Molecular Simulation on Cement-Based Materials (eBook)

Foreword 5
Preface 7
Contents 9
1 Background and Objectives 13
1.1 Introduction 13
1.2 Research Motivation of Atomistic-Scale Simulation 14
1.3 Outline of Book 16
References 16
2 Introduction to Modeling of Cement Hydrate at Nanoscale 18
2.1 Formation of the C–S–H Gel 18
2.2 Experimental Characterization of the C–S–H Gel 21
2.2.1 Morphology 21
2.2.2 Ca/Si Ratios 21
2.2.3 Water States 23
2.2.4 Density and Water Content 24
2.2.5 Layered Feature 25
2.2.6 Silicate Polymerization 27
2.2.7 Mechanical Properties 30
2.3 Mineral Analogues of C–S–H Gel 30
2.3.1 Tobermorite 30
2.3.2 Jennite 33
2.4 Models of the C–S–H Gel 34
2.4.1 Models for the Nanostructure and Morphology 34
2.4.2 Models for the Atomic Structure 38
2.4.3 Models Based on Molecular Simulation 39
2.5 Chapter Summary 40
References 41
3 Introduction to Simulation Techniques on the Cement-Based Materials 45
3.1 Introduction to the Molecular Simulation Method 45
3.2 Molecular Mechanics 46
3.2.1 Potential Forms 46
3.2.2 Energy Minimization 52
3.2.3 Elastic Properties 54
3.3 Molecular Dynamics 55
3.3.1 Ensembles 55
3.3.2 MD Algorithm 57
3.3.3 MD Trajectories Analysis 59
3.4 Grand Canonical Monte Carlo (GCMC) 62
3.5 Chapter Summary 63
References 63
4 Modeling the Calcium Silicate Hydrate by Molecular Simulation 65
4.1 Introduction 65
4.2 Computational Details 66
4.3 Experimental Validation of the C–S–H Model 68
4.4 Molecular Structure of C–S–H Model 70
4.4.1 Layered Structure 70
4.4.2 Local Structure of Silicon 72
4.4.3 Local Structure of Calcium Atoms 74
4.4.4 Local Structure of Water Molecule 76
4.5 Mechanical Properties of C–S–H Gel 78
4.5.1 Stress–Strain Relations 78
4.5.2 Chemical Reaction in the Deformed C–S–H Gel 79
4.6 Ca/Si Ratio Influence 84
4.6.1 Model Construction at Different Ca/Si Ratios 85
4.6.2 Molecular Structures at Different Ca/Si Ratios 85
4.6.3 Mechanical Properties at Different Ca/Si Ratios 91
4.7 Chapter Summary 94
References 95
5 Molecular Simulation of Water and Ions Migration in the Nanometer Channel of Calcium Silicate Phase 97
5.1 Introduction 97
5.2 Adsorption Model for Water and Ions Confined in C–S–H Gel Pore 99
5.2.1 Computational Details 100
5.2.2 Atomic Intensity and Orientation Files for Water Confined in Gel Pore 103
5.2.3 H-Bond Network and Coordinated Atoms 107
5.2.4 Diffusion Coefficient 111
5.2.5 Interaction Between Ions and Tobermorite Substrate 113
5.3 Capillary Transport Model for Ions and Water in the Gel Pore 116
5.3.1 Computational Details 116
5.3.2 Capillary Adsorption of NaCl Solution 117
5.3.3 Local Structure of Water and Ions in the Gel Pore 121
5.3.4 Dynamic Properties of Atoms in the Gel Pore 125
5.3.5 Pore Size Effect on Capillary Transport 132
5.4 Chapter Summary 136
References 137
6 Models for the Cross-Linked Calcium Aluminate Silicate Hydrate (C–A–S–H) Gel 141
6.1 Background of Cross-Linked C–A–S–H Gel 141
6.2 Model Construction 143
6.3 Connectivity Factor 147
6.4 Coordination Number of Al Atoms 148
6.5 Structure and Dynamic Properties of Interlayer Water Molecules 149
6.6 Stress–Strain Relation 154
6.7 Deformation of the Structure 157
6.8 Chapter Summary 163
References 164
7 Molecular Dynamics Study on Cement–Graphene Nanocomposite 168
7.1 Introduction 168
7.2 Simulation Methods 170
7.2.1 Force Field 170
7.2.2 Model Construction 170
7.3 Molecular Structural Properties of Graphene/GO and C–S–H Model 172
7.3.1 Molecular Structure of Graphene/GO and C–S–H 172
7.3.2 Local Structure of the Graphene and GO in the Interlayer 174
7.3.3 Local Structure of Interlayer Ca and Al Ions 177
7.3.4 The Local Structure of Water and Hydroxyl Groups 179
7.4 Dynamic Properties of the Graphene/GO and C–S–H Model 181
7.4.1 Dynamic Properties of Carbon Atoms 181
7.4.2 Dynamic Properties for Hydrogen Atoms 183
7.4.3 Time Correlation Function for Chemical Bonds 185
7.5 Reinforcement Mechanism of G/Go on C–S–H 187
7.6 Chapter Summary 192
References 192
8 The Future and Development Trends of Computational Chemistry Applied in Concrete Science 195
8.1 Force Field Database Development for Cement-Based Material 196
8.2 Mesoscale Modeling of the Cement Hydrate by Coarse Grain Molecular Dynamics 197
8.3 Molecular Modeling of Low Carbon Geopolymer Binders 200
8.4 Solutions of Concrete Structural Engineering from Molecular Dynamics 202
References 204