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Characterization of portland cement hydration products by thermal dilatometric analysis
Dvořáková, Tereza ; Švec, Jiří (referee) ; Šoukal, František (advisor)
The paper presents the results of thermal dilatometric analysis of cement pastes during the heating at high temperatures. Volume changes were observed in samples of cement paste at selected time intervals during the hydration. Based on the measured data the dTDAc urves course has been described and the results have been compared with the curves of differential thermal analysis. To characterize the microstructure of the cement paste during the considerable shrinkage at higher temperatures the images by scanning electron microscope have been acquired.
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Preparation of WDXRF analysis cement tablets
Kozlová, Romana ; Lerch, Jiří (referee) ; Svěrák, Tomáš (advisor)
This bachelor's thesis is focused on the sample preparation for the X-ray fluorescent analysis (XRF) of cement. The thesis aims to contribute to finding optimal method of the sample preparation of cement in the form of tablets, which would then provide the most accurate XRF analysis. This activity is related with finding a method of the sample preparation with an appropriate granulometry and homogeneity of the powder material, and also is related with creating the conditions of pressing of this material in the form of compact tablets, which are not prone to fracture. Selected problem was solved by adjusting twenty possible parameters of the mill and press. The milling was evaluated by granulometric composition of the sample, which was determined by a laser diffraction. For the smallest sample the repeatability of measurement was performed. Sieve distribution was used to achieve a finer sample, followed by XRF analysis. Tests of strength of samples pressed into ringlets were performed using a three-point tensile strength in bending, for samples with the finest and most coarse composition. The chemical composition of the finest and most coarse sample, which was prepared by milling and also the sample after milling and sieve distribution, was verified with the XRF analysis. By combining the 20 parameters during the sample preparation, maximum accuracy of the XRF analysis was achieved. The final setting meet the granulometric requirements and also abrasive and strength tests of tablets after pressing the sample. The contribution of this work is an increase in accuracy of the XRF analysis to a better level than ever before. As a result the negative impacts, which directly affect he accuracy and reproducibility of the sample preparation for the XRF analysis, were minimized. The resulting sample preparation was applied to the laboratory of quality and quality control at Českomoravský cement a.s., Mokrá plant, for which this work has been performed.
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Influence of Zinc in Byproducts on Hydration and Properties of Blended Portlands Cements
Šilerová, Iva ; Palou, Martin (referee) ; Rovnaníková, Pavla (referee) ; Havlica, Jaromír (advisor)
The theme of this work is to monitor the effect of zinc on the properties of blended Portland cements. Zinc was tested in the form of two-soluble salts: Zn(NO3)22 H2O and ZnCl2 and a very slightly soluble compound ZnO. Blended cements were prepared by partial replacement with finely ground granulated blast furnace slag, high-temperature and fluidized bed combustion filter fly ash. Flow properties were studied on the prepared pastes. Impact on hydration reactions was examined by using of isothermal and isoperibolic calorimetry. Flexural and compressive strength were measured as mechanical properties of the prepared test specimens. The phase composition of the prepared composites and incorporation of zinc ions in the cement matrix via leaching tests and FTIR analyzes were also studied. Microstructure development of cement samples was tested by SEM analysis with EDS. Influence on ecotoxicity was also measured.
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Systems of self-setting foundry mixtures on the base portland cements
Janíčková, Petra ; Cupák, Petr (referee) ; Rusín, Karel (advisor)
The project elaborated in frame of engineering studies branch N2332-00. The project is submitting design of technology production sand mixture with cement binder – Portland binder CEM I 42,5 N. Pursuant to of the literary pursuit a problem of the sand mixture with cement binder was tested few sand mixture. As optimal composition it turned out application sand mixture with 2 % CaCl2 content and 1 – 2 % Dextrin content. Sand mixture with cement has good moulder and regenerating.
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Thermodynamic Stability of Thaumasite
Pospíšilová, Klára ; Dvořák, Karel (referee) ; Fridrichová, Marcela (advisor)
This work deals with the resolution of the identification characteristics of the thaumasit, which falls into the same group of AFt phases as the mineral ettringit. Both of these stages have the same structural arrangement and the morphology. This work’s specific goal is the synthetic preparation of thaumasit in a variety of conditions and its evaluation.
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