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Use of Concrete for Road Infrastructure: A SWOT Analysis Related to the three Catchwords Sustainability, Industrialisation and Digitalisation

Abstract

This paper aims at identifying the direction for more sustainable development of the use of concrete in road infrastructure in an industrialised context.

The increase in the global mean temperature is one of the most severe challenges today. The concrete industry is responsible for significant emissions of greenhouse gases, most attributable to cement production. However, concrete is one of the most important building materials in the world and indispensable for the societal development in countries at all development stages. Thus, the concrete industry needs to take measures for reducing emissions.

This paper investigates possible directions for the development of the concrete industry, to reduce climatic impact and accommodate positive societal growth. The investigation is carried out as a SWOT analysis, focusing on three terms dominating the present discussion on any development within the construction industry; sustainability, industrialisation and digitalisation. The result is a thorough discussion and a set of recommendations for the direction of future research and innovation on sustainable use of concrete in the construction of road infrastructure. The major opportunities and threats are summarised in the conclusions, and future research to be carried out in two of the authors’ PhD-projects are described.

Open access
Wetting properties of titanium oxides, oxynitrides and nitrides obtained by DC and pulsed magnetron sputtering and cathodic arc evaporation

Abstract

Thin films of titanium oxides, titanium oxynitrides and titanium nitrides were deposited on glass substrates by the methods of direct current (DC) and pulsed magnetron sputtering and cathodic arc evaporation. Phase analysis of the deposited films by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) showed the presence of phases with various Ti oxidative states, which indicated a high concentration of oxygen vacancies. The films morphology was investigated by scanning electron microscopy (SEM). Investigations of the films wettability, either with water or ethylene glycol, showed that it depends directly on the concentration of oxygen vacancies. The wettability mechanism was particularly discussed.

Open access
X-Ray Computer Tomography Study of Degradation of the Zircaloy-2 Tubes Oxidized at High Temperatures

ABSTRACT

The investigations of high-temperature oxidation of zirconium alloys, applied for fuel pellets in nuclear power plants, are usually limited to oxidation kinetics, phase transformations and microstructural characterization. The purpose of this research was to characterize the degradation phenomena occurring within oxide layer and at the interface oxide/metal, on internal and external Zircaloy-2 tube surfaces, below and over crystalline transformation temperature of zirconium oxides. The commercial tubes were oxidized at 1273 K and 1373 K in calm air for 30 min and then examined with a technique novel for such purpose, namely a high-resolution X-ray computer tomography. The light microscopy was used to examine the cross-surfaces. The obtained results show that the form and intensity of oxide damage is significant and it is in a complicated way related to oxidation temperature and on whether external or internal tube surface is studied. The found oxide layer damage forms include surface cracks, the detachment of oxide layers, the appearance of voids, and nodular corrosion. The oxidation effects and damage appearance are discussed taking into account the processes such as formation of oxides, their phase transformation, stress-enhanced formation and propagation of cracks, diffusion of vacancies, formation of nitrides, diffusion of hydrogen into interface oxide-metal, incubation of cracks on second phase precipitates are taken into account to explain the observed phenomena.

Open access
Complex analysis of uniaxial compressive tests of the Mórágy granitic rock formation (Hungary)

Abstract

Understanding the quality of intact rock is one of the most important parts of any engineering projects in the field of rock mechanics. The expression of correlations between the engineering properties of intact rock has always been the scope of experimental research, driven by the need to depict the actual behaviour of rock and to calculate most accurately the design parameters. To determine the behaviour of intact rock, the value of important mechanical parameters such as Young’s modulus (E), Poisson’s ratio (ν) and the strength of rock (σcd) was calculated. Recently, for modelling the behaviour of intact rock, the crack initiation stress (σci) is another important parameter, together with the strain (σ). The ratio of Young’s modulus and the strength of rock is the modulus ratio (M R), which can be used for calculations. These parameters are extensively used in rock engineering when the deformation of different structural elements of underground storage, caverns, tunnels or mining opening must be computed. The objective of this paper is to investigate the relationship between these parameters for Hungarian granitic rock samples. To achieve this goal, the modulus ratio (M R = Ec) of 50 granitic rocks collected from Bátaapáti radioactive waste repository was examined. Fifty high-precision uniaxial compressive tests were conducted on strong (σc >100 MPa) rock samples, exhibiting the wide range of elastic modulus (E = 57.425–88.937 GPa), uniaxial compressive strength (σc = 133.34–213.04 MPa) and Poisson’s ratio (ν = 0.18–0.32). The observed value (M R = 326–597) and mean value of M R = 439.4 are compared with the results of similar previous researches. Moreover, the statistical analysis for all studied rocks was performed and the relationshipbetween M R and other mechanical parameters such as maximum axial strain (εa,max)for studied rocks was discussed.

Open access
Effective Width Rule in the Analysis of Footing on Reinforced Sand Slope

Abstract

This paper presents the results obtained from an experimental programme and numerical investigations conducted on model tests of strip footing resting on reinforced and unreinforced sand slopes. The study focused on the determination of ultimate bearing capacity of strip footing subjected to eccentric load located either towards or opposite to the slope facing. Strip footing models were tested under different eccentricities of vertical load. The obtained results from tests conducted on unreinforced sand slope showed that the increase in eccentricity of applied load towards the slope facing decreases the ultimate bearing capacity of footing. Predictions of the ultimate bearing capacity obtained by the effective width rule are in good agreement with those proposed from the consideration of total width of footing subjected to eccentric load. The ultimate bearing capacity of an eccentrically loaded footing on a reinforced sand slope can be derived from that of axially loaded footing resting on horizontal sand ground when adopting the effective width rule and the coefficient of reduction due to the slope. When increasing the distance between the footing border to the slope crest, for unreinforced and reinforced ground slope by geogrids, the ultimate bearing capacity of footing is no more affected by the slope ground.

Open access
Global Stability For Double-Diffusive Convection In A Couple-Stress Fluid Saturating A Porous Medium

Abstract

We show that the global non-linear stability threshold for convection in a double-diffusive couple-stress fluid saturating a porous medium is exactly the same as the linear instability boundary. The optimal result is important because it shows that linearized instability theory has captured completely the physics of the onset of convection. It is also found that couple-stress fluid saturating a porous medium is thermally more stable than the ordinary viscous fluid, and the effects of couple-stress parameter (F ) , solute gradient ( S f ) and Brinkman number ( D a ) on the onset of convection is also analyzed.

Open access
Effects of Additive Manufacturing on the Mechanical and Corrosion Properties of Austenic Stainless Steel

Abstract

Additive manufacturing (AM) offers the possibility to produce complex parts without the design constraints of traditional manufacturing routes. Our aim was to determine different mechanical and corrosion properties of direct metal laser sintered austenitic stainless steel (X2CrNiMo17-12-2) material with tensile test, Charpy impact test, scanning electron microscopy and corrosion test. The measured values were evaluated, and our results compared with literary values, furthermore, we also examined how the printing direction affects the properties.

Open access
Electrospinning of Polymer Fibres Using Recycled PET

Abstract

The effective recycling of polymer materials remains unresolved to this day, and this has had a devastating effect on the environment. This study examines an alternative method to PET recycling that is the generation of polymer fibers and fiber mats for filtration applications. The electrospinning instrumentation used in this study had to be designed and built in order to carry out the research. We have managed to produce PET fibers with 200-600 nm diameter, and free-standing fiber mats that could potentially be used in filtration applications.

Open access
Examination of Laser Microwelded Joints of Additively Manufactured Individual Implants

Abstract

Digital product processing and the utilization of novel, tissue-friendly materials allow the use of fixed dentures for patients. Its basis is a titanium plate fixed to the cortical bone surface at given screw positions. A digital dental cast is created from the existing bone surface, and modelling and necessary statistical analyses are carried out in a virtual environment. Safety of the welded joint is evaluated with mechanical methods. When designing the fixing points, an idealized denture is used that was previously designed for the patient. The number and position of pillar elements used for screw fixation of the denture are determined by the complex geometry of the denture itself, and the location, direction, and articulating position of existing teeth. The additively manufactured implant and the machined pillar sleeves are joined with laser-welding at given nesting positions. Homogeneity of the metallic material structure at the welded joint zone of the product is examined with micro-CT. Due to this implementation method, surgical time decreases together with complication rates and post-operative problems.

Open access
Examination of Layer Thicknesses of a Model Produced by Fused Filament Extrusion

Abstract

Nowadays additive manufacturing continues to gain more and more space in industrial technology. In particular, FDM (fused deposition modelling) machines have become easily available to the public. Quality of parts is impacted by several factors. In this study we investigate layer thicknesses of a prototype manufactured from PLA, and we pay special attention to the thickness of sequentially deposited layers.

Open access