Alkali-Aggregate Reaction and Structural Damage to Concrete

Engineering Assessment, Repair and Management

Geoffrey E. Blight, Mark G Alexander

• Publisher: CRC Press
• Year: 2011
• Topic: Technology & Engineering
• eBook ISBN:
  9781040162804
• Subtopic: Civil Engineering
• Index: Technology & Engineering

Since AAR was first identified in 1940, it has been a subject dominated by studies of the mineralogy of AAR-susceptible aggregates, the chemistry of the AAR and related reactions and laboratory tests used to diagnose AAR and predict potential future swelling. Civil and structural engineers have found the literature bewildering and difficult to appl

Table of contents

• Cover
• Halftitle Page
• Title Page
• Copyright Page
• Contents
• Author
• Acknowledgements
• Symbols
• 1 Alkali-aggregate reaction (AAR) and its effects on concrete – an overview
• 1.1 AAR and its visible characteristics
• 1.2 The chemical characteristics of AAR
• 1.3 Guarding against AAR
• 1.4 Main types of AAR and the appearance of fractures caused by AAR
• 1.4.1 Alkali-silica reaction (ASR)
• 1.4.2 Alkali-silicate reaction
• 1.4.3 Alkali-carbonate rock reaction (ACR)
• 1.5 Chemical mechanisms of AAR
• 1.6 Necessary and sufficient requirements for AAR to occur
• 1.6.1 Alkalis
• 1.6.2 Reactive silica
• 1.6.3 The environment and moisture
• 1.7 What is still to come
• References
• Plates
• 2 Diagnostic investigations and tests and their interpretation
• 2.1 Investigation of the cause of cracking in a concrete structure
• 2.1.1 Planning the site inspection
• 2.1.2 Observations on the structure
• 2.1.3 Preliminary assessment of the site inspection
• 2.1.4 Sampling of concrete
• 2.2 Petrology of AAR-susceptible mineral and rock types
• 2.2.1 Mineral constituents
• 2.2.2 The alkali-silica reaction
• 2.3 Assessing aggregates for AAR-potential
• 2.3.1 Initial screening tests
• 2.3.2 Indicator tests
• 2.3.3 Performance tests
• 2.3.4 RILEM technical committee contributions
• 2.3.5 Drawing conclusions from tests for AAR-susceptibility
• 2.4 Aggregate petrography
• 2.4.1 Petrographic composition and examination of aggregates
• 2.4.2 Analysis techniques
• 2.4.3 Assessing residual ultimate expansion of concrete in structures
• References
• Plates
• 3 Effects of AAR on engineering properties of concrete – results of laboratory determinations
• 3.1 Laboratory specimens and cores taken from structures
• 3.2 The process of cracking
• 3.3 Differences between laboratory specimens and cores taken from AAR-affected structures
• 3.4 The testing of cores and laboratory-prepared cylinders or prisms
• 3.4.1 Stresses in a cylinder subject to compression between rigid platens
• 3.4.2 Load-controlled and strain-controlled testing
• 3.4.3 Measuring the elastic modulus and Poisson’s ratio for concrete in compression
• 3.4.4 Measuring the direct tensile strength
• 3.4.5 Measuring the indirect or splitting tensile strength
• 3.5 The strength of disrupted or disintegrated concrete
• 3.6 Elastic properties, compressive, indirect and direct tensile strengths of AAR-affected concrete
• 3.7 Creep of AAR-damaged concrete under sustained load
• 3.8 The effects on expansion of compressive stress
• 3.8.1 Restraint on expansion imposed by reinforcing
• 3.8.2 Restraint on expansion imposed by adjacent structures or structural elements
• 3.9 Fracturing of reinforcing steel in AAR-affected structures
• 3.10 The possibility of bond failure in AAR-affected reinforced concrete structures
• 3.11 Review and summary of conclusions
• References
• Plates
• 4 Assessment of risk of structural failure based on the results of laboratory or field tests
• 4.1 Introduction, definitions and examples
• 4.2 An acceptable probability of failure
• PART 1 Statistical considerations
• 4.3 Statistical calculation of the probability of failure
• 4.4 Assessing demand D and capacity C
• 4.4.1 Assessing the demand D
• 4.4.2 Assessing the capacity C
• 4.5 A simple example of calculating pf
• 4.6 Conclusions on statistical assessment of risk
• PART 2 Full-scale test loading
• 4.7 Full-scale test loading as a means of assessing risk
• 4.8 Instruments used for measurements in laboratory and in situ load testing
• 4.8.1 Determining principal and shear strains
• 4.8.2 Mechanical methods for measuring deflection and strain
• 4.8.3 Electrical methods for measuring deflection and strain
• 4.8.4 Measuring temperature
• 4.8.5 Measuring rotation or change of slope
• 4.8.6 Recent developments for in situ measurement of displacement, rotation and strain in structures
• 4.8.7 Testing by ultra-sonic pulse velocity (UPV)
• 4.9 Planning, preparing and performing an in situ load test on a structure
• 4.9.1 The history of the structure
• 4.9.2 Objectives, extent of testing and preliminary information-gathering
• 4.9.3 Detailed planning – choice of date and time, lighting and access
• 4.9.4 Loading system, stages of loading, predicted and actual movements and strains
• 4.9.5 Briefing the testing team
• 4.10 “Special” or “once or twice off” test loadings of complete structures
• 4.10.1 Motorway double-cantilever structures: (northern cold-temperate coastal climate)
• 4.10.2 Motorway portal frame (southern warm-temperate, water deficient continental climate)
• 4.10.3 Motorway bridge (northern cold-temperate climate)
• 4.10.4 Unreinforced concrete road pavement (southern mediterranean-type temperate climate)
• 4.10.5 Underground mass concrete plug
• 4.10.6 Industrial structural pavement
• 4.11 Routine periodic test loading of complete structures
• 4.11.1 Loading jetty over sea (southern moist tropical coastal climate)
• 4.11.2 Bridges on highway (north temperate climate)
• 4.12 Tests on relatively small components removed from site and tested in laboratory
• 4.12.1 Prestressed concrete railway sleepers (southern temperate semi-desert climate)
• 4.12.2 Beams sawn from flat slab bridges (northern cold-temperate climate)
• 4.12.3 Prestressed planks taken from road bridge (southern warm-temperate climate)
• 4.13 Review and conclusions
• References
• Plates
• 5 Repair and rehabilitation of AAR-affected structures
• 5.1 Types of repair or remedial treatment
• 5.2 Arresting the AAR process – experiments with surface treatments
• 5.2.1 Experiments in Iceland (cold climate) and France (cool temperate climate)
• 5.2.2 Laboratory experiments in South Africa (warm temperate, water-deficient continental climate)
• 5.2.3 Field experiments in South Africa
• 5.2.4 Additional observations and conclusions
• 5.2.5 Treatment of structures with lithium compounds
• 5.3 Restoring design properties by resin-injection
• 5.3.1 General consideration of crack injection as a method of repair
• 5.3.2 Repair of sports stadium
• 5.4 Repair by externally applied stressing
• 5.4.1 Repair of cantilever projection supporting beam spans on either side
• 5.4.2 Repair of knee of reinforced concrete portal frame
• 5.4.3 Principle of increasing resistance to vertical stress by increasing horizontal stress
• 5.4.4 Strengthening column by means of stressed precast concrete encasement
• 5.5 Strengthening by glued-on steel plates
• 5.5.1 Experiments on external plating to strengthen concrete structures
• 5.6 Repair by partial demolition and reconstruction
• 5.6.1 Partial demolition and rebuilding of bridge piers
• 5.6.2 Refurbishing a bridge underpass
• 5.6.3 Partial demolition and rebuilding of highway structure
• 5.7 Repair and rehabilitation of concrete highway pavement
• 5.8 Repair or mitigation of effects of AAR in large mass concrete structures
• 5.8.1 Use of slot-cutting to relieve distress in hydroelectric power machinery
• 5.8.2 Effects of AAR on movements of arch dams
• 5.8.3 Slot-cutting for relief of swelling stress
• 5.9 Repair of broken reinforcement in AAR-damaged concrete
• 5.10 Review and conclusions
• 5.10.1 Arresting AAR
• 5.10.2 Repair by resin injection
• 5.10.3 Repair by externally applied stressing
• 5.10.4 Repair by external reinforcing
• 5.10.5 Partial demolition and reconstruction
• 5.10.6 Repair and rehabilitation of concrete pavements
• 5.10.7 Alleviation of AAR effects in mass concrete structures
• 5.10.8 Broken reinforcement
• 5.10.9 Repair and ongoing maintenance
• References
• Plates
• 6 Epilogue – A check-list of important structural consequences of AAR
• 6.1 AAR is a durability problem that is unlikely to cause structural failure
• 6.2 AAR results in the deterioration of concrete properties
• 6.3 In situ concrete properties can usually be expected to be considerably better than properties measured on cores in a laboratory
• 6.4 Compression members are relatively unaffected by AAR
• 6.5 Flexural members need more consideration
• 6.6 The performance of structural concrete pavements
• 6.7 Compressive stresses in AAR-affected concrete
• 6.8 AAR-damaged structures can reach and exceed their design service life with minimal repair and preventive maintenance
• Subject index