Science and Technology of Concrete Admixtures

1st Edition - October 11, 2015
Editors: Pierre-Claude Aïtcin, Robert J Flatt
Language: English
Hardback ISBN:
9 7 8 - 0 - 0 8 - 1 0 0 6 9 3 - 1
eBook ISBN:
9 7 8 - 0 - 0 8 - 1 0 0 6 9 6 - 2

Science and Technology of Concrete Admixtures presents admixtures from both a theoretical and practical point-of-view. The authors emphasize key concepts that can be used to be… Read more

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Science and Technology of Concrete Admixtures presents admixtures from both a theoretical and practical point-of-view. The authors emphasize key concepts that can be used to better understand the working mechanisms of these products by presenting a concise overview on the fundamental behavior of Portland cement and hydraulic binders as well as their chemical admixtures, also discussing recent effects in concrete in terms of rheology, mechanics, durability, and sustainability, but never forgetting the fundamental role played by the water/binder ratio and proper curing in concrete technology.

Part One presents basic knowledge on Portland cement and concrete, while Part Two deals with the chemical and physical background needed to better understand what admixtures are chemically, and through which mechanism they modify the properties of the fresh and hardened concrete. Subsequent sections present discussions on admixtures technology and two particular types of concrete, self-consolidating and ultra-high strength concretes, with final remarks on their future.

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About the contributors
Woodhead Publishing Series in Civil and Structural Engineering
Preface
Acknowledgments
Introduction
Terminology and definitions
Glossary
Historical background of the development of concrete admixtures
Part One. Theoretical background on Portland cementand concrete
- 1. The importance of the water–cement and water–binder ratios
  - 1.1. Introduction
  - 1.2. The hidden meaning of the w/c
  - 1.3. The water–cement and water–binder ratios in a cement paste made with a blended cement
  - 1.4. How to lower the w/c and w/b ratios
  - 1.5. Conclusion
- 2. Phenomenology of cement hydration
  - 2.1. Introduction
  - 2.2. Le Chatelier's experiment
  - 2.3. Powers' work on hydration
  - 2.4. Curing low w/c ratio concretes
  - 2.5. Conclusion
- 3. Portland cement
  - 3.1. Introduction
  - 3.2. The mineral composition of Portland cement clinker
  - 3.3. The fabrication of clinker
  - 3.4. Chemical composition of Portland cement
  - 3.5. The grinding of Portland cement
  - 3.6. The hydration of Portland cement
  - 3.7. Hydrated lime (portlandite)
  - 3.8. Present acceptance standards for cements
  - 3.9. Side-effects of hydration reaction
  - 3.10. Conclusion
  - Appendices
- 4. Supplementary cementitious materials and blended cements
  - 4.1. Introduction
  - 4.2. Crystallized and vitreous state
  - 4.3. Blast-furnace slag
  - 4.4. Fly ashes
  - 4.5. Silica fume
  - 4.6. Calcined clays
  - 4.7. Natural pozzolans
  - 4.8. Other supplementary cementitious materials
  - 4.9. Fillers
  - 4.10. Ground glass
  - 4.11. Blended cements
  - 4.12. Conclusion
- 5. Water and its role on concrete performance
  - 5.1. Introduction
  - 5.2. The crucial role of water in concrete
  - 5.3. Influence of water on concrete rheology
  - 5.4. Water and cement hydration
  - 5.5. Water and shrinkage
  - 5.6. Water and alkali/aggregate reaction
  - 5.7. Use of some special waters
  - 5.8. Conclusion
- 6. Entrained air in concrete: Rheology and freezing resistance
  - 6.1. Introduction
  - 6.2. Entrapped air and entrained air
  - 6.3. Beneficial effects of entrained air
  - 6.4. Effect of pumping on the air content and spacing factor
  - 6.5. Entraining air in blended cements
  - 6.6. Conclusion
- 7. Concrete rheology: A basis for understanding chemical admixtures
  - 7.1. Introduction
  - 7.2. Definition of rheology
  - 7.3. Different rheological behaviours
  - 7.4. Micromechanical behaviour of suspensions
  - 7.5. Factors affecting concrete rheology
  - 7.6. Thixotropy of concrete
  - 7.7. Conclusions
  - Terminology and definitions
- 8. Mechanisms of cement hydration
  - 8.1. Introduction
  - 8.2. Hydration of C3A
  - 8.3. Hydration of alite
  - 8.4. Hydration of ordinary Portland cement
  - 8.5. Conclusions
Part Two. Chemistry and working mechanisms
- 9. Chemistry of chemical admixtures
  - 9.1. Introduction
  - 9.2. Water reducers and superplasticizers
  - 9.3. Retarders
  - 9.4. Viscosity-modifying admixtures
  - 9.5. Air-entraining admixtures
  - 9.6. Shrinkage-reducing admixtures
  - 9.7. Conclusions
- 10. Adsorption of chemical admixtures
  - 10.1. Introduction
  - 10.2. Adsorption and fluidity
  - 10.3. Adsorption isotherms
  - 10.4. Molecular structure and adsorption
  - 10.5. Dynamic exchanges between surface and solution
  - 10.6. Consumption (ineffective adsorption)
  - 10.7. Surfactant adsorption at the liquid–vapor interface
  - 10.8. Experimental issues in measuring adsorption
  - 10.9. Conclusions
- 11. Working mechanisms of water reducers and superplasticizers
  - 11.1. Introduction
  - 11.2. Dispersion forces
  - 11.3. Electrostatic forces
  - 11.4. DLVO theory
  - 11.5. Steric forces
  - 11.6. Effect of superplasticizers
  - 11.7. Conclusions
- 12. Impact of chemical admixtures on cement hydration
  - 12.1. Introduction
  - 12.2. Mechanisms of retardation
  - 12.3. Retardation by superplasticizers
  - 12.4. Retardation by sugars
  - 12.5. Conclusions
- 13. Working mechanisms of shrinkage-reducing admixtures
  - 13.1. Introduction
  - 13.2. Basic principles of the shrinkage of cementitious systems
  - 13.3. Impact of SRAs on drying shrinkage
  - 13.4. Dosage response of SRA on drying shrinkage
  - 13.5. Conclusions
- 14. Corrosion inhibitors for reinforced concrete
  - 14.1. Introduction
  - 14.2. Corrosion mechanisms of reinforcing steel in concrete
  - 14.3. Corrosion inhibitors for steel in concrete
  - 14.4. Critical evaluation of corrosion inhibitors
  - 14.5. Concluding remarks
Part Three. The technology of admixtures
- 15. Formulation of commercial products
  - 15.1. Introduction
  - 15.2. Performance targets
  - 15.3. Cost issues
  - 15.4. Conclusions
- Section One. Admixtures that modify at the same time the properties of the fresh and hardened concrete
  - 16. Superplasticizers in practice
    - 16.1. Introduction
    - 16.2. Application perspective on superplasticizers and their use
    - 16.3. Impact of superplasticizers on rheology
    - 16.4. Unexpected or undesired behaviors
    - 16.5. Conclusions
  - 17. Air entraining agents
    - 17.1. Introduction
    - 17.2. Mechanisms of air entrainment
    - 17.3. Principal characteristics of a bubble network
    - 17.4. Production of a bubble network
    - 17.5. Stability of the network of entrained bubbles
    - 17.6. Conclusion
- Section Two. Admixtures that modify essentially the properties of the fresh concrete
  - 18. Retarders
    - 18.1. Introduction
    - 18.2. Cooling concrete to retard its setting
    - 18.3. The use of retarders
    - 18.4. Addition time
    - 18.5. Some case history of undue retardations
    - 18.6. Conclusion
  - 19. Accelerators
    - 19.1. Introduction
    - 19.2. Different means to accelerate concrete hardening
    - 19.3. Different types of accelerators
    - 19.4. Calcium chloride as an accelerator
    - 19.5. Shotcrete accelerators
    - 19.6. Conclusions
  - 20. Working mechanism of viscosity-modifying admixtures
    - 20.1. Introduction
    - 20.2. Performance of VMAs
    - 20.3. Working mechanisms of water retention agents
    - 20.4. Influence of polymeric VMAs on hydration of cement
    - 20.5. Use of VMAs in SCC formulation
    - 20.6. Conclusions
  - 21. Antifreezing admixtures
    - 21.1. Introduction
    - 21.2. Winter concreting in North America
    - 21.3. Antifreeze admixtures
    - 21.4. The construction of high-voltage power lines in the Canadian North
    - 21.5. The use of calcium nitrite in Nanisivik
    - 21.6. Conclusion
- Section Three. Admixtures that modify essentially the properties of the hardened concrete
  - 22. Expansive agents
    - 22.1. Introduction
    - 22.2. Principle
    - 22.3. Expansion mechanisms
    - 22.4. Measurement of free and restrained expansion
    - 22.5. Factors affecting the expansion
    - 22.6. Field applications of concretes containing expansive agents
    - 22.7. Conclusion
  - 23. Shrinkage-reducing admixtures
    - 23.1. Introduction
    - 23.2. Principal molecules used as shrinkage-reducing admixtures
    - 23.3. Typical dosages
    - 23.4. Laboratory studies on the use of shrinkage-reducing admixtures
    - 23.5. Field applications
    - 23.6. Conclusion
  - 24. Corrosion inhibition
    - 24.1. Introduction
    - 24.2. The effect of chloride ions on reinforcing steel bars
    - 24.3. Increasing the protection of steel reinforcement against corrosion
    - 24.4. Mitigating steel corrosion
    - 24.5. Eliminating steel corrosion
    - 24.6. Conclusion
- Section Four. Admixtures used to water cure concrete
  - 25. Curing compounds
    - 25.1. Introduction
    - 25.2. Curing concrete according to its w/c
    - 25.3. Specifying the curing of a concrete with a w/c greater than the critical value of 0.42
    - 25.4. Specifying the curing of concretes having a w/c lower than the critical value of 0.42
    - 25.5. Enforcing adequate curing practices in the field
    - 25.6. Conclusion
Part Four. Special concretes
- 26. Self-consolidating concrete
  - 26.1. Introduction
  - 26.2. SCC formulation
  - 26.3. Quality control
  - 26.4. Fresh properties
  - 26.5. Hardened properties
  - 26.6. Case studies
  - 26.7. Selling SCC to contractors
  - 26.8. Conclusion
- 27. Ultra high strength concrete
  - 27.1. Introduction
  - 27.2. Ultra high strength concrete concept
  - 27.3. How to make a UHSC
  - 27.4. Construction of the Sherbrooke pedestrian bikeway
  - 27.5. Testing the structural behaviour of the structure
  - 27.6. Long-term behaviour
  - 27.7. Some recent applications of UHSC
  - 27.8. Conclusion
Part Five. The future of admixtures
- 28. Conclusions and outlook on the future of concrete admixtures
  - 28.1. Chemical admixtures are to concrete, what spices are to cooking
  - 28.2. Of good and bad concrete
  - 28.3. Environmental challenges
  - 28.4. The science of chemical admixtures
Appendix 1. Useful formulae and some applications
Appendix 2. Experimental statistical design
Appendix 3. Statistical evaluation of concrete quality
Index

Pierre-Claude Aïtcin

Pierre-Claude Aïtcin is professor emeritus in the Department of Civil Engineering of the Faculty of Engineering at the Université de Sherbrooke, Quebec, Canada. He is the author of:

- High Performance concrete published by E and FN SPON. This book has been translated in French, Spanish, Portuguese and Czech.

- Binders for Durable and Sustainable Concrete published by Taylor and Francis.

- In collaboration with Sidney Mindess he wrote Sustainability of Concrete published by Taylor and Francis. This book has been published in French by Eyrolles under the title Ecostructures en béton- Comment diminuer l’empreinte carbone des structures en béton.

Affiliations and expertise

Professor Emeritus, Dept. of Civil Engineering, Faculty of Engineering, Université de Sherbrooke, Quebec, Canada

Robert J Flatt

Robert J. Flatt is Professor of Building Materials at ETHZ. Before that he was Principal Scientist at Sika Technology AG and postdoctoral researcher at the Princeton University. He owns a master in Chemical Engineering and a PhD from EPFL. His main research interest deals with the working mechanisms of chemical admixtures, an area in which his publications are very well cited and in which he has received several awards. These include the RILEM Robert L’Hermite Medal, the Ross C. Purdy and the Brunauer awards from the American Ceramic Society, the best short presentation at the 13th International Conference on Cement Chemistry, as well an Outstanding Research Contribution in the Broad Area of Chemical Admixtures presented at the 10th International Conference on Superplasticizers and Other Chemical Admixtures.

He was also nominated two years in a row among the 5 finalists for the Spark award recognizing the best invention of the year at ETH Zürich (each time among more than 100 filed patents covering all subjects). He also was awarded the best paper award in two of the four categories at the 1st International conference on concrete innovation in 2014.

Affiliations and expertise

Professor of Building Materials, ETH Zürich, Switzerland

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