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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Podlahové systémy na bázi druhotných surovin z energetického průmyslu / Floor systems based on secondary raw materials from power industry

Kalina, Martin January 2014 (has links)
This thesis deals with the possibility of using secondary raw materials from the energy industry especially the solid residues of high temperature combustion of coal. These materials should be now seen as a material with wide usage especially in the construction industry. One possibility of their usage is a replacement of binding parts in floor systems. The aim is to find the optimal composition of the mixture, which fits all the technical requirements and at the same time reduces the cost of its production. An advanced methods of powder X-ray diffraction analysis, particle size laser diffraction analysis and X-ray fluorescence analysis were used to determine the raw materials. Based on these analysis the experiments were designed focusing on the mechanical properties, the observation of the evolution of hydration’s heat in prepared mixtures and their time of setting and hardening.
22

Vývoj cementotřískových desek s matricí modifikovaného složení / Development of cement-bonded particleboards with modified matrix composition

Konečný, Dalibor January 2014 (has links)
In manufacture of cement-bonded particle boards are in present-days used exclusively wooden particles as filler. This thesis deals with a research of possible substitution of this material, especially of waste emerging by production of CBPB itself. At first is completed a survey of possible substitute fillers and czech and foreign literature, dealing with issues of modification of composition of cement-bonded particle boards. In practical part are tested some treatments of waste and its adding to recipe. Further are analysed the influences of substitution of cement by slag and substitution of wooden particles by recycled fibreglass. By laboratory work with CBPB is monitored the influence of amounts of added wather to fresh mixture and also to properties of finished elements.
23

Testování možností využívání druhotných surovin jako náhrady přírodních kameniv / Testing ways of use of secondary raw materials replacing naturals aggregate.

Vašek, Tomáš January 2014 (has links)
Master's thesis consists of two parts, theoretical and practical. In the theoretical section are listed basic information about alternative aggregates used for concrete mixture, like polystyrene, cinder and recycled concrete. Further, the influence of these alternative aggregates, used as secondary raw materials, on the behaviour and properties of fresh respectively hardened concrete. Possibilities of application concrete containing secondary raw materials are mentioned. In the practical part are experimentally verified physical and mechanical properties of concrete containing crushed waste polystyrene beads, furthermore thermal insulation properties and resistance to elevated temperatures is tested. Influence of heating plant cinder powder as active addition to concrete mixture was tested. As a next is prepared concrete with replacement of coarse aggregate by cinder and recycled concrete and tested. The influence of these secondary raw materials on workability, compressive strength, frost resistance and water permeability of concrete is also defined. The last part of research is focused on recycled concrete such as main material used in mixture of aggregates bonded with cement, dispose for base layers in roads. In conclusion are discussed results from experimental research and summary of knowledge’s about using polystyrene, cinder and recycled concrete as aggregates for concrete mixtures.
24

Vliv aktivních příměsí a jejich dávkování na CHRL ve stáří 28 a 90 dnů. / Effect of active ingredients, and their dosing to CHRL 28,90 days of age

Kodešová, Monika January 2017 (has links)
Subject of this work is to design a batch of concrete with additives, which are to replace the cement of various doses so as to not adversely affect the properties of fresh and hardened concrete and simultaneously withstand the environment XF.
25

Kompozitní materiály se silikátovou matricí do prostředí vysokých teplot / Composite materials with silica matrix in the environment of high temperatures

Lisztwanová, Ewa January 2017 (has links)
This thesis deals with the study and design of composite materials based on silica matrix suitable for extreme conditions, eg. for the repair of concrete structures with anticipated increased risk of fire. The theoretical part summarizes basic knowledge concerning the fire resistance of structures and the behavior of the composite system during extreme conditions. Theoretically oriented section also contains information on alkali-activated materials and their use in high temperature environments. Based on the evaluation of the theoretical part of the experiment were designed and tested different types of composite materials with increased content of raw materials from alternative sources. Laboratory research has been based on testing of basic physico-mechanical parameters including phase composition and microstructure of the proposed formulations before and after thermal exposure of 1200 ° C. Also considered was the effect of different cooling conditions.
26

Vliv iontů na účinnost přísad redukující smrštění v alkalicky aktivovaných systémech / Influence of ionts on the efficiency of shrinkage reducing admixtures in alkali activated systems

Vašíčková, Kateřina January 2017 (has links)
Alkali activated materials, especially when activated with waterglass, are subjected to substantial drying shrinkage that hinders their broader industrial application. The effect of shrinkage reducing admixtures (SRA), based on poly(propylene glycol), on drying shrinkage of alkali activated blast furnace slag (BFS) mortars was studied. The aim of this thesis is to determine the efficiency of SRA as well as the influence of different type of alkali activator with varying silicate modulus on drying shrinkage characteristics. It was observed that the high amount of alkalis positively influenced the effect of SRA. The higher the amount of alkalis, the lower the drying shrinkage was. It also caused more water to be incorporated in the alkali activated structure and prevent it from evaporation. Thus, the weight change of such mortars was the lowest. Reduced effect of SRA on mechanical strength properties was observed in mortars with low amount of alkalis which was connected with delayed hydration resulting in insufficient amount of created C-S-H gel. The presented thesis further discussed and underlines the role of different kinds of alkali ions as well as their amount on the properties of alkali activated BFS systems.
27

Vliv různé technologie mletí a mechanické aktivace na vlastnosti hydraulických pojiv / Effects of the different grinding technology and of mechanical activation on the properties of hydraulic binders

Hladík, Václav January 2018 (has links)
This diploma thesis mainly tracks the effect of grinding technology on the final properties of portland cement and selected pozzolanic materials. For grinding of portland cement, was also observed the effect of storage time on the final mechanical properties and hydratation process. Pozzolan activity of selected materials was monitored by evaluation of the reaction with CaO by differential thermal analysis.
28

Lehké malty s obsahem alternativních surovin odolné působení nepříznivých vlivů / Lightweight mortars with content of alternative raw materials and resistant to adverse effects

Morkusová, Kristýna January 2018 (has links)
This diploma thesis describes research and following development of lightweight cement mortars with alternative raw materials. Attention was focused on study of the effects of extreme influences such as high temperature (up to 1200 °C), freeze-thaw and agressive sulfur dioxide. Verification of durability of developed mortars was realized using physical and mechanical tests (density and strength), physical and chemical methods (computed tomography) and scanning electron microscopy. Assessment of durability was realized in a longer period of time (90 days).
29

Vliv ohybového namáhání na elektrické vlastnosti alkalicky aktivovaných struskových kompozitů / Effect of flexural loading on electrical properties of alkali-activated slag composites

Šimko, Lukáš January 2018 (has links)
Ordinary concrete is the most commonly used building material, but nowadays the requirements for low energy consumption, durability of structures together with their easy diagnostics as well as ecological production raises. This thesis deals with cement and aluminosilicate composites with content of conductive fillers, which allows to monitor the change in electrical properties, most commonly electrical resistance in dependence on mechanical stress. In the experimental part of the thesis, test beams were produced based on alkali-activated slag with content of carbon nanotubes, graphite powder, carbon black and carbon fibre. The beams were subjected to flexural loading in a three-point bending configuration and the shift in electrical resistance was monitored.
30

Senzorické vlastnosti alkalicky aktivovaných struskových kompozitů při namáhání v tlaku / Self-sensing properties of alkali-activated slag composites under compressive loading

Míková, Maria January 2019 (has links)
Production of construction materials requires a large amount of energy. That can be decreased by using of waste materials. This thesis deals with the self-sensing properties of composites. It presents electrical properties of building materials and their measurement. In the experimental part, the influence of conductive fillers on the self-sensing properties of aluminosilicate composites was examined. Test cubes were made of alkali-activated slag with a content of graphite powder, carbon black, carbon fibers, steel fibers or carbon nanotubes. The fractional change in resistence during cyclic compressive loading was monitored.

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