National Repository of Grey Literature 25 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Chemical and microstructural analysis of sandstone samples from the cemetery portal at the Gothard in Hořice
Slížková, Zuzana ; Frankeová, Dita ; Bauerová, Pavla ; Náhunková, Pavla ; Mácová, Petra ; Ševčík, Radek ; Vondráčková, Michaela
Determination of the chemical and mineralogical composition of the surface layer of sandstone and the speed of water transport through the surface of the stone (comparison of the properties of the light ocher surface and the black surface of sandstone.
Chemical and microstructural analysis of brick samples from the object of Zákupy castle horse stables
Frankeová, Dita ; Bauerová, Pavla ; Náhunková, Pavla ; Ševčík, Radek ; Mácová, Petra ; Slížková, Zuzana ; Vondráčková, Michaela
As part of the construction-technical survey, historical brick samples were characterized using thermal analysis (TGA), scanning electron microscopy (SEM/EDS), ion chromatography (IC), infrared spectrometry (FTIR) and physical tests. The results of the tests testify to the good production quality of the masonry elements used. Based on the analyzes carried out, it can be assumed that the observed damage to the bricks is caused by high wetting of the masonry in combination with frost cycles, as well as crystallization cycles of water-soluble salts present in the surface layer of some bricks.
Characterization of injection material Ledan TA1 for the needs of the preservation of the architectural fragment located under the 3rd courtyard of Prague Castle
Slížková, Zuzana ; Viani, Alberto ; Frankeová, Dita ; Mácová, Petra ; Ševčík, Radek ; Fabeš, Roman
For the purpose of restoring a Romanesque fragment of marl nearby the Old Royal palace, a material survey of the LEDAN TA1 product was carried out. The study aimed to assess the compatibility of this preservative material with historic marl masonry.
Survey of salinity of masonry under III. courtyard at Prague Castle
Slížková, Zuzana ; Ševčík, Radek ; Viani, Alberto ; Mácová, Petra
Archaeological architectural monuments in the area under III. in the courtyard of Prague Castle were monitored in 2021 in terms of the extent of salt efflorescences and their chemical composition. Salt efflorescence on the marlstone walls of the church of St. Bartholomew contain sodium carbonate and bicarbonate, sodium sulfate and calcium sulfate. Sodium nitrate and potassium nitrate were also present in some samples. The aim of the research is to propose measures to mitigate the effect of salts on the degradation of historic masonry.
Chemical and mineralogical analyses of the stucco marble „scagliola“ sampled from a decoration part of the historic cabinet placed in the chateau Konopiště (CR).
Slížková, Zuzana ; Mácová, Petra ; Viani, Alberto ; Frankeová, Dita ; Jurkovská, Lucie ; Kozlovcev, Petr
Chemical and mineralogical analyses results focused on the composition of the stucco marble „scagliola“. The material was sampled from a decoration part of the historic cabinet placed in the chateau Konopiště (CR).
Analyses of baroque gypsum based plasters in the Czech Republic – mineralogy and microstructure
Slížková, Zuzana ; Mácová, Petra ; Frankeová, Dita ; Koudelková, Veronika ; Jurkovská, Lucie
Set of ancient gypsum based plasters imitating marble stone in the Czech baroque churches and palaces was analysed for the purpose of the research and restoration of historic plasters. Raman spectrometry was used for identification pigments in gypsum plasters and SEM-EDX analysis for studying microstructure and chemical composition of plasters.
Evaluation of self-healing in concrete by means of analytical techniques
Aspiotis, K. ; Sotiriadis, Konstantinos ; Kumpová, Ivana ; Mácová, Petra ; Badogiannis, E. ; Tsivilis, S.
In the present work, the self-healing process in concrete was evaluated using analytical techniques. For this purpose, two concrete mixes of different composition (one used as reference) were prepared with a W/B of 0.45. The self-healing process was triggered by the introduction in the concrete mix of a commercial expansive admixture (calcium sulfo-aluminate), two dicarboxylic acids, and sodium carbonate salt. After 28 days curing in water, the specimens were artificially cracked (crack width ≈ 400 μm) and then again water-cured for 40 days until self-healing occurred. The progress of self-healing was investigated with a stereo-microscope at 40, 50 and 60 days. The efficiency of the process was evaluated using micro-Raman spectroscopy and X-ray micro-computed tomography (XmCT). Significant reduction in the crack width was observed as a result of filling the crack with calcite generated during the self-healing process. In some cases, the crack was completely healed. The experimental methodology used provided new insights into the evolution of the self-healing phenomenon in concrete.
Quantification of microstructural changes in limestone cement paste stored in sulfate environment at low temperature
Sotiriadis, Konstantinos ; Hlobil, Michal ; Machová, Dita ; Mácová, Petra ; Viani, Alberto ; Vopálenský, Michal
Samples of cement paste based on mixed cement with limestone admixture were stored in a magnesium sulfate solution for 6 months at 5 ° C to monitor the development of sulfate corrosion and its effect on microstructure. The extent of corrosion was evaluated by several different techniques. The paste samples were scanned at monthly intervals by X-ray tomography for non-destructive quantification of the pore structure and extent of damage, along with a description of the phase changes in the microstructure using X-ray diffraction and infrared spectroscopy. Compressive strength testing confirmed the effect of corrosion on the mechanical resistance of the samples. The results show a rapid course of degradation propagating in an irregular band, caused primarily by the formation of expandable sulfur-based corrosion products, the consequent crack formation and loss of internal cohesion of the material. The occurrence of both ettringite and thaumasite and gypsum was confirmed in the damaged parts.
Corrosion products phase identification using micro-Raman and FTIR
Majtás, Dušan ; Mácová, Petra
Phase identification of corroded metal objects might be problematic because corrosion products are usually a complex mixture of different phases. Furthermore, some of present phases may be either semi-crystalline or amorphous. The most suitable procedure is to use X-ray diffraction (XRD), for identification of crystalline phases in bulk, in combination with micro-Raman spectroscopy to obtain information on smaller scale and given location. Micro-Raman spectroscopy identifies crystalline and semi-crystalline phases. The literature also reports of the application of Mössbauer spectroscopy to identify amorphous phases. In this work, the combined use of Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy is evaluated. The methods may be interchangeable to some point. But is it safe to assume that all phases present can be detected?
Iron alloys outdoor corrosion and laboratory simulation - comparison
Majtás, Dušan ; Mácová, Petra ; Kreislová, Kateřina ; Příhoda, J.
Simulation of iron alloy corrosion is widespread used to predict corrosion resistance. The simulation using corrosion chambers or climatic chambers provides reasonable information on corrosion resistance, the corrosion rate however must be compared to real exposition as the corrosion in simulated environment is accelerated compared to real situation. However the composition of corrosion products and its structure is different question. The corrosion products composition is dependent on corrosion process. The phases present are most likely the same, most voluminous hydrated oxides and oxy-hydroxides on the outside where the less voluminous oxides are present in the lower layers. However this macroscopic phase structure may not fully describe the layered structure of corrosion products, thickness of corrosion products or mechanical properties. In the vicinity of crack in corrosion products the structure is more likely to be similar to the structure near the surface.

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1 MÁCOVÁ, Pavlína
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