Contents

Foreword ....................................................................................................

ix

Preface .......................................................................................................

xi

1. Introduction ........................................................................................

1

1.1

Historical Background .............................................................................

1

1.2

Scope of this Book ..................................................................................

3

1.3

Inspection and in Situ Testing of Structures ............................................

5

1.4

Petrographic Examination of Concrete ...................................................

7

2. Petrographic Examination Techniques ............................................

10

2.1

Introduction .............................................................................................

10

2.2

Initial Methods of Examination ................................................................

10

2.3

Low-Power Stereo Microscope ...............................................................

11

2.4

Universal Polarising Microscope .............................................................

12

2.4.1 Adjustment of the Polarising Transmitted Light Microscope ...........................................................................

21

2.4.2 Using the Microscope ...........................................................

22

2.4.3 Looking Down the Microscope ..............................................

23

Polarising Incident-Light Microscope ......................................................

24

2.5.1 Adjustment of the Polarising Incident-Light Microscope ...........................................................................

25

Analysis of Light Using the Polarising Microscope ..................................

26

2.6.1 Qualitative Compensators .....................................................

26

2.6.2 Quantitative Compensators ...................................................

27

2.6.3 The Wright Eyepiece .............................................................

28

2.6.4 The Universal and Spindle Stages ........................................

28

2.6.5 Filters ...................................................................................

28

2.5

2.6

This page has been reformatted by Knovel to provide easier navigation.

v

vi

Contents 2.7

Fluorescence Microscopy .......................................................................

29

2.8

Fourier Transform Infrared Microscopy (FT-IR) ......................................

31

2.9

Phase Contrast and Related Techniques ...............................................

31

2.10 Photography in Concrete Petrography ....................................................

31

2.10.1 Photomicrography .................................................................

33

2.10.2 Rules for Photomicrography ..................................................

34

2.10.3 Selection of Micrographs for Publication ................................

35

2.11 Quantitative Microscopy ..........................................................................

36

2.11.1 Modal Analysis .....................................................................

37

2.11.2 Alternative Methods of Counting ...........................................

38

2.11.3 Image Analysis .....................................................................

41

2.12 Examination of Particles ..........................................................................

42

2.12.1 Dispersion Staining ...............................................................

43

2.13 Examination of Thin-Sections .................................................................

43

2.13.1 Staining Minerals for Identification .........................................

44

2.14 Spectroscopic Methods of Identification ..................................................

44

2.15 Scanning Electron Microscopy ................................................................

46

2.15.1 Electron Probe Microanalysis ................................................

47

2.15.2 Specialised Scanning Electron Microscopes ..........................

47

2.16 Thermal Analysis .....................................................................................

47

2.17 Chemical Analysis of Cement .................................................................

48

2.17.1 Chemical Analysis of Blended Cements ................................

48

2.17.2 Chemical Analysis of Hardened Cement Paste in Concrete ...............................................................................

49

2.18 The Petrographer's Bookshelf .................................................................

51

Plates ................................................................................................................

P1

Plate 1 .............................................................................................

P1

Plate 2 .............................................................................................

P2

Plate 3 .............................................................................................

P3

Plate 4 .............................................................................................

P4

Plate 5 .............................................................................................

P5a

Plate 6 .............................................................................................

P6

Plate 7 .............................................................................................

P7

Plate 8 .............................................................................................

P8

This page has been reformatted by Knovel to provide easier navigation.

Contents

vii

Plate 9 .............................................................................................

P9

Plate 10 ...........................................................................................

P10

Plate 11 ...........................................................................................

P11

Plate 12 ...........................................................................................

P12

Plate 13 ...........................................................................................

P13

Plate 14 ...........................................................................................

P14a

Plate 15 ...........................................................................................

P15a

Plate 16 ...........................................................................................

P16

Plate 17 ...........................................................................................

P17

Plate 18 ...........................................................................................

P18a

Plate 19 ...........................................................................................

P19

Plate 20 ...........................................................................................

P20

3. Sampling and Specimen Preparation ...............................................

53

3.1

Sampling Problems .................................................................................

53

3.2

Inspection of Structures ..........................................................................

55

3.2.1 The Surface Expression of Concrete Deterioration ................

56

3.3

Specimen Selection and Investigative Objectives ...................................

57

3.4

Particulate Materials ................................................................................

57

3.4.1 Preparation of Particulate Samples for Examination ..............

60

Sampling Concrete ..................................................................................

62

3.5.1 Bulk Sampling .......................................................................

62

3.5.2 Sampling Methods ................................................................

64

3.5.3 Subsampling .........................................................................

65

Preparation of Finely Ground and Polished Surfaces .............................

69

3.6.1 Laboratory Methods of Cutting Concrete ...............................

70

3.6.2 Preparation of Ground Surfaces ............................................

71

3.6.3 Preparation of Polished Surfaces ..........................................

73

3.7

Preparation of Petrographic Thin-Sections .............................................

74

3.8

Specimen Preparation for Special Purposes ..........................................

77

3.8.1 The Powdered Specimen ......................................................

77

3.8.2 Small Selected Samples .......................................................

78

Preparation Involving Dyes, Stains and Etches ......................................

79

3.9.1 Dyes for Resins ....................................................................

79

3.5

3.6

3.9

This page has been reformatted by Knovel to provide easier navigation.

viii

Contents 3.9.2 Staining Procedures ..............................................................

81

3.9.3 Etching Procedures for Cement Clinkers ...............................

81

4. Composition of Concrete ..................................................................

83

4.1

Scope ......................................................................................................

83

4.2

Cement Types .........................................................................................

83

4.2.1 Anhydrous Portland Cement Phases and Clinker ..................

83

4.2.2 Identification of Cement Type in Concrete .............................

88

4.2.3 Hydrated Cement Phases .....................................................

94

4.2.4 Blended and Special Cements ..............................................

106

4.2.5 Building Lime and Cement/Lime Mixtures ..............................

119

Aggregate Types and Characteristics .....................................................

123

4.3.1 Petrographic Identity of Aggregate ........................................

123

4.3.2 Particle Size and Aggregate Size Grading .............................

129

4.3.3 Particle Shape ......................................................................

135

4.3.4 Other Particle Characteristics ................................................

137

Water/Cement Ratio ................................................................................

139

4.4.1 Definitions and Relationship to Concrete Properties ..............

139

4.4.2 Indicators of Water/Cement Ratio ..........................................

141

4.4.3 Determination of Water/Cement Ratio by the PhysicoChemical Method ..................................................................

145

4.4.4 Determination of Water/Cement Ratio by Fluorescence Microscopy ...........................................................................

146

Air-Void Content and Air-Entrainment .....................................................

150

4.5.1 Types of Voids in Concrete ...................................................

150

4.5.2 Quantification of Air- Void Content in Hardened Concrete ...............................................................................

157

4.5.3 Microscopical Measurement of the Air- Void System .............

160

Mineral Additions and Pigments ..............................................................

166

4.6.1 Fly Ash and Pulverised-Fuel Ash ...........................................

166

4.6.2 Blastfurnace Slag Materials ...................................................

170

4.6.3 Microsilica (Condensed Silica Fume) .....................................

176

4.6.4 Natural Pozzolanas and Other Reactive Additions .................

178

4.6.5 Pigments ..............................................................................

179

4.3

4.4

4.5

4.6

This page has been reformatted by Knovel to provide easier navigation.

Contents

ix

4.7

Chemical Admixtures ..............................................................................

182

4.8

Modal Analysis of Concrete ....................................................................

183

Plates ................................................................................................................

P21a

Plate 21 ...........................................................................................

P21a

Plate 22 ...........................................................................................

P22a

Plate 23 ...........................................................................................

P23a

Plate 24 ...........................................................................................

P24a

Plate 25 ...........................................................................................

P25a

Plate 26 ...........................................................................................

P26a

Plate 27 ...........................................................................................

P27a

Plate 28 ...........................................................................................

P28a

Plate 29 ...........................................................................................

P29a

Plate 30 ...........................................................................................

P30a

Plate 31 ...........................................................................................

P31a

Plate 32 ...........................................................................................

P32a

Plate 33 ...........................................................................................

P33a

Plate 34 ...........................................................................................

P34a

Plate 35 ...........................................................................................

P35a

Plate 36 ...........................................................................................

P36a

Plate 37 ...........................................................................................

P37a

Plate 38 ...........................................................................................

P38a

Plate 39 ...........................................................................................

P39a

Plate 40 ...........................................................................................

P40a

Plate 41 ...........................................................................................

P41a

Plate 42 ...........................................................................................

P42a

Plate 43 ...........................................................................................

P43a

Plate 44 ...........................................................................................

P44a

Plate 45 ...........................................................................................

P45a

Plate 46 ...........................................................................................

P46a

Plate 47 ...........................................................................................

P47a

This page has been reformatted by Knovel to provide easier navigation.

x

Contents

5. The Appearance and Textures of Concrete .....................................

186

5.1

Introduction .............................................................................................

186

5.2

Hardened Cement Paste .........................................................................

187

5.2.1 Typical Composition of a Hardened Cement Paste ................

188

5.2.2 Remnant or Oversized Grains of Cement Clinker ..................

188

5.2.3 Information from Remnant and Partially Hydrated Grains of Cement ..................................................................

190

5.2.4 The Colour of Hardened Cement Paste .................................

191

5.2.5 Ettringite ...............................................................................

192

5.2.6 High-Alumina Cement ...........................................................

193

5.2.7 Portland Limestone Cement ..................................................

193

5.2.8 Portland Pozzolana Cements ................................................

194

5.2.9 Information from Thin-Sections Containing Pozzolanas ...........................................................................

199

5.2.10 Portland Blastfurnace Slag Cements .....................................

199

5.2.11 The Microscopical Examination of Blastfurnace Slags ...........

202

Calcium Hydroxide ..................................................................................

202

5.3.1 The Occurrence of Calcium Hydroxide in Hardened Cement Paste .......................................................................

203

5.3.2 The Effects of Curing, Leaching and Reaction on Calcium Hydroxide ................................................................

204

5.3.3 Effect of Temperature on Calcium Hydroxide ........................

204

5.3.4 Effect of Calcium Hydroxide on Strength ...............................

205

5.3.5 Information from the Observation of Calcium Hydroxide in Concrete ...........................................................................

205

Carbonation .............................................................................................

205

5.4.1 Effect of Carbonation on Porosity and Strength .....................

208

5.4.2 Typical Textures of Carbonation ............................................

208

5.4.3 Carbonation of the Outer Layers of Concrete ........................

209

5.4.4 Carbonation Associated with Crack Systems .........................

209

5.4.5 Carbonation Associated with Lightweight Aggregates ............

210

5.4.6 Carbonation Associated with Limestone Aggregates .............

212

5.4.7 Carbonation Shrinkage .........................................................

212

5.4.8 Carbonation Curing of Concrete Products .............................

212

5.3

5.4

This page has been reformatted by Knovel to provide easier navigation.

Contents

5.5

5.6

5.7

5.8

xi

5.4.9 Well-Crystallised Carbonation ...............................................

212

5.4.10 Carbonation and the Ph of Hardened Cement Paste .............

213

5.4.11 Information from Observation of Carbonation in Concrete Thin-Section ..........................................................

214

Surface Layer of Concrete ......................................................................

214

5.5.1 Observation of the Visible Surface ........................................

214

5.5.2 Microscopical Appearance of a Weathered Concrete Surface .................................................................................

215

5.5.3 Efflorescences and Exudations .............................................

215

5.5.4 Discoloration Due to Efflorescence ........................................

217

5.5.5 Corroded and Abraded Surfaces ...........................................

218

Interfaces ................................................................................................

218

5.6.1 Nature of the Aggregateicement Paste Interface ...................

219

5.6.2 Cement Paste Surrounding Aggregates in ThinSection .................................................................................

220

5.6.3 Cement Paste to Steel Reinforcing Interfaces .......................

221

5.6.4 Cement Paste/Fibre Reinforcing Interfaces ...........................

221

5.6.5 Effect of Mineral Additions and Curing on Interfaces ..............

221

5.6.6 Render Interfaces .................................................................

222

5.6.7 Other Interfaces ....................................................................

223

5.6.8 Observation of Interfaces with the Light Microscope ..............

223

Void Space in Concrete ..........................................................................

223

5.7.1 Entrapped Air Voids ..............................................................

224

5.7.2 Entrained Air Void Systems ...................................................

226

5.7.3 Capillary Voids ......................................................................

226

5.7.4 Other Voidage in Concrete ....................................................

226

5.7.5 Aerated and No Fines Concretes ..........................................

228

5.7.6 Information from Microscopic Observation of Void Space in Concrete ................................................................

229

Cracking in Concrete ...............................................................................

229

5.8.1 Cracking and Tensile Strain ..................................................

229

5.8.2 Differentiating Between Structural and Non-Structural Cracking ...............................................................................

230

5.8.3 Classification of Non-Structural Cracking ...............................

231

This page has been reformatted by Knovel to provide easier navigation.

xii

Contents 5.8.4 Cracking in Thin-Section, at the Surface, and the Interior of a Concrete ............................................................

231

5.8.5 Microscopic Attributes of Cracks, Channels, Fissures and Voids .............................................................................

243

5.8.6 Dimensions of Cracks and Infillings in Thin-Section ...............

244

5.8.7 Cracking as an Artefact of Sampling and Specimen Preparation ...........................................................................

245

5.8.8 Interpretation of Crack Systems Observed in ThinSection .................................................................................

246

Plates ................................................................................................................

P48a

Plate 48 ...........................................................................................

P48a

Plate 49 ...........................................................................................

P49a

Plate 50 ...........................................................................................

P50a

Plate 51 ...........................................................................................

P51a

Plate 52 ...........................................................................................

P52a

Plate 53 ...........................................................................................

P53a

Plate 54 ...........................................................................................

P54a

Plate 55 ...........................................................................................

P55a

Plate 56 ...........................................................................................

P56

Plate 57 ...........................................................................................

P57a

Plate 58 ...........................................................................................

P58a

Plate 59 ...........................................................................................

P59a

Plate 60 ...........................................................................................

P60a

Plate 61 ...........................................................................................

P61a

Plate 62 ...........................................................................................

P62a

Plate 63 ...........................................................................................

P63a

Plate 64 ...........................................................................................

P64a

Plate 65 ...........................................................................................

P65a

Plate 66 ...........................................................................................

P66a

Plate 67 ...........................................................................................

P67a

Plate 68 ...........................................................................................

P68a

Plate 69 ...........................................................................................

P69a

Plate 70 ...........................................................................................

P70a

Plate 71 ...........................................................................................

P71

This page has been reformatted by Knovel to provide easier navigation.

Contents 6. Examination of Deteriorated and Damaged Concrete ....................

xiii 247

6.1

Introduction .............................................................................................

247

6.2

Sulfate Attack ..........................................................................................

250

6.2.1 Ground Water Sulfates ..........................................................

251

6.2.2 Salt and Sea Water Attack ....................................................

259

6.2.3 Internal Sulfate Attack ...........................................................

261

6.2.4 Sulfate Attack in Sewage Systems ........................................

265

6.3

Frost and Freeze-Thaw Damage ............................................................

268

6.4

Acid and Alkaline Attack on Concrete .....................................................

270

6.4.1 Natural Acidic Waters and the Calcium - Bicarbonate Carbon Dioxide Equilibria ......................................................

271

6.4.2 Carbonation and Corrosion by Geothermal Fluids .................

275

6.4.3 Acid Type Attack from Sulfates, Iron Sulfides, Brine Solutions and Microbial Action ..............................................

279

6.4.4 Industrial Chemical Attack on Concrete .................................

279

Corrosion of Steel Reinforcement ...........................................................

283

6.5.1 Steel Corrosion Mechanisms .................................................

284

6.5.2 Carbonation and Corrosion of Reinforcement ........................

285

6.5.3 Chlorides and Corrosion of Reinforcement ............................

285

Plastic and Drying Shrinkage ..................................................................

286

6.6.1 Macroscopic Effects of Plastic and Drying Shrinkage ............

286

6.6.2 Petrographic Examination of Shrinkage Cracking ..................

287

6.6.3 Shrinkage of Aggregates in Concrete ....................................

288

Alkali-Aggregate Reaction (AAR) ............................................................

289

6.7.1 The Chemistry of Alkali-Silica Reactions ...............................

290

6.7.2 External Appearance of Concrete Affected by AlkaliSilica Reaction ......................................................................

292

6.7.3 Microscopic Textures of Alkali-Silica Reaction in Concrete ...............................................................................

294

6.7.4 Internal Texture of Cracking in Concrete Affected by Alkali-Silica Reaction ............................................................

295

6.7.5 Microscopic Texture of Alkali-Silica Gel in Concrete Affected by Alkali-Silica Reaction ..........................................

295

6.5

6.6

6.7

This page has been reformatted by Knovel to provide easier navigation.

xiv

Contents 6.7.6 Types of Reactive Minerals and Their Microscopic Identification .........................................................................

297

6.7.7 Texture of Reacting Aggregates ............................................

299

6.7.8 Reaction of Lightweight Concretes ........................................

299

6.7.9 The Interpretation of the Textures of Alkali-Silica Reaction ...............................................................................

301

6.7.10 Examination of Concretes Suspected of Alkali-Silica Reaction ...............................................................................

302

6.7.11 Other Factors to Be Considered ............................................

302

6.7.12 The Alkali-Carbonate Reaction ..............................................

305

6.7.13 Petrographic Texture of Concretes Containing Expansive Argillaceous Dolomitic Limestones .......................

306

6.7.14 Supplementary Tests ............................................................

308

6.7.15 Petrographic Textures of the Alkali-Carbonate Reaction ...............................................................................

308

Fire-Damaged Concrete ..........................................................................

308

6.8.1 Thermal Expansion of Concrete ............................................

309

6.8.2 Mineralogical Changes on Heating ........................................

310

6.8.3 Visual Effects of Fire Damage ...............................................

310

6.8.4 Petrographic Study of Fire-Damaged Concrete .....................

312

6.8.5 Optical Petrographic Examination .........................................

312

6.8.6 Other Methods of Examination of Fire-Damaged Concrete ...............................................................................

316

General Aspects of Deterioration and Weathering ..................................

316

Plates ................................................................................................................

P72a

Plate 72 ...........................................................................................

P72a

Plate 73 ...........................................................................................

P73a

Plate 74 ...........................................................................................

P74a

Plate 75 ...........................................................................................

P75a

Plate 76 ...........................................................................................

P76a

Plate 77 ...........................................................................................

P77a

Plate 78 ...........................................................................................

P78a

Plate 79 ...........................................................................................

P79a

Plate 80 ...........................................................................................

P80

6.8

6.9

This page has been reformatted by Knovel to provide easier navigation.

Contents

xv

Plate 81 ...........................................................................................

P81

Plate 82 ...........................................................................................

P82a

Plate 83 ...........................................................................................

P83a

Plate 84 ...........................................................................................

P84a

Plate 85 ...........................................................................................

P85

Plate 86 ...........................................................................................

P86a

Plate 87 ...........................................................................................

P87

Plate 88 ...........................................................................................

P88

Plate 89 ...........................................................................................

P89a

7. Concrete Products and Miscellaneous Materials ............................

318

7.1

Introduction .............................................................................................

318

7.2

Examination of Laboratory Specimens ...................................................

319

7.3

Fibre-Reinforced Products ......................................................................

319

7.3.1 Asbestos-Cement Products ...................................................

320

7.3.2 Synthetic-Fibre Reinforced Products .....................................

322

7.3.3 Natural-Fibre Reinforced Products ........................................

323

Concrete Pipe, Block, Brick, Tile and Pavers ..........................................

324

7.4.1 Concrete Pipes .....................................................................

324

7.4.2 Concrete Block, Brick, Tile and Pavers ..................................

327

Plaster, Mortar and Grout Based on Portland Cement ...........................

330

7.5.1 Plaster ..................................................................................

331

7.5.2 Sprayed Concrete .................................................................

332

7.5.3 Grout ....................................................................................

334

Floor Finishes ..........................................................................................

335

7.6.1 Floor Screeds .......................................................................

336

7.6.2 Terrazzo ...............................................................................

336

7.6.3 Tiled Finishes .......................................................................

339

7.6.4 Polymer Floor Coatings .........................................................

339

Lime Materials and Products ...................................................................

340

7.7.1 Limestone and Lime ..............................................................

340

7.7.2 Lime Plaster and Mortar ........................................................

342

7.7.3 Calcium Silicate Products .....................................................

345

7.4

7.5

7.6

7.7

This page has been reformatted by Knovel to provide easier navigation.

xvi

Contents 7.8

Gypsum, Hemihydrate and Anhydrite .....................................................

347

7.8.1 The Petrography of Faults in Products Made from Hemihydrate and Anhydrite ...................................................

350

7.8.2 Gypsum Plaster Finishes ......................................................

351

Lightweight Aggregates and Concretes ..................................................

351

Glossary of Minerals ................................................................................

355

Introduction .......................................................................................................

355

Cement Minerals ..............................................................................................

357

The Calcium Silicate Hydrates .........................................................................

361

The Sulfate Minerals .........................................................................................

366

Asbestos and Other Fibrous Materials .............................................................

372

Glass ................................................................................................................

373

The Silica Minerals and Mineraloids .................................................................

376

Carbonates and Related Calcium Minerals ......................................................

380

Aluminium Minerals ..........................................................................................

383

Grinding and Polishing Compounds .................................................................

384

Pigments and Colorants ...................................................................................

386

Magnesium Oxychloride Cement Hydrates (Sorel Cement) .............................

388

Appendix 1 Recent Descriptions of Attack by Chemicals on Concrete ..............................................................................

390

Appendix 2 Micrometric Determination of Mix Proportions ................

406

References ................................................................................................

410

A-H ...................................................................................................................

410

I-Z .....................................................................................................................

432

Index ..........................................................................................................

456

7.9

This page has been reformatted by Knovel to provide easier navigation.