Corrosion map of zinc in Slovakia

The subject of this research was influence of the environmental parameters, like temperature, humidity and pollutants, on the corrosion rate of the zinc protective coating of the steel structural elements. Zinc is usually used to protect those elements against corrosion. The idea was to study the corrosion of zinc in different parts of Slovak Republic in order to create the so-called corrosion map of the country. The corrosion rate of zinc rcorr was calculated according to standard ISO 9223. Results have shown that both the input parameters, as well as the corrosion rate of zinc, are changing with time

Innovative strengthening of RC columns using a layer of a fibre reinforced concrete

Reinforced concrete structures that are influenced by degradation, overloading, the thawing and freezing cycles, abrasive damage and corrosion of reinforcement, should be repaired or strengthened. Each of those mentioned situations lead to decreasing the load-carrying capacity of the construction. The damage of a structure or its member causes exceeding the serviceability limit states and ultimate limit states. For this reason, for further use of the structures, they have to be strengthened to increase the load-carrying capacity and to extend the remaining lifetime. A new method for strengthening the vertical members, e.g., columns, is using the fibre reinforced concrete layer and its increased tensile strength in comparison to common RC concrete. This article deals with the theoretical design of dimensioning the columns using a layer of fibre concrete around a column (wrapping). In this case, it is necessary to calculate the residual strength of fibre concrete, which is a crucial factor for the tensile strength of the element

The Roofing of the Sport Multipurpose Hall

Úlohou diplomovej práce je vypracovať návrh a posúdenie zastrešenia viacúčelovej športovej haly. Viacúčelová športová hala má pôdorys o rozmeroch 48 x 35 m a výšku 16,0 m. Hala je tvorená priečnymi väzbami z oceľových priehradových väzníkov uložených kĺbovo na valcovaných profiloch stĺpov votknutých do betónových základov tvorených pilótami. Sedlová strecha skrytá za atikou z oceľových štvorcových trubiek má sklon 7,0°. Konštrukciu väzníc tvoria tenkostenné profily od firmy Voestalpine. Tuhosť konštrukcie je zaistená oceľovými prvkami v rovine strešnej konštrukcie a v rovine pozdĺžnej a štítovej steny. Práca je riešená v súlade s európskymi normami.Main task of this thesis is to design a roofing of multi-purpose sport hall. Multipurpose sport hall has a floor dimensions 48 x 35 m and is 16.0 m high. The hall is composed of cross-linked steel girders saved on rolled profiles of columns, which transmit loads into concrete pile foundations. Gable roof has a slope 7° and it is hidden behind a parapet which consists of steel square profiles. The construction consists of thin-walled purlins made by the company Voestalpine. Rigidity is ensured by steel elements in the plane of the roof structure in the longitudinal plane and gable walls. The thesis is carried out in compliance with the Eurocodes.

Measurement of corrosion rates on reinforcement using the field test

Reinforcement corrosion is a phenomenon that affects not only the durability and serviceability of the structure itself but the economy of the countries, as well. In many cases, structures and bridges must be repaired or reconstructed as a result of corrosion of the reinforcement. In extreme cases, when maintenance is neglected, it is necessary to completely replace the structures with new ones, even if their planned service lifetime has not been reached - it is not enough to strengthen them or it is economically inefficient. Corrosion of the reinforcement primarily causes a reduction in the cross-sectional resistance of the load-bearing elements by reducing the cross-sectional area of the reinforcement, which means a reduction in the force in the reinforcement that it transmits. For this reason, it is necessary to know the rate of corrosion over time depending on the environment in which the element is located. The paper is focused on the experimental measurements of corrosion losses due to atmospheric corrosion on reinforcement samples using the field test. As a part of experimental measurements, corrosion rates on reinforcements of four diameters (diameters 6, 10, 14, and 25 mm) of steel for reinforcement, grade B 500B, are monitored at measuring stations and bridges in various aggressive environments.This research was supported by Research Projects No. 1/0623/21 of the Slovak Grant Agency

Influence of the type of cement and the addition of an air-entraining agent on the effectiveness of concrete cover in the protection of reinforcement against corrosion

The concrete cover is the basic protection of the reinforcement against the influence of external factors that may lead to its corrosion. Its effectiveness depends mainly on the composition of the concrete mix, including the cement used. Depending on external environmental factors that may aggressively affect the structure, various types of cements and concrete admixtures are recommended. The paper presents the results of tests that allow us to assess the effect of the type of cement used and the air-entraining agent on the effectiveness of the concrete cover as a layer protecting the reinforcement against corrosion. In order to initiate the corrosion process, the reinforced concrete specimens were subjected to cycles of freezing and thawing in a sodium chloride solution. The degree of advancement of the corrosion process was investigated using the electrochemical galvanostatic pulse technique. Additionally, the microstructure of specimens taken from the cover was observed under a scanning electron microscope. The research has shown that in the situation of simultaneous action of chloride ions and freezing cycles, in order to effectively protect the reinforcement against corrosion, the application of both blast-furnace slag cement and an air-entraining agent performed the best.Web of Science1416art. no. 465

Experimental verification of real behavior of bridge structures using proof-load tests

The aim of the paper is to point out the inevitability of the proof-load tests for the real and correct behavior of bridge structures in ultimate limit state and maximum allowable deformations in serviceability limit states. It is needed to point to the most consequences of resistance, reliability, durability and lifetime of the bridge structures. Using the proof-load tests for new bridges is prescribed by the Slovak standard STN 73 6209

ANALYSIS OF PROPERTIES OF THE FRP REBAR TO CONCRETE STRUCTURES

The application of the FRP (Fiber Reinforced Polymer) rebar is presented in this paper. The various kinds of fibers, depending on the types of the FRP rebar and types of matrix of FRP are listed. The main tasks of matrix and fibers are specified. The two methods of FRP bars production are explained. The selected physical and mechanical properties of the various types of the FRP rebar are shown and compared. The long-term properties of the FRP rebar, as relaxation and creeping processes, are also introduced. The FRP properties were compared to conventional steel reinforcement properties. Moreover, the typical disadvantages of traditional reinforced concrete, as the susceptibility to corrosion were presented. It is shown that the FRP reinforcement is quite opposite, since it has almost total resistance to corrosion. The corrosion factors, to which the FRP is resistant, are presented and explained

Diagnostic and Analysis of Selected Masonry Railway Bridges on Slovak Railways

The paper presents an overview of the current state of railway masonry arch bridges that are in operation on Slovak Railways. The material of the vault is either stone or brick. It also presents the current possibilities of diagnostics, monitoring and evaluation of failures, the method of measuring selected material characteristics of masonry elements (especially the determination of compressive strength). Within the cooperation of our department and the Research and Development Institute of ŽSR, applications of diagnostic measurements and evaluation of the current state of these bridges are presented on selected bridge structures