|
|
Suitability of vitrified lignite bottom ash for composite cements.
Bayer, Petr ; Krátký, Josef (referee) ; Wolter, Albrecht (advisor)
Předložená magisterská práce se zabývá možným použitím vitrifikovaného lignitového lóžového popele jako náhrada slinku v kompozitních cementech. Byly zkoumány vlivy přidaného vitrifikovaného lóžového popele, jeho jemnosti, alkalických roztoků a jejich koncentrací. Byly připraveny kompozitní cementy v souladu s normou DIN EN 197 – 1. V těchto cementech bylo nahrazeno 30 % slinku vitrifikovaným lóžovým popelem. Konkrétně byly připraveny kompozitní cementy s vitrifikovaným lóžovým popelem o jemnosti 5549 cm2/g a 8397 cm2/g. Dále byly přidány alkalické roztoky hydroxidů a síranů vždy o dvou různých koncentracích, za účelem stimulace pucolánové a/nebo geopolymerní reakce. Mechanické vlastnosti připravených vzorků byly charakterizovány mechanickým testováním na prizmách s rozměry 40×40×160 mm, jak je specifikováno v normě DIN EN 196 – 1. Byla provedena nedestruktivní měření dynamického elastického modulu a destruktivní testovaní na pevnosti v tlaku a v ohybu. Distribuce velikosti částic a chemická analýza vstupních materiálů byla vykonána pomocí laserové granulometrie a rentgenové fluorescence. U zatvrdlých kompozitů bylo dále zkoumáno po 2 a 28 dnech hydratace fázové složení s využitím metody rentgenové difrakce a mikrostruktura s využitím skenovací elektronové mikroskopie. Výsledky ukázaly, že mechanické vlastnosti jsou nezávislé na množství přidaných alkálií stejně jako na jemnosti přidaného vitrifikovaného lóžového popele. Nicméně, znatelně nižší mechanické pevnosti byly pozorovány pro vzorky, které byly aktivovány hydroxidy, pravděpodobně kvůli brzké tvorbě silikátového hydrogelu. Vzorky aktivované sírany nedosáhly pevností jako referenční malta.
|
|
| |
|
|
The effect of particles size on the properties of mortars.
Sehnal, Tomáš ; Krátký, Josef (referee) ; Šiler, Pavel (advisor)
The consumption of concrete as a building material is still increasing over the world. Concrete production is closely associated with CO2 and other greenhouse gases emissions. The reduction of these emissions can be achieved by a higher utilization of secondary raw materials in cement mixtures. This bachelor work is focused on the using of secondary raw material, finely ground granulated blast furnace slag and fly ash from fluidized bed combustion and high temperature combustion. The properties of milling pure cement and cement mortars with addition of secondary raw material will be measured. Compressive strength, flexural strength, and calorimetric measurement will be performed for these prepared mortars.
|
|
|
Effect of pH of mixing water on hydration and mechanical properties of cement composites.
Bezděk, Ondřej ; Krátký, Josef (referee) ; Šiler, Pavel (advisor)
This master’s thesis is focused on the effect of mixing water pH value on hydration and mechanical properties of cement composites based on portland cement. Source material was CEM I 42,5 R. Hydration process was analyzed by isoperibolic calorimetry, X-ray diffraction analysis and differential thermal analysis. Compressive and flexural strength was examined as mechanical properties. The samples microstructure was observed by scanning electron microscopy. Influence of mixing water pH value on flexural and compressive strength, retardation of hydration and ratio of individual phases was shown.
|
|
|
Study of the influence of compositon on the mechanical properties of high performance concrete
Veleba, Ondřej ; Šoukal, František (referee) ; Krátký, Josef (advisor)
This work is devoted to study the influence of the composition on mechanical properties of high performance concret based on portland cement. 29 samples of high performance concrete (HPC) warying in composition were prepared. The constituents used for HPC preparation were: cement Aalborg White, silica fume, finelly ground blast furnace slag, finelly ground silica, calcinated bauxite and polycarboxylate based superplasticizer. The mechanical parameters (flexural and compressive strength) of the samples were observed after 7 and 28 days of moist curing. Compressive strength values after 28 days were in the range of 92 to 194 MPa and the flexural strength values were in the range of 7 to 23 MPa (without using of fiber reinforcement). The graphs showing mechanical parameters depending on the mixture composition were constructed and consequently evaluated.
|
|
|
Latexes modified cementitious materials
Vinter, Václav ; Krátký, Josef (referee) ; Šoukal, František (advisor)
In this thesis, the development of mechanical properties and structure of latex modified cementious materials during hydration was studied. Latex modified materials are composites of inorganic cement (portland cement) and organic polymer latex. Preparation, processing and fabrication of the polymer cement material based on portland cement was optimized with aim to reach the most compact structure of the product with the finest mechanical characters. The experimental part was pointed to observe influence of the type and amount of polymer latex with focus on mechanical characters and hydration kinetics with given filling as well as without it. In presented work, the possibility of compaction of the material by high-shear mixing within twin-roll mixer (the prototype for production of MDF composite) was verified. The second part of the labor was aimed to analysis of prepared polymer-cementitious material. For determination of influence of batching of added polymer latex on hydration of cement paste the thermal analysis (DTA/TGA) and infrared spectroscopy of composite was done. At last the microscopic observation by optical microscope was carried.
|
|
|
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.
|
|
|
Introduction of the MST method for the study of interactions between biomolecules
Krátký, Josef ; Szotáková, Barbora (advisor) ; Boušová, Iva (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Bc. Josef Krátký Supervisor: prof. Ing. Barbora Szotáková, Ph.D. Title of diploma thesis: Introduction of the MST method for the study of interactions between biomolecules MicroScale thermophoresis (MST) is currently a recognized method for studying interactions between biomolecules; the method is using directed movement of biomolecules in a temperature gradient, which allows to analyze practically all interactions where changes in analyte properties are possible. This thesis was focused on introduction of the MST method for research of protein interactions with low molecular weight substances focusing on verifying the possibility of using MST in monitoring the interaction of glutathione S-transferase (GST) with selected terpenes ((-)-fenchone, (-)-isopulegole, (+)-isomenthone, (-)-carvone, (+)-carvone, piperitone, and thujone). Another aim was to determinate the properties of terpenes by classical spectrofluorimetric methods and MST. Using spectrofluorimetric methods it was found that terpenes affect the fluorescence of human serum albumin, and they do not affect the fluorescence spectrum of the dye NHS, which is used as a dye for samples for MST. Next part of experimental work was to determine...
|
|
|
Dvoupodlažní penzion s podkrovím
Krátký, Josef
The aim of the thesis is the design of a two-storey house with an attic, in which wood-based materials were used for implementation. The first part is mainly devoted to a literary review of the issue, focusing on the technical requirements needed to design the house, including an introduction to static analysis. The practical outcome of this work is drawing documentation, static report structure, thermal and technical assessment of selected details and 3D visualization object. In the design legislative requirements for accommodation facilities in force in the Czech Republic are respected. The conclusion is devoted to a summary and evaluation of the results of the given issue.
|
|
| |
guest ::
RSS feed.