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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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Determination of the coefficient of linear thermal expansion of sintered PZT ceramics
Šašek, Petr
Působením teploty dochází v materiálech ke změnám velikosti. Toto může být problém v případě, že se jedná o vrstevnatý materiál, kdy jednotlivé vrstvy mají rozdílné vlastnosti. Cílem této studie bylo zjistit součinitel teplotní roztažnosti piezoelektrické keramiky s tenkou stříbrnou vrstvou. Teplotní rozsah byl od -20 do 60 °C, resp. od -30 do 160 °C. Rychlost ohřevu byla 1°C/min. Celkem byly měřeny 3 vzorky. Srovnání tepelné roztažnosti nám ukazuje, že jeden vzorek se liší od dvou vzorků, které mají podobné vlastnosti.
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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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