Science and technology of concrete admixtures / edited by Pierre-Claude Aïtcin and Robert J. Flatt. Amsterdam [etc.], cop

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1 Science and technology of concrete admixtures / edited by Pierre-Claude Aïtcin and Robert J. Flatt. Amsterdam [etc.], cop Spis treści About the contributors Woodhead Publishing Series in Civil and Structural Engineering Preface Acknowledgments Introduction Terminology and definitions Glossary xiii xv xix xxiii xxv xxxi xxxvii Historical background of the development of concrete admixtures xli Part One Theoretical background on Portland cement and concrete 1 1 The importance of the water-cement and water-binder ratios Introduction The hidden meaning of the w/c The water-cement and water-binder ratios in a cement paste made with a blended cement How to lower the w/c and w/b ratios Conclusion 12 References 13 2 Phenomenology of cement hydration Introduction Le Chatelier's experiment Powers' work on hydration Curing low w/c ratio concretes Conclusion 24 References 24 3 Portland cement 27

2 3.1 Introduction The mineral composition of Portland cement clinker The fabrication of clinker Chemical composition of Portland cement The grinding of Portland cement The hydration of Portland cement Hydrated lime (portlandite) Present acceptance standards for cements Side-effects of hydration reaction Conclusion 45 Appendices 45 References 50 4 Supplementary cementitious materials and blended cements Introduction Crystallized and vitreous state Blast-furnace slag Fly ashes Silica fume Calcined clays Natural pozzolans Other supplementary cementitious materials Fillers Ground glass Blended cements Conclusion 72 References 72 5 Water and its role on concrete performance Introduction The crucial role of water in concrete Influence of water on concrete rheology Water and cement hydration Water and shrinkage Water and alkali/aggregate reaction Use of some special waters Conclusion 84 References 85 6 Entrained air in concrete: rheology and freezing resistance Introduction Entrapped air and entrained air Beneficial effects of entrained air Effect of pumping on the air content and spacing factor 93

3 6.5 Entraining air in blended cements Conclusion 94 References 94 7 Concrete rheology: a basis for understanding chemical admixtures 97 A. Yahia, S. Mantellato, R.J. Flatt 7.1 Introduction Definition of rheology Different rheological behaviours Micromechanical behaviour of suspensions Factors affecting concrete rheology Thixotropy of concrete Conclusions 120 Terminology and definitions 121 Acknowledgements 122 References Mechanisms of cement hydration 129 D. Marchon, R.J. Flatt 8.1 Introduction Hydration of C 3 A Hydration of alite Hydration of ordinary Portland cement Conclusions 141 Acknowledgments 141 References 141 Part Two Chemistry and working mechanisms Chemistry of chemical admixtures 149 G. Gelardi, S. Mantellato, D. Marchon, M. Palacios, A.B. Eberhardt, R.J. Flatt 9.1 Introduction Water reducers and superplasticizers Retarders Viscosity-modifying admixtures Air-entraining admixtures Shrinkage-reducing admixtures Conclusions 207 Acknowledgements 207 References Adsorption of chemical admixtures 219 D. Marchon, S. Mantellato, A.B. Eberhardt, R.J. Flatt 10.1 Introduction Adsorption and fluidity 220

4 10.3 Adsorption isotherms Molecular structure and adsorption Dynamic exchanges between surface and solution Consumption (ineffective adsorption) Surfactant adsorption at the liquid-vapor interface Experimental issues in measuring adsorption Conclusions 248 Acknowledgments 248 References Working mechanisms of water reducers and superplasticizers 257 G. Gelardi, R.J. Flatt 11.1 Introduction Dispersion forces Electrostatic forces DLVO theory Steric forces Effect of superplasticizers Conclusions 275 Acknowledgements 275 References Impact of chemical admixtures on cement hydration 279 D. Marchon, R.J. Flatt 12.1 Introduction Mechanisms of retardation Retardation by superplasticizers Retardation by sugars Conclusions 299 Acknowledgment 299 References Working mechanisms of shrinkage-reducing admixtures 305 A. B. Eberhardt, R.J. Flatt 13.1 Introduction Basic principles of the shrinkage of cementitious systems Impact of SRAs on drying shrinkage Dosage response of SRA on drying shrinkage Conclusions 318 References Corrosion inhibitors for reinforced concrete 321 B. Elsener, U. Angst 14.1 Introduction Corrosion mechanisms of reinforcing steel in concrete Corrosion inhibitors for steel in concrete Critical evaluation of corrosion inhibitors 334

5 14.5 Concluding remarks 335 References 336 Part Three The technology of admixtures Formulation of commercial products 343 S. Mantellato, A.B. Eberhardt, R.J. Flatt 15.1 Introduction Performance targets Cost issues Conclusions 347 Acknowledgments 347 References 347 Section One Admixtures that modify at the same time the properties of the fresh and hardened concrete Superplasticizers in practice 353 P.-C. Nkinamubanzi, S. Mantellato, R.J. Flatt 16.1 Introduction Application perspective on superplasticizers and their use Impact of superplasticizers on rheology Unexpected or undesired behaviors Conclusions 371 Acknowledgments 372 References Air entraining agents 379 R. Gagné 17.1 Introduction Mechanisms of air entrainment Principal characteristics of a bubble network Production of a bubble network Stability of the network of entrained bubbles Conclusion 390 References 390 Section Two Admixtures that modify essentially the properties of the fresh concrete Retarders Introduction Cooling concrete to retard its setting The use of retarders Addition time Some case history of undue retardations 400

6 18.6 Conclusion 404 References Accelerators Introduction Different means to accelerate concrete hardening Different types of accelerators Calcium chloride as an accelerator Shotcrete accelerators Conclusions 412 References Working mechanism of viscosity-modifying admixtures 415 M. Palacios, R.J. Flatt 20.1 Introduction Performance of VMAs Working mechanisms of water retention agents Influence of polymeric VMAs on hydration of cement Use of VMAs in SCC formulation Conclusions 430 Acknowledgments 430 References Antifreezing admixtures Introduction Winter concreting in North America Antifreeze admixtures The construction of high-voltage power lines in the Canadian North The use of calcium nitrite in Nanisivik Conclusion 438 References 438 Section Three Admixtures that modify essentially the properties of the hardened concrete Expansive agents 441 R. Gagné 22.1 Introduction Principle Expansion mechanisms Measurement of free and restrained expansion Factors affecting the expansion Field applications of concretes containing expansive agents Conclusion 454 References 455

7 23 Shrinkage-reducing admixtures 457 R. Gagné 23.1 Introduction Principal molecules used as shrinkage-reducing admixtures Typical dosages Laboratory studies on the use of shrinkage-reducing admixtures Field applications Conclusion 468 References Corrosion inhibition Introduction The effect of chloride ions on reinforcing steel bars Increasing the protection of steel reinforcement against corrosion Mitigating steel corrosion Eliminating steel corrosion Conclusion 478 References 479 Section Four Admixtures used to water cure concrete Curing compounds Introduction Curing concrete according to its w/c Specifying the curing of a concrete with a w/c greater than the critical value of Specifying the curing of concretes having a w/c lower than the critical value of Enforcing adequate curing practices in the field Conclusion 486 References 487 Part Four Special concretes Self-consolidating concrete 491 A. Yahia, 26.1 Introduction SCC formulation Quality control Fresh properties Hardened properties Case studies Selling SCC to contractors Conclusion 501

8 References Ultra high strength concrete Introduction Ultra high strength concrete concept How to make a UHSC Construction of the Sherbrooke pedestrian bikeway Testing the structural behaviour of the structure Long-term behaviour Some recent applications of UHSC Conclusion 522 References 523 Part Five The future of admixtures Conclusions and outlook on the future of concrete admixtures 527 R.J. Flatt 28.1 Chemical admixtures are to concrete, what spices are to cooking Of good and bad concrete Environmental challenges The science of chemical admixtures 529 References 530 Appendix 1: Useful formulae and some applications 531 Appendix 2: Experimental statistical design 549 Appendix 3: Statistical evaluation of concrete quality 565 Index 585 oprac. BPK