|
|
The optimization of quarried limestone analysis and usage.
Sidelnicov, Vitalii ; Bednárek, Jan (referee) ; Šiler, Pavel (advisor)
Limestones are rocks formed predominantly from the mineral calcite. The Czech Republic is quite rich in this type of rock. Limestone may have a very diverse composition, properties and uses. For this reason, it is beneficial to study and analyze this material, to better utilize it to its full potential. This bachelor thesis deals with the possible uses of limestone from Lesní lom in Líšna in the city of Brno, which consists of two limestones - Hádsko-Ričský and Vilemovický. Limestone analyses were performed using by the following analytical methods: XRF, XRD and ICP-OES. Furthermore, the thesis deals with the preparation of samples for individual analytical methods and the differences of the results obtained by individual methods. Part of the thesis is also an overview of the possible uses of analysed limestones.
|
|
|
Improving of dispersion of silica fume in high performance concrete
Janča, Martin ; Koutný, Ondřej (referee) ; Šiler, Pavel (advisor)
The goal of this work was to create a method for improving the dispersion of silica fumes for use in high performance concrete. Traditional methods used to design and manufacture high performance concrete emphasize the removal of coarse aggregates. Use of specially sorted fine aggregates at relatively low doses, the use of super-plasticizers and siliceous excrement. The low water content was achieved by using superplasticizer on a polycarboxylate basis. The standard ultrasound technology found in each laboratory was selected for the dispersion of silica fume. For experiments were we used dry silica fume powder and aqueous stabilized suspension. For comparison, were prepared different mixtures which showed the effects of the treatment prior to the use of silica fume.
|
|
|
The influence of zinc oxide on the cement composite with silica fume.
Dobiáš, Jiří ; Koutný, Ondřej (referee) ; Šiler, Pavel (advisor)
The aim of this work was to investigate the influence of zinc oxide on the properties of blended Portland cement mixed with silica fume. On the pastes were monitored flow properties and by using of isoperibolic calorimetry process of the hydration. On the prepared samples were studied mechanical properties of obtaining values of compressive and flexural strength after 1, 7 and 28 days. By using of XRD were measured phase composition and microstructure development war observed by SEM. The elemental composition of cement leaches was measured by using of ICP-OES.
|
|
|
The Study of Aditives and Admixture Influence on High-Performance Concrete Properties
Šiler, Pavel ; Bílek, Vlastimil (referee) ; Brandštetr, Jiří (referee) ; Havlica, Jaromír (advisor)
The aim of this work was to develop the method for the determination of the superperplasticizers (SP) content in the water solution. The method developed was then applied to study the SP adsorption on the individual components used for high-performance concrete and the influence of the temperature and pH values over this adsorption. Furthermore the influence of the water to binder ratio, SP, finely grounded granulated blast furnace slag, fly ash, silica fume, finely ground silica sand and bauxite on the hydration process was studied by means of isoperibolic, isothermal and solution calorimetry. The compressive and flexural strength of most samples used in calorimetric experiments was also determined.
|
|
|
Preparation of MDF composites of increased moisture resistance
Žůrová, Marcela ; Šiler, Pavel (referee) ; Šoukal, František (advisor)
The subject of the thesis is to improve the moisture resistance of MDF (macro-defect-free) composites prepared on the basis of aluminous cement and polyvinyl alcohol. These materials are characterized by the absence of defects in the structure and high mechanical performance. These features make MDF composites a promising type of material that could be used in the future for construction purposes. The basic deficiency of MDF composites is insufficient resistance to water or moisture, accompanied by a significant decrease in strength. Therefore, this work deals with increasing of moisture resistance using organotitanate agent and modification of the polymer. Two types of polyvinyl alcohols differing in hydrolysis degree and degree of the polymerization has been modified. Based on the results of the measurement the effect of storage conditions on the properties and structure of prepared MDF composites was observed. The characterization of MDF composites were realized by measurement of flexural strength in bending, scanning electron microscopy with EDS analysis, TG-DTA-EGA, water absorption and consequently the porosity of all prepared MDF composites.
|
|
| |
|
|
Effect of pH of mixing water on hydration and mechanical properties of cement composites.
Bezděk, Ondřej ; Krátký, Josef (referee) ; Šiler, Pavel (advisor)
This master’s thesis is focused on the effect of mixing water pH value on hydration and mechanical properties of cement composites based on portland cement. Source material was CEM I 42,5 R. Hydration process was analyzed by isoperibolic calorimetry, X-ray diffraction analysis and differential thermal analysis. Compressive and flexural strength was examined as mechanical properties. The samples microstructure was observed by scanning electron microscopy. Influence of mixing water pH value on flexural and compressive strength, retardation of hydration and ratio of individual phases was shown.
|
|
|
The preparation of cellular concrete for insulating purposes
Koutný, Ondřej ; Šiler, Pavel (referee) ; Opravil, Tomáš (advisor)
In these days of economic crisis subsiding, in the civil engineering the attention is pointed especially to the systems, which effectively reduce energy and decrease costs associated with using of residential or industrial premises. Especially the heat-insulating systems are mentioned, because of their characteristics and construction which will be applied economical solutions. It is possible to use the materials based on aerated concrete which excel within construction materials due to its heat-insulating properties. The use of this material for clearly heat-insulations seems to be fully-fledged alternative to standard heat-insulating systems also due to combination of nature character and sufficient strength. This work deals with possibility of preparation non-bearing, heat-insulating material based on autoclaved aerated concrete with volume weight under 200 kg/m3.
|
|
|
The optimalization of clay building components
Melichar, Jindřich ; Šiler, Pavel (referee) ; Opravil, Tomáš (advisor)
Clay building components are nowadays one of the most used building materials in the world. Except easy availability and processability clay building components have also heat storage function. This master´s thesis will be considering possibilities of improving thermal and mechanic properties of these materils by additing suitable reinforcements.
|
|
|
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.
|
guest ::
