Recent Advances on Green Concrete for Structural Purposes: The contribution of the EU-FP7 Project EnCoRe (Research for Development)

This book is mainly based on the results of the EU-funded UE-FP7 Project EnCoRe, which aimed to characterize the key physical and mechanical properties of a novel class of advanced cement-based materials incorporating recycled powders and aggregates and/or natural ingredients in order to allow partial or even total replacement of conventional constituents. More specifically, the project objectives were to predict the physical and mechanical performance of concrete with recycled aggregates; to understand the potential contribution of recycled fibers as a dispersed reinforcement in concrete matrices; and to demonstrate the feasibility and possible applications of natural fibers as a reinforcement in cementitious composites. All of these aspects are fully covered in the book. The opening chapters explain the material concept and design and discuss the experimental characterization of the physical, chemical, and mechanical properties of the recycled raw constituents, as well as of the cementitious composite incorporating them. The numerical models with potentialities for describing the behavior at material and structural level of constructions systems made by these composites are presented. Finally, engineering applications and guidelines for production and design are proposed. Preface 6 Acknowledgements 8 Contents 9 Recycled Aggregate Concrete 11 1 State of Knowledge on Green Concrete with Recycled Aggregates and Cement Replacement 12 Abstract 12 1.1 Sustainable Concrete Constituents 14 1.1.1 Recycled Aggregates 14 1.1.2 Alternative Binders 17 1.2 Fresh-State Behaviour 20 1.3 Hardened-State Behaviour 21 1.4 Codes and Guidelines 25 1.4.1 Europe 25 1.4.2 United States, Hong Kong and Australia 26 1.4.3 Some Remarks About Existing Regulations and Standards 27 1.5 Insights into Concrete Sustainability 28 References 31 2 Concrete with Recycled Aggregates: Experimental Investigations 37 Abstract 37 2.1 The Influence of Processing Procedures for RCAs in RAC 38 2.1.1 Materials and Methods 38 2.1.2 Results and Analysis 39 2.2 Influence of the Initial Moisture Condition of RCAs 41 2.2.1 Materials and Methods 42 2.2.2 Results and Analysis 45 2.3 Influence of the Aggregate Replacement and Water to Cement Ratios 47 2.3.1 Materials and Methods 47 2.3.2 Results and Analysis 50 2.4 Concluding Remarks 53 References 54 3 Cement Replacement: Experimental Results for Concrete with Recycled Aggregates and Fly-Ash 55 Abstract 55 3.1 The Experimental Campaign 56 3.1.1 Materials 56 3.1.2 Concrete Mixtures Proportions 60 3.1.3 Test Matrix 62 3.1.4 Casting and Curing Processes 64 3.2 Experimental Results 65 3.2.1 Workability 66 3.2.2 Density 67 3.2.3 Compressive Strength 69 3.2.4 Tensile Strength 72 3.2.5 Bond-Slip 73 3.2.6 Permeability 75 3.2.7 Resistance to Chlorides 78 3.2.8 Carbonation Depth 80 3.2.9 Analysis of Results and Evolution of the Compressive Strength 86 3.3 Concluding Remarks 89 References 90 4 Insights into the Triaxial Behaviour of Recycled Aggregate Concrete 92 Abstract 92 4.1 The Experimental Campaign 95 4.1.1 Materials 96 4.1.2 Physical Properties of Recycled Coarse Aggregates 97 4.1.3 Mixture Proportioning and Mixing Procedure 98 4.1.4 Fresh Concrete Test Results 99 4.1.5 Curing, Casting, and Specimen’s Preparation 100 4.1.6 Equipment for Mechanical Tests 101 4.2 Mechanical Tests 102 4.2.1 Uniaxial Compression Tests (UC) 102 4.2.2 Splitting Tensile Tests (ST) 104 4.2.3 Triaxial Compression Tests (TC) 106 4.3 Concluding Remarks 113 References 114 5 Constitutive Formulations for Concrete with Recycled Aggregates 116 Abstract 116 5.1 Thermodynamic Framework of Gradient Constitutive Theory 118 5.2 Leon-Drucker-Prager Model for NAC 119 5.3 The Extended LDP for Failure Analysis of RAC 120 5.3.1 Maximum Strength Surface and Yield Condition 120 5.3.2 Ductility in Pre-peak Regime 121 5.3.3 Ductility in Post-peak Regime 123 5.3.4 Inelastic Volumetric Deformation and Plastic Potential 124 5.4 Numerical Analysis 125 5.4.1 Uniaxial Tensile Test 126 5.4.2 Uniaxial Compression Test 126 5.4.3 Triaxial Compression Test 128 References 128 6 Generalised Mix Design Rules for Concrete with Recycled Aggregates 130 Abstract 130 6.1 Experimental Results and Modelling Techniques 131 6.1.1 Experimental Characterisation of RCAs 132 6.1.2 Experimental Characterisation of RACs and Hydration Process Modelling 133 6.2 Physical Properties of RCAs: The Role of Attached Mortar 135 6.3 A Rational Mix Design Approach for RAC 136 6.4 Design Charts and Model Potential 137 6.5 Conclusions 140 References 140 Cementitious Materials Reinforced with Recycled or Natural Fibers—Technology, Properties, Design and Applications 142 7 Introduction 143 References 144 8 Cementitious Composites Reinforced with Recycled Fibres 146 Abstract 146 8.1 Recycling Waste Tyres: Technological Issues and Applications in Concrete Production 146 8.1.1 Waste Tyres: Key Facts 146 8.1.2 Classification of Pneumatic Tyres 149 8.1.3 Alternative Recycling Processes 151 8.1.3.1 Grinding Processes 152 Ambient Grinding 152 Cryogenic Grinding 152 8.1.3.2 De-vulcanisation and Surface Treatment 153 8.1.3.3 Thermal Conversion Technologies 153 Pyrolysis 154 Microwave Treatment 155 8.1.3.4 Energy Recovery Solutions 155 8.1.3.5 Re-treading 156 8.1.3.6 Comments About Feasibility and Convenience of the Available Technical Solutions 156 8.1.4 Recycling of Waste Tyres in Concrete Production 157 8.1.5 Recycled Fibres from Waste Tyres for FRCC 158 8.1.5.1 Characterizing Recycled Fibres for Producing Steel Recycled Fibre Reinforced Concrete 158 8.1.5.2 Insights into the Mechanical Behaviour 162 8.2 Mechanical Properties 164 8.2.1 Introduction 164 8.2.2 Compression 164 8.2.3 Direct Tension 166 8.2.4 Indirect Tensile Tests 170 8.2.4.1 Brazilian Type Test 170 8.2.4.2 Double Edge Wedge Splitting Test (DEWST) 174 8.2.5 Bending Tests 175 8.2.6 Direct Shear 185 8.2.7 Round and Square Panel Tests 186 8.2.8 Fatigue Behaviour 189 8.2.9 Bond Performance of RFRC-Steel Bar Reinforcement 189 8.2.10 Durability Properties of RSFRC 190 References 194 9 Cementitious Composites Reinforced with Natural Fibres 201 Abstract 201 9.1 Introduction 201 9.2 Physical and Mechanical Properties of Natural Fibres 203 9.3 Mechanical Properties of NFRCCs 214 9.4 Durability of NFRCCs 225 9.5 Natural Fibres as Promoters of Self-healing in Cementitious Composites 241 9.5.1 Index of Strength Recovery 251 9.5.1.1 Deflection-Softening Specimens 251 9.5.1.2 Deflection-Hardening Specimens 253 9.5.2 Index of Stiffness/Damage Recovery 255 9.5.3 Crack Opening Measurements and Crack Sealing Evaluation 256 9.5.3.1 Image Analysis Processing of Cracks Observed by Optical Microscopy 256 9.5.3.2 Index of Crack Healing 258 9.5.4 Comparison Indices of Mechanical Properties Recovery and Index of Crack Healing 260 9.5.5 Microscopical Characterization 263 9.5.6 Comparison Between Healing Capacities of Hybrid Steel + Sisal and Steel Only HPFRCCs 265 9.6 Cellulose-Based Micro- and Nano-reinforcement in Cementitious Composites 267 9.6.1 Cellulose 267 9.6.2 Nano-cellulose 269 9.6.3 Cellulose Nanocrystals 270 9.6.4 Cellulose Nanofibrils 271 9.6.5 Micro-cellulose 271 9.6.6 Use of Micro and Nano-cellulose in Pastes for Cementing Oil Wells 274 9.6.7 Dispersion of Nano-and Micro-cellulose Fibres in Cement Pastes 276 9.6.8 Effect of Cellulose Nanopulp and Other Micro- and Macro-cellulose Based Fibres on Autogenous and Drying Shrinkage of Cement Based Composites 277 9.7 Conclusions 280 Appendix: Natural Fibres in Cementitious Composites 281 Jute Fibres 281 Hemp Fibres 284 Flax Fibres 287 Kenaf Fibres 291 Ramie Fibres 294 Sisal Fibres 295 Pineapple Leaf Fibres (PALF) 298 Curaua Fibres 300 Piassava Fibres 303 Banana and Abaca Fibres 305 Palm Fibres 309 Coconut/Coir Fibres 312 Cotton fibres 315 Bamboo Fibres 316 Straw and Cane Fibres 319 References 322 10 Approaches for the Design of Structures Made by Concrete Reinforced with Sustainable Fibres 336 Abstract 336 10.1 Introduction 336 10.2 Constitutive Relationships 338 10.2.1 RILEM TC 162-TDF Approach 338 10.2.2 CEB-FIP Model Code 2010 Approach 338 10.3 Flexural Reinforcement 342 10.4 Shear Reinforcement 343 10.4.1 RILEM TC 162-TDF Approach 343 10.4.2 CEB-FIP Model Code 2010 Approach 344 10.4.3 Assessment of the Potentialities of RSFRC for the Shear Reinforcement of RC Beams 345 10.5 Punching Reinforcement 347 10.5.1 Introduction 347 10.5.2 Load-Rotation Approach 348 10.5.3 Failure Criterion 350 10.6 Minimum Flexural Reinforcement, Crack Width and Crack Spacing 351 10.6.1 Minimum Flexural Reinforcement 351 10.6.2 Crack Width and Crack Spacing 351 10.7 Approaches of General Applicability for Composite Materials 353 References 353 11 Inverse Analysis for Deriving the Fracture Properties of RSFRC 355 Abstract 355 11.1 Fracture Mode I Parameters 355 11.2 Fracture Mode II Parameters 360 References 363 12 Advanced Numerical Models for the Analysis of Sustainable FRC Structures 364 Abstract 364 12.1 Introduction 364 12.2 Discrete Fibre Reinforcement Approaches (DFRAs) 365 12.2.1 Bi-phase Type Models 365 12.2.2 Lattice Type Models 370 12.2.3 Strong Discontinuity Approaches 373 12.2.4 Particle Models 377 12.2.5 Zero-Thickness Based Interface Models 380 12.3 Smeared Fibre Reinforcement Approaches (SFRAs) 385 12.3.1 Bibliographic Overview on the Smeared Crack Approaches (SCAs) 385 12.3.2 Fixed, Rotating and Multidirectional Fixed Smeared Crack Models 387 12.3.3 Micro-plane Models 392 References 396 13 Exploring the Use of Cement Based Materials Reinforced with Sustainable Fibres for Structural Applications 403 Abstract 403 13.1 Natural Fibre Reinforced Concrete 403 13.1.1 Tiles and Sheets for Roofing 403 13.1.2 Formwork Elements 409 13.1.3 Wall Elements 410 13.1.4 Beams and Columns 414 13.2 Concrete Reinforced with Recycled Fibres 416 13.3 Concluding Remarks 422 References 422 Conclusions 425 Front Matter....Pages i-x Front Matter....Pages 1-1 State of Knowledge on Green Concrete with Recycled Aggregates and Cement Replacement....Pages 3-27 Concrete with Recycled Aggregates: Experimental Investigations....Pages 29-46 Cement Replacement: Experimental Results for Concrete with Recycled Aggregates and Fly-Ash....Pages 47-83 Insights into the Triaxial Behaviour of Recycled Aggregate Concrete....Pages 85-108 Constitutive Formulations for Concrete with Recycled Aggregates....Pages 109-122 Generalised Mix Design Rules for Concrete with Recycled Aggregates....Pages 123-134 Front Matter....Pages 135-135 Introduction....Pages 137-139 Cementitious Composites Reinforced with Recycled Fibres....Pages 141-195 Cementitious Composites Reinforced with Natural Fibres....Pages 197-331 Approaches for the Design of Structures Made by Concrete Reinforced with Sustainable Fibres....Pages 333-351 Inverse Analysis for Deriving the Fracture Properties of RSFRC....Pages 353-361 Advanced Numerical Models for the Analysis of Sustainable FRC Structures....Pages 363-401 Exploring the Use of Cement Based Materials Reinforced with Sustainable Fibres for Structural Applications....Pages 403-424 Back Matter....Pages 425-427