Ing. Radka Navrátilová, Ph.D.

Ing. Radka Navrátilová, Ph.D.

This article deals with the development of concretes intended to be used as construction materials in the Czech deep repository for radioactive waste. The basic requirements for this concrete are a reduced pH value, which must maintain a constant reduced pH with a value of around 11 in the long term, and mechanical properties comparable to conventional concrete. The raw materials for the production of the proposed low pH concrete come exclusively from the Czech Republic. Material characteristics were measured on fresh mixtures and concrete after 28, 56, and 90 days of curing. In addition to the basic raw materials (aggregate, cement, water), plasticizers, microsilica or slag, and defoaming agents were added to the mixture. The aggregate:binder ratio was approximately 5:1 and the w/c water coefficient was approximately 0.6. The mechanical properties of the final concrete were similar to the reference recipe of conventional concrete (the decrease was less than 10%) and the pH value was even below 11 after 90 days. The issue of a sprayed variant of the LPC mixture was solved within the project.

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Ing. Radka Navrátilová, Ph.D.

Ochrana povrchových vrstev stavebních materiálů je ve stavebnictví velmi důležitá. Omítky, které se používají jako krycí vrstva nosné konstrukce, musí odolávat nejen nepříznivým přírodním podmínkám, ale také třeba mechanickému poškození či korozi, proto se na jejich povrch nanáší povrchová úprava ve formě nátěrů. Tento článek je zaměřen na silikon-akrylátové povlaky. Silikony (polysiloxany) mají velmi dobré materiálové a fyzikální vlastnosti v oblasti ochrany proti degradaci materiálu, ale jsou na druhou stranu dost drahé. Akryláty jsou levnější, avšak méně odolné než polysiloxany. Vzorky povlaku byly měřeny v modulu ATR v infračerveném spektrometru. Výsledkem je vytvoření matematického modelu pro kvantitativní analýzu – kvadratická závislost plochy karbonylového píku na koncentraci akrylátu. Nepřímo by mohlo být možné vypočítat koncentraci polysiloxanu. Ve skutečnosti je ale výpočet koncentrace polysiloxanu problémem kvůli přísadám a příměsím.

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Ing. Radka Navrátilová, Ph.D.

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Ing. Radka Navrátilová, Ph.D.

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Ing. Radka Navrátilová, Ph.D.

Coating materials are used for surface finishing of buildings products and have a protective, appearance and economic function. Silicone materials are used as one of the best, which have excellent physical - mechanical properties. Due to the high price of silicone, in practice they are commonly used in mixtures. Silicone-acrylate coat mixtures are often produced in the industry, which are both high-quality due to the silicone content and cheaper due to the presence of acrylate coatings. The aim of this work is to propose a model that could be used to determine the amount of silicone and the amount of acrylate in coat mixtures. This model is based on the exact identification of the acrylate spectra that are investigated in this article.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

Colored concrete is widely used in contemporary architecture due to its aesthetic potential. Adding a color pigment to the concrete mix opens up for architects other possibilities for work with concrete. They are no longer limited by its natural gray color. Choosing the right type of pigment is essential for quality and long-term satisfaction with the final work, while it is necessary to be aware of certain limits resulting from the natural behavior and nature of concrete. The article characterizes an overview of pigments suitable for coloring concrete mixtures and demonstrates the change in color saturation after exposure to weathering over time. The measurement was performed on experimental concrete samples stained with yellow, red and green pigments

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

This article is focused on changes in the properties of colored concrete due to frost. In contrast to conventional concrete structures, fair-faced concrete is exposed to external conditions and is therefore also prone to degradation of its surface. The durability of the surface layers is mainly reflected in the color saturation and resistance to mechanical damage. Therefore, the paper focuses on measuring the change in color and strength characteristics after 75 cycles of frost resistance. The measurement was performed on concrete samples colored with yellow, red and green powdered metal oxide-based pigments. Based on the results, we can concluded the frost resistance of colored concrete depends primarily on the type of pigment used.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

Předkládané řešení je novou možností jak spolehlivě poměřovat míru chemické a biologické odolnosti omítek nebo obkladů blízké kvality, což je zejména potřebné pro operativní posuzování správnosti korekcí složení materiálu omítek při jejich vývoji nebo výstupních kontrolách jejich výroby.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

V posledních letech vzniká v České republice řada zajímavých realizací z pohledového betonu, či staveb, které jsou doplněné betonovým výrazovým prvkem. Mapový průvodce je rozdělen do několika prohlídkových okruhu dle místa vyskytu staveb.

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Ing. Radka Navrátilová, Ph.D.

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