Foreword... Preface Introduction Petrographic Examination Techniques... 10

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1 Contents Foreword... Preface... ix xi 1. Introduction Historical Background Scope of this Book Inspection and in Situ Testing of Structures Petrographic Examination of Concrete Petrographic Examination Techniques Introduction Initial Methods of Examination Low-Power Stereo Microscope Universal Polarising Microscope Adjustment of the Polarising Transmitted Light Microscope Using the Microscope Looking Down the Microscope Polarising Incident-Light Microscope Adjustment of the Polarising Incident-Light Microscope Analysis of Light Using the Polarising Microscope Qualitative Compensators Quantitative Compensators The Wright Eyepiece The Universal and Spindle Stages Filters v

2 vi Contents 2.7 Fluorescence Microscopy Fourier Transform Infrared Microscopy (FT-IR) Phase Contrast and Related Techniques Photography in Concrete Petrography Photomicrography Rules for Photomicrography Selection of Micrographs for Publication Quantitative Microscopy Modal Analysis Alternative Methods of Counting Image Analysis Examination of Particles Dispersion Staining Examination of Thin-Sections Staining Minerals for Identification Spectroscopic Methods of Identification Scanning Electron Microscopy Electron Probe Microanalysis Specialised Scanning Electron Microscopes Thermal Analysis Chemical Analysis of Cement Chemical Analysis of Blended Cements Chemical Analysis of Hardened Cement Paste in Concrete The Petrographer's Bookshelf 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

3 Contents vii Plate 9... P9 Plate P10 Plate P11 Plate P12 Plate P13 Plate P14a Plate P15a Plate P16 Plate P17 Plate P18a Plate P19 Plate P20 3. Sampling and Specimen Preparation Sampling Problems Inspection of Structures The Surface Expression of Concrete Deterioration Specimen Selection and Investigative Objectives Particulate Materials Preparation of Particulate Samples for Examination Sampling Concrete Bulk Sampling Sampling Methods Subsampling Preparation of Finely Ground and Polished Surfaces Laboratory Methods of Cutting Concrete Preparation of Ground Surfaces Preparation of Polished Surfaces Preparation of Petrographic Thin-Sections Specimen Preparation for Special Purposes The Powdered Specimen Small Selected Samples Preparation Involving Dyes, Stains and Etches Dyes for Resins... 79

4 viii Contents Staining Procedures Etching Procedures for Cement Clinkers Composition of Concrete Scope Cement Types Anhydrous Portland Cement Phases and Clinker Identification of Cement Type in Concrete Hydrated Cement Phases Blended and Special Cements Building Lime and Cement/Lime Mixtures Aggregate Types and Characteristics Petrographic Identity of Aggregate Particle Size and Aggregate Size Grading Particle Shape Other Particle Characteristics Water/Cement Ratio Definitions and Relationship to Concrete Properties Indicators of Water/Cement Ratio Determination of Water/Cement Ratio by the Physico- Chemical Method Determination of Water/Cement Ratio by Fluorescence Microscopy Air-Void Content and Air-Entrainment Types of Voids in Concrete Quantification of Air- Void Content in Hardened Concrete Microscopical Measurement of the Air- Void System Mineral Additions and Pigments Fly Ash and Pulverised-Fuel Ash Blastfurnace Slag Materials Microsilica (Condensed Silica Fume) Natural Pozzolanas and Other Reactive Additions Pigments

5 Contents ix 4.7 Chemical Admixtures Modal Analysis of Concrete Plates... P21a Plate P21a Plate P22a Plate P23a Plate P24a Plate P25a Plate P26a Plate P27a Plate P28a Plate P29a Plate P30a Plate P31a Plate P32a Plate P33a Plate P34a Plate P35a Plate P36a Plate P37a Plate P38a Plate P39a Plate P40a Plate P41a Plate P42a Plate P43a Plate P44a Plate P45a Plate P46a Plate P47a

6 x Contents 5. The Appearance and Textures of Concrete Introduction Hardened Cement Paste Typical Composition of a Hardened Cement Paste Remnant or Oversized Grains of Cement Clinker Information from Remnant and Partially Hydrated Grains of Cement The Colour of Hardened Cement Paste Ettringite High-Alumina Cement Portland Limestone Cement Portland Pozzolana Cements Information from Thin-Sections Containing Pozzolanas Portland Blastfurnace Slag Cements The Microscopical Examination of Blastfurnace Slags Calcium Hydroxide The Occurrence of Calcium Hydroxide in Hardened Cement Paste The Effects of Curing, Leaching and Reaction on Calcium Hydroxide Effect of Temperature on Calcium Hydroxide Effect of Calcium Hydroxide on Strength Information from the Observation of Calcium Hydroxide in Concrete Carbonation Effect of Carbonation on Porosity and Strength Typical Textures of Carbonation Carbonation of the Outer Layers of Concrete Carbonation Associated with Crack Systems Carbonation Associated with Lightweight Aggregates Carbonation Associated with Limestone Aggregates Carbonation Shrinkage Carbonation Curing of Concrete Products

7 Contents xi Well-Crystallised Carbonation Carbonation and the Ph of Hardened Cement Paste Information from Observation of Carbonation in Concrete Thin-Section Surface Layer of Concrete Observation of the Visible Surface Microscopical Appearance of a Weathered Concrete Surface Efflorescences and Exudations Discoloration Due to Efflorescence Corroded and Abraded Surfaces Interfaces Nature of the Aggregateicement Paste Interface Cement Paste Surrounding Aggregates in Thin- Section Cement Paste to Steel Reinforcing Interfaces Cement Paste/Fibre Reinforcing Interfaces Effect of Mineral Additions and Curing on Interfaces Render Interfaces Other Interfaces Observation of Interfaces with the Light Microscope Void Space in Concrete Entrapped Air Voids Entrained Air Void Systems Capillary Voids Other Voidage in Concrete Aerated and No Fines Concretes Information from Microscopic Observation of Void Space in Concrete Cracking in Concrete Cracking and Tensile Strain Differentiating Between Structural and Non-Structural Cracking Classification of Non-Structural Cracking

8 xii Contents Cracking in Thin-Section, at the Surface, and the Interior of a Concrete Microscopic Attributes of Cracks, Channels, Fissures and Voids Dimensions of Cracks and Infillings in Thin-Section Cracking as an Artefact of Sampling and Specimen Preparation Interpretation of Crack Systems Observed in Thin- Section Plates... P48a Plate P48a Plate P49a Plate P50a Plate P51a Plate P52a Plate P53a Plate P54a Plate P55a Plate P56 Plate P57a Plate P58a Plate P59a Plate P60a Plate P61a Plate P62a Plate P63a Plate P64a Plate P65a Plate P66a Plate P67a Plate P68a Plate P69a Plate P70a Plate P71

9 Contents xiii 6. Examination of Deteriorated and Damaged Concrete Introduction Sulfate Attack Ground Water Sulfates Salt and Sea Water Attack Internal Sulfate Attack Sulfate Attack in Sewage Systems Frost and Freeze-Thaw Damage Acid and Alkaline Attack on Concrete Natural Acidic Waters and the Calcium - Bicarbonate - Carbon Dioxide Equilibria Carbonation and Corrosion by Geothermal Fluids Acid Type Attack from Sulfates, Iron Sulfides, Brine Solutions and Microbial Action Industrial Chemical Attack on Concrete Corrosion of Steel Reinforcement Steel Corrosion Mechanisms Carbonation and Corrosion of Reinforcement Chlorides and Corrosion of Reinforcement Plastic and Drying Shrinkage Macroscopic Effects of Plastic and Drying Shrinkage Petrographic Examination of Shrinkage Cracking Shrinkage of Aggregates in Concrete Alkali-Aggregate Reaction (AAR) The Chemistry of Alkali-Silica Reactions External Appearance of Concrete Affected by Alkali- Silica Reaction Microscopic Textures of Alkali-Silica Reaction in Concrete Internal Texture of Cracking in Concrete Affected by Alkali-Silica Reaction Microscopic Texture of Alkali-Silica Gel in Concrete Affected by Alkali-Silica Reaction

10 xiv Contents Types of Reactive Minerals and Their Microscopic Identification Texture of Reacting Aggregates Reaction of Lightweight Concretes The Interpretation of the Textures of Alkali-Silica Reaction Examination of Concretes Suspected of Alkali-Silica Reaction Other Factors to Be Considered The Alkali-Carbonate Reaction Petrographic Texture of Concretes Containing Expansive Argillaceous Dolomitic Limestones Supplementary Tests Petrographic Textures of the Alkali-Carbonate Reaction Fire-Damaged Concrete Thermal Expansion of Concrete Mineralogical Changes on Heating Visual Effects of Fire Damage Petrographic Study of Fire-Damaged Concrete Optical Petrographic Examination Other Methods of Examination of Fire-Damaged Concrete General Aspects of Deterioration and Weathering Plates... P72a Plate P72a Plate P73a Plate P74a Plate P75a Plate P76a Plate P77a Plate P78a Plate P79a Plate P80

11 Contents xv Plate P81 Plate P82a Plate P83a Plate P84a Plate P85 Plate P86a Plate P87 Plate P88 Plate P89a 7. Concrete Products and Miscellaneous Materials Introduction Examination of Laboratory Specimens Fibre-Reinforced Products Asbestos-Cement Products Synthetic-Fibre Reinforced Products Natural-Fibre Reinforced Products Concrete Pipe, Block, Brick, Tile and Pavers Concrete Pipes Concrete Block, Brick, Tile and Pavers Plaster, Mortar and Grout Based on Portland Cement Plaster Sprayed Concrete Grout Floor Finishes Floor Screeds Terrazzo Tiled Finishes Polymer Floor Coatings Lime Materials and Products Limestone and Lime Lime Plaster and Mortar Calcium Silicate Products

12 xvi Contents 7.8 Gypsum, Hemihydrate and Anhydrite The Petrography of Faults in Products Made from Hemihydrate and Anhydrite Gypsum Plaster Finishes Lightweight Aggregates and Concretes Glossary of Minerals Introduction Cement Minerals The Calcium Silicate Hydrates The Sulfate Minerals Asbestos and Other Fibrous Materials Glass The Silica Minerals and Mineraloids Carbonates and Related Calcium Minerals Aluminium Minerals Grinding and Polishing Compounds Pigments and Colorants Magnesium Oxychloride Cement Hydrates (Sorel Cement) Appendix 1 Recent Descriptions of Attack by Chemicals on Concrete Appendix 2 Micrometric Determination of Mix Proportions References A-H I-Z Index