Physical Properties and Behaviour of High-Performance Concrete at High Temperature (eBook)

Foreword 7
Acknowledgements 9
RILEM Technical Committee 227-HPB (Physical Properties and Behaviour of High-Performance Concrete at High Temperature) 10
RILEM Publications 12
RILEM Proceedings (PRO) 12
RILEM REPORTS (REP) 20
Contents 23
1 Introduction 25
1.1 General Comments 25
1.2 Context and Objectives 26
1.3 Contents 27
References 28
2 Degradation Reactions in Concretes Exposed to High Temperatures 29
2.1 Methodologies to Identify the Degradation Processes of Heated Concrete at Microstructural Level 29
2.2 Thermal Analytical Reactions of Concrete Components 31
2.2.1 Crystalline Phase Transformation in Cement Paste 31
2.2.2 Amorphous Phase Transformation in Cement Paste 36
2.2.3 Molecular Transformations in Cement Paste 38
2.2.4 Thermal Stability Transformations of Concrete Components 39
2.2.5 Microscopy of Microstructure Transformations in Concrete Components 46
2.3 Physical Transformations at Microstructural Level 49
2.4 Thermal Changes 57
2.4.1 Determination of Heat of Reactions 57
2.4.2 Ablation, Heat of Melting and Erosion of Concrete 60
References 63
3 Mass Transport Properties 65
3.1 Introduction 65
3.1.1 Transport Characteristics 65
3.1.2 Weight Loss 67
3.1.3 Permeability 68
3.2 Evolution of Permeability After Heating 69
3.2.1 High Performance Concrete 70
3.2.2 High Performance Concrete with Polypropylene (PP) Fibres 71
3.3 Discussion 71
3.3.1 The Role of the Fibres 76
3.3.2 Permeability During Heating 78
3.4 Conclusion 80
References 81
4 Thermal Properties 84
4.1 Thermal Conductivity 84
4.1.1 Aggregate Type and Volume Ratio 86
4.1.2 Water to Cement Ratio of Cement Paste 88
4.1.3 Moisture Content 88
4.1.4 Effect of Cooling 89
4.1.5 Effect of Steel Fibres 90
4.2 Heat Capacity 90
4.2.1 Thermal Diffusivity 90
References 91
5 Mechanical Properties 93
5.1 Introduction 94
5.2 Test Methods 95
5.2.1 Steady State Tests 96
5.2.2 Transient Tests 99
5.3 Stress-Strain-Relation, Compressive Strength and Modulus of Elasticity 100
5.3.1 Preliminary Remarks 100
5.3.2 Influence of the Initial Compressive Strength 102
5.3.3 Influence of the Type of Aggregate 103
5.3.4 Influence of Additional Binders 104
5.3.5 Influence of PP-Fibres Additions 105
5.3.6 Influence of the Steel Fibres 106
5.3.7 Influence of Moisture Content (Drying at 105 °C) and Type of Curing 106
5.3.8 Influence of Water to Cement Ratio 108
5.3.9 Influence of the Mechanical Load During Heating 108
5.3.10 Influence of the Heating Rate 111
5.3.11 Comparison of “Hot” Versus “Residual” Properties 112
5.4 Steady State Creep and Creep Recovery 114
5.4.1 Basic Creep and Drying Creep 115
5.4.2 Creep Recovery 121
5.5 Thermal Strain, Transient Thermal Strain and Restraint Forces 122
5.5.1 Thermal Strain of Concrete 122
5.5.2 Transient Thermal Strain of Concrete 124
5.5.3 Restraint Forces 139
5.6 Tensile Strength 141
5.6.1 Introduction 141
5.6.2 Testing Methods 142
5.6.3 Conclusions 145
References 146
6 Conclusion 151