HB 84-2006 Guide to Concrete Repair and Protection

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HB 84—2006

HB


Guide to

CONCRETE REPAIR AND PROTECTION

Guide to Concrete Repair and Protection


A Joint publication of ACRA, CSIRO and Standards Australia.

Originated as HB84-1996 2nd Edition 2006 ISBN 0 7337 7831 3

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

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


Standards Australia develops Australian Standards® and other documents of public benefit and national interest. These standards are developed through an open process of consultation and consensus, in which all interested parties are invited to participate. Through a Memorandum of Understanding with the Commonwealth Government, Standards Australia is recognised as Australia’s peak non-government national standards body. Standards Australia also supports excellence in design and innovation through the Australian Design Awards. For further information visit www.standards.org.au 286 Sussex Street, Sydney, NSW, 2000 GPO Box 476, Sydney, NSW, 2001 Telephone: +61 2 8206 6000 Email: [email protected] Website: www.standards.org.au

AUSTRALIAN CONCRETE REPAIR ASSOCIATION LTD ABN 41 059 791 374


Level 6, 504 Pacific Highway St Leonards NSW 2065 (Locked Bag 2011, St Leonards NSW 1590) Tel: 61 2 9903 7733 Fax: 61 2 9437 9703 Email: [email protected] Website: www.acrassoc.com.au

The Australian Concrete Repair Association (ACRA) was incorporated in 1991 with the aim of providing a forum to promote excellence in all spheres of concrete repair and protection work. The Association is fundamental to the ongoing nationwide development of a professional industry whose key objectives include providing the highest levels of expertise, experience, training and quality. ACRA demands a continuing commitment from its members to maintaining the quality standards it has set for the concrete repair industry. Through its membership base, which includes manufacturers, specialist contractors, consultants and owners, ACRA provides stakeholders with confidence in the remedial concrete repair process. This insistence on quality and best practise underpins the increasing penetration of ACRA into the concrete repair market. ACRA has established a scheme of awards for excellence in concrete repair which are open to Corporate Members of the Association. These awards, which have been run every two years since 1998, showcase the work of the member companies. The role ACRA plays in the industry is clearly demonstrated in the levels of excellence on display in all entries and the winning projects in particular. ACRA is firmly committed to ongoing training of its members in the very latest developments in both the technology and practical application of concrete repair and protection. Maintaining up-to-date levels of knowledge and expertise is vital to providing clients with the level of professional service expected of an ACRA member. As such ACRA is extremely grateful to its fellow collaborators in the production of this document, The Guide to Concrete Repair and Protection.

CSIRO AUSTRALIA CSIRO


THE COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION

The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is Australia’s national science agency and one of the largest and most diverse scientific research organisations in the world. CSIRO has more than 6500 staff carrying out research 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 supports the building, construction and engineering industries with research, consulting and testing. 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, and water systems and products.

CSIRO Manufacturing and Infrastructure Technology Telephone: International: Fax: Email: Web:

1300 363 400 +61 3 9545 2176 +61 3 9545 2175 [email protected] www.cmit.csiro.au



PREFACE The original 1996 edition of this document was originally prepared by Dr Kwesi Sagoe-Crentsil from the CSIRO division of Manufacturing and Infrastructure Technology at the request of the Australian Concrete Repair Association (ACRA), who also provided the technical, editorial and funding input. The document is intended for widespread use by anyone engaged in the maintenance, repair and production of concrete structures. However, this document is intended as an overview of the typical methods and practices in the industry but it should not be used as a standard or as part of any contract relating to the repair of concrete. In preparing this document, one of the fundamental aims has been to provide a publication that can be read and understood by a diverse group of persons, ranging from professionals engaged in specifying or carrying out repairs to concrete structures, to those involved in the management of buildings and structures. The guidance in this document has been specifically influenced by RILEM Technical Recommendation 124-SRC, Guide to Repair Strategies for Concrete Structures Damaged by Reinforcement Corrosion, 1993. Previously available publications on investigatory and repair technologies for concrete are of overseas origin. The development and support of this document by ACRA underlines its belief that 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 the advances and more wide-spread use of electrochemical prevention and protection systems.

Contact: CSIRO Manufacturing and Infrastructure Technology Telephone: International: Fax: Email: Web:

1300 363 400 +61 3 9545 2176 +61 3 9545 2175 [email protected] www.cmit.csiro.au

i


NOTES

ii


CONTENTS Preface

i

Chapter 1 – Concrete Properties

1

1.1 1.2

Concrete Material Properties 1.2.1 Concrete quality 1.2.2 Porosity 1.2.3 Curing 1.2.4 Durability 1.2.5 Concrete properties and rebar corrosion

1 2 2 3 4 4 5

1.3

Acknowledgments

5

1.4

Further Reading 1.4.1 Standards

5 5

Chapter 2 – Causes of Concrete Deterioration 2.1

2.2

2.3 2.4 2.5 2.6

Internal Factors 2.1.1 Alkali-silica (alkali-aggregate) reaction 2.1.2 Other reactions Extemal Factors 2.2.1 Sulfate attack 2.2.2 Carbonation 2.2.3 Effect of chlorides Steel Reinforcement Corrosion Summary Acknowledgments Further Reading 2.6.1 Standards

7 7 8 8 8 9 9 9 11 13 14 14 14

Chapter 3 – Formation and Types of Cracks

15

3.1

16 17 17 18 18 18 20 20

3.2 3.3 3.4 3.5 3.6

Cracking of Plastic Concrete 3.1.1 Plastic shrinkage cracks 3.1.2 Plastic settlement cracks Cracking of Hardened Concrete Other Types of Cracks Impact of Cracks on Steel Reinforcement Corrosion Acknowledgments Further Reading

iii

Chapter 4 – Inspection Techniques

21

4.1 4.2 4.3

22 23 23 23 24 24 24 24 24 25 25 25 25 26 26 26 26 27 27 27 27 27 28 28 28 28 28


4.4

4.5

4.6 4.7 4.8

Condition Survey Visual Inspection Sampling and Testing 4.3.1 Lump Samples 4.3.2 Core Samples 4.3.3 Dust Samples In Situ Testing 4.4.1 Delamination/Drummy Surveys 4.4.2 Rebound Hammer 4.4.3 Crack Width Measure 4.4.4 Reinforcement Depth/Location 4.4.5 Depth of Carbonation 4.4.6 Half-cell Potential Mapping 4.4.7 Concrete Resistivity 4.4.8 Ultrasonic Pulse Velocity (UPV) Measurements 4.4.9 Pull-Out Test 4.4.10 Corrosion Rate Measurement 4.4.11 Ground-Penetrating Radar (GPR) 4.4.12 Gamma Radiography 4.4.13 Infra-Red Thermography Laboratory Testing 4.5.1 Petrographic Tests 4.5.2 Chloride Profiles 4.5.3 Elastic Modulus Structural Integrity Summary Further Reading

Chapter 5 – Protective and Remedial Systems

29

5.1

30 30 31 31 31 32 32 32 33 33 33 33 36 36 36 36 37

5.2

5.3

iv

Patch Repair Systems (Repair Principle R) 5.1.1 Concrete removal 5.1.2 Surface preparation – concrete 5.1.3 Surface preparation – reinforcement 5.1.4 Materials for patch repair 5.1.5 Cement-based materials 5.1.6 Polymer concrete 5.1.7 Polymer-modified cement systems 5.1.8 Polymer impregnation 5.1.9 Hydrophobic impregnation 5.1.10 Joint sealants Protective coatings 5.2.1 Sealers 5.2.2 Anti-Carbonation Coatings 5.2.3 Renderings Moisture Barrier Systems (Repair Principle W) 5.2.1 Materials and methods

5.4 5.5

5.6


5.7 5.8

Coating on Steel Reinforcement (Repair Principle C) 5.4.1 Materials and methods Cathodic Protection, Chloride Extraction and Re-alkalization (Repair Principle K) 5.5.1 Cathodic prevention 5.5.2 Cathodic Protection 5.5.3 Re-alkalisation 5.5.4 Chloride Extraction New Methods 5.6.1 Externally bonded fibre-reinforced plastic (FRP) 5.6.2 Impregnating corrosion inhibitors Acknowledgments Further Reading

37 37 37 37 38 39 40 40 40 40 41 41

Chapter 6 – Repair Practices

43

6.1

44 44 46 50 50 50 52 52 53 54 54 54 56 57 58 58 59 60 60 60 61 62 62 62 62

6.2 6.3 6.4

6.5

6.6

6.7 6.8 6.9

Patch Repair Systems 6.1.1 Patch repair practice 6.1.2 Surface preparation – concrete 6.1.3 Finishing 6.1.4 Curing 6. 1.5 Preparation of reinforcing steel 6.1.6 Repair procedures 6. 1.7 Repair mortars Moisture Barrier Systems Protection by Coating Steel reinforcement Electrochemical Systems 6.4.1 Application of a Cathodic Prevention (CP) system 6.4.2 Application of an electrochemical re-alkalization system 6.4.3 Application of a chloride extraction system Crack Repair 6.5.1 Crack filling 6.5.2 Crack sealing 6.5.3 Other processes Quality Assurance 6.6.1 Concrete patch repair 6.6.2 Post-repair degradation Conclusion Acknowledgment Further Reading 6.9.1 Standards

Chapter 7 – Case Studies

63

7.1

63 63 64 64 64 64 65 65

7.2

High-rise Building 7.1.1 Investigation 7.1.2 Specification for repair 7.1.3 The repair Marine Structure 7.2.1 Investigation 7.2.2 Specification for repair 7.2.3 The repair

v

7.3


7.4 7.5 7.6

Highway Bridge 7.3.1 Investigation 7.3.2 Specification for repair 7.3.3 The repair Commercial Complex Apartment Building Retaining Wall 7.6.1 Introduction 7.6.2 History 7.6.3 Inspection 7.6.4 Remedial options 7.6.5 The trials 7.6.6 Summary

65 66 66 66 66 68 69 69 69 69 70 71 72

Appendix A – Repair Strategies for Carbonation-induced Steel Corrosion

73

A.1 A.2 A.3 A.4

73 74 74 74

Repair Principle R Repair Principle W Repair Principle C Repair Principle K

Appendix B – Repair Strategies for Chloride-induced Steel Corrosion

75

B.1 B.2 B.3 B.4 B.5

75 76 76 75 76

Repair Principle R Repair Principle W Repair Principle C Repair Principle K Re-alkalization and Chloride Extraction Techniques

Appendix C – Strategies for Crack Repair

vi

77

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HB 84-2006, Guide to Concrete Repair and Protection

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HB 84-2006 Guide to Concrete Repair and Protection

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