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Průša, David ; Žižková, Nikol (referee) ; Čermák, Jan (referee) ; Šuhajda, Karel (advisor)
In construction practice, microwave radiation is widely used for drying building materials, remediating damp masonry or sterilizing biotic pests that have invaded building structures. Another, albeit less frequent, use may be, for example, in accelerating the solidification of materials and components, where the time required to obtain the handling strength is reduced due to the effect of microwave radiation. The available scientific and technical literature indicates that some materials, such as brick elements, do not change their physical and mechanical properties when exposed to microwave radiation for moisture remediation, although this has not yet been sufficiently verified, and, in contrast, that there is a significant change in properties when microwave radiation is used to accelerate the setting of fresh mixtures, such as those containing a cementitious binder matrix. This thesis builds on many years of research in the area, complements and refines existing information, provides new insights into the mechanical and physical properties of commonly available building materials that have been exposed to controlled microwave radiation, and compares them with reference values. It also provides an opportunity for further experiments that can build on this research. The experimental research was conducted on two independent sets of samples. The first experiment was carried out on a set of clay brick samples, using tests according to European standards, and focused on the effect of microwave radiation on compressive strength and water absorption. The experimental specimens were exposed to moisture followed by exposure to microwave radiation for drying and then compared with reference specimens. The data from these experiments suggest that microwave radiation can be used for the rehabilitation of brick elements and there is no significant change in the resulting mechanical properties with respect to the initial condition. The second experiment was carried out on a set of concrete mixtures, where the curing process was accelerated using microwave radiation, and the mechanical and physical properties obtained were compared with those of reference specimens. The data from this experiment suggest that microwave radiation can be used to accelerate the curing of concrete specimens, thereby obtaining the handling strength in a relatively short time, but a reduction in the resulting strength can be expected compared with reference specimens.
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Difuzní vlastnosti OSB desek v důsledku zasažení nadměrnou vlhkostí.
Žižková, Lucie ; Vertal', Marián (referee) ; Chybík, Josef (referee) ; Bečkovský, David (advisor)
The presented dissertation focuses on the change of diffusion properties in oriented strand board (OSB) panels after exposure to excessive moisture. OSB panels undergo a change in their diffusion properties after being affected by excessive moisture and subsequently dried, causing them to deviate from the original design of the wooden wall structure. The aim of this study is to describe the experimentally measured change in diffusion properties and incorporate it into the composition of a real wooden wall structure, evaluating its performance through computer simulation. The introduction of the dissertation provides the theoretical basis for the experimental section, which includes measurements of water absorption, diffusion properties, and the risk of mold growth. The experimental section describes the approaches and methods used to achieve the objectives of the dissertation. The measurements were conducted on test samples of OSB panels in the laboratories of the Institute of Civil Engineering. After being exposed to excessive moisture, the test samples were dried using two drying methods. The dried test samples were placed in testing assemblies, where diffusion was measured using the dry cup method. The measurements were carried out in two stages, with more than 80 samples measured in each research stage. In the final part, the measurements are evaluated through graphs. The change in diffusion properties was then incorporated into the composition of a real wooden wall structure and assessed using computer simulation, which is more commonly used in practice according to ČSN 73 0540 (Czech Technical Standard).
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New trends in pavement maintenance
Březina, Ilja ; Stryk, Josef (referee) ; Hýzl, Petr (advisor)
The diploma thesis is dealing with the topic of new trends in asphalt road routine maintenance with a focus on new possibilities to repair damaged road surface, especially potholes and cracks. In the diploma thesis, a new advice which uses microwave heating in resurfacing asphalt roads was developed with the aim to observe its effectiveness and the optimal repair time. The obtained results were consulted with the producer of the equipment in order to utilize this new technology for repairing potholes and cracks on asphalt road surface in standard practice.
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Interaction of microwave radiation with moisture in porous building materials
Paťha, Martin ; Šuhajdová, Eva (referee) ; Šuhajda, Karel (advisor)
This thesis deals with interaction of microwave radiation with wet in porous material. It examines the distribution of the temperature field, the efficiency of the method and the financial demands of the method. The most important part of this thesis was an experiment, from which all important values ??were based. The first part deals with the necessary theory and the second part is the experiment itself. The experiment was carried out for three levels of material wet. Eight samples were used for this experiment, which remained unchanged throughout the experiment. The thesis draws on previous researches that were carried out on this or similar topic.
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Rozměrová stabilizace lisovaných dřevěných dílců
Karásek, Lukáš
This diploma thesis deals with wood plasticization using microwave (MW) radiation for wood densification purposes. In this work, the literary sources of the investigated issue were summarized. The experiment was carried out on test samples of white poplar (Populus alba) with dimensions of 190 x 40 x 30 mm. Microwave plasticization was carried out by passing through a microwave laboratory line at a power of 1.5 kW and a conveyor speed of 0.1 m/min. After plasticization, the test samples were compacted in compression molds by a press by 50%. The compacted test samples were stabilized in compression molds at a temperature of 103°C for 7 days. Using heat modification at 180°C and 200°C improved moisture resistance and reduced swelling. The samples were subjected to density profile analysis to evaluate the plasticization quality.
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Interaction of microwave radiation with moisture in porous building materials
Paťha, Martin ; Šuhajdová, Eva (referee) ; Šuhajda, Karel (advisor)
This thesis deals with interaction of microwave radiation with wet in porous material. It examines the distribution of the temperature field, the efficiency of the method and the financial demands of the method. The most important part of this thesis was an experiment, from which all important values ??were based. The first part deals with the necessary theory and the second part is the experiment itself. The experiment was carried out for three levels of material wet. Eight samples were used for this experiment, which remained unchanged throughout the experiment. The thesis draws on previous researches that were carried out on this or similar topic.
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New trends in pavement maintenance
Březina, Ilja ; Stryk, Josef (referee) ; Hýzl, Petr (advisor)
The diploma thesis is dealing with the topic of new trends in asphalt road routine maintenance with a focus on new possibilities to repair damaged road surface, especially potholes and cracks. In the diploma thesis, a new advice which uses microwave heating in resurfacing asphalt roads was developed with the aim to observe its effectiveness and the optimal repair time. The obtained results were consulted with the producer of the equipment in order to utilize this new technology for repairing potholes and cracks on asphalt road surface in standard practice.
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Lepení materiálů na bázi dřeva pomocí mikrovlnného záření
Hlučka, Marek
The thesis delas with the influence of microvawe radiation on shear strength. For this experiment were selected two of our most common wood species which are used in furniture, construction and other industries and fields. Namely spruce wood and beech wood. All species were bonded by water-based dispersion adhesive (coating 150 g/m
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Porovnání hmotnostních úbytků zdravého a mikrovlnně ošetřeného dřeva napadeného dřevomorkou domácí
Hess, Dominik
The bachelor thesis presents a comparison of mass loss and moisture content of samples from Norway spruce (Picea abies), that were dried by different proces -- natural air drying and microwave drying.. All of samples were degraded by wood-destroying brown rot fungi -- Serpula lacrymans -- in the range from two to twelve weeks. Measurements were made every fourteen days. At the end of experiment several samples were selected for the production of microscopical slides, on which one can observe the progressive degradation of the cell wall of spruce wood. The measurements show that the use of microwaves radiation output of 2 kW has a minimal influence on the fungi spread rate and wood degradation. The highest difference was measured after eight weeks, the average mass loss of microwave dried samples was 25.41%, while in natural dried samples only 23.54%.
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