National Repository of Grey Literature 10 records found  Search took 0.00 seconds. 
Influence of calcined clays on the properties of cement pastes
Florian, Vojtěch ; Šilerová, Iva (referee) ; Šiler, Pavel (advisor)
V této práci byl studován vliv kalcinovaných jílů na vlastnosti portlandského cementu. Jíly a jílové materiály jsou studovány již mnoho let, přičemž nejvíce studovaný jíl je kaolín a kalcinovaný kaolín. Avšak kvůli změnám ekonomické situace původně levné materiály, např kaolín, zdražily. Vzhledem k důležitosti ekonomické stránky byly v této práci používany primárně jílové materály, které by bylo možné považovat za odpadní. Studovali jsme směs přírodních a syntetických jílů získaných z okolí Brna v České Republice, což je region bohatý na ložiska jílů. Tyto jíly byly analyzovány, kalcinovány, pomlety a byla u nich změřena pucolánová aktivita. Nově schválená norma ČSN EN 197-5 povoluje až 65% náhradu cementu jinými materiály, např jíly, což je téměř dvojnásobek v porovnání s původní maximální náhradou 35 %. Z toho důvodu byly v této práci připraveny cementovo-jílové směsi s až 70% obsahem jílu. Bylo zjištěno, že cementovo-jílové směsi s 60% obsahem jílu vykazovaly mechanické vlastnosti přinejhorším srovnatelné s referenčním vzorkem portlandského cementu, v některých případech měly tyto směsi dokonce lepší mechanické vlastnosti. Směsi s obsahem jílu kolem 30-40 % měly všeobecně lepší mechanické vlastnosti než referenční vzorek. Ze studovaných materiálů měly směsi připravené z jílu z opuštěné cihelny nejlepší ohybovou pevnost. Při stáří 28 dní měly směsi až o 60% vyšší ohybovou pevnost než referenční vzorek. Nejvyšší tlakovou pevnost vykazovaly cementovo-jílové směsi připravené z glaukonitického jílu. S rostoucím obsahem jílu tlaková pevnost klesala. V 90 dnech při 10% obsahu jílu měla směs o 60 % vyšší pevnost než referenční vzorek. Při 60% obsahu jílu byla pevnost ve srovnání s referenčním vzorkem o 26,5 % vyšší. Použití těchto cementovo-jílových směsí se zdá být slibné díky dobrým mechanickým vlastnostem a z ekonomického a ekologického hlediska. Tyto cementovo-jílové směsi by mohly snížit emise oxidu uhličitého a zároveň být levnější než portlandský cement.
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.
The determination of the composition of refractory material by X-ray fluorescence.
Janča, Martin ; Šilerová, Iva (referee) ; Šiler, Pavel (advisor)
The goal of this Bachelor thesis is to find the right way for the analysis of the refractory materials that would be accurate and could be repeated. The ideal method that would help us achieve our goal seems to be the fluorescent spectrometric analysis. This method is used very often in case of instant control of the quality of production in the cement and other heavy industry enterprises. Using the fluorescent spectrometric analysis comes with one issue, which is the presence of many distorting interferences. From this particular reason it is necessary to identify these interferences and then find the ideal solution of their elimination. Because of the possibility to have the sample in any shape or form at the x-ray florescent spectrometer it was necessary to choose the right method of preparing the sample for the analysis as well as choose the right parameter for the measuring itself and for the elimination of undesirable interferences.
Indirect spectrophotometric determination of fluoride on the base of zirconium complexes
Šilerová, Iva ; Komendová, Renata (referee) ; Sommer, Lumír (advisor)
The objective of this study was the calculation and optimalization methods of the indirect spectrophotometric determination of fluoride based on the zirconium complex. Three organic reagent eriochromcyanin R chromazurl S and xylenol orange were tested. As the most sensitive system was shown the complex of zirconium with xylenol orange. Linear standard curve was ranged from 1,5.10-6 to 7,5.10-5 mol.dm-3. H2PO4-, Fe3+ and the highest concentrations of Fe2+, SO42- were tested for interferent. The Fe2+ and SO4- interfere only above the concentration which cannot be found in natural water. The optimized method was applied for the determination of fluoride in the model and real drinking, mineral and surface water.
Transport of selected metals from the soil to the plants
Šilerová, Iva ; Sommer, Lumír (referee) ; Dočekalová, Hana (advisor)
This bachelor thesis focuses on the soil, contamination of selected heavy metals and transport of heavy metals from soil to plants. The entry of heavy metals, their reactions in the soil and their transport into the plant material are described here. Lead, cadmium and copper have been selected as the studied toxic metals. There are also described methods of soil sampling, sample preparation for analysis and determination of heavy metals in the sample.
Influence of hydration accelerators on zinc - doped cement mortars
Beneš, Pavel ; Šilerová, Iva (referee) ; Šiler, Pavel (advisor)
This work deals with monitoring the hydration of cement mortars and cement pastes made from CEM I 42.5 R cement doped with zinc oxide in an amount of 1 % wt. To eliminate the delay in the onset of hydration due to the presence of zinc oxide, the following accelerators were added to the cement mixtures in different proportions: calcium oxide, formic acids and calcium formate. Hydration was monitored using isoperibolic calorimetry. Furthermore, the mechanical properties of mixtures were investigated, namely the tensile strength after bending and the compressive strength after 7 days and after 28 days. The cement mortars were further subjected to additional analyses, such as porosimetry, DTA/TG and SEM.
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.
Indirect spectrophotometric determination of fluoride on the base of zirconium complexes
Šilerová, Iva ; Komendová, Renata (referee) ; Sommer, Lumír (advisor)
The objective of this study was the calculation and optimalization methods of the indirect spectrophotometric determination of fluoride based on the zirconium complex. Three organic reagent eriochromcyanin R chromazurl S and xylenol orange were tested. As the most sensitive system was shown the complex of zirconium with xylenol orange. Linear standard curve was ranged from 1,5.10-6 to 7,5.10-5 mol.dm-3. H2PO4-, Fe3+ and the highest concentrations of Fe2+, SO42- were tested for interferent. The Fe2+ and SO4- interfere only above the concentration which cannot be found in natural water. The optimized method was applied for the determination of fluoride in the model and real drinking, mineral and surface water.
The determination of the composition of refractory material by X-ray fluorescence.
Janča, Martin ; Šilerová, Iva (referee) ; Šiler, Pavel (advisor)
The goal of this Bachelor thesis is to find the right way for the analysis of the refractory materials that would be accurate and could be repeated. The ideal method that would help us achieve our goal seems to be the fluorescent spectrometric analysis. This method is used very often in case of instant control of the quality of production in the cement and other heavy industry enterprises. Using the fluorescent spectrometric analysis comes with one issue, which is the presence of many distorting interferences. From this particular reason it is necessary to identify these interferences and then find the ideal solution of their elimination. Because of the possibility to have the sample in any shape or form at the x-ray florescent spectrometer it was necessary to choose the right method of preparing the sample for the analysis as well as choose the right parameter for the measuring itself and for the elimination of undesirable interferences.
Transport of selected metals from the soil to the plants
Šilerová, Iva ; Sommer, Lumír (referee) ; Dočekalová, Hana (advisor)
This bachelor thesis focuses on the soil, contamination of selected heavy metals and transport of heavy metals from soil to plants. The entry of heavy metals, their reactions in the soil and their transport into the plant material are described here. Lead, cadmium and copper have been selected as the studied toxic metals. There are also described methods of soil sampling, sample preparation for analysis and determination of heavy metals in the sample.

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