interval (Eisazadeh et al., 2011) 81 2.40 Horizontal distribution of geogrid strain (a) fill height = 4 m; (b) fill height = 6.5 m (Jie et al., 2012) 83 2.41 Vertical distribution of geogrid strain 2 m inside the wall (Jie et al., 2012) 83 2.42 Schematic view of the experimental model (All dimensions are in mm) (Ahmadi and Hajialilue-Bonab, 2012) 84 2.43 Monitoring general scheme (Bourgeois et al., 2011) 86

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2.44 Horizontal displacement of the wall under the effect of the applied load of 90 kN (comparison measurements/simulations) (Bourgeois et al., 2011) 86 2.45 Setup of instrumentation (Chen and Chiu, 2008) 88 2.46 Comparison of test results for various facing inclinations (a) horizontal displacement of the facing (Chen and Chiu, 2008) 88 2.47 FLAC model of reinforced wall (Hatami and Bathurst, 2006) 89 2.48 Model test instrumentation (Georgiadis and Anagnostopoulos, 1998) 91 2.49 Effect of surcharge distance on bending moments (H= 250 mm; q= 12 kN/m2) (Georgiadis and Anagnostopoulos, 1998) 91 2.50 Physical modelling instrumentation schematic (Shinde and Mandal, 2007) 92 2.51 Deformed mesh of backfill materials and wall (Shinde and Mandal, 2007) 93 3.1 Flowchart of research methodology 95 3.2 Collection of soil samples from UTM campus 97 3.3 Laterite soil samples under air-drying process 98 3.4 Non-traditional soil additives used in this study 99 3.5 pH measurement equipment 104 3.6 Equipment used in compaction tests 106 3.7 Samples under curing condition 108 3.8 Unconfined compressive strength test machine 109 3.9 Direct shear test machine 110 3.10 One dimensional consolidation test equipment 112 3.11 Diffraction from crystal planes according to Bragg’s Law (Mitchell and Soga, 2005) 113 3.12 Sample preparation for XRD test 114 3.13 Bruker D8 X-ray Diffractometer 115 3.14 Field Emission Scanning Electron Microscope 116 3.15 Scanning Electron Microscope 117 3.16 Vacuum sputter coater 117 3.17 Sample preparation for fourier transform infrared test 118 3.18 Fourier transform infrared device connected to the computer 119

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3.19 Thermal Gravimetric device 120 3.20 Surface area measurement device 121 3.21 Particle size analysis device (CILAS 1180) 122 3.22 Failure mechanism from general shear failure of foundation (Sutjiono and Najoan, 2005) 125 3.23 Schematic picture of test box 127 3.24 Loading frame used for physical model tests 128 3.25 Test box transfer to the loading frame 129 3.26 Wall and footing used in physical model tests 130 3.27 Schematic view of experimental model 131 3.28 Test box showing prepared soil, wall, footing, LVDT, strain gauges and load cell before test 134 3.29 Finite element model and mesh for various footing distance from the wall, (a) 5 cm from wall; (b) 10 cm from wall; (c) 15 cm from wall 137 4.1 Particle size distribution of laterite soil 142 4.2 Plasticity chart in accordance with USCS 144 4.3 Diffragtogram of untreated granitic residual soil 147 4.4 Particle size distribution of SH-85 148 4.5 Compaction curve of natural laterite soil 150 4.6 Relationship between maximum dry density and optimum moisture content with percentage of added SH-85 on laterite soil 152 4.7 Relationship between maximum dry density and optimum moisture content with percentage of added TX-85 on laterite soil 153 4.8 Strength gained for SH-85 treated laterite soil with different stabilizer content and curing time 155 4.9 Strength gained for TX-85 treated laterite soil with different stabilizer content and curing time 157 4.10 Comparison between SH-85 and TX-85 strength developments for 7 days cured samples 159 4.11 Consolidation curve of natural laterite soil 160 4.12 Compression curves of untreated and SH-85 treated soils at different curing time 162

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4.13 Variation of compression index and swelling index at different curing time 162 4.14 Compression curves of untreated and TX-85 treated soils at different curing time 163 4.15 Variation of compression index and swelling index at different curing time 163 4.16 Direct shear test result on untreated laterite soil 165 4.17 Variation of cohesion of treated samples with SH-85 at different time intervals 167 4.18 Variation of friction angle of treated samples with SH-85 at different time intervals 168 4.19 Variation of cohesion of treated samples with TX-85 at different time intervals 169 4.20 Variation of friction angle of treated samples with TX-85 at different time intervals 169 4.21 Comparison between SH-85 and TX-85 treated samples’ cohesion in different time intervals 170 4.22 XRD patterns of untreated and treated laterite soil with SH-85 at different time intervals 172 4.23 XRD patterns of untreated and treated laterite soil with TX-85 at different time intervals 173 4.24 EDAX spectrums of untreated laterite soil 175 4.25 EDAX spectrums of SH-85 additive 175 4.26 EDAX spectrums of SH-85 treated laterite soil at different curing times 177 4.27 EDAX spectrums of TX-85 treated laterite soil at different time intervals 179 4.28 Micrographs of natural laterite soil 181 4.29 Micrographs of SH-85 additive 182 4.30 FESEM images of SH-85 treated laterite soil at different time intervals 184 4.31 FESEM micrographs of TX-85 treated laterite soil at different curing time 186

4.32 FTIR spectrums for untreated and SH-85-treated laterite soil with various curing time 188 4.33 FTIR spectrums for untreated and TX-85-treated laterite soil at various time intervals 188 4.34 TGA spectrums for untreated laterite soil 189 4.35 TGA spectrums for SH-85 treated laterite soil at 7, 28 and 90 days curing time 190 4.36 TGA spectrums of TX-85 treated laterite soil at 7, 28 and 90 days curing time 191 4.37 BET surface area for untreated and SH-85 treated samples at various curing periods 194 4.38 BET results for untreated and TX-85 treated samples at various curing periods 194 4.39 Particle size distribution of untreated and treated samples with SH-85 at various curing periods 196 4.40 Particle size distribution of untreated and treated samples with TX-85 at various curing periods 196 4.41 Variation of pH for SH-85 and TX-85 treated laterite soil 199 4.42 Stabilization mechanisms of SH-85 and TX-85 additives on laterite soil 201 5.1 Variation of pressure-settlement of footing when the footing was placed at 5 cm from the wall 206 5.2 Variation of pressure-footing settlement at 366 kPa, when the footing was placed at 5 cm from the wall 207 5.3 Variation of pressure-horizontal displacement of wall when the footing was placed at 5 cm from the wall 208 5.4 Variation of pressure-wall horizontal displacement at 366 kpa, when the footing was placed at 5 cm from the wall 209 5.5 Effect of backfill stabilization on the wall strain distribution at 366 kPa pressure, placed at 5 cm from the wall 210 5.6 Variation of pressure-settlement of footing when the footing was placed at 10 cm from the wall 211 5.7 Variation of pressure-footing settlement at 470 kPa, when the footing was placed at 10 cm from the wall 212

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5.8 Variation of pressure-horizontal displacement of wall when the footing was placed at 10 cm from the wall 213 5.9 Variation of pressure-wall horizontal displacement at 470 kPa, when the footing was placed at 10 cm from the wall 214 5.10 Effect of backfill stabilization on the wall strain distribution at 470 kPa pressure, placed at 10 cm from the wall 215 5.11 Variation of pressure-settlement of footing when the footing was placed at 15 cm from the wall 216 5.12 Variation of pressure-footing settlement at 572 kPa, when the footing was placed at 15 cm from the wall 217 5.13 Variation of pressure-horizontal displacement of wall when the footing was placed at 15 cm from the wall 218 5.14 Variation of pressure-wall horizontal displacement at 572 kPa, when the footing was placed at 15 cm from the wall 219 5.15 Effect of backfill stabilization on the wall strain distribution at 572 kPa pressure, placed at 15 cm from the wall 220 5.16 Ultimate pressure of footing on untreated and treated backfill with SH-85 and TX-85, placed at various distance from the wall 221 5.17 Horizontal wall displacement of untreated and treated backfills at ultimate pressure of footing placed at various distance from the wall 222 5.18 Comparison graphs of footing settlement when the load was placed at 5 cm from the wall 226 5.19 Comparison graphs of wall horizontal displacement when the load was placed at 5 cm from the wall 227 5.20 Comparison graphs of strain distribution when the load was placed at 5 cm from the wall 228 5.21 Comparison graphs of footing settlement when the load was placed at 10 cm from the wall 229 5.22 Comparison graphs of wall horizontal displacement when the load was placed at 10 cm from the wall 230 5.23 Comparison graphs of strain distribution when the load was placed at 10 cm from the wall 231

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5.24 Comparison graphs of footing settlement when the load was placed at 15 cm from the wall 232 5.25 Comparison graphs of wall horizontal displacement when the load was placed at 15 cm from the wall 233 5.26 Comparison graphs of strain distribution when the load was placed at 15 cm from the wall 234

5.27 Comparison between qult obtained from numerical and physical modelling for footing placed behind the wall, with untreated and treated backfill 235

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LIST OF ABBREVIATIONS AND SYMBOLS

A - Activity ADU - Acquisition data unit AEC - Anion exchange capacity Al - Aluminum Al3+ - Aluminum cation ASTM - American society of testing material BET - Brunauer emmett and teller BS - British standard c - Constant c - Cohesion Ca - Calcium Ca2+ - Calcium cation CAH - Calcium aluminate hydrate CaO - Calcium oxide

Ca(OH)2 - Calcium hydroxide CASH - Calcium aluminate silicate hydrate CaSO4 - Calcium sulphate CEC - Cation exchange capacity

Cc - Compression index

Cs - Swelling index cv - Coefficient of consolidation

CO2 - Carbon dioxide cps - Counts per second Cu - Copper d - Distance of interplanar spacing as function of  D - Day

Df - Depth of the foundation

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DTA - Differential thermal analysis DTG - Derivative thermal gravimetric e - electronic charge EDAX - Energy dispersive x-ray analysis F - Fluoride Fe - Iron Fe2+ - Iron (II) cation Fe3+ - Iron (III) cation

Fe2O3 - Ferric Oxide FESEM - Field emission scanning electron microscopy FTIR - Fourier transform infrared H - Hydrogen H+ - Hydrogen cation HCL - Hydrochoric acid

H2O - Water

Hs - Depth of failure zone ICP - Inductively coupled plasma K - Potassium K+ - Potassium cation KBr - Potassium bromide LC - Laterite Clay LL - Liquid limit LOI - Loss on ignition LST - Liquid Stabilizer Treated LVDT - Linear variable displacement transducer

Lsh - Length of horizontal failure line MDD - Maximum dry density Mg - Magnesium MgO - Magnesium oxide MM - Mercury microporosimetry mv - Coefficient of volume change n - Order of diffraction n0 - electrolyte concentration Na - Sodium

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Na+ - Sodium cation

Na2O - Sodium oxide NASH - Sodium AluminoSilicate Hydrate

NO3 - Nitrate NUM - Numerical Modelling O - Oxygen OC - Organic content (OH) - - Hydroxide ion OMC - Optimum moisture content P - Phosphorous PHM - Physical Modelling PI - Plasticity index PL - Plastic limit ppm - Parts per million PST - Powder Stabilizer Treated Pt - Platinum qult - Ultimate pressure qa - Allowable pressure S - Sulfur Sec - Seconds SEM - Scanning electron microscope Si - Silicon

SiO2 - Silica

SO4 - Sulphate SSA - Specific surface area T - Temperature TEM - Transmission electron microscopy TG - Thermal gravimetric TGA - Thermal gravimetric analysis UCS - Unconfined compressive strength UNT - Untreated ν - Volume of gas adsorbed per unit weight of clay at a ressure

νm - Volume of gas adsorbed for monolayer coverage XRD - X-ray diffraction

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XRF - X-ray fluorescene Zn - Zinc 1/k - The effective thickness of the diffuse layer  - Strain  - Micro  - Wave-length  - Critical angle of incidence of the x-ray beam on the crystal plane  - Internal friction angle

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LIST OF APPENDICES

APPENDIX TITLE PAGE

A Samples of data obtained from EDAX 270 B Samples of data obtained from CILAS 278 C Data obtained from ICP-MS test 292 D Calibration of pH meter 294 E Data obtained from BET 297 F Strain gauge calibration 299 G XRD patterns of SH-85 and laterite soil 300

CHAPTER 1

1 INTRODUCTION

1.1 Background

High quality soil as materials for geotechnical engineering construction are rare in many parts of the world, and most often than not, engineers are forced to seek alternatives to reach the stipulated requirements. In addition, the gradual increase in population as well as rapid development in the construction industry in recent years have make it more urgent than ever to gain the sufficient knowledge and information needed to improve existing soil for geotechnical engineering purposes.

Soil stabilization is the process of improving the physical and engineering properties of soil to obtain some predetermined targets. It operates in various ways such as mechanical, biological, physical, chemical and electrical. Nowadays, among the different methods of soil improvement, using chemical additives for soil stabilization in order to increase soil strength parameters and loading capacity is catching more attention. Engineers in construction industry particularly in the geotechnical sector use chemically soil stabilization techniques in many ways such as road construction, slope stabilization and erosion control, foundation and embankment treatment, and improving the coastal line for construction. This popularity is due to their low cost and convenience, particularly in the geotechnical projects that require a high volume of soil.

Each type of chemical additives has different mechanism and influence on soil properties. For instance, there have been noticeable important dissimilarities

2 between tropical soils from the more ordinary soils of moderate climates. Rock weathering in these areas is very rigorous that can be described by fast disintegration of feldspars as well as ferromagnesian raw materials, the displacement of bases including Na2O, K2O, and MgO and silica, and the absorption of aluminum and iron oxides (Eisazadeh et al., 2011). This procedure which includes leakage of silica and decomposition of iron and aluminum oxides is called laterization (Gidigasu, 1972).

There are six areas of the globe that laterite soil is found and they are; Africa, India, South- East Asia, Australia, Central and South America. However, there is an emphasis that, due to the movement of climatic zone in the geological past, relevant regions of laterite can be located in places that are not within the tropics (Zilalem, 2005). This soil category is affluent in aluminum, iron, and kaolinite clays (Townsend, 1985). This soil group usually exists at hillside and offers brilliant borrow areas for wide adoption in many different construction operations. The optimum utilization is determined by the quantity of issues encountered in construction connected to their workability, field compaction, and strength. Studies shows that the laterite soil forms a large part of Malaysia’s soil, and it has been used in different areas and projects as natural soil (Salih, 2012; Eisazadeh, 2013).

The stabilization of soils with additives is a chemical method that can be used to improve soils with poor engineering properties. However, sometimes it is necessary to add some additives to the soil in order to improve certain properties of the soil to be used for specific purpose of the project. The soil stabilizers are categorized as traditional and non-traditional (Eisazadeh, 2010). Traditional additives include cement, lime, fly ash, and bituminous materials, while non-traditional additives consist of various combinations such as enzymes, liquid polymers, resins, acids, silicates, ions, and lignin derivatives (Tingle et al., 2007; Hafez et al., 2008).

The non-traditional additives can be produced using different kinds of chemical agent that give different reactions while added to soil. Nevertheless, published reports on such additives are still scarce compared to traditional additives, either in terms of their geotechnical performance or basic stabilization mechanisms. Moreover, their exact chemical components are mostly kept confidential by their

3 respective owners. In recent years studies have been done by some researchers on the mixtures of different types of soil and calcium-based powder type of non-traditional stabilizers. The results of their assessment indicated that these additives has potential to improve soil parameters, in particular the soil strength ( Peethamparan et al., 2008; Obuzor et al., 2012; Manso et al., 2013; Agapitus, 2013).

Non-calcium-based liquid soil stabilizers are actively marketed by a number of companies. In addition to being cheaper to transport than traditional bulk stabilizer materials, these products are a potentially attractive alternative for soil treatment. The exact chemical composition of these stabilizers has not been released due to their commercially registered brand. These are mostly sold as concentrated liquids, which are diluted with water at site. Some are directly applied to the soil before compaction while other is pressure injected into deeper layers. It should be noted that the result of previous study indicated that the non-traditional liquid additives can help to increase soil strength with curing time (Zhu and Liu, 2008; Fon, 2010; Liu et al., 2011; Ahmad et al., 2013).

Unfortunately, millions of dollars are lost in some occasions due to improper use of chemical stabilizers (Eisazadeh, 2010). Therefore, proper knowledge on soil- additive reactions is an essential part of this technique. In this research the mechanisms responsible for improving the soil properties of Malaysian laterite soil using domestic non-traditional additives has been studied. In addition, the changes on physicochemical and engineering characteristics of stabilized soil and its performance as a field material has been discussed.

1.2 Problem Statement

Traditional stabilizers such as cement, lime, fly ash, and bituminous products have been intensely researched, and their fundamental stabilization mechanisms have been identified (Obuzor et al., 2012). Nowadays, various types of non-traditional additives in liquid and powder form are actively marketed by a number of companies. The stabilizing mechanisms of these products are not fully understood,

4 and their confidential chemical composition makes it hard to evaluate the stabilizing mechanisms and predict their performance. In addition, laboratory experimentation had focused only on evaluating the effects of stabilized materials on engineering properties.

During recent years, many studies have been done on traditionally stabilized laterite soil, which forms a large part of Malaysia’s soil and their relevant mechanism is well understood (Eisazadeh et al., 2011). Nevertheless, no research on the macro- and microstructural study and efficiency of the tropical residual soil, in particular the laterite soil, mixed with domestically produced chemical additives known as SH- 85 and TX-85 has been carried out. It is therefore important to fully understand the physicochemical behaviour of this soil stabilized with those stabilizers and its performance in field applications.

1.3 Objectives of Study

In view of the current understanding and the incomplete research to date, this study was conducted to determine the stabilization mechanism and performance of the laterite soil mixed with non-traditional additives. Hence, the following objectives had been established to achieve the aim of the research:

1. To assess the changes of soil engineering properties due to treatment with selected chemical stabilizers through “macro-characterization” study. 2. To determine the changes induced on the mineralogy, morphology, molecular structure, and elemental composition of soil-stabilizer matrix at the particle level through “micro-characterization” study of untreated (laterite) and treated soil (laterite treated with optimum percentage of additives). 3. To verify and complement the data obtained in the macro and micro- characterization studies by performing pH test, thermal gravimetric, particle size and surface area analysis on the cured samples.

4. To determine the performance of untreated and selected additives treated laterite soil as the backfill materials retained by sheet pile wall through laboratory physical model tests. 5. To determine the suitability of elasto-plastic Mohr-Coulomb model in numerical simulation of the laterite soil as the backfill materials treated with selected additives, through comparison with laboratory physical model tests.

1.4 Scope and Limitation of Study

The scope and limitation of the research are as follows:

1. The soil used in this study was granitic residual soil obtained from the campus of Universiti Teknologi Malaysia, Johor Bahru, Johor. Results

from the ratio of Silica oxide (SiO2) and Alumina oxide (Al2O3) showed that this soil was categorized as laterite soil. 2. The chemical used, considered as non-traditional additives, were obtained from a company called Probase Sdn. Bhd., located in Johor. 3. The percentages of the chemical used in the mixture of laterite- additives were 3%, 6%, 9%, 12% and 15% cured at 3, 7, 14, 28 and 90 days curing periods. The 9% optimum value was determined through the analysis of the results obtained. Then the soil treated with 9% additives (later used as “treated” soil) had been subjected to various tests after being cured at 7, 28 and 90 days curing period to determine the stabilization mechanism of the treated soil. 4. The macro-structural study involved compaction test, unconfined compression test, direct shear test and consolidation test while the micro-structural study involved X-ray Diffraction, Field Emission Scanning Electron Microscopy and X-ray Spectrometry, Fourier Transform Infrared Spectroscopy, Thermal Gravimetric Analysis, Surface Area Value, Particle Size Analysis and pH measurement.

5. Nine laboratory physical model tests had been conducted on the untreated and treated soil (cured at 7 days) as materials, retained 30 cm by sheet pile. The sheet pile was embedded 15 cm into compacted untreated laterite soil. The model tests were carried out by applying loads to the strip footing placed on the retained soil until failure occurred to the footing. The footing was placed at 5, 10 and 15 cm behind the wall. The settlement of the footing, horizontal displacement of the wall and strain distribution through the depth of the wall had been monitored during loading tests to ascertain the performance of the treated soil as backfill material. 6. The commercial 2D finite element software called “PLAXIS” Version 2010 was used in numerical simulation to evaluate and compare the results obtained from laboratory physical model tests. The Mohr- Coulomb soil model under undrained condition was used in the simulation work.

1.5 Significance of Study

From this study, the mechanism of the stabilization of laterite soil treated with locally produced additives had been established. The significant of the study includes:

1. Results of the study could contribute to existing knowledge, in particular regarding the behaviour of laterite soil treated with these selected non-traditional additives. It can close the gap in understanding the mechanism of the stabilization through the results from macro and micro-structural study, verified by physico-chemical tests. 2. The mineralogical changes, morphological changes, molecular changes and physical changes of the laterite soil treated with the selected non-traditional additives are new findings and can be used for further and other research on laterite soils.

3. Treating of soils using the chosen additives could be an economical alternative method in soil stabilization. This is due to the time taken to obtain increment up to 70% strength of the treated soil could be achieved only after 7 days curing periods. Besides that, stabilizing the soil with these non-traditional additives is easy and quick at the level of implementation compared to other methods of soil reinforcement. 4. Good performance shown by the treated laterite soil as backfill materials could give the confident to the practicing engineers in using these non-traditional additives for treating soils to be used in Geotechnical Engineering project especially in regions with laterite clay as foundation soils. This could also be supported by the results of macro-structural tests from UCT, direct shear tests and consolidation tests which shows the increased resistant of treated soil to settlement and shear failure.

1.6 Thesis Organization

This thesis consists of six chapters. The first chapter has presented a brief introduction on the role of chemical additives in soil stabilization practices and the need to understand its underlying mechanisms. The research philosophy including ‘problem statement’, ‘objectives of study’, ‘scope of study’, and ‘significance of study’ have also been discussed.

Chapter 2 lays out the fundamentals of clay mineralogy to understand more sophisticated soil-chemical reactions. Different chemical stabilization techniques as well as traditional and non-traditional soil additives are discussed, followed by some hypotheses on the formatting mechanisms of reaction products. Previous researches on the physical and numerical simulation of backfills and retaining walls had also been discussed briefly. Based on the current scientific knowledge on soil stabilization, a research framework was established taking into consideration the gap in the current research.

Chapter 3 presents the research methodology of the study by elucidating the chemical analyses and methods used in depth. Laboratory experiments were done to determine the soil’s geotechnical properties according to British Standard. Furthermore, the characterization study of stabilized soil was done using spectroscopic and microscopic techniques previously published in papers and standards. This chapter ends with an elaborated description on the physical and numerical simulation tests procedures. The results obtained from these tests are presented and discussed comprehensively in Chapter 4 and 5.

Finally, Chapter 6 gives the conclusion of this study and highlights the contributions of the work. Besides that, recommendations for future studies are also specified.

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