National Repository of Grey Literature 74 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Development of materials for 3D printing of elements meeting the requirements of transport structures
Romanová, Dorota ; Melichar, Jindřich (referee) ; Žižková, Nikol (advisor)
This bachelor thesis deals with the use of supplementary cementitious materials as a partial replacement of Portland cement in cement composites, focusing on the requirements of transport constructions. The theoretical part consists of a description of the input raw materials as well as cement substitutes, the studied properties of the 3D printed mixtures and a description of the characteristics of the technology. The practical part is focused on the experimental testing of the selected properties with monitoring of the influence of polymer and bio-polymer additive dosage in the proposed formulations and subsequent analysis of the most convenient one for 3D printing.
Use of calcined clays for polymer modified mortars
Macíková, Barbora ; Sokola, Lubomír (referee) ; Žižková, Nikol (advisor)
This bachelor thesis deals with the use of metakaolin as a partial cement replacement for polymer modified mortars. The theoretical part describes negative impact of cement production on the environment. Attention is being paid to the use of supplementary cementitious materials in an effort to reduce the carbon footprint, with the metakaolin being considered as the main alternative. Its composition, availability, use, properties and suitability for use in polymer modified mortars are investigated. The practical part is focused on the verification of the relevant properties of mortars with metakaolin as a binder component and its suitability for future use as a supplementary cementitious material.
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.
Analysis of the Setting Process of Portland Cements Focused on False Set
Pertlová, Alena ; Skotal, Václav (referee) ; Gazdič, Dominik (advisor)
The thesis deals with the setting process of Portland cement focused on false set. It focuses on modeling the conditions leading to the so-called false set of Portland cement and finding a simple method by which it will be possible in practice to verify the course of setting. To this end, several methods have been proposed and tested to allow monitoring of the setting and consistency parameters of fresh cement paste.
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.
Influence of ettringite formation on mechanical properties of zinc doped cements.
Kunovský, Ondřej ; Matějka, Lukáš (referee) ; Šiler, Pavel (advisor)
This bachelor thesis deals with the study of the effect of hydration accelerators in cement pastes doped with zinc ions. Their influence on hydration reactions, mechanical properties and the amount of ettringite formed was studied. CEM I 42.5 R cement was used and zinc was added in the form of ZnO in an amount of 1 wt. % of Zn relative to cement content. Strengths were measured over a time horizon of 98 days. In addition, analyzes by SEM, XRD and DTA methods were performed on selected samples to determine the amount of ettringite. It has been found that compressive strengths can also decrease during hydration. At this decrease, SEM, XRD and DTA showed a reduction in the amount of ettringite in the sample.
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.
Issues of stopping the hydration of alkali-activated slag using organic substances
Chadima, Jan ; Novotný, Radoslav (referee) ; Bílek, Vlastimil (advisor)
This thesis deals with the stopping of hydration of alkali activated slag by organic solvents and investigates to what extent the selected organic solvent affects the results of the analyses. The solvents used were acetone, diethyl ether, ethanol, isopropanol and methanol, and this is because these are the most commonly used organic solvents in practice. Thermogravimetric analysis along with differential thermal analysis was used to assess the degree of influence of organic solvents on the alkali activated slag and Portland cement samples. Methanol and acetone affected the samples the most and the longer the sample was stored in the solvent, the more it reacted with the organic solvent. The adverse interaction of organic solvent was greatest for the Portland cement samples. Samples that were rinsed with diethyl ether prior to analysis had lower mass losses than samples that were not rinsed. In the case of alkali activated slag, it was found that the way in which the thermogravimetric results were affected by organic solvents was highly dependent on the activator used, with the smallest effect observed for Na2CO3 activation, while the largest effect was observed for NaOH activation at temperatures below 600 °C, and for higher temperatures for water glass activation.
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.
Recyclation of dust from production of dry mortar blends
Ondrůšková, Nela ; Novotný, Radoslav (referee) ; Šoukal, František (advisor)
The work deals with the problem of disposal of ever-increasing waste (dust) from the production of building materials and examines the possibility of recycling dust dust into cement repair mortar. The aim of this work was to determine the composition of individual dust particles from the production of cement mixtures and to determine their mechanical properties, as well as to determine the ideal ratio of dust particles to each other when mixing the dust mixture and its mechanical properties. This mixture consisted mainly of dust from products based on Portland cement, aluminous cement, gypsum and lime hydrate. The mixture further replaced part of the cementitious mortar and the impact of the additive on the mechanical properties of the cementitious mortar was determined. X-ray fluorescence spectrometry was used to determine the elemental composition, and X-ray diffraction analysis was used to determine the mineralogical composition. Test specimens were prepared according to the ČSN EN 12390 standard. Mechanical strength tests were performed on the test specimens. A large part of the test specimens could not be subjected to mechanical tests because the test specimen did not solidify even after a long time. The individual measurements that could be made show that the mechanical properties of the dust samples show values which have shown that the dust cannot be recycled into the product due to its instability. Dust particles have too diverse composition and in combination with cementitious repair mortar do not have the required properties. The problem is especially the sampling from the data, which did not solidify at all and thus excluded the remaining samples with already good properties of the same sample. When designing the method of recycling, it was necessary to take into account which product of the company is most in demand, where recycling would also make economic sense, which is also an important indicator for the operation of the company today. Dust particles could prove successful in another product, but it would not be advantageous for the company now, so now the recycling of dust particles will not start and they will be further disposed of in the same way.

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