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Possibilities of utilization of brick-grind-dust in systems based on portland cement
Palovčík, Jakub ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
This thesis deals with possibilities of using brick-grind-dust which is a secondary product from manufacturing of grinded bricks. A boom in this method of masonry is connected with an increase of production of these secondary materials. These secondary materials are partly returned to brick manufacturing and partly buried in a landfill site. Due to their composition and origin, these materials are potentially pozzolan active, making them interesting for applications in hydraulic binders. The aim of the work was to study the physical and chemical properties of several brick-grind-dust and brick sands. Subsequently, binders based on these materials and Portland cement were prepared. The properties of the binders were modified by means of adding a commercially available polycarboxylate superplasticizer. The development of mechanical properties of the prepared binders has been studied over time. Hydration of the selected binders was analyzed by isothermal calorimetry.
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Influence of zinc on mechanical properties of cement composites
Štarha, Tomáš ; Šilerová,, Iva (referee) ; Šiler, Pavel (advisor)
The theme of this bachelor thesis is to monitor the effect of zinc on mechanical properties of portland cement. Zinc was tested in the form of zinc oxide. Three acceleration additives were added, calcium oxide, formic acid and calcium formate in various proportions. Furthermore, the mechanical properties of all these mixtures were monitored by measuring flexural strength and compressive strength at 7 and 28 days after mixing and mixtures were analyzed by XRD and DTA. Also using isoperibolic calorimetry, the hydration of CEM 42.5 R cement zinc oxide was monitored.
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The study of sulfate depletion in cement binders
Jurko, Michal ; Švec, Jiří (referee) ; Novotný, Radoslav (advisor)
This bachelor thesis deals with the study of sulfate depletion in cement binders. Basic knowledge about cement binders is summarised at the beginning of the theoretical part. The theoretical part goes on to describe the hydration of Portland cement (PC) and to briefly describe the influence of different types of milling on PC particle size. In the experimental part, PC fractions of various average particle sizes were prepared on a planetary ball mill for wet conditions. On the prepared cement, their hydration was studied using isothermal calorimetry; especially sulfate depletion, portlandite precipitation, heat flow rate and induction period interval. n the thesis were also used analyzes for autogenous shrinkage, XRD and STA. The input raw materials are cement CEM I 42,5 R (grey, Českomoravský cement, a.s. – Mokrá, Czech Republic) and sulfate-resistant cement CEM I 52,5 R (white, Aalborg Portland, a.s. – Aalborg, Denmark). On the basis of the results analysis, a proposal was made to correct the presence of sulfate ions by adding gypsum in these cements. In the case of CEM I 52,5 R the correction is recommended and in the case of CEM I 42,5 R the correction is necessary.
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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.
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Influence of calcium sulphate type on hydration of Portland cement
Šimčíková, Ivana ; Šiler, Pavel (referee) ; Šoukal, František (advisor)
My bachelor thesis deals with the study of the influence of calcium sulphate types on the hydration of Portland cement. Hydration is performed at 15 °C, 25 °C and 40 °C. In the theoretical part we find a description of the hydration of Portland cement and the influence of the type and amount of gypsum on the hydration period. The experimental part contains the preparation of samples for measurement and the principle of calorimetry including a description of the calorimetric curve. The data obtained from the calorimetric curve was processed into ternary diagrams for illustration. The diagrams show that the more calcium sulphate is soluble, the shorter the induction period, the times of reaching the minimum heat flow and heat flow at the maximum silicate peak will have. Further, the diagrams showed that as the amount of water in sulphate increases, so does the amount of hydration heat released.
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The thermodynamic stability of etringite
Magrla, Radek ; Durica,, Tibor (referee) ; Bílek,, Vlastimil (referee) ; Brauner,, Josef (referee) ; Fridrichová, Marcela (advisor)
The theoretical part of this doctoral thesis summarizes the current knowledge of portland cement and its manufacturing technology, information of FBC ash, Aft phases, AFm phases and the current knowledge of thermodynamic stability of ettringite. The practical part of the doctoral thesis focuses on manufacturing of ettringite based on yeelimite clinker, studying the influence of environment on thermodynamic stability of ettringite and manufacturing of ettringite by direct addition of calcium hydroxide and aluminum sulfate.
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Possibilities of affecting the portland cement hydration by the addition of fluidized ash
Nehybka, Josef ; Bartoníčková, Eva (referee) ; Opravil, Tomáš (advisor)
This work is focused on study of possibilities of influence of hydration of Portland cement with an admixture of fluid ashes. The work deals with the tests with fluid filter ashes and milled fluid bed combustion ashes. Predominantly, a calorimetric measurement is used for study of admixtures. The prepared samples were found out on their mechanical parameters as the tensile bending strength and compressive stress. X-ray powder diffraction was used to determine of phase composition of the raw materials and created samples after hydration.
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Reduction of hexavalent chromium in cement binders
Hrubý, Petr ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
The issue of hexavalent chromium contained in cement binders and the possibilities of its reduction are very current, due to the toxicity of Cr (VI) and constantly stricter regulations of the EU. The effort of achieving a cement binder with Cr (VI) concentration lower than 2 ppm and keeping this concentration unchanged during the long term storage is a frequently studied issue which needs to be solved. Requirements are put on the low cost for industrial use and without inducing changes of final properties of cement binders. A reducing agents based on iron (II) sulphate monohydrate potentially combined with some additives were studied in this study. The efficiency of reducing agents was analysed by commonly used UV-VIS spectrophotometry technique which uses 1,5-diphenylcarbazide as an indicator. The influence of added reducing agent on the mechanical properties was noticed by compressive strength test.
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The influence of aggregate on the properties of high performance concrete.
Bezděk, Ondřej ; Krátký, Josef (referee) ; Šiler, Pavel (advisor)
This bachelor thesis is focused on the influence of aggregates on the mechanical properties of high-performance concrete. The flexural strenght and the compressive strenght were observed after 1, 7 and 28 days. The process of hydratation was monitored using isoperibolic calorimetry. Laser particle size analysis of aggregates was also performed. As materials were used: Portland cement CEM I 42,5 R-Sc Mokrá, finelly ground silica sand, calcinated bauxite, fine test sand ČSN EN 196-1, medium test sand ČSN EN 196-1, rough test sand ČSN EN 196-1 and polycarboxylate superplasticizer Glenium Ace 40.
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