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Effect of the composition of alkaline activator on the properties of hybrid cements
Šimko, Lukáš ; Vyšvařil, Martin (referee) ; Rovnaník, Pavel (advisor)
Building industry, especially production of Portland cement is the most ecologically and energetically demanding sector. Therefore, there is an effort of using waste products of energy industry as a (partial) substitution of conventional building materials. This bachelor thesis deals with the possibility of using the power station fly ash as a major part of mixtures with Portland cement, and therefore as a hybrid cement. In the experimental part, the influence of silicate module on the characteristics of mortars, whose binder is composed of 20% of Portland cement and 80% of fly ash from Dětmarovice power station, is examined. It further deals with influence of composition of alkaline activator on its characteristics. Its properties are examined in terms of porosity, strength and microstructure. Size and distribution of pores are examined by means of mercury intrusion porosimetry and evaluation of microstructure is based on scanning electron microscopy.
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New possibilities of using superabsorbent polymers in cement composites
Holubová, Petra ; Melichar, Jindřich (referee) ; Černý, Vít (advisor)
The work deals with the influence of superabsorbent polymers (SAP) on the structure and properties of cement composites. SAPs excel in their unique ability to hold large amounts of water. This property can be used in hydration processes for internal curing of concrete. Two types of mixtures were tested in cement paste, which were further modified by two types of SAP. SAPs were always used in two dosing modes (dry, in suspension). The samples were then stored for 28 days in a laboratory conditions, respectively. in an conditions with a temperature of 30 °C. Physical and mechanical properties, such as compressive strength, flexural tensile strength and bulk density, were determined. The addition of SAP to the mixture resulted in an increase in tensile strength of almost twofold. It can therefore be concluded that SAP helped with hydration processes.
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Study of influence of secondary raw materials on mechanical resistence of the industrial floors
Figala, Petr ; Bydžovský, Jiří (referee) ; Drochytka, Rostislav (advisor)
Secondary raw materials are nowadays increasingly used as materials in many sectors of the construction industry. This thesis evaluates current state of industrial floor systems and their final adjustments to increase its mechanical and chemical resistance. At the same timethis thesis focuses on the possibilities of using secondary raw materials in the development of new industrial floors. The goal is to partly replace the silicate binder in the raw material mix of cement screed with a secondary raw material to achieve the same or better physical and mechanical characteristics. This part is also verified experimentally, and its conclusion is to design an optimal recipe of screed by using secondary raw materials.
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High-performance concretes based on the secondary raw materials
Sáček, Josef ; Brandštetr, Jiří (referee) ; Šoukal, František (advisor)
This work is devoted to study of physical-mechanical properties and structure of high performance concretes (HPC) based on portland cement. The attention is focused on possibility of substitution of economic high-cost components of concrete with utilization of secondary raw materials or cheaper components. Properties of raw materials and their influence on whole quality of concrete were tracked by various methods. Mechanical properties of prepared HPC samples were tested especially (compression and flexural strength) with further microscopic study of structure. Isoperibolic calorimetry and X-ray powder diffraction method were also used for concrete characterisation. These methods allowed to determine the influence of raw materials on prepared HPC and to carry out a certain optimization among price and quality of this material.
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Vorm conveyor
Mazálek, Karel ; Jonák, Martin (referee) ; Škopán, Miroslav (advisor)
This bachelor thesis consists of calculations, design and drawings of an inclined screw conveyor used for transporting ash from the powerplant. The technical report contains basic calculations as well as selected strength calculations. Drawing part consists of assebly drawing and welding subassembly of trough end. KEYWORDS
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Effect of fly ash on the durability of concrete
Vašek, Tomáš ; Kulísek, Karel (referee) ; Hela, Rudolf (advisor)
Bachelor thesis consists of two parts, theoretical and practical. In the theoretical section provides basic information on the manufacture of fly ash, development and principle of High Volume Fly Ash Concrete and view on this type of concrete in the Czech Republic. Listed below are the world´s knowledge of conduct of durability and potential problems that can act on them. The theoretical part ends with summary of the utilization of fly ash in various areas of construction industry. In the practical part compares the characteristics of each recipe containing fly ash with recipe containing only Portland cement. Finally, is evaluation of results of practical part and influence on the durability of fly ash concrete.
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Frost susceptibility of soils and waste materials to pavement subgrade
Sokolová, Veronika ; Mondschein,, Petr (referee) ; Stehlík, Dušan (advisor)
Destruction of road constructions due to the frost is in locations with temperatures under the zero a problem which leads to permanent deformation. The theoretical part of this thesis deals with the freezing process of the pavement and its subgrade. It presents methods for determining the rate of frost susceptibility in both the Czech Republic and abroad. Describes the materials used in the subgrade of roads and their suitability in terms of frost susceptibility. The thesis closely examines the fly-ashes, their properties and possibilities of using in the construction industry. The practical part of the thesis focuses on the performance of direct laboratory frost heave tests, immediate bearing index tests, California bearing ratio tests and cyclic load triaxial tests to determine the modulus of elasticity. Tests are carried out on the soil, the soil mixtures with certain percentages of fly ash from different sources at the same soil treated with lime. Then the results are compared and dependence between the measured characteristics of materials is created.
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Research of effective use and activation of activ concrete additions
Mikhailova, Olesia ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The theoretical part describes the admixtures that are used in cement replacement. Here also summarizes the findings on the influence of granulomentry, grain shape and fineness of admixtures on the density of the cement matrix. The practical part is experimentally verified the influence of fineness admixtures and grain size on the mechanical properties of concrete. Also, the rheological properties of cement are compared with admixtures depending on the type and dosage and time.
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Dust separators for small power boilers
Szweda, Martin ; Baláš, Marek (referee) ; Milčák, Pavel (advisor)
This thesis is divided into two parts. The first part of this thesis contains research on pollutants, separators and its legislation, while this part is focused on dust particles and their separation behavior. This is followed by a search on the different types of separators that can be used for small power boilers. The second part is followed by an experimental part, where the practical efficiency of the given separator is verified and then the measured values are compared and the result is evaluated. The results are used to determine whether the separator used is suitable for the separation of biomass for low-power boilers.
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