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CHAPTER 3 SYNTHETIC FE-CONTAINING HYDRATES hydroxide concentrations were lower (pH 11.6 to 11.9). In contrast, Fe-Friedel’s salt prepared from C2F, CaCl2.2H2O and CaO co-precipitated with portlandite and Fe- hydroxide at pH values from 12.4 to 12.8. The aqueous phase had lower concentrations of calcium and chloride. The calculated ion activity products for Fe(OH)3 were (10 -4 to 10 -3 ) unexpectedly high, which indicates that either the presence of chloride ions could result in a kinetic hindrance for Fe(OH)3 formation or alternatively mixed complexes between Fe 3+ , OH - and Cl - occur. Note that the latter complexes are not accounted for in the thermodynamic database (the known iron chloride complexes are rather weak and give no significant contribution at high pH values: FeCl 2+ , log K = 1.48, FeCl2 + , log K = 2.13, and FeCl3 0 , log K = 1.13 in GEMS-PSI TDB. A literature search gave no evidence for the existence of FeCl4 - or mixed hydroxide-chloride-iron(III) complexes). The solubility product of the solid was calculated according to: Ks0, Fe-Friedel’s salt = {Ca 2+ } 4 . {FeO2 - } 2 {Cl - } 2 {OH - } 4. {H2O} 8 The Ks0 values were calculated based on the measured concentrations of Ca, Fe, Cl and K and the activity coefficients obtained with GEMS. The pH values were adapted by varying the concentrations of KOH to the measured pH values. The solubility products of Fe-Friedel’s salt prepared at different pH values are presented in Table 22 and Table 23. 101
CHAPTER 3 SYNTHETIC FE-CONTAINING HYDRATES Table 22 Measured ion concentrations and calculated solubility products at 20 °C and sampled after different equilibration times synthesized from FeCl3.6H2O and CaO in 0.1M K OH. Age Ca K Fe Cl #pH +pH log Ks0 log Ks0 log Ks0 (days) [mmol/l] [mmol/l]l [mmol/l] [mmol/l] Fe-Fr Fe(OH)3 CH 7 162 93 0.0027 422 11.62 11.61 -28.40 -3.14 -6.55 28 161 98 0.0020 419 11.40 11.42 -29.45 -3.08 -6.94 180 146 87 0.0023 427 11.61 11.53 -29.04 -3.13 -6.76 270 144 88 0.0028 399 11.69 11.70 -28.23 -3.22 -6.41 1100 149 88 0.0059 410 11.94 11.88 -26.83 -3.07 -6.06 Average -28.39±0.50 -3.13±0.20 -6.55±0.30 Detection limits [mmol/l]: Al = 0.001 Ca = 0.0004, Fe = 0.0000006, K = 0.0024, S=0.0014, Si=0.0002, Cl=0.003 , measurement uncertainty ±10%, #pH measured at 20°C, + calculated pH by GEMS. Table 23 Measured ion concentrations and calculated solubility products at 20 and 50°C and sampled after different equilibration times synthesized from C2F, CaCl2.2H2O and CaO in distilled water and in 0.1 M KOH. Age Temp. Ca K Fe Cl #pH +pH log Ks0 log Ks0 log Ks0 (days) [°C] [mmol/l] [mmol/l] [mmol/l] [mmol/l] Fe-Fr Fe(OH)3 CH 180 20 35.0
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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 1 INTRODUCTION Fig. 4 Sampl
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CHAPTER 1 INTRODUCTION Identificat
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CHAPTER 2 MATERIALS AND METHODS han
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3CaOAl2O3 + 6H2O → 3CaOAl2O36H2O
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CHAPTER 2 MATERIALS AND METHODS Tab
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CHAPTER 2 MATERIALS AND METHODS 2.2
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CHAPTER 2 MATERIALS AND METHODS fil
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CHAPTER 2 MATERIALS AND METHODS at
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CHAPTER 2 MATERIALS AND METHODS the
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CHAPTER 2 MATERIALS AND METHODS 0 t
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CHAPTER 2 MATERIALS AND METHODS Tab
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CHAPTER 2 MATERIALS AND METHODS 2.3
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CHAPTER 2 MATERIALS AND METHODS The
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CHAPTER 3 SYNTHETIC FE-CONTAINING H
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a). b). CHAPTER 3 SYNTHETIC FE-CONT
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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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