Utilization of steel slag for stabilization of a lateritic soil

• CERTIFICATION ii DEDICATION iii ACKNOWLEDGEMENTS iv LIST OF FIGURES viii LIST OF TABLES ix LIST OF ABBREVIATIONS AND ACRONYMS x ABSTRACT xiCHAPTER ONE INTRODUCTION 11 Preamble 1 12 Statement of the Problem 1 13 Justification for the Study 2 14 Aim and Objectives 3 15 Scope of the Study 3 16 Significance of Study 4CHAPTER TWO LITERATURE REVIEW 6 21 Background 6 22 What is Slag? 7 221 Slag Recycling 10 222 Utility and Usage of Slag Products 11 23 Efforts in Utilizing Slag 13 24 Production of Steel Slag 13 241 BOF Slag from Basic Oxygen Steelmaking 14 242 EAF Slag 17 243 Steel Slag Utilization 19 25 Properties of Steel Slag 20 251 Physical and Mechanical Properties 20 252 Chemical and Mineralogical Properties 23 26 Environmental and Health Considerations 27 27 Laterite and Lateritic Soils 27 28 Stabilization of Lateritic Soils 30

Chapter THREE

SYSTEM DESIGN AND IMPLEMENTATION

• MATERIALS AND METHODS 33 31 Materials and Preparation 33 311 Steel slag 33 312 Soil 33 32 Methods 34 321 Chemical composition of steel slag 36 322 Natural moisture content 36 323 Sieve analysis 37 324 Specific gravity 38 325 Atterberg limits 36 326 Compaction characteristics 39 327 Strength characteristics 38 328 Permeability 39CHAPTER FOUR RESULTS AND DISCUSSION 40 41 X-ray Fluorescence 41 42 Natural Soil 41 43 Sieve Analysis 41 44 Specific Gravity 42 45 Atterberg Limits 43 46 Compaction Characteristics of Lateritic Soil Sample 45 47 California Bearing Ratio 47 48 Unconfined Compressive Strength 49 49 Permeability 51 410 Optimal Stabilization 52CHAPTER FIVE CONCLUSION AND RECOMMENDATION 53 51 Conclusion 53 52 Recommendation 54 REFERENCES 55 APPENDIX: LABORATORY RESULT SHEETS 61 LIST OF FIGURES Figure 21: Types of Slag 7 Figure 22: Types of Ferrous Slag 8 Figure 23: Flow of Steel Slag Production (Nippon Slag Association, 2006) 10 Figure 24: Major Productive Use of Steel Slag in Europe 11 Figure 25: Steel Slag Utilization in Europe 11 Figure 26: A Typical BOF (National Slag Association, 2011) 14 Figure 27: Schematic of Operational Steps in Oxygen Steelmaking Process (BOF) (Fruehan, 1998) 15 Figure 28: Typical Composition after Sampling (Corus, 2011) 17 Figure 29: A Typical EAF (National Slag Association, 2011) 18 Figure 210: Schematic of Operational Steps in EAF Processes (Corus, 2011) 19 Figure 31: Steel Slag Sample Collection Site 34 Figure 32: Lateritic Soil Sample Collection Site 34 Figure 41: Particle Size Distribution of Soil 42 Figure 42: Variation of Specific Gravity with Slag Content 42 Figure 43: Variation of Average Liquid Limit with Slag Content 42 Figure 44: Variation of Plastic Limit with Slag Content 44 Figure 45: Variation of Plasticity Index with Slag Content 45 Figure 46: Variation of OMC with Slag Content 46 Figure 47: Variation of MDD with Slag Content 46 Figure 48: Variation of Unsoaked CBR with Slag Content 47 Figure 49: Variation of Soaked CBR with Slag Content 48 Figure 410: Variation of Swell Potential with Slag Content 48 Figure 411: Variation of Unconfined Compressive Strength with Slag Content 50 Figure 412: Variation of Undrained Shear Strength with Slag Content 50 Figure 413: Variation of Permeability with Slag Content 51LIST OF TABLES Table 21 Typical Use of Slag in Civil Engineering Applications (National Slag Ass, 2011) 12 Table 22: Basic Oxygen Steelmaking Event Times (Fruehan, 1998) 16 Table 23: Applications of Steel Slag (Nippon Slag Association, 2006) 20 Table 24: Typical Physical Properties of Steel Slag 21 Table 25: Particle Size Distribution Results for BOF and EAF Slags 22 Table 26: Typical Mechanical Properties of Steel Slag 22 Table 27: Range of Metal Concentration in BOF and EAF Slags 24 Table 28: Typical Chemical Composition of Steel Slag 25 Table 29: Comparison of Chemical Comp of Steel Slag and Portland Cement 27 Table 210: Properties of a Lateritic Soil (Okafor and Okonkwo, 2009) 30 Table 41: XRF Result of Steel Slag Sample 40 Table 42: Geotechnical Properties of Natural Soil 41 Table 43: Some Geotechnical Properties at Optimal Stabilization 52LIST OF ABBREVIATIONS AND ACRONYMS AASHTO American Association of State Highway and Transportation Officials ASTM American Association for Testing and Materials BOF Basic Oxygen Furnace slag BS British Standards CBR California Bearing Ratio CERD Centre for Energy and Research Development EAF Electric Arc Furnace slag HERA Human Health and Ecological Risk Assessment LL Liquid Limit MDD Maximum Dry Density OMC Optimum Moisture Content OSC Optimum Steel-slag Content PI Plasticity Index PL Plastic Limit SEM Scanning Electron Microscope SSC Steel Slag Coalition UCS Unconfined Compressive Strength USC Unified Soil Classification System XRD X-ray Diffraction XRF X-ray Fluorescence