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The effect of artificial weathering on overburden properties
Zadinová, Radka ; Frouz, Jan (advisor) ; Bartuška, Martin (referee)
Surface mining of coal cause massive changes of landscape. Dumps, heaps and tailings created vast areas in post mining landscape. Soil formation is influenced by the weathering process. Sample-the most common substrates have been subject of accelerated weathering. Samples were watered by distilled water, left to soak in, then froze, thaw and dried. This cycle was repeated twenty times. Before the experiment and after experiment pH, conductivity, organic matter loss on ignition, grain size and water absorption were measured. Before and after the experiment were tested for toxicity to plants using yellow mustard seeds (Sinapis alba). Accelerated weathering showed the possible development of weathering spoil substrates over time namely shift of pH towards neutral value, and increase in water holding capacity, despite of this no changes in plant toxicity in toxic substrates were found.
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Permeability of sandstone surfaces and water flow in shallow zone of ruiniform sandstone landscape
Sysel, Ondřej ; Slavík, Martin (advisor) ; Tesař, Miroslav (referee)
Water in porous rocks (e.g. sandstone) plays a fundamental role in their disintegration. However, the places where water enters the sandstone rocks are somewhat overlooked. At two sites in the Český ráj region, I use Karsten tube to measure capillary water absorption (CWA) of natural sandstone exposures and, using TDR (Time Domain Reflectometry) method, I study movement of water in a shallow zone of ruiniform sandstone landscape. The CWA differed up to four orders of magnitude at a distance of tens of meters, mostly depending on the type of the surface. The highest CWA was measured at highly weathered surfaces, the second most absorbent were less weathered surfaces covered with a biologically-initiated rock crust. The horizontal surfaces on the tops of the rock formations were even less absorbent, probably due to clogging by fine particles from soil. Surfaces covered with iron crust were the least absorbent. The differences between those surfaces are significant. After simulated infiltration, the maximum rate of the propagation of the wet front in the sandstone was from 5,5.10-6 do 1,9.10-4 m.s-1 measured by TDR. The water propagated at this rate only to a certain depth (the first tens of cm), but then the propagation stopped or slowed down rapidly. From a long-term measurement of volumetric...
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The optimization of the wood polymer composite composition regarding its utilization in building structures
Benešová, Anna ; Pospíšil,, Ladislav (referee) ; Ďurica,, Tibor (referee) ; Bodnárová, Lenka (referee) ; Vaněrek, Jan (advisor)
Wood-polymer composite is a relatively new type of material that combines shattered wood mass and a thermoplastic polymer. This material is utilized especially as an alternative to hard wood in the area of non-bearing exterior elements, as it reaches better properties in terms of the basic durability and low maintenance. Raw material composition and processing of the composite enable to provide a significant modification with further matters leading to an improvement of the end-product properties. Research and development in this field focuses predominantly on the utilization of such modifying additives that either enhance the resistance to weathering or are of the recycled nature, as a significant part of the raw material mixture comprises the constituent obtained from non-renewable resources. The aim of the thesis is the evaluation of the influence of the wood-polymer composite modification separately at two levels. First of them is the modification to matrix by using a recycled polymer, the second one comprises the modification of the wood flour with a secondary spherical filler. Both types of modified composites have been assessed in terms pf the prime characteristics and the resistance to adverse ambient.
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Optimization of methods for determining the durability of wood coating systems
Škvařil, Michael ; Žák, Antonín (referee) ; Vaněrek, Jan (advisor)
The bachelor thesis deals with the optimization of methods for determining the durability of wood coating systems. The theoretical part deals with a detailed analysis of wood coating systems, including the specification of their composition, especially with a focus on modern water-borne coating systems. In the practical part an experiment was carried out, where on the selected types of coatings applied to lumber was performed analysis of selected durability parameters of coatings after exposure to short-term and long-term exposure to degradation factors
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Determination of the age of secondary uranium minerals using 230Th/234U in selected localities of the Bohemian massif
Roll, Michal ; Goliáš, Viktor (advisor) ; Mizera, Jiří (referee)
This thesis is focused on prominent uranium deposits in Czech Republic and their secondary uranium mineralization. Main goal of this thesis is to analyze collected minerals and to determine their ages. Next step is to prove or disprove hypothesis that this secondary uranium minerals are products of Quaternary glacier weathering. As a suitable analytical method, an alpha spectrometry was used and the age was calculated by 230 Th/234 U ratio. Firstly, chosen methodology was verified with admixture of reference material PU1 (Přibram uraninite) in secular equilibrium and internal standard, both with known activity. Analyzed spectra confirmed that some of the samples lay on the very edge of datability, especially in case of PL1 and GF1, both samples are very young, so they easily could be products of anthropogenic activity (changed environment due to mining works). On the other hand, in case of sample GF3, the age was successfully determined, although it is also quite young phase. In case of samples ME3, ME4 and ME6 was used threshold dating method, because they were considered to be too old for age calculation. The rest of the samples chosen for age determination was analyzed without further complications. Based on the age and geological setting, samples GF3 (3 725 ± 845 years), JE1 (10 655 ± 1 795...
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Greisens of Slavkovský les and their use as building and sculptural stone
Kocíková, Pavla ; Přikryl, Richard (advisor) ; Kuchařová, Aneta (referee)
Use of greisen - a rock mined primarily for (Sn-W) ore components - in sculpture and construction industry is typical for the Slavkovský les area and its surroundings. Material mined in the greisenized granite stock near Prameny for construction purposes was the source of stone used for a valuable Baroque sight - the Holy Trinity column in a nearby town of Teplá. Samples collected in the abandoned construction stone quarry were analysed for the study of properties of the original material mined in the locality Prameny. These samples were compared with the material collected from the monument in the pre-restoration research to prove the source locality of the original material. Provenance of the original material was determined on the basis of qualitative and quantitative petrographic and micro-structural characteristics. Micro-structural petrographic parameters of the studied samples were determined by the microscopic study using the Petrographic Image Analysis (PIA). Distribution of accessories and micro-structural characteristics were observed using the cathode-luminescence. Conventional index and mechanical parameters with respect to the use of the material in construction industry and sculpture were determined for the material collected in the abandoned quarry. Studied material collected in the...
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In situ weathering experiments of sulphides and silicates
Jarošíková, Alice ; Mihaljevič, Martin (advisor) ; Drahota, Petr (referee)
Weathering is a natural process which is occuring on the Earth's surface. Its effect on minerals and other materials is significant. Besides mechanical alteration, the result of weathering can reach the chemical reactions, which can lead to contamination of the environment (e.g. ground water and soils). Not only for this reason has weathering become an object of intensive studies. In situ weathering experiments are one way of research. The aim of this bachelor thesis is to review the advantages and disadvantages of these experiments, to describe their course and the complications which can happen during the experiments, and how to use knowledge of these observations. Attention is also focused on several concrete experiments which were concerned with the weathering of sulphides and silicates, and where it is possible to observe these things on them.
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Comprehensive study of the sandstone rock forms deterioration (Case study: Pravčická brána Arch, Bohemian Switzerland National Park)
Vařilová, Zuzana ; Přikryl, Richard (advisor) ; Vilímek, Vít (referee) ; Mikuláš, Radek (referee)
This PhD thesis contains the results of comprehensive research into the Pravčická brána Arch and surrounding sandstone massifs with focus on gaining more knowledge about natural dynamics and evolution of this rock formation, its current level of stability and the weathering processes it displays. Non-destructive methods were used for this comprehensive study; these ranged from detailed field documentation to monitoring temperature regime of the rock and included application of a geophysical survey and control monitoring of the course of arch body deformation. Laboratory testing was carried out for strength parameters and salt efflorescences together with weathered sandstones were analysed for chemical compounds. Main operating factors were monitored simultaneously, which particularly involved changes in external temperature, degree of sunlight and chemical composition of rainfall. Conventional as well as entirely new assessment procedures were used in synthesis and interpretation of the data collected, including knowledge of nonlinear dynamics of complex systems. The survey was designed to fully respect the protective conditions of the site, to make follow-up activities possible in future and to monitor any possible negative changes in the rock massif. The main results incorporate description of...
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Origin and evolution of silcretes
Kohoutová, Iveta ; Zachariáš, Jiří (advisor) ; Adamovič, Jiří (referee)
Summary: Silcretes are rocks with high content of SiO2 (usually more than 90 wt. %) formed by mobilization of SiO2 during weathering processes. Silcretes formed near the Earth's surface by soil weathering in warm and humid climate are termed as pedogenic silcretes. Another type of silcrete is groundwater silcrete, whose origin is usually associated with the groundwater table and depths of 5-50 m below the surface and arid to semi-arid climate. The third type of silcretes is associated with evaporites. Its genesis is complicated; as well it is difficult to date this silicification. There are four types of silcrete textures: GS-, F-, M-, C- textures; the most common is the F-texture. In the Czech Republic silcretes are more known under the term "sluňáky" or "quartzite". Indeed, in every country where they occur, have their own specific name. Silcretes are essentially composed of SiO2, minor constituents represent heavy minerals and/or feldspar. Cement is mostly α-quartz, chalcedony and opal. Average thickness of silcretes is 1-3 m, rarely 5 meters. Main source of SiO2 is chemical weathering of silicate minerals or quartz dust grains carried by wind and deposited on natural barriers, like blades of grass. There are two models of silcrete formation: lateral and vertical transport model SiO2. Sedimentary...
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Microforms of sandstone relief and their using in relative dating
Krbcová, Klára ; Křížek, Marek (advisor) ; Engel, Zbyněk (referee)
Microforms and mesoforms play the main role in the sandstone relief. Their origin is conditioned by some processes, the main are weathering and erosion. Based on the background research, the deffinition, classification, diagenesis and occurrence of sandstones was described. The second part of the bachelor thesis is focused on the mechanism of weathering and erosion. The microforms and mesoforms of the sandstone relief were divided into groups according to the guiding process of their origin. The description of the sandstone forms, the way of their origin, the stage of development and their extension were described. In the practical part of the bachelor thesis, the microforms in the gorge Apatyka in CHKO Kokořínsko were analyzed. The practical part was focused expecially on honeycombs, because their extension in the gorge is huge and they enable the complex analyse of their location in the gorge and in the rock outcrops. Using suitable methods it was found, that the honeycombs are located primarily in the eastern quadrant, their coverage decrease with the decreasing height of the rock outcrops and their presence in the lowest and the highest parts of the rock walls is limited. The second part of the fieldwork was focused on the relative dating of the parts of the gorge with honeycombs. The odlest part of the...
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