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Properties of commercially available, ready-to-use mortars for restoration of historic renders and masonry
Janotová, Dana ; Niedoba, Krzysztof ; Gláser, Petr ; Šašek, Petr ; Fabeš, Roman
There is a wide range of premixed, dry mortars, on the market, designed with the reconstruction of historic renders and masonry in mind. The use of such materials has some advantages, including good workability and standard quality, however, due to unknown composition, being a secret of a manufacturer, it is frequently impossible to predict their influence on the substrate and on the ageing. If the ready-to-use mortar is to be applied during the renovation of the historic masonry, it is necessary to know: how close the mortars’ properties match the properties of the original material; will the repair be durable enough and will it degrade faster than the original material. Technical information, provided by the manufacturer, does not contain such data. The only parameters given, are the strength, porosity of hardened mortar and water vapour diffusion coefficient, however, it is not specified in which conditions these values were measured.
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Stanoveni koeficientu délkové teplotní roztažnosti slinuté PZT keramiky
Šašek, Petr
When a material is subjected to heating, a change of its dimensions may occur. This can be a problem, in case that the individual layers have different expansion properties. The aim of this study was to determine the thermal expansion coefficient of piezoelectric ceramics with thin layer of silver. The temperature range was from -20 to +60 °C and for one sample from -30 to +160 °C. The heating rate was 1 °C/min. Three samples were measured. The comparison of thermal expansion shows, that one of the samples differs from the other two, the latter having similar properties.
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Characterization of by-products from the combustion of solid fuels with SEM/EDS and micro-Raman spectroscopy
Šašek, Petr ; Viani, Alberto ; Mácová, Petra ; Pérez-Estébanez, Marta ; Černá, M.
The solid residues from the combustion currently represent a problem that needs to be addressed. Quality products from combustion of solid biomass and coal is significantly different, may contain heavy metals and therefore their application difficult. Total used 4 samples of solid residues from the combustion of solid fuels, where two samples consisted of ash from the combustion of coal, respectively lignite and two samples were made with ash from the combustion of biomass, namely straw and hay. The microscopic analysis was used a scanning electron microscope (SEM) and energy dispersive spectrometry (EDS) and Micro Raman. The qualitative analysis was used in addition X-ray diffraction. Within the microscopic analyses were tested superficially different types of materials.
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