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The comparison of testing methods using for determining the frost resistance of concrete
Kněbort, David ; Vymazal, Tomáš (referee) ; Kocáb, Dalibor (advisor)
The diploma thesis deals with the possibilities of evaluating the degradation of mechanical resistance of non-air-entrained concrete in the structure by frost cycles. The first part is focused on concrete, its resistance and test methods. This is followed by the definition of frost resistance, the effects of freeze-thaw on concrete at all stages of its service life and the possibilities of determining freeze-thaw resistance according to current standards. It describes in more detail selected test methods for determining frost resistance. In the practical part, it focuses on the determination of degradation resistance of test specimens made in molds and taken from the structure using reference and non-reference methods. In conclusion, it compares the different test methods and their suitability for the determination of freeze-thaw resistance.
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Diagnostic methods for the evaluation of the state of timber structures
Dvořáčková, Soňa ; Anton, Ondřej (referee) ; Heřmánková, Věra (advisor)
This Bachelor´s thesis is focused on diagnostics methods which are destructive, semidestructive and non-destructive. Thanks to these methods, we find out features and characteristics of the material. In the thesis, there is performed diagnostic measurement on a wooden beam and comparing of the results from the method of thorn resistance placement and the results from wood strength measured along the grain. At the end of the thesis there are mentioned statistics calculations.
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Design of reinforced concrete structure of administration building
Blažek, Jan ; Girgle, František (referee) ; Šimůnek, Petr (advisor)
The subject of this thesis is the project of the foundational board and of reinforced concrete walls of the underground office building with respect to the limit state of crack width. There is designed the execution of joints of various parts of the construction against infiltration of groundwater into the interior. The drawing documentation of designed parts is performed there. In the theoretical part, there are logged the design principles and implementation of the white tubs.
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The development of grouting for additional sealing of embankment dams
Michalčíková, Magdaléna ; Klablena,, Petr (referee) ; Drochytka, Rostislav (advisor)
Seal of sand or gravel by chemical injection is known and used for a long time. Chemical grouting are however expensive and sometimes the use of cement does not lead to desire effects. So it is trying to find new materials and methodologies injection arrangement works. To achieve savings of chemical products are added to a mixture clay and cement. Clay-cement grouting mix are used not only in order that they are better quality, but also because in this way proposed mixtures have a tendency to penetrate better into incoherent sediments that need additional sealant of chemical injection. For further possible reductions of economic terms the mixture is trying to replace the classic clay. As a suitable substitute for classic clay is to a certain extent the use of secondary raw materials. Above all it is fly ash. As a part of my thesis I deal with the appropriateness use of these materials and examining their properties in the mixture. It was found that by using fly ash were improving consistency of the fresh mixture, reducing the amount of water-cement ratio and reduce shrinkage of the mixture. On the other hand, by using fly ash has been increasing decantation, permeability atc. In the next stage of my work was examined the influence of the quality of cement, lime and liquefaction in the mixture. The aim of thesis is to propose the optimal injection mixture for additional sealing earth dams.
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Development of process parameters for the stereolithography
Vítek, Jan ; Škaroupka, David (referee) ; Paloušek, David (advisor)
This bachelor thesis deals with the search for optimal process parameters to reach a high strength of the Detax Solflex model material, with the DLP (digital light processing) 3D Solflex 650 printer. In the first part of this thesis the principle of printing using a laser and using a DLP projector and their comparison are presented. Further information about materials and impact of the process parameters on a printing are discussed. Based on a knowledge two assumptions were set: influence of exposure time and influence of layer thickness on strength. Firstly, samples were tested by the hardness Shore D test and the results from the test were compared. New samples for the stress test with the optimal set of parameters given by the previous test were printed and tested. Process parameters influence on strength was determined from the achieved results.
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Development of new technology of sand autoclaved aerated concrete with using of secondary raw materials
Ondříčková, Pavlína ; Suchý, Peter (referee) ; Drochytka, Rostislav (advisor)
Autoclaved sand aerated concrete is a modern building material with high thermal insulation properties. Only sand is used as the primary silicate component of aerated concrete in the Czech Republic. For the more favourable economic and ecological properties of aerated concrete, the use of secondary raw materials is used in this work. The secondary raw materials examined included fluidized bed and fly ash, slag and glass recycled. The aerated concrete composite with secondary admixtures was developed under hydrothermal conditions of a laboratory autoclave for 7 and 12 hours at 190°C. From the secondary raw materials tested, a 10% glass recycler additive yielded the highest strength. Other additives that have a positive effect on mechanical properties include SAKO and Oslavany. From the results of the work it is evident that the use of secondary raw materials increases the strength, improves the rheology of the mixture and supports the formation of tobermorite.
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Effect of Cement Bypass Dust on Cracking Tendency of Alkali-Activated Slag during Drying
Krejčová, Marie ; Švec, Jiří (referee) ; Bílek, Vlastimil (advisor)
This bachelor thesis deals with the influence of bypass cement dust on cracking of alkali activated slag. Significant shrinkage and cracking prevent greater use of alkali activated slag. The length changes and strength of the mixtures with different amount of bypass cement dust were measured at various curing conditions. In these mixtures, cracks were observed and their amount was evaluated by image analysis. It has been found that the addition of dust can reduce the amount of cracks. Treating the prisms in a humid environment leads to a reduction of cracks, especially during long-term treatment. In order to improve flexural and compressive strength, it is preferable to use dust as a replacement for part of aggregates and not as a partial slag replacement.
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