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The influence of the amount of sulfates on the formation of ettringite in cement-concrete covers
Mrhálková, Leona ; Palovčík, Jakub (referee) ; Opravil, Tomáš (advisor)
This bachelor´s thesis is focused on the influence of the amount of sulfates on the formation of ettringite in cement-concrete covers. For the experiments, samples of cement pastes, mortars, and concretes in the form of small beams were created. Cements of class CEM I 42.5 R – SC were used as the binder. In some mixtures, gypsum from the production of titanium dioxide was added as an additional source of sulfates. To assess the impact of ettringite formation on the properties of the samples, strength tests of the prepared materials were conducted, followed by CHRL tests. The results of these experiments were subsequently confirmed by XRD and EDX analyses along with images from a scanning electron microscope.
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Preparation of high-valueable gypsum binder
Hájková, Iveta ; Gazdič,, Dominik (referee) ; Fridrichová, Marcela (advisor)
This work is oriented on the preparation of high-voluable sulphate binder based on gypsum waste. One of the potential mineral resources in Moravia is Pregips chemical gypsum, produced by Precheza. This is the raw material, which is characterized by high purity, high quality and is economically acceptable. Beta burned gypsum plaster from this, however, need to modify due to suppression of the high needs of water mixing, which is determined by its morphology. The need for mixing water has a large impact on the strength of gypsum binders. Therefore it is necessary to find a suitable additive, which would reduce the coefficient of water in the preparation of porridge normal consistency.
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Preparation of modified tricalcium aluminate phases and study of their hydratation processes
Vávrová, Alžběta ; Koplík, Jan (referee) ; Másilko, Jiří (advisor)
This diploma thesis deals with the preparation of modified tricalcium aluminate phases using sodium ions, and the study of their hydration processes and products. The X-ray diffraction analysis, isothermal calorimetry, laser diffraction, and scanning electron microscopy with energy dispersion analysis were used to solve this task. The preparation of modified tricalcium aluminate phases using high temperature methods has been described in the experimental section. Furthermore, the X-ray diffraction analysis was used to determine the purity of the prepared phases and the scanning electron microscopy with energy dispersion analysis was used to define the volume of sodium. Laser diffraction was used to measure a particle size distribution in the individual phases. Subsequently, hydration of the pure phases was performed in an isothermal calorimeter. It was followed by hydration of phases in the presence of different gypsum content and then in the presence of saturated portlandite solution. Hydration of some samples was stopped in order to better understand the hydration process. Hydration products were studied by X-ray diffraction analysis. The obtained results were compared with each other and the influence of sodium ions on both the structure of the prepared phases and the course of hydration and its products has been discussed. The effect of adding different volumes of gypsum and portlandite on the course of hydration of the individual phases was also compared.
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Methods of excitation of binders based on anhydrite
Sedlák, Michal ; Dvořák, Karel (referee) ; Gazdič, Dominik (advisor)
The bachelor thesis deals with the internal excitation of anhydrite-based mortars. In the theoretical part, the general theory of sulphate binders, the formation of gypsum binders and their resulting products during firing are described. The theoretical part also describes the anhydrite mortars, their hydration process and collects the existing research on anhydrite excitation in the world, where, among other things, it deals with the further usability of the resulting gypsum by-products. The experimental part focuses on the internal excitation of anhydrite, which is based on the existing research at the THD Institute. The work builds on previous studies that also dealt with internal excitation research. It includes an experiment performed to optimize the thermal regime in the form of increased isothermal endurance with subsequent evaluation by XRD analysis.
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The admixtures which are influencing setting time of portland cement
Hlaváček, Jaroslav ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
During the production of concrete is important the careful selection of raw materials. Nowadays, we are trying in the production to minimize the economic burden and to maximize the use of secondary raw materials. This work is focused on the use of secondary raw materials from the energy industry in construction for the preparation of hydraulic binders. As the main raw materials were used different power plant fly ash from fluidized combustion. The composition of these secondary materials is quite different from conventional high-temperature ash, due to mixing with water they solidify and harden. Experiments were performed with three lodge fly ash from electrostatic precipitators of the fluidized combustion and one high-temperature fly ash. This work is focused on the possibility of monitoring the use of these secondary materials in construction, especially when tests were evaluated characteristics of strength and speed of setting and hardening.
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Evaluation of methods for determining an air humidity in building constructions
Nogová, Tereza ; Šuhajda, Karel (referee) ; Žák, Antonín (advisor)
This thesis compares the methods for the determination of air and moisture condensation in the construction. There are descriptions of the various methods and formulas for measuring humidity and methods for the calculation of condensation in building structures. The practical part describes the development of a method for verifying the condensation of moisture in construction. Parts of this work are the materials and methods for the development of the humidity sensor. There were used two methods – capacitive and resistive for measuring moisture condensation. In the conclusion is the evaluation of the humidity sensor and compares the results of individual measurements.
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Study of Hydration of Anhydrite Binders
Duda, Štěpán ; Smetanová,, Lenka (referee) ; Gazdič, Dominik (advisor)
Presented bachelor thesis deals with the study of hydration of anhydrite binders. This thesis is primary focused on testing the various hydration exciters of anhydrite and subsequent monitoring of the hydration process by the XRD analysis and also builts on previous research in this area at the institute of THD. Conceptually is this work divided into two parts. The first part deals with the general theory of sulphate binders. The second part is devoted to the partical testing of the various hydration exciters and their subsequent comparsion.
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Comparison of microstructure of standard and modified fly ash autoclaved aerated concrete
Fleischhacker, Ján ; Kulísek, Karel (referee) ; Drochytka, Rostislav (advisor)
Nowadays, the amount of produced fly ash and fluidized ash is huge, so it is important to find ways of its proper use.Significant influence in field of fly ash consumption is production of autoclaved aerated concrete. Most important factor in production is properties of raw materials such as mineralogical and chemical composition. The study of raw materials is important to understand the mechanism of hydratation, tobermorite formation and mineralogy of final product. In present study, we investigate influence of raw materials to mineralogy of autoclaved aerated concrete, significantly to influence of fluidized ash on quality of autoclaved aerated concrete. Closure of study is design of the methodology, specialized in field of bachelor’s thesis study.
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