Systematic Approach of Characterisation and Behaviour of Recycled Aggregate Concrete

Foreword

Preface

Acknowledgements

Contents

About the Authors

Symbols and Abbreviations

List of Figures

List of Tables

1 Introduction

1.1 Introduction

1.2 Applications of Recycled Aggregates

1.3 Benefits of Recycled Aggregates

1.3.1 Economic Aspects

1.3.2 Reducing Environmental Impacts

1.3.3 Saving Resources

1.4 Constraints of Recycled Aggregate Concrete

1.4.1 Management Problems (Tam and Gao 2003)

1.4.1.1 Lack of Suitable Regulations

1.4.1.2 Lack of Codes, Specifications, Standards and Guidelines

1.4.1.3 Lack of Experience

1.4.2 Technology Problems

1.4.2.1 Cement Mortar Attached to Aggregate

1.4.2.2 Poor Grading

1.4.2.3 High Porosity of Recycled Aggregates

1.4.2.4 Weak Interfacial Transition Zone

1.4.2.5 Transverse Cracks Generated

1.4.2.6 Variations in Quality

1.4.2.7 High Impurity

1.4.2.8 Low Quality

1.5 Classification of Recycled Aggregates

1.6 Current Global Scenario

1.6.1 Japan

1.6.2 Germany

1.6.3 United Kingdom

1.6.4 Hong Kong

1.6.5 Australia

1.6.6 China

1.6.7 Spain

1.6.8 RILEM Specifications

1.6.9 India

1.7 Summary

References

2 Demolition Techniques and Production of Recycled Aggregate

2.1 Introduction

2.2 Methods of Demolition

2.2.1 Non-engineering Demolition

2.2.2 Engineering Demolition Techniques

2.2.2.1 Mechanical Methods

2.2.2.2 Demolition by Implosion or Explosion

2.2.2.3 Deconstruction

2.2.3 Top-Down demolition

2.3 Production Technology of Recycled Aggregates

2.3.1 Mobile Plants

2.3.2 Stationary/Fixed Plants

2.4 Process of Recycling Technology

2.4.1 Jaw Crusher

2.4.2 Impact Crusher

2.4.3 Gyratory Crushers

2.4.4 Pre-crushing Separation

2.5 Summary

References

3 Properties of Recycled Aggregates

3.1 Introduction

3.2 Physical Properties of Recycled Aggregates

3.2.1 Grading, Shape and Surface Texture

3.2.2 Density and Specific Gravity

3.2.3 Water Absorption

3.2.4 Flakiness and Elongation Indices

3.3 Mechanical Properties of Recycled Aggregates

3.3.1 Aggregate Crushing Value

3.3.2 Los Angeles Abrasion Resistance Value

3.4 Summary

References

4 Properties of Recycled Aggregate Concrete

4.1 Introduction

4.2 Workability

4.2.1 Factors Influencing the Workability

4.2.1.1 Effect of Water Requirement on Workability

4.2.1.2 Influence of Moisture State of Recycled Aggregate

4.2.1.3 Influence of Strength of Parent Concrete

4.3 Mechanical Properties

4.3.1 Compressive Strength

4.3.1.1 Effect of Amount of Recycled Aggregate

4.3.1.2 Effect of Method of Curing

4.3.1.3 Effect of Strength of Parent Concrete

4.3.1.4 Effect of W/C Ratio

4.3.1.5 Effect of Moisture State of RA

4.3.2 Static Modulus of Elasticity

4.3.3 Split Tensile Strength

4.3.4 Flexural Strength

4.3.5 Density

4.3.6 Ultrasonic Pulse Velocity (UPV)

4.4 Interrelationships Among Mechanical Properties

4.4.1 Relationship Between Compressive Strength and Split Tensile Strength

4.4.2 Compressive Strength and Flexural Strength or Modulus of Rupture Relationship

4.4.3 Compressive Strength and Static Modulus of Elasticity Relationship

4.4.4 Compressive Strength and Ultrasonic Pulse Velocity (UPV) Relationship

4.4.5 Compressive Strength and Density Relationship

4.5 Summary

References

5 Long-Term and Durability Properties

5.1 Introduction

5.2 Shrinkage

5.2.1 Influence of Amount of Recycled Aggregate

5.2.2 Effect of Quality of Recycled Aggregate

5.2.3 Effect of Mineral Admixtures

5.2.4 Effect of Source Concrete, Crushing Method, and Age of Crushing

5.2.5 Effect of Method of Curing

5.2.6 Effect of Method of Mixing

5.3 Creep

5.3.1 Effect of Water to Cement (w/c) Ratio

5.3.2 Effect of Mineral Admixtures

5.3.3 Effect of Method of Curing and Period of Curing

5.3.4 Estimation of Creep of RAC

5.4 Durability Performance of RAC

5.4.1 Permeability

5.4.2 Chloride Penetration

5.4.3 Carbonation Depth

5.5 Summary

References

6 Microstructure of Recycled Aggregate Concrete

6.1 Introduction

6.2 Sample Preparation for Microscopic Study

6.3 Scanning Electron Microscope (SEM)

6.4 Image Acquisition

6.5 Image Analysis

6.6 Vickers Microhardness (HV)

6.7 Characteristics of Interfacial Transition Zone (ITZ)

6.7.1 Hydration Compounds, Anhydrous Cement, and Porosity

6.7.2 Distribution of Hydration Compounds, Anhydrous Cement, and Porosity Across the Width of ITZ

6.7.3 Effect of Aggregate

6.8 Compressive Strength–Porosity Relationship

6.9 Microhardness of ITZ

6.10 Compressive Strength–ITZ Microhardness Relationship

6.11 Influence of Binder on ITZ

6.12 Influence of the Water–Binder Ratio, Quality and Quantity of Adhesion Mortar

6.13 Influence of Strength of Source Concrete

6.14 Influence of Treatment of RCA on ITZ

6.15 Summary

References

7 Structural Behavior of RAC

7.1 Introduction

7.2 Impact Behavior

7.2.1 Instrumented Drop Hammer Impact Test Setup and Devices

7.2.2 Impact Test Results

7.2.2.1 Accelerations

7.2.2.2 Displacement

7.2.2.3 Strains

7.2.2.4 Support Reactions

7.2.2.5 Failure Pattern

7.3 Flexural Behavior of RAC

7.4 Shear Behavior of RAC

7.5 Other Structural Aspects

7.6 Summary

References

8 Quality Improvement Techniques

8.1 Introduction

8.2 Quality Improvement Techniques for Recycled Aggregate

8.2.1 Mechanical Treatment

8.2.2 Thermal Treatment

8.2.3 Chemical Treatment (Tam et al. 2007a, b)

8.2.4 Three-Step Method (Gao et al. 2013)

8.3 Impregnation Techniques

8.3.1 Silica Fume Impregnation

8.3.2 Ultrasonic Cleaning

8.3.3 Polymer Emulsion Impregnation

8.3.4 Surface Treatment with Nanomaterials

8.4 New Mixing Techniques

8.4.1 Two-Stage Mixing Approach

8.4.2 Diversifying Two-Stage Mixing Approach

8.4.3 Self-healing

8.5 Summary

References

Appendix A: Additional Results of Microstructure of Concrete

A.1 Introduction