an engineering geological characterisation of tropical clays - GBV

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Chapter 6. Chemical and mineralogical analysis 58
6.1 Introduction 58
6.2 X-ray fluorescence (XRF) studies 58
6.2.1 Scope and method 58
6.2.2 Results 58
6.3 X-ray diffraction (XRD) studies 59
6.3.1 Scope and method 59
6.3.2 Results 60
6.4 Scanning electron microscope (SEM) analysis 67
6.4.1 Scope and method 67
6.4.2 Results 68
6.4.2.1 Nairobi phonolite 68
6.4.2.2 Nairobi trachytes 70
6.4.2.3 Black clays 71
6.4.2.4 Red soils 75
6.5 Importance and influence of clay minerals on engineering
properties of black clays and red soils 77
6.6 Carbon and sulphur content of soils 78
6.6.1 Method of analysis 78
6.6.2 Results 79
6.6.3 Analysis of results 80
Chapter 7. Laboratory soils index and engineering properties determination 83
7.1 Moisture content and index tests 83
7.1.1 Introduction 83
7.1.2 Natural moisture content 83
7.1.3 Atterberg limits and consistency of clay soils 84
7.1.4 Free swell test (after Gibbs & Holtz, 1956) 91
7.1.5 Linear shrinkage 95
7.2 Grain/ particle size analysis 96
7.2.1 Scope 96
7.2.2 Procedure and results 97
7.3 Direct shear tests 104
7.3.1 Scope 104
7.3.2 Procedure 104
7.3.3 Results 106
7.3.4 Evaluation and analysis of results 110
7.4 Oedometer consolidation tests 115
7.4.1 Scope 115
7.4.2 Theory of consolidation 115
7.4.3 Consolidation coefficients and other parameters 119
7.4.4 Procedure 124
7.4.5 Analysis of consolidation test data 125
7.4.6 Results of consolidation tests 126
7.4.7 Swelling pressure and percentage swelling 138
7.4.8 Evaluation and application of results of oedometer consolidation,
swelling pressure and percentage swelling 152