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Göran Fagerlund

Abstract

Well-known frost destruction mechanisms applicable to concrete not exposed to salt are, (1) hydraulic pressure during freezing, (2) growth of ice-bodies in capillaries during freezing. Theories behind these mechanisms are presented. A third mechanism, ice expansion during heating of frozen concrete, is put forward. The validity of a certain mechanisms is discussed by analyzing its ability to explain experimental observations.

Open access

Ya Peng, Bård Pedersen, Serina Ng, Klaartje de Weerdt and Stefan Jacobsen

Abstract

Bleeding and sedimentation quantify the stability of fresh cement paste, whereas the addition of fillers and water reducers affect the stability. The effect of various types of fillers and water reducers was investigated by measuring bleeding, hydrostatic pressure and electroacoustic zeta-potential. Depending on their characteristics and use, fillers can improve stability by reducing sedimentation rate and bleeding. The combined effects of fillers and water reducers on the sedimentation rates, quantified as time-dependent hydrostatic pressure changes (dp/dt) in fresh matrix, correspond to their effects on zeta-potentials. The influence of the water reducers on sedimentation and bleeding exceed that of filler type.

Open access

Lamis Ahmed

Abstract

Knowledge of the elastic properties of concrete at early age is often a pre-requisite for numerical calculations. This paper discusses the use of a laboratory technique for determining Poisson’s ratio at early concrete age. A non-destructive test set-up using the impact resonance method has been tested and evaluated. With the method, it has been possible to obtain results already at 7 hours of concrete age. Poisson’s ratio is found to decrease sharply during the first 24 hours to reach a value of 0.08 and then increase to approximately 0.15 after seven days.

Open access

Louise Andersson, Johan Silfwerbrand, Anders Selander and Jan Trägårdh

Abstract

As part of a report [1] on continuous preventive bridge maintenance, a survey was conducted with Swedish municipalities. The survey’s focus was on bridges and preventive maintenance, as well as the demands and performance control stated by the municipalities. The preventive maintenance the survey focused on was the annual maintenance concerning washing, cleaning of drainage system and removal of vegetation. The survey showed both similarities and differences within the municipalities but also in comparison with Swedish Transport Agency (STA).

Open access

Vladislav Kaverinsky

Abstract

Using an originally-developed computer model and appropriate software the impact of deformation on austenite phase transformation in low carbon alloyed steel was carried out. The computer simulation takes into account an impact of the deformation degree and takes into account non-constant cooling rate. That makes it useful for the development of thermal and deformation technological processes development. Based on the simulation results a technology of controlled rolling of low carbon steel alloyed by carbide forming elements (Nb, V, Ti) was developed. The proposed technique allows production of rolled steel sheets with high strength and plastic properties, as well as high impact strength in normal and low temperatures.

Open access

László Tóth, Ferenc Haraszti and Tünde Kovács

Abstract

It is known that fusion welding can cause a decrease in the corrosion resistance of the heat affected zone of unstabilized stainless steels. The reason for this problem is that the welding heat (in the heat affected zone (HAZ)) can cause chromium-carbide (Cr23C6) precipitation with the simultaneous reduction of chromium content at the local grain boundaries. The chromium content dictates the corrosion resistance level. The relationship between surface roughness and corrosion behaviour is well known. We sought to find the difference between the corrosion resistance and surface roughness relationship in the case of cold rolled stainless steel and in the case of heat treated (welding heat effect simulated) stainless steel [1-3].

Open access

János Dobránszky and Enikő Bitay

Abstract

A unique method for producing aluminium matrix composite wires is the Blücher’s process, i.e. continuous gas-pressure infiltration. An essential condition of the process is that the fibre roving of the reinforcing fibres can be pulled across the orifices of the gas-pressure system with the least damage. The article describes a new test procedure that is capable of characterizing this essential functional property of the ceramic reinforcing fibres in a manner comparable and quantitative.

Open access

Emőd Filep, Dénes Nimród Kutasi and Lajos Kenéz

Abstract

Knowledge of the surface emissivity of metals is becoming more and more important both from the material science, process modelling and control point of view. Previous research results have shown that the emissivity of most metals depends on the temperature of the surface. It has also been reported that the most important temperature region is between 300 – 1000 K degrees, where the change of the emissivity is the most intense, which is also the most significant from a process control point of view [1]. We also report temperature dependent emissivity observed during plasma nitriding of low alloy steels [2]. Related to one of our present research topics the study of the low alloy aluminum (AlMg1, AlMg3) emissivity has prooven relevant. In this article the developed emissivity estimation model is presented. In the first part a literature overview and the theoretical approach of the new method is discussed, followed by the experimental results for low alloy aluminium emissivity determination and a comparison with the results available in the literature.

Open access

Tamás Antal Varga and Tamás Mankovits

Abstract

The geometrical modelling of metal foams remains one of the greatest challenges facing researchers in the field. In this paper the analysis of the inner structure of closed-cell aluminium foam - an essential part of the construction of an idealized foam model - is presented. With the application of special purpose software the properties of the foam cells can be mapped precisely and the results applied to the development of idealized foam geometry constructed in CAD applications.

Open access

József Gyulai

Abstract

This introductory paper summarizes the characteristics of how “Science” and “Engineering” differ from each other, forming the interdisciplinary topic of Materials Science and Engineering (MS&E). It will be shown how microelectronics has developed from modern materials science, causing a change in paradigm, and how microelectronics has become the “mother” science of informatics, changing life on Earth. To prove the importance of materials, a table is shown summarizing how modern MS&E forms the basis of practically all industries. The situation and development state of MS&E in CEE countries - despite different levels of industrialization – have some characteristics in common, and the way to development might also have techniques in common.

We will also mention the knowledge base that CEE countries possessed during the period of political change, and the likely future that an elderly scientist foresees for the region with the help of young ambitious scientists.