Cement-based concrete is one of the main construction materials that is widely used for many construction applications due to its strength, durability, reflectivity, and versatility. However, it is acknowledged that production of cement as a primary material of concrete releases 1.8 Gt carbon dioxide (CO2) into the environment. It is estimated that one ton of cement production releases one ton of CO2 to the atmosphere. That is why, this work aims to create a concrete that could be an alternative to cement-based concrete. Geopolymer concrete (GPC) is an eco-friendly construction material and an alternative to conventional concrete that is produced by reacting aluminate and silicate bearing constituents with a caustic activator (i.e. sodium-based or potassium-based). Both potassium and sodium have been considered as generally safe intergradient by the FDA, based upon the observance of several good manufacturing practice conditions of use. Theses activators are used in various application including concrete, food, as a stabilizer, and as a thickening agent. Moreover, these activators are also used in making soap, as an electrolyte in alkaline batteries and in electroplating, lithography, and paint and varnish removers. Medically, these activators are widely used in the wet mount preparation of various clinical specimens for microscopic visualization of fungi and fungal elements in skin, hair, nails, and even vaginal secretions, Currently, it was determined that these activators solution were found to be a safe and effective treatment of plane warts. Despite the developments in the studies relating to GPC made by various precursors such as fly-ash and slag in the literatures, the use of GPC made by fly-ash and bottom-ash has not been overly researched. In this study, attempts have been made to produce a unique mix proportion for Potassium-based GPC made by fly-ash and bottom-ash and investigate various mechanical properties of this type of GPC including elastic modulus, freeze-thaw resistance, heavy metal leach-ability and corrosion in both laboratory and real environmental conditions using Non-Destructive Tests (NDT)s. / Graduate / 2021-12-15

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Title: Model of training preparation for young future flyboarders Objectives: The objective of the work is to create a model of training preparation for young future flyboarders based on the empiricism of the most successful professional flyboarders. Methods: Ten intentionally selected respondents filled out the survey on their current sports specializations. Three of them were selected based on the frequency of specific and non-specific sports. Individual non- standardized interviews were conducted with them, which were based on direct verbal communication with the respondents. Results: We created a model of training preparation for young future flyboarders. The training preparation model is divided for children from six to nine years old, in which we recommend general sports training (gymnastics, athletics, swimming, sports games). For children from ten to twelve years old, we recommend trampoline jumping, high jumping, swimming, balance exercises, body strengthening and stretching. For children over the age of thirteen, we recommend starting to fly on a flyboard. Keywords: extreme sport, fly on water , water sport, training preparation, change of sport, adrenaline

Concrete is a brittle material prone to cracking due to its low tensile strength. Crack repairs are not only expensive and time-consuming but also increase the carbon footprint. Designing a novel concrete material possessing the ability to self-repair cracks would enhance its sustainability. Self-healing can be defined as a material’s ability to repair inner damage without any external intervention. In the case of concrete, the process can be autogenous, based on an optimized mix composition, or autonomous, when additional capsules containing some healing agent and/or bacteria spores are incorporated into the binder matrix. The first process uses unhydrated cement particles as the healing material while the other utilizes a synthetic material or bacteria precipitating calcite which are released into the crack from a broken capsule or activated by access to water and oxygen. The main disadvantages of the autonomous method are the loss of the fresh concrete workability, worsened mechanical properties, low efficiency, low survivability of the capsules and bacteria during mixing and the very high price. On the other hand, the autogenous self-healing was found to be more efficient, more cost effective, safer, and easier to implement in full-scale applications. Knowledge related to mechanisms and key factors controlling the autogenous self-healing is rather limited. Therefore, the aim of this research work was to better understand the autogenous self-healing process of concrete and to optimize the mix design and exposure conditions to maximize its efficiency. This licentiate thesis summarizes the main findings of the first 2.5 years of the PhD project. Several factors affecting autogenous self-healing were studied, including the amount of unhydrated cement, mix composition, age of material, self-healing duration and exposure conditions. The process was investigated both externally, at the surface, and deeper inside of the crack, by evaluating the crack closure and chemical composition of formed self-healing products. In addition, the flexural strength recovery was also studied. It was observed that a large amount of cement in the concrete mix does not ensure an efficient autogenous self-healing of cracks. A very dense and impermeable binder microstructure limited the transport of calcium and silicone ions to the crack and diminished the precipitation of the healing products. Addition fly ash increased the crack closure ratio close to the crack mouth, but its presence did not support the recovery of the flexural strength, presumably due to a very limited formation of load bearing phases inside the crack. Calcium carbonate was detected mainly at the crack mouth, whereas calcium silicate hydrate (C-S-H) and ettringite were found deeper inside the crack. The formation of C-S-H and ettringite presumably resulted in a regain of the flexural strength. On the other hand, calcite crystals formed close to the surface of the specimen controlled conditions inside the crack through its external closure. Healing exposure based on pure water appeared to be inefficient even despite the application of different temperature cycles and water volumes. The application of a phosphate-based retarding admixture in the curing water resulted in the highest self-healing efficiency. The admixture presumably inhibited the formation of a dense hydration shell on the surface of the unhydrated cement grains and promoted the precipitation of calcium phosphate compounds inside the crack. In addition, water mixed with microsilica particles caused a regain of the flexural strength through formation of C-S-H in the crack.

This thesis is focused on the possibilities of the utilization of the fludized fly ash in ceramic technology, especially in the field of brick manufacturing and ceramic tiles. There were used fly ashes from thermal power plants in Hodonín, Ledvice and Tisová. Fluidized fly ash can be used for manufacturing of building materials. There hasn’t been done extensive research in this area. One of the problem is sulphur dioxide leakage during burning. The work describes the behaviour of fluidized ash during firing. The attention is focused on air pollution of sulphur dioxide. The production of SO2 is controlled so that the aim of the work is to find a way how to avoid leaking. It was proved that addition of sodium ions causes the formation of minerals hauyne and nosean during firing. Also is described the behaviour of the fly ash-soil mixtures. The anhydrite decomposition temperature is lower than in pure fly ash. In the end is fluidized ash applied for the production of dry pressed ceramic tiles. This ash can be used in ceramic technology. However, despite the interesting results there are number of problems that need to be solved.

The thesis is focused on the application of brick powder in production of binary alkali-activated binders with metakaolin, slag and fly ash. The theoretical part summarizes recent fields of use of the ceramic waste in construction and binder industry and prerequisite properties of the brick powder for alkaline activation. Brick powder based geopolymers made in the experimental work were tested for their mechanical properties, porosity and microstructure, flow properties of the fresh geopolymers were evaluated by rheometric measurements. In accordance with the results it can be concluded that brick powder could be a suitable precursor for blended binders with metakaolin and slag, these samples exhibited good mechanical properties and microstructure characteristics. The combination with fly ash was less applicable due to a rapid setting, hardening retarder used in these binders caused significant deterioration of the mechanical properties of the material.

This thesis deals with the use of by–products from the production of cement–bonded particle boards as an alternative raw material for the stabilization of the subsoil or into a ground solid. The theoretical part briefly describes the current status of waste management. A set of alterantive raw materials used to hydraulically cemented mixtures is listed here as well as the recherche of the foreign research is elaborated from this area. The experimental part of the thesis firstly deals with the choice of raw materials and basic recipes. In the advanced stage the laboratory analyses are carried out on the modified formulas. Based on the results of these analyses the posibility of using by–products from the production of cement–bonded boards for the stabilization of the subsoil is evaluated here.

The diploma thesis is focused on the use of the waste glass with different fineness on alkali - activated composites, mainly based on slag and fly ash. The theoretical part is focused on materials that are most used for alkaline activation - slag, fly ash and their composites with waste glass. The theoretical part also deals with the alkaline activation of composites from these materials and the factors that influences the microstructure and properties of these composites. In the experimental part were prepared composites from slag and fly ash with a waste glass as substitute. These composites then have been examined on mechanical properties and microstructure, also how different fineness of glass influences these properties. Then it will be decided whether it is economically advantageous grinding waste glass to finer fractions

V mnoha oborech jsou stále využívána anorganická filtrační media založená na materiálech, jejichž výroba využívá primární suroviny. Jejich výroba je tedy energeticky náročná a v důsledku nákladná a neohleduplná k životnímu prostředí. Cílem této práce je ověřit možnost využití alkalicky aktivovaných materiálů na bázi sekundárních surovin, především vysokopecních strusek (BFS) a popílků z uhelných elektráren (FA), pro výrobu porézních médií schopných v budoucnosti nahradit keramické a jiné anorganické filtry. Výzkum je rozvinut skrze experimentální design založený na výpočetním schématu samostatně vyvinutém s pomocí programu MATLAB. Toto schéma počítá vhodná složení směsí na základě poměrů obsahu nejdůležitějších oxidů ve vstupních surovinách. Tak je zajištěno zohlednění proměnlivého složení vstupních surovin a práce je tím hodnotnější, že její výsledky jsou skrze početní nástroj zohledňující základní oxidové složení surovin zobecnitelné. Zároveň byly však pro srovnání a lepší názornost závislostí vlastností na složení navrhnuty a připraveny i série vzorků založené vždy pouze na jedné ze surovin. Z výsledků vyplývá, že pevnost vzorků z těchto směsí (vytvrzených 24 hodin při 70 °C) ve čtyřbodové ohybové zkoušce dle ČSN EN 12390 5 může přesáhnout 7,6 MPa. Dosažením co možná nejvyšší porozity však zákonitě negativně ovlivňuje pevnost materiálu a výsledný materiál tedy dosahuje pevnosti těsně nad hranicí 6,3 MPa. Výsledky obecně dokazují, že nejvíce je pevnost materiálů ovlivněna poměrem SiO2/Al2O3 a množstvím alkalického aktivátoru. Z výsledků vyplývá, že alkalicky aktivované materiály (AAM) na bázi strusky dosahují i více než dvojnásobné pevnosti analogických materiálů na bázi elektrárenského popílku. Velikost pórů materiálů připravených z tříděných surovin s velikostí zrna od desítek po lehce přes sto mikronů se ve většině případů pohybuje v rozmezí desetin ž jednotek mikronů, v případě výsledného materiálu je to pak přibližně 0,2 mikronu. Celková porozita lisovaných těles se pohybuje těsně pod 40 %, což je v tomto případě téměř dvojnásobek ve srovnání s totožnými materiály na bázi netříděných surovin. Výsledky rovněž ukazují, že materiály na bázi strusky vykazují nižší porozitu než ty na bázi popílku, což je patrně způsobeno rozdílnou morfologií částic obou materiálů – částice strusky jsou nepravidelně hranaté a částice popílku kulaté. V průběhu experimentální činnosti byla pozorována tvorba výkvětů u materiálů na bázi elektrárenských popílků. Pomocí Energo-disperzní spektroskopické analýzy (EDS) byly výkvěty identifikovány jako hydroxid sodný procházející karbonatací za účasti vzdušného CO2. Test permeability vyžadoval, kvůli velmi jemné povaze porézní struktury, přípravu asymetrických filtračních přepážek. Tyto přepážky dosáhli propustnosti 138 L/h.m2.bar pro vodu a 1320 L/h.m2.bar pro vzduch.

This thesis deals with a design of an electrical drive for a sliding side door. Goal of the thesis is to design of a frequency converter for an asynchronous motor with a gearbox. In the first part, the power supply for the freqency converter is solved in form of a single phase rectifier. Power section is solved by an integrated module IKC10H60GA manofactured by Infineon. The control board is provided with circuits for communication between the processor and the power section. Auxiliary power supply is designed as a fly - back converter. The drive of the converter is realized by STM32 Nucleo - 64 board. The design of the converter and drive algorithm are described in detail.