Technologie a postupy pro ochranu historických zděných mostů z 19. a začátku 20. století

Coatings are key industrial materials used to protect a variety of surfaces, including metals, wood, concrete and plastics. Their purpose is to provide protection against external influences such as corrosion processes, UV radiation, moisture and mechanical wear. However, despite their surface protection function, coatings are prone to degradation, which can have serious consequences for the surfaces they are intended to protect. This text will deal with the analysis of the degradation of coatings used to protect concrete surfaces by means of Fourier transform infrared spectrometry.

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Historic concrete bridges are invaluable cultural and engineering heritage assets, often representing significant milestones in civil engineering history. However, these structures are subjected to various environmental stresses, including moisture, freeze-thaw cycles, carbonation, and chloride ingress, which can compromise both their durability and aesthetic qualities. Coating systems have emerged as one of the most effective strategies to protect these structures while maintaining their historical significance.

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Prague has two iconic views. The first is Charles Bridge with the silhouette of Prague Castle in the background, the second is the Vyšehrad Railway Bridge framed by the imposing structure of Vyšehrad. It has been a listed cultural monument since 2004. The Vyšehrad Railway Bridge was opened in its first form on 15 August 1872, its current appearance dates back to 1901. It is a riveted structure with three parabolic arches spanning about 70 m with verticals and diagonals in the shape of segmented cross-sections. The structure is an important technical cultural monument, which is also located in an exposed part of the Prague Monument Reserve. However, due to long neglected basic maintenance, the structure deteriorated to such an extent that the Railway Administration decided to demolish it. Having carried out an inspection and structural assessment of the bridge we are confident that it can be repaired, refurbished, and modified to provide a long and satisfactory additional service life for future operation of the railway and footways. In particular, localized corrosion defects resulting from inadequate maintenance over many years can be repaired and the structural components which fail to meet the assessment criteria in their current condition can be repaired or replaced. Expressed in weight, only 15 % of the structure by mass needs structural repair or improvement; the rest is satisfactory without further intervention, other than renewing the corrosion protection system. The paper is based on a study by Petr Tej, Andreas Galmarini and Ian Firth and will focus on a detailed survey of the bridge’s condition and the possibilities of its reconstruction for rail traffic. It describes the reconstruction system, replacement of individual elements and contact points. Part of the paper is also a proposal for the reconstruction and use of the stone viaduct for trade and services, including static and visual rehabilitation.

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Zařízení je navrženo tak, aby automaticky pořizovalo fotografické snímky jednotlivých vrstev odebraných vzorků z mostních konstrukcí. Tyto vzorky podléhají destruktivní analýze, což znamená, že se materiálové vlastnosti zjišťují metodou, při které dochází k nevratnému poškození vzorku. Nejčastěji se jedná o vzorky malt a kameniva, které obsahují plniva rozpustná v silných kyselinách, například karbonátová plniva. Hlavní funkcí tohoto zařízení je umožnit vytvoření 3D modelu analyzovaného materiálu a jeho jednotlivých složek. Proces začíná pořízením řady fotografií vrstev vzorku. Tyto snímky jsou následně digitálně zpracovány a pomocí specializovaného softwaru, který se používá i v technologiích CT skenování, jsou propojeny do podoby 3D modelu struktury směsi (tzv. matrixu).

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