Belay Zeleke Dilnesa - Eawag-Empa Library

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CHAPTER 3 SYNTHETIC FE-CONTAINING HYDRATES 3.5.3. Fe-katoite, C3FH6 C3FH6 was attempted to synthesize at 20, 50 and 80 °C by mixing C2F and CaO in 0.1 M KOH. Trace amounts of metastable C3FH6 were observed in the samples equilibrated up to 1 year at 20 °C (2θ = 19.71, Fig. 51). However, C3FH6 disappeared and decomposed to portlandite and iron hydroxide with time. At longer equilibration time C4FcH12 was formed due to CO2 contamination, which destabilized the CaO-Fe2O3-H2O system. This shows the metastability of C3FH6 with respect to Fe-hydroxide and portlandite and in the presence of CO2 to hemi/monocarbonate. This metastability of C3FH6 agrees with the findings of Ecker et al. [12] and Rogers et al. [119]. The CaO-Fe2O3-H2O system is very sensitive to carbonation at room temperature. The sample synthesized hydrothermally at 110° C contained portlandite and Fe-oxide/hydroxides and traces of C3FH6. Another weak reflection was observed corresponding to a basal spacing d = 7.58 Å (2θ=11.65°) which persisted at longer age. It does fit neither to C4Fc0.5H10 nor to C4FcH12. The peak was tentatively assigned to C4FHx with an unknown number of water molecules. All the samples showed a reddish color of the solids indicating the formation of XRD amorphous Fe-oxide/hydroxide in the CaO-Fe2O3-H2O system. The TGA-DTG curve also revealed the formation of traces of metastable C3FH6 (see Fig. 49). 117
CHAPTER 3 SYNTHETIC FE-CONTAINING HYDRATES Fig. 51 Time-dependent XRD pattern of C3FH6 synthesized at 20 °C and the sample synthesized at 110 °C and equilibrated for 5 days. At 50 °C small amount of C3FH6 and C4FHx were observed in the solid equilibrated for 7 days. Portlandite and iron hydroxide were the main phases observed at all equilibration times. At longer age, hematite (Fe2O3) started to crystallize as clearly observed by XRD. At 80 °C portlandite and hematite were the main constituents in the solid (see Table 26). This indicates the decomposition of iron hydroxide to hematite at higher temperature. Carbonation was not encountered at higher temperatures. The ion activity product of the metastable C3FH6 was estimated according to: Ks0 (C3FH6) = {Ca 2+ } 3 {FeO2 - } 2 {OH - } 4 {H2O} 4 Synthesis of the solid shows that OH-AFm persisted up to one year. Assuming C4FHx is stable in the absence of carbonate, the solubility products were estimated as follows: Ks0 (C4FH13) = {Ca 2+ } 4 {FeO2 - } 2 {OH - } 6 {H2O} 10 118
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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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Page 118 and 119: Intensity [arb. units] Fe-Fr CHAPTE
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Page 182 and 183: (Al+Fe)/Ca (Al+Fe)/Ca 0.8 0.6 0.4 0
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CHAPTER 4 FE-CONTAINING HYDRATES IN
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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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