National Repository of Grey Literature 14 records found  previous11 - 14  jump to record: Search took 0.01 seconds. 
The influence of barium oxide on the formation and properties of portland clinker
Zezulová, Anežka ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
Portland clinker is thanks to its large-scale production a continuously studied topic. Clinker, or Portland cement, is used for construction purposes, or for insulation and special applications. One of these special applications could be shielding of different types of radiation by making use of the content of barium ions. The present master’s thesis examines the influence of barium oxide on the formation and properties of Portland clinker, which could be, by incorporation of barium ions into the system, used as a binder for buildings resistant to various types of radiation. Barium sulfate and barium carbonate were added to the raw meal in order to prepare clinkers with different content of barium oxide. The effect of barium on the formation of clinker phases was studied (by XRD – Rietveld analysis and by the microscopic point integration), as well as the effects on the variations of temperature of the phase formation (TG-DTA) and the rate of alite formation under isothermal conditions. Furthermore, the ability of barium to become a part of clinker minerals was studied by SEM with EDS, and the solubility of barium phases by ICP-OES. The hydration of clinker minerals containing barium was studied by isothermal calorimetry.
Possibilities of hexavalent chromium reduction within portland cement hydration
Mončeková, Miroslava ; Koplík, Jan (referee) ; Šoukal, František (advisor)
The issue of Hexavalent chromium toxicity to Portland cement hydration is a very actual these days. It takes much effort to obtain a cement containing Cr(VI) less than 2 ppm. The primary objective of this diploma theses is to find appropriate reducing substances and specify their efficiency, as well as to make an attempt to optimize their dosage. As reducing substances there were plumbed sulphites and tin(II) salts. The influence of reducing substances applied to the hydration and cement properties were validated by strenght tests, the calorimetric measurement and the volume-variation measurement. And also the changes in hydration products microstructure of Portland clinker after the gypsum replacement by sulphite ions were plumbed. The study of microstructure is based on SEM and XRD methods.
Possibilities of utilization of solid residues from fluidized bed combustion for preparation of composite Portland cements
Beranová, Denisa ; Šiler, Pavel (referee) ; Opravil, Tomáš (advisor)
The bachelor thesis deals with possibilities of utilization of solid residues from fluidized bed combustion of coal, bed and filter ash, to be used in the production of composite Portland cements. 6 ash types were investigated, of which 3 were bed ash (finely ground) and 3 were filter ash colected from Ledvice, Tisová and Poříčí K8 power plants. The chemical composition of the ash collected was determined and the progress of a hydration reaction monitored, and then samples mixed with Portland clinker were prepared. Their respective compressive strength and flexural strength were then analysed and observations made on the hydration and composition of products of the hydration reaction. Finally the results of selected mixtures were verified with prepared standardized mortars.
Supersulphates cements
Mohelská, Lucie ; Wirthová, Michaela (referee) ; Opravil, Tomáš (advisor)
The work is studying posibilities of use secondary materials produced by energetical industry. In fact it studies posibilities of preparing supersulphates cements with secondary raw materials. Its main system for simulation was used milled portland clinker. To clinker were added diferent secondary raw materials from energetical industry with sulphate. On prepared samples were watched mechanical properties in time. Tested were different samples of secondary raw materials.

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