HB 84—2006

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Guide to

CONCRETE REPAIRAND PROTECTION

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Guide to Concrete Repair and Protection A Joint publication of ACRA, CSIRO and Standards Australia.

Originated as HB84-19962nd Edition 2006ISBN 0 7337 7831 3

© Australian Concrete Repair Association 2006, Standards Australia Limited 2006and CSIRO Australia 2006

Except where the Copyright Act allows otherwise, no part of this publication may be reproduced, storedin a retrieval system in any form or transmitted by any means without prior permission in writing of theAustralian Concrete Repair Association, Standards Australia Limited and CSIRO Australia.

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Standards Australia develops Australian Standards® and other documents of publicbenefit and national interest. These standards are developed through an openprocess of consultation and consensus, in which all interested parties are invited toparticipate. Through a Memorandum of Understanding with the CommonwealthGovernment, Standards Australia is recognised as Australia’s peak non-governmentnational standards body. Standards Australia also supports excellence in design andinnovation through the Australian Design Awards.

For further information visit www.standards.org.au

286 Sussex Street, Sydney, NSW, 2000GPO Box 476, Sydney, NSW, 2001Telephone: +61 2 8206 6000Email: mail@standards.org.auWebsite: www.standards.org.au

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The Australian Concrete Repair Association (ACRA) was incorporated in 1991 withthe aim of providing a forum to promote excellence in all spheres of concrete repairand protection work.

The Association is fundamental to the ongoing nationwide development of aprofessional industry whose key objectives include providing the highest levels ofexpertise, experience, training and quality. ACRA demands a continuingcommitment from its members to maintaining the quality standards it has set for theconcrete repair industry.

Through its membership base, which includes manufacturers, specialist contractors,consultants and owners, ACRA provides stakeholders with confidence in theremedial concrete repair process. This insistence on quality and best practiseunderpins the increasing penetration of ACRA into the concrete repair market.

ACRA has established a scheme of awards for excellence in concrete repair which areopen to Corporate Members of the Association. These awards, which have been runevery two years since 1998, showcase the work of the member companies. The roleACRA plays in the industry is clearly demonstrated in the levels of excellence ondisplay in all entries and the winning projects in particular.

ACRA is firmly committed to ongoing training of its members in the very latestdevelopments in both the technology and practical application of concrete repair andprotection. Maintaining up-to-date levels of knowledge and expertise is vital toproviding clients with the level of professional service expected of an ACRAmember. As such ACRA is extremely grateful to its fellow collaborators in theproduction of this document, The Guide to Concrete Repair and Protection.

AUSTRALIAN CONCRETE REPAIR ASSOCIATION LTDABN 41 059 791 374

Level 6, 504 Pacific HighwaySt Leonards NSW 2065(Locked Bag 2011, St Leonards NSW 1590)

Tel: 61 2 9903 7733Fax: 61 2 9437 9703Email: acrabats@acrassoc.com.au

Website: www.acrassoc.com.au

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The Commonwealth Scientific and Industrial Research Organisation (CSIRO) isAustralia’s national science agency and one of the largest and most diverse scientificresearch organisations in the world. CSIRO has more than 6500 staff carrying outresearch in a wide range of areas including construction, materials, energy, minerals,agriculture and natural resources.

Manufacturing and Infrastructure Technology is a division of CSIRO that supportsthe building, construction and engineering industries with research, consulting andtesting. With over 350 researchers, the division’s science spans building materials -including concretes, timbers, polymers and tiles - to heating and cooling, air quality,urban planning and infrastructure, IT applications for construction, fire testing, andwater systems and products.

CSIRO Manufacturing and Infrastructure Technology

Telephone: 1300 363 400International: +61 3 9545 2176Fax: +61 3 9545 2175Email: cmit.enquiries@csiro.auWeb: www.cmit.csiro.au

CSIRO AUSTRALIA

THE COMMONWEALTH SCIENTIFIC ANDINDUSTRIAL RESEARCH ORGANISATION

C S I R O

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PREFACE

The original 1996 edition of this document was originally prepared by Dr Kwesi Sagoe-Crentsilfrom the CSIRO division of Manufacturing and Infrastructure Technology at the request of theAustralian Concrete Repair Association (ACRA), who also provided the technical, editorial andfunding input.

The document is intended for widespread use by anyone engaged in the maintenance, repairand production of concrete structures. However, this document is intended as an overview ofthe typical methods and practices in the industry but it should not be used as a standard or aspart of any contract relating to the repair of concrete.

In preparing this document, one of the fundamental aims has been to provide a publication thatcan be read and understood by a diverse group of persons, ranging from professionals engagedin specifying or carrying out repairs to concrete structures, to those involved in the managementof buildings and structures.

The guidance in this document has been specifically influenced by RILEM TechnicalRecommendation 124-SRC, Guide to Repair Strategies for Concrete Structures Damaged byReinforcement Corrosion, 1993.

Previously available publications on investigatory and repair technologies for concrete are ofoverseas origin. The development and support of this document by ACRA underlines its beliefthat a document describing the local scenario for techniques and materials was necessary.

The new 2006 edition of this document has now been updated and modified to reflect theadvances and more wide-spread use of electrochemical prevention and protection systems.

Contact:

CSIRO Manufacturing and Infrastructure Technology

Telephone: 1300 363 400International: +61 3 9545 2176Fax: +61 3 9545 2175Email: cmit.enquiries@csiro.auWeb: www.cmit.csiro.au

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NOTES

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CONTENTSPreface i

Chapter 1 – Concrete Properties 1

1.1 Concrete 11.2 Material Properties 2

1.2.1 Concrete quality 21.2.2 Porosity 31.2.3 Curing 41.2.4 Durability 41.2.5 Concrete properties and rebar corrosion 5

1.3 Acknowledgments 5

1.4 Further Reading 5 1.4.1 Standards 5

Chapter 2 – Causes of Concrete Deterioration 7

2.1 Internal Factors 7 2.1.1 Alkali-silica (alkali-aggregate) reaction 82.1.2 Other reactions 8

2.2 Extemal Factors 8 2.2.1 Sulfate attack 92.2.2 Carbonation 92.2.3 Effect of chlorides 9

2.3 Steel Reinforcement Corrosion 112.4 Summary 13 2.5 Acknowledgments 14 2.6 Further Reading 14

2.6.1 Standards 14

Chapter 3 – Formation and Types of Cracks 15

3.1 Cracking of Plastic Concrete 163.1.1 Plastic shrinkage cracks 17 3.1.2 Plastic settlement cracks 17

3.2 Cracking of Hardened Concrete 183.3 Other Types of Cracks 183.4 Impact of Cracks on Steel Reinforcement Corrosion 18 3.5 Acknowledgments 203.6 Further Reading 20

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Chapter 4 – Inspection Techniques 21

4.1 Condition Survey 224.2 Visual Inspection 234.3 Sampling and Testing 23

4.3.1 Lump Samples 234.3.2 Core Samples 24 4.3.3 Dust Samples 24

4.4 In Situ Testing 24 4.4.1 Delamination/Drummy Surveys 24 4.4.2 Rebound Hammer 244.4.3 Crack Width Measure 254.4.4 Reinforcement Depth/Location 254.4.5 Depth of Carbonation 254.4.6 Half-cell Potential Mapping 254.4.7 Concrete Resistivity 264.4.8 Ultrasonic Pulse Velocity (UPV) Measurements 264.4.9 Pull-Out Test 264.4.10 Corrosion Rate Measurement 264.4.11 Ground-Penetrating Radar (GPR) 274.4.12 Gamma Radiography 274.4.13 Infra-Red Thermography 27

4.5 Laboratory Testing 274.5.1 Petrographic Tests 274.5.2 Chloride Profiles 284.5.3 Elastic Modulus 28

4.6 Structural Integrity 28 4.7 Summary 284.8 Further Reading 28

Chapter 5 – Protective and Remedial Systems 29

5.1 Patch Repair Systems (Repair Principle R) 305.1.1 Concrete removal 305.1.2 Surface preparation – concrete 315.1.3 Surface preparation – reinforcement 315.1.4 Materials for patch repair 315.1.5 Cement-based materials 325.1.6 Polymer concrete 325.1.7 Polymer-modified cement systems 325.1.8 Polymer impregnation 335.1.9 Hydrophobic impregnation 335.1.10 Joint sealants 33

5.2 Protective coatings 335.2.1 Sealers 365.2.2 Anti-Carbonation Coatings 365.2.3 Renderings 36

5.3 Moisture Barrier Systems (Repair Principle W) 365.2.1 Materials and methods 37

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5.4 Coating on Steel Reinforcement (Repair Principle C) 375.4.1 Materials and methods 37

5.5 Cathodic Protection, Chloride Extraction and Re-alkalization (Repair Principle K) 375.5.1 Cathodic prevention 375.5.2 Cathodic Protection 385.5.3 Re-alkalisation 395.5.4 Chloride Extraction 40

5.6 New Methods 405.6.1 Externally bonded fibre-reinforced plastic (FRP) 405.6.2 Impregnating corrosion inhibitors 40

5.7 Acknowledgments 415.8 Further Reading 41

Chapter 6 – Repair Practices 43 6.1 Patch Repair Systems 44

6.1.1 Patch repair practice 446.1.2 Surface preparation – concrete 46 6.1.3 Finishing 50 6.1.4 Curing 506. 1.5 Preparation of reinforcing steel 506.1.6 Repair procedures 526. 1.7 Repair mortars 52

6.2 Moisture Barrier Systems 536.3 Protection by Coating Steel reinforcement 546.4 Electrochemical Systems 54

6.4.1 Application of a Cathodic Prevention (CP) system 546.4.2 Application of an electrochemical re-alkalization system 566.4.3 Application of a chloride extraction system 57

6.5 Crack Repair 586.5.1 Crack filling 586.5.2 Crack sealing 596.5.3 Other processes 60

6.6 Quality Assurance 606.6.1 Concrete patch repair 606.6.2 Post-repair degradation 61

6.7 Conclusion 626.8 Acknowledgment 626.9 Further Reading 62

6.9.1 Standards 62 Chapter 7 – Case Studies 637.1 High-rise Building 63

7.1.1 Investigation 63 7.1.2 Specification for repair 647.1.3 The repair 64

7.2 Marine Structure 64 7.2.1 Investigation 64 7.2.2 Specification for repair 657.2.3 The repair 65

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7.3 Highway Bridge 65 7.3.1 Investigation 66 7.3.2 Specification for repair 667.3.3 The repair 66

7.4 Commercial Complex 66 7.5 Apartment Building 687.6 Retaining Wall 69

7.6.1 Introduction 697.6.2 History 69 7.6.3 Inspection 69 7.6.4 Remedial options 707.6.5 The trials 717.6.6 Summary 72

Appendix A – Repair Strategies for Carbonation-induced Steel Corrosion 73

A.1 Repair Principle R 73A.2 Repair Principle W 74A.3 Repair Principle C 74A.4 Repair Principle K 74

Appendix B – Repair Strategies for Chloride-induced Steel Corrosion 75

B.1 Repair Principle R 75B.2 Repair Principle W 76B.3 Repair Principle C 76B.4 Repair Principle K 75 B.5 Re-alkalization and Chloride Extraction Techniques 76

Appendix C – Strategies for Crack Repair 77

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