Belay Zeleke Dilnesa - Eawag-Empa Library

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5. GENERAL CONCLUSION AND OUTLOOK at any conditions. Portlandite and Fe-hydroxide co-precipitated with the different AFm phases. Generally, the AFm phases form very slowly (over the course of a few years) at 20 °C from C2F, while at 50 °C the formation is faster. The structure of the stable Fe-containing AFm hydrates (Fe-monocarbonate, Fe- monosulfate, Fe-Friedel’s salt) were determined and refined using synchrotron powder diffraction data. Fe-monocarbonate, Fe-monosulfate and Fe-Friedel’s salt show a rhombohedral R3 c symmetry. The solubility products obtained at standard conditions (25 °C, 1 atm) for the Fe- containing AFm phases are generally 2 to 3 log units lower than those of the Al- containing AFm phases, comparable to the difference between Fe(OH)3 and gibbsite. logKs0 (Fe) log Ks0 (Al) Monosulfate -31.57 -29.26 Monocarbonate -34.59 -31.47 Hemicarbonate -30.83 -29.13 C4(A,F)H13 -30.64 -25.4 Friedel’s salt -28.62 -27.69 (Al,Fe)(OH)3 -4.1 -1.24 Notable exceptions are Fe-Friedel’s salt and Fe-hemicarbonate which have relatively high solubility products compared to the Al-phases, indicating that Fe-Friedel’s salt and Fe- hemicarbonate are most probably not stable in hydrated cements. Also the formation of hydrogarnets (Al-katoite (C3AH6), Fe-katoite (C3FH6), Al-siliceous hydrogarnet and Fe-siliceous hydrogarnet) was studied. C3AH6 was the stable phase in the CaO-Al2O3-H2O system in the absence of other ions, in all cases co-precipitation of traces of C4AH13 was observed. In contrast, C3FH6 was found to be metastable while C4FH13, portlandite, amorphous Fe-hydroxide and carbonate containing AFm phases 183
5. GENERAL CONCLUSION AND OUTLOOK formed. The investigation of Al- and Fe-siliceous hydrogarnet was complicated due to the formation of two hydrogarnets with different silica contents in both systems. In addition, C(-A)-S-H co-precipitated during the preparation of Al-containing siliceous- hydrogarnet. Al-containing siliceous hydrogarnet did not form at room temperatures but only at 110 °C. In contrast, stable but poorly crystalline Fe-siliceous hydrogarnet formed slowly at room temperature. At 110 °C the formation of two well crystalline Fe-siliceous hydrogarnet (C3FS0.95H4.1 and C3FS1.5H2.96) was observed both with the typical cubic crystal structure. The solubility products of Al and Fe-containing Si-hydrogarnets decreases strongly with increasing silica content indicating that a strong stabilisation. The solubility products obtained at standard conditions (25 °C, 1 atm) for the Fe-containing hydrogarnets were 5 to 7 log units lower than those of the Al-containing hydrogarnets. log Ks0 (Fe) log Ks0 (Al) C3(A,F)H6 -25.56 -20.56 C3AS0.41H5.18 C3AS0.84H4.32 C3FS0.95H4.1 -32.75 C3FS1.52H2.96 -34.68 -25.47 -26.70 The relatively low solubility products of the Fe-containing siliceous hydrogarnets compared to the Al-phases, together with the observation that Fe-siliceous hydrogarnets form at room temperature, indicates that Fe-containing siliceous hydrogarnets could be stable in hydrated cements. 184
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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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o layer thickness (A) 8.0 7.8 7.6 C
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Phase log KSo CHAPTER 3 SYNTHETIC F
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volume [cm 3 ] 700 600 500 400 300
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Intensity [arb. units] Fe-Fr CHAPTE
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Page 158 and 159: CHAPTER 3 SYNTHETIC FE-CONTAINING H
Page 172 and 173: CHAPTER 4 FE-CONTAINING HYDRATES IN
Page 182 and 183: (Al+Fe)/Ca (Al+Fe)/Ca 0.8 0.6 0.4 0
Page 188 and 189: k 3 (k) CHAPTER 4 FE-CONTAINING HYD
Page 200 and 201: differentiated relative weight Weig
Page 202 and 203: Early reaction CHAPTER 4 FE-CONTAIN
Page 204 and 205: weight loss in % differentiated rel
Page 210 and 211: Speciation of iron(III) in hydrated
Page 212 and 213: 5. GENERAL CONCLUSION AND OUTLOOK
Page 214 and 215: Techniques XRD X-ray diffraction TG
Page 216 and 217: APPENDIX APPENDIX Appendix A: Addit
Page 218 and 219: Intensity (arb. Units) P Fe 2O 3 R
Page 220 and 221: APPENDIX Appendix B7 XRD patterns o
Page 222 and 223: REFERENCES REFRENCES [1] H.F.W. Tay
Page 224 and 225: REFRENCES [29] M. Vespa, R. Dähn,
Page 226 and 227: REFRENCES [54] M. Balonis, B. Lothe
Page 228 and 229: REFRENCES [81] H.F.W. Taylor, Cryst
Page 230 and 231: REFRENCES [107] K. Kyritsis, N. Mel
Page 232 and 233: REFRENCES [134] M. Wilke, F. Farges
Page 235 and 236: CURRCULUM VITAE Curriculum Vitae Na
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