|
|
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...
|
|
|
The effect of artificial weathering on overburden properties
Zadinová, Radka ; Bartuška, Martin (referee) ; Frouz, Jan (advisor)
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.
|
|
|
Influence of material base of coating systems onto wood durability
Bednářová, Ilona ; Petránek, Vít (referee) ; Vaněrek, Jan (advisor)
The thesis deals with the influence of the base material of the coating systems for wood durability when we exposed them to external conditions. The theoretical part is devoted to wood durability and weather resistance with a detailed description of the tests the durability of coating systems. A substantial part of the theory is devoted to description binder component of the coating material. In the practical part was performed the experiment, which examined the influence of the thickness of the coating system, the type of coating material (paint or lasure) as well as the type of binder (water dispersion with an alkyd or acrylic resin, respectively solution coating system with the alkyd resin). All coating systems were exposed to natural and artificial durability tests. The criterions for evaluation were chosen differences of colours.
|
|
|
Modulus of elasticity of natural stone
Hoduláková, Michaela ; Cikrle, Petr (referee) ; Kocáb, Dalibor (advisor)
The value of the modulus of elasticity of concrete depends on the concrete composition (particularly on the aggregate used). The contemporary construction industry literature lacks comprehensive studies of the modulus of elasticity for each type of the rock stone. Therefore, this study focuses on testing and comparing the modulus of elasticity of selected types of rock stones used for the production of crushed coarse aggregates into the concrete. The modulus of elasticity are determined by static and dynamic methods. The work also deals with the modulus of elasticity of granite in different stages of weathering.
|
|
|
Optimizing requirements for wood coatings
Bednářová, Ilona ; Petránek, Vít (referee) ; Vaněrek, Jan (advisor)
The work deals with wood coating systems. It is focused on the theoretical division of paints due to different aspects, moreover on testing of wood coating systems. In the practical part of the work, the experimental work regarding the influence of weather conditions onto durability of different wood coatings system was preceded. They were compared two different coatings within the basic tests in different environments.
|
|
| |
|
| |
|
| |
|
|
Impact of weathering on chemical and morphological changes in stabilized polymers
Pospíšil, Jan ; Pilař, Jan ; Billingham, N. C. ; Marek, Antonín ; Kruliš, Zdeněk ; Nešpůrek, Stanislav ; Habicher, W. D.
Photooxidation, considered as the principal component of natural and accelerated weathering, affects together with oxygen,oxidizing and acid atmospheric pollutants durability of stabilized polymers by changing their chemical and supramolecular structure and influencing efficiency of stabilizers. Effects of the harshness of accelerated photooxidation, negative influences of atmospheric pollutants, heterogeneity in polymer oxidation together with formation of concentration gradients in stabilizer consumption and spatial distribution of stabilizer sacrificial transformation products are outlined. The data give more information on processes accompanying testing of stabilizer polymers and help to minimize misleading influences from over-accelerated tests.
|
|
| |
guest ::
