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Chemical and microstructural characterization of the render, sampled from the Garden wall of the US Embassy in Prague 1
Slížková, Zuzana; Frankeová, Dita; Viani, Alberto; Hauková, Petra; Koudelková, Veronika; Svoboda, Milan
2017 - anglický
The aim of the work was to analyze the mortar taken from the Garden wall (US Embassy, Prague 1). Analyzes were performed for the binder and filler characterization and the sample was also dissolved in HCl to determine the mixing ratio.
Klíčová slova:
survey; material characterization; chemical composition; binder and aggregate characterization
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Chemical and microstructural characterization of the render, sampled from the Garden wall of the US Embassy in Prague 1
The aim of the work was to analyze the mortar taken from the Garden wall (US Embassy, Prague 1). Analyzes were performed for the binder and filler characterization and the sample was also dissolved in ...
Microscopic features of cement paste modified by fine perlite
Hrbek, V.; Koudelková, Veronika; Padevět, P.; Šašek, Petr
2017 - anglický
The use of waste material and replacement of binder element in cementitious composites is in focus of material development. Perlite in the construction industry is usually used in form of lightweight aggregate enhancing the insulating performance of concrete. This paper focuses on integration of fine perlite into the cement matrix and possible replacement of the cement binder in the composition of the material. The macromechanical performance of the modified paste is tested on specimens with 5, 10, 15 and 20% fine perlite substitution and pure cement sample. To distinguish the effect of the perlite on the microstructural level, pure cement material and specimen containing 10% of fine perlite are investigated by the electron microscopy. Furthermore, the mechanical properties of individual phases are examined and compared on same samples by instrumented indentation. The presented results enabled estimation of fine perlite impact on the macro and microscopic performance of the material..
Klíčová slova:
perlite; SEM; nanoindentation; mechanical properties
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Microscopic features of cement paste modified by fine perlite
The use of waste material and replacement of binder element in cementitious composites is in focus of material development. Perlite in the construction industry is usually used in form of lightweight ...
Semi-automated assessment of micromechanical properties of the metal foams on the cell-wall level
Krčmářová, Nela; Šleichrt, J.; Doktor, T.; Kytýř, Daniel; Jiroušek, O.
2017 - anglický
Metal foams are innovative porous material used for wide range of application such as deformation energy or sound absorption, filter material, or microbiological incubation carrier. To predict mechanical properties of the metal foam is necessary to precisely describe elasto–plastic properties of the foam on cell–wall level. Indentation with low load is suitable tool for this purpose. In this paper custom designed instrumented microindentation device was used for measurement of cell-wall characteristics of two different aluminium foams (ALPORAS and ALCORAS). To demonstrate the possibility of automated statistical estimation of measured characteristics the device had been enhanced by semi-automatic indent positioning and evaluation procedures based on user-defined grid. Vickers hardness was measured on two samples made from ALPORAS aluminium foam and one sample from ALCORAS aluminium foam. Average Vickers hardness of ALPORAS foam was 24.465 HV1.019 and average Vickers hardness of ALCORAS was 36.585 HV1.019..
Klíčová slova:
metal foam; Vickers hardness; cell-wall; indentation under low loads
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Semi-automated assessment of micromechanical properties of the metal foams on the cell-wall level
Metal foams are innovative porous material used for wide range of application such as deformation energy or sound absorption, filter material, or microbiological incubation carrier. To predict ...
A concept for testing and monitoring of building structures – theoretical case study
Bayer, Jan
2017 - anglický
A mere comparison of measured and analytical deformations, natural frequencies and mode\nshapes provides us with just a small part of the information contained in the data, especially when component- level damage prevention is needed. The presented analysis studies in detail a few criteria for evaluation of measured data, with the example of simulated plane trusses in respect to the ultimate limit state. It demonstrates the high potential of a systematic approach, while combining several criteria, particularly when using simultaneous strain and deformation measurements, as it documents the proposed Relative Mode Difference (RMD) criterion. On the other hand, the study points out the major limitation of practical applications that is caused by unknown inherent uncertainties of various kinds, providing us with the incentive for further experimental research.
Klíčová slova:
testing; monitoring; building structures; ultimate limit state; mode shapes; strains
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
A concept for testing and monitoring of building structures – theoretical case study
A mere comparison of measured and analytical deformations, natural frequencies and mode\nshapes provides us with just a small part of the information contained in the data, especially when component- ...
Research report 2013-11-10 Calcite_SS3
Kumpová, Ivana; Vopálenský, Michal; Vavřík, Daniel
2017 - anglický
Porosity was measured on a irregular sample of calcite, designated Calcite_S43, using the TORATOM device in the Centre of Excellence Telč.
Klíčová slova:
calcite; TORATOM; porosity
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Research report 2013-11-10 Calcite_SS3
Porosity was measured on a irregular sample of calcite, designated Calcite_S43, using the TORATOM device in the Centre of Excellence Telč.
Research report 2013-11-19 Calcite_S43
Kumpová, Ivana; Vopálenský, Michal; Vavřík, Daniel
2017 - anglický
Porosity was measured on a irregular sample of calcite, designated\nCalcite_S43, using the TORATOM device in the Centre of Excellence Telč.\n
Klíčová slova:
calcite; TORATOM; measuring
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Research report 2013-11-19 Calcite_S43
Porosity was measured on a irregular sample of calcite, designated\nCalcite_S43, using the TORATOM device in the Centre of Excellence Telč.\n
Research report 2013-11-19 Calcite_S11
Kumpová, Ivana; Vopálenský, Michal; Vavřík, Daniel
2017 - anglický
Porosity was measured on a irregular sample of calcite, designated Calcite_S11, using the TORATOM device in the Centre of Excellence Telč.
Klíčová slova:
calcite; TORATOM; measuring
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Research report 2013-11-19 Calcite_S11
Porosity was measured on a irregular sample of calcite, designated Calcite_S11, using the TORATOM device in the Centre of Excellence Telč.
Numerical assessment of stability of the ball vibration absorber
Fischer, Cyril; Náprstek, Jiří
2017 - anglický
The ball vibration absorber (BVA) is in principle a heavy ball rolling inside a semi-spherical cavity. It is a convenient alternative to the usual pendulum-based dampers. The dynamics of the real ball absorber is significantly more complicated in comparison to the pendulum one. However, the numerical examination of the non-linear model of the BVA indicates that its resonance behaviour is similar to the spherical pendulum. Despite the theoretical differences, the resonance curves in both cases form similar patterns. It seems that detailed study of both separate cases can provide complementary results, whose parallels appear in the other model.
Klíčová slova:
ball vibration absorber (BVA); non-linear model; resonance
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Numerical assessment of stability of the ball vibration absorber
The ball vibration absorber (BVA) is in principle a heavy ball rolling inside a semi-spherical cavity. It is a convenient alternative to the usual pendulum-based dampers. The dynamics of the real ...
Grid indentation and statistic deconvolution: limitations and accuracy
Hrbek, V.; Koudelková, Veronika
2017 - anglický
The evaluation of heterogeneous materials used in civil engineering on the microscopic level has become important aspect in proper understanding of the macroscopic behavior of the material. This contribution aims at advantages and problems related to the technique of grid indentation and at the evaluation of mechanical properties.
Klíčová slova:
indentation; microstructure; phase; heterogeneity; grid indentation; scanning electron microscopy
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Grid indentation and statistic deconvolution: limitations and accuracy
The evaluation of heterogeneous materials used in civil engineering on the microscopic level has become important aspect in proper understanding of the macroscopic behavior of the material. This ...
Experimental study of horizontal forces of pedestrian dynamics
Urushadze, Shota; Pirner, Miroš
2017 - anglický
At present similar detailed examination of pedestrian dynamics has been brought about chiefly by the requirements of determining the loads on footbridges. In their case – contrary to bridges – the magnitude of dynamic response is more important than that of static response, as it determines also the serviceability of the footbridge with reference to pedestrian comfort. The forces frequencies of step or strides for different walking velocities is the most important for the further analysis and analysis of the mechanisms.s.
Klíčová slova:
pedestrian dynamics; dynamic response of footbridge; stride strength; stride frequency; step frequency; dynamic coefficient; effects of striding velocity
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Experimental study of horizontal forces of pedestrian dynamics
At present similar detailed examination of pedestrian dynamics has been brought about chiefly by the requirements of determining the loads on footbridges. In their case – contrary to bridges – the ...
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