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The influence of admixtures on the hydration of Calcium Aluminate phases
Skalík, Martin ; Másilko, Jiří (referee) ; Koplík, Jan (advisor)
This thesis focuses on the effect of admixtures on the hydration time and on the formation of hydration products of calcium aluminate cement and its phases. Three main calcium aluminate phases, CA, CA2 and C12A7, were prepared to study using a high temperature sintering method that was optimised to be as fast as possible. The admixtures used were LiCl, NaCl, sodium tetraborate and citric acid. Prior to the actual hydration, the optimization of the admixture dosage was performed by Vicat test on two commercial aluminate cements, Secar 71 and Secar 80. The hydration with the right amnout of admixtures was monitored by heat flow calorimetry. Hydration products were investigated by X-ray diffraction analysis, Fourier transform infrared spectroscopy and electron microscopy.
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Preparation of calcium-aluminate phases
Ohaňka, Zdeněk ; Novotný, Radoslav (referee) ; Koplík, Jan (advisor)
This work focuses on the preparation of calcium aluminates by solid state synthesis and by sol-gel method. Phases prepared were monocalcium aluminate (CA), dodecacalcium heptaaluminate (C12A7), tricalcium aluminate (C3A) and calcium dialuminate (CA2). Two modifications of sol-gel method were used – the difference between them was in the addition of EDTA. Each method was closely described and results were compared according to the achieved purity of prepared phases. X-ray diffraction analysis was used to determine the purity of prepared calcium-aluminates.
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Calcium aluminates - hydration under various initial conditions
Tomala, Libor ; Másilko, Jiří (referee) ; Koplík, Jan (advisor)
This thesis deals with the preparation of calcium aluminate phases, namely monocalcium aluminate (CA), monocalcium dialuminate (CA2) and dodecalcium heptaaluminate (C12A7) and their hydration at temperatures of 20, 30 and 60 ° C. Preparation was carried out by sintering aluminium oxide and calcium carbonate in the correct molar ratio at a temperature typical for each of the phase preparation (1450, 1600 respectively 1360 ° C) in superkanthal furnace. Firings were conducted repeatedly until reaching the sufficient purity, which was determined by X-ray diffraction analysis on the diffractometer Empyrean from the PANalytical company. The pure calcium aluminate phases were subsequently hydrated in the already mentioned temperatures and progress was monitored on TAM Air isothermal calorimeter made by TA Instruments. The resulting hydrated products were identified again by using XRD.
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The influence of particle size and methods of preparation of calcium aluminate phases on their hydration
Ohaňka, Zdeněk ; Másilko, Jiří (referee) ; Koplík, Jan (advisor)
This work focuses on the hydration of four calcium aluminate phases – C3A, C12A7, CA and CA2. Above all, the influence of particle size and method of preparation on hydration behaviour were studied. Influence of these factors on hydration products were also investigated. Calcium aluminates were prepared by solid state synthesis and amorphous citrate method. Both methods were described in detail. The particle size was determined by laser diffraction. Isothermic calorimetry was used to investigate the process of hydration. Hydration products were identified by X-ray diffraction analysis and simultaneous thermogravimetric and differential thermal analysis.
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Praparation and characterization of calcium aluminate hydrates
Hubáček, Václav ; Švec, Jiří (referee) ; Koplík, Jan (advisor)
This thesis deals with the preparation of pure calcium aluminate phases, specifically CA, CA2, C3A and C12A7 by two different methods - the solid state synthesis and the amorphous citrate method. The hydration of these phases at different temperatures was also studied The effect of the phase preparation method used and the simultaneous effect of temperature were observed on the prepared hydrates, using suitable analytical methods. The characterization and identification of the prepared phases and their hydrates were studied by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and simultaneous thermogravimetric and differential thermal analysis. The prepared hydration products were mostly identified in accordance with the literature data. TGA/DTA of the prepared hydrates helped to clarify some of the hydrate decomposition processes, especially for the hexagonal hydrate CAH10 and the cubic hydrate C3AH6, which were prepared in a sufficiently pure form suitable for analysis.
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The influence of particle size and methods of preparation of calcium aluminate phases on their hydration
Ohaňka, Zdeněk ; Másilko, Jiří (referee) ; Koplík, Jan (advisor)
This work focuses on the hydration of four calcium aluminate phases – C3A, C12A7, CA and CA2. Above all, the influence of particle size and method of preparation on hydration behaviour were studied. Influence of these factors on hydration products were also investigated. Calcium aluminates were prepared by solid state synthesis and amorphous citrate method. Both methods were described in detail. The particle size was determined by laser diffraction. Isothermic calorimetry was used to investigate the process of hydration. Hydration products were identified by X-ray diffraction analysis and simultaneous thermogravimetric and differential thermal analysis.
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Preparation of calcium-aluminate phases
Ohaňka, Zdeněk ; Novotný, Radoslav (referee) ; Koplík, Jan (advisor)
This work focuses on the preparation of calcium aluminates by solid state synthesis and by sol-gel method. Phases prepared were monocalcium aluminate (CA), dodecacalcium heptaaluminate (C12A7), tricalcium aluminate (C3A) and calcium dialuminate (CA2). Two modifications of sol-gel method were used – the difference between them was in the addition of EDTA. Each method was closely described and results were compared according to the achieved purity of prepared phases. X-ray diffraction analysis was used to determine the purity of prepared calcium-aluminates.
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Calcium aluminates - hydration under various initial conditions
Tomala, Libor ; Másilko, Jiří (referee) ; Koplík, Jan (advisor)
This thesis deals with the preparation of calcium aluminate phases, namely monocalcium aluminate (CA), monocalcium dialuminate (CA2) and dodecalcium heptaaluminate (C12A7) and their hydration at temperatures of 20, 30 and 60 ° C. Preparation was carried out by sintering aluminium oxide and calcium carbonate in the correct molar ratio at a temperature typical for each of the phase preparation (1450, 1600 respectively 1360 ° C) in superkanthal furnace. Firings were conducted repeatedly until reaching the sufficient purity, which was determined by X-ray diffraction analysis on the diffractometer Empyrean from the PANalytical company. The pure calcium aluminate phases were subsequently hydrated in the already mentioned temperatures and progress was monitored on TAM Air isothermal calorimeter made by TA Instruments. The resulting hydrated products were identified again by using XRD.
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