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CHAPTER 3 SYNTHETIC FE-CONTAINING HYDRATES Additionally, the solutions equilibrated at 50 °C and 80 °C were thermodynamically oversaturated with respect to Fe-hydroxide and hematite. The kinetics of formation of hematite, however, was very slow, so that the solid did not form at 20 °C or 50 °C within the experimental period. For both Al-Mc and Al-Hc, an increase in the solubility with increasing temperature was observed [52], while in contrast, for both Fe-Hc and Fe-Mc a slight decrease was observed suggesting a slight stabilization of Fe-Hc and Fe-Mc (Fig. 20). 3.1.5.2. Estimation of the solubility product under standard conditions The solubility products at standard conditions were calculated with the help of GEMS- PSI using temperature extrapolation from the solubility products calculated at 20 °C and 50 °C as previously demonstrated by Matschei et al. [7]. The calculated solubility products at 20 °C and 50 °C (Table 11 and Table 12) were used to develop the temperature-dependent ‘log K’ function which allowed the solubility products to be calculated at different temperatures (Fig. 20) as described in section 2.3. The entropy was adjusted until good agreement between measured and calculated solubility was reached. The thermodynamic properties of the solids at 25 °C are listed in Table 13. 59
Calc.solubility product log K sp -29 -30 -31 -32 -33 -34 -35 -36 CHAPTER 3 SYNTHETIC FE-CONTAINING HYDRATES Fe-Mc Fe-Hc -37 5.0 25.0 45.0 Temperature (°C) 65.0 85.0 Fig. 20. Calculated solubility products of Fe-Mc and Fe-Hc from the solubility experiments. Squares: experimental solubility product of Fe-Hc, Triangles: experimental solubility product of Fe-Mc. The solubility products of Fe-Mc (-34.59) and Fe-Hc (-30.83) are about 2-3 log units lower than those of Al-Mc (-31.47) and Al-Hc (-29.12), respectively. Note that a similar difference in the solubility products between Al- and Fe-monosulfate was found (see next section), while the solubility product of Fe-ettringite (-44.0) was found to be slightly higher than that of Al-ettringite (-44.9). This indicates that the Fe-AFm phases are potentially stable under conditions where Al-AFm can be formed while the formation of Fe-ettringite is less probable under conditions where Al-ettringite is stable. 60
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Fe-containing hydrates and their fa
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The measured composition of the liq
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ZUSAMMENFASSUNG Thermodynamische Mo
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konnten die Fe-haltigen Hydrate im
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I owe to thank all the laboratory t
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Table 19 Compositions of Al/Fe-mono
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LIST OF FIGURES Fig. 1 Calculated v
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Fig. 34 Calculated solubility produ
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Fig. 62 Calculated solubility produ
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Table of Contents TABLE OF CONTENTS
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TABLE OF CONTENTS 3. SYNTHETIC FE
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TABLE OF CONTENTS 3.5.4. Solid solu
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1 INTRODUCTION CHAPTER 1 INTRODUCTI
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CHAPTER 1 INTRODUCTION be formed. T
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cm 3 /100 g cement 85 80 75 70 65 6
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CHAPTER 1 INTRODUCTION 1.4 Characte
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CHAPTER 3 SYNTHETIC FE-CONTAINING H
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CHAPTER 4 FE-CONTAINING HYDRATES IN
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(Al+Fe)/Ca (Al+Fe)/Ca 0.8 0.6 0.4 0
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k 3 (k) CHAPTER 4 FE-CONTAINING HYD
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differentiated relative weight Weig
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Early reaction CHAPTER 4 FE-CONTAIN
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weight loss in % differentiated rel
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5. GENERAL CONCLUSION AND OUTLOOK a
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Speciation of iron(III) in hydrated
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5. GENERAL CONCLUSION AND OUTLOOK
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Techniques XRD X-ray diffraction TG
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APPENDIX APPENDIX Appendix A: Addit
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Intensity (arb. Units) P Fe 2O 3 R
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APPENDIX Appendix B7 XRD patterns o
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REFERENCES REFRENCES [1] H.F.W. Tay
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REFRENCES [29] M. Vespa, R. Dähn,
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REFRENCES [54] M. Balonis, B. Lothe
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REFRENCES [81] H.F.W. Taylor, Cryst
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REFRENCES [107] K. Kyritsis, N. Mel
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REFRENCES [134] M. Wilke, F. Farges
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CURRCULUM VITAE Curriculum Vitae Na
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