Možnosti zvyšování trvanlivosti a odolnosti povrchu architektonického betonu vůči působení vnějších vlivů

Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

The purpose of the article was to draw attention to various aspects of sustainable development of the construction and durability of building materials. A special emphasis was put to concrete, which is one of the most used building materials in the present. Elaborated was not only the issue of emissions released by the production of components necessary for fabrication of concrete mixtures, but also a number of environmental, economic and social advantages the use of concrete offers. At the same time, attention was drawn also to the limits of durability, in particular of visible concrete, which can show signs of wear significantly before the final phase of its life cycle. External conditions are one of the most powerful factors affecting the surface layers of buildings. The consequence of their action is degradation of architectural works - function of buildings is preserved but loses its artistic impression. In the context of efforts to minimize negative environmental and economic impact and contribute to sustainable development, the focus was given also to the possibilities of increasing durability of reinforced concrete structures and their surfaces.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

The paper deals with the properties, quality and durability of the exposed concrete. The main part of this paper are characteristic of architectural (sometimes called visible or naked) concrete and the criterion of the quality evaluation of the performed work. This is mainly the colour balance of the subject area, the quantity and the size of the pores, the quality of the raw material and the surface structure. Achieving the quality of architectural concrete is considerably more technologically demanding compared with conventional concrete. This is reflected also in its cost. In conclusion, the problems of surface layers of architectural concrete are summarized. Especially environments can cause faster degradation, reducing the lifetime of the whole construction, but also pointing to one of the main problems in construction, which is technological discipline.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

This paper analyses the structure made from fair faced concrete compared to a conventional concrete sandwich structure with a surface finish in terms of bound CO2 emissions. This article also takes into account the length of service life of the individual constructions. For each of these structures, an analysis for high-performance concrete (HPC) and conventional iron-reinforced concrete (sometime called normal strength concrete NSC) is provided. Due to the current tendency of construction from colored fair-face concrete, tentative calculation of color pigments’ influence on the amount of bound CO2 emissions production is also performed. From the results we can concluded, that The structure made of HPC shows a higher production of bound CO2 emissions, but its declared durability is higher compared to the NSC construction. The use of colored inorganic pigments resulted in an increase in GWP (Global Warming Potential), and the construction of colored exposed concrete shows nearly three times the production of bound CO2 emissions.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

Influence of different type of mould-release agent on surface properties of coloured concrete is presented in this paper. The quality of exposed concrete areas is directly affected by several factors. In addition to the most important factor, which is the influence of the outdoor environment, has the inconsiderable influence on surface properties of concrete manufacturing technology and the used material. This article is focus on roughness and colour intensity of concrete elements. Concrete samples were created in two color variations: yellow and red. Colour was obtained by measuring RGB number (Red-Green-Blue value) on several points on concrete surface. Two kind of mould–releasing agent on different chemical base were tested, (mineral oil base and silicon base). From the results, follows that the different kind of separators has impact on the colour of concrete. Measured data also show that there are differences in roughness and quality of concrete surface depending on used mould-release agents.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

Článek analyzuje problematiku absence technických norem a předpisů pro pohledový beton v závislosti na jeho estetické kvalitě a definuje možnosti přístupu k návrhu a projektové dokumentaci, které by účinně vedly k požadovanému vizuálnímu výsledku.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

In this paper, the influence of the cement type on the final coloring of the concrete with colored powdered inorganic pigments used currently with increasing tendency in construction and modern architecture is presented. In the experimental testing, the difference in intensity/saturation of the color of the concrete containing white cement (CEM I 52.5 R - SR 5 white), which is preferred when using color pigments, and gray (conventional) Portland cement (CEM I 52.5 R) from the same manufacturer has been measured and compared. Three colored inorganic powder pigments (red, green and yellow pigment) containing iron oxides (Fe2O3) have been used to color the concrete mixture. Objectivity of measurement, comparison, and subsequent analysis of individual resulting shades has been ensured by measuring exact RGB values at several places of the concrete cured surface by means of the Colorimeter Colorcatch nanodevice which automatically eliminates all irrelevant color shades, shadows, and impurities. This eliminated the subjective color impression which is usually always biased by external circumstances. Comparison of the color intensity of six experimental samples, including three pigment colors and two types of cement (white/grey), is conclusively related to the color efficiency ratio, the resulting costs, and the ecological footprint arising from the production of the cements above.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

The paper analyzes the issue of the absence of technical standards and regulations for exposed concrete in relation to its aesthetic quality and defines the possibilities of approach to the design and project documentation that would effectively lead to the desired visual result. Achieving a high-quality exposed concrete area is only possible if all the mentioned phases of the process are adhered to and the standards related to the execution of concrete structures are respected.

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Ing. Radka Navrátilová, Ph.D.

15124 Ústav stavitelství II

Influence of pigments on mechanical properties of colored concrete is presented in this paper. The paper is focus on the issue of dosing a powder pigment in the form of iron oxide into a prefabricated dry concrete mixture and its effect on mechanical properties of mixture. Based on the performed experimental tests, it follows that the proportion of added pigment has a fundamental influence not only on the resulting color intensity of concrete, but also on its mechanical properties. The measured values of flexural and compressive strength show a significant decrease with increasing amount of pigment contained.

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