Prohlížení ČVUT - elektronické publikace dle autora "7ad5cdff-2301-4f39-a8d5-568f2c059583"
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CHLORIDE RESISTANCE OF NANO-PARTICLE REPAIRED CONCRETE
Autor: Šulc, Rostislav; Himmel, Michal; Němeček, Jiří
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2019)This paper describes the results of the experimentally modeled chloride ion penetration into different quality concrete structures with fully developed carbonation. Parts of concrete samples were further treated, to increase ... -
Effect of electric current on porosity of concrete
Autor: Ňachaj, Daniel; Němeček, Jiří; Kouřil, Milan; Keppert, Martin; Němeček, Jiří
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2023)The paper describes the influence of electric current on the porosity of concrete samples after electrically accelerated tests and other electrokinetic treatments. Three different concrete mixtures consisting of CEM I ... -
EXPERIMENTAL AND NUMERICAL INVESTIGATION OF CEMENT PASTE MICROSTRUCTURE AND ITS HYDRATION UNDER SHORT-TERM EXPOSURE TO ACETONE
Autor: Khmurovska, Yuliia; Štemberk, Petr; Němeček, Jiří; Doleželová, Magdaléna
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2020)The solvent exchange methods are commonly used in order to arrest cement hydration reaction. This paper presents preliminary results of experimental investigation of cement paste microstructure under short-term (24 hours) ... -
EXPERIMENTAL STUDIES OF ACCELERATED CHLORIDE TRANSPORT IN CONCRETE
Autor: Zacharda, Vojtěch; Němeček, Jiří
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2019)This contribution deals with the efficiency of electromigration of chlorides used as a repair method for reinforced concrete structures. Experimental studies of accelerated chloride transport tests were performed on samples ... -
Measurement and evaluation of cement paste porosity by electrochemical impedance spectroscopy
Autor: Chalupová, Jana; Němeček, Jiří; Hybášek, Vojtěch; Pommer, Vojtěch; Němeček, Jiří
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2023)Porosity is an important part of cement paste microstructure, which significantly influences the mechanical properties (especially durability and strength) of cement-based materials. Electrochemical impedance spectroscopy ... -
MICRO-MECHANICAL PROPERTIES OF CEMENT AND SLAG COMPOSITES MEASURED BY NANOINDENTATION
Autor: Němeček, Jiří; Němeček, Jiří
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2020)In this study, the micromechanical response of two cementitious composites was characterized by nanoindentation. Pure Portland cement paste and Portland cement with 50 vol. % replaced with granulated blast furnace slag ... -
MICROMECHANICAL CHARACTERIZATION OF CEMENT PASTE MODIFIED BY NANOCLAYS
Autor: Zacharda, Vojtěch; Němeček, Jiří
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2020)This work deals with the comparison of micromechanical properties and microstructure of cement pastes with additives used in concrete to reduce the lateral pressure on the formwork. This work is a steppingstone for broader ... -
Microstructure modification of cement pastes using nanosilica
Autor: Ňachaj, Daniel; Němeček, Jiří; Němeček, Jiří
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2022)The paper describes modifications of cement paste mixtures using nanosilica to affect their physical and chemical properties. Cement pastes from Portland cement CEM I 42.5R with three different substitution ratios of ... -
MODELING OF MONOCRYSTALLINE MAGNESIUM MICROBEAM BENDING
Autor: Němeček, Jiří; Maňák, Jan; Němeček, Jiří
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2018)This paper presents a numerical simulation of a micro-scale experiment on a magnesium alloy. Micro cantilever beams were fabricated using Focused Ion Beam technology in a single crystal of Mg. The cantilever beams have ... -
NANOINDENTATION AND ACCELERATED PROPERTY MAPPING OF PORTLAND CEMENT PASTE
Autor: Němeček, Jiří; Němeček, Jiří; Lukeš, Jaroslav
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2020)This paper presents a new nanoindentation mode: accelerated property mapping (XPM) applied to one year old Portland cement paste. The principle of the innovative method is similar to classical quasi-static nanoindentation ... -
NUMERICAL SIMULATION OF SLUMP FLOW TEST OF CEMENT PASTE COMPOSITES
Autor: Němeček, Jiří; Němeček, Jiří
(České vysoké učení technické v PrazeCzech Technical University in Prague, 2021)This study presents a numerical simulation of the mini-slump flow test performed on the Haegerman table, according to EN 1015-3. The two-dimensional axisymmetrical Volume of fluid (VOF) model is used for the calculation. ...