Papers by Keyword: Glass

Abstract: At the present stage of urban fabric formation, the problem of adapting existing buildings to modern socio-economic conditions and functional needs is very important. In the conditions of constraint of already existing urban development, the issue of reconstruction and renovation of existing buildings becomes particularly relevant. There are frequent examples of new additions and superstructures over the “historical foundation”. In the light of the solution of functional and especially constructive tasks, the choice of building materials becomes extremely important. Examples of reconstructed buildings have been considered, it has been revealed that the most used in the reconstruction of modern materials for today are glass and composite panels. Since the reconstructed buildings are mainly built of stone or brick, the building and composite panels with color and texture features contrast with the old masonry, thereby highlighting and complementing it. The quality and characteristics of the above mentioned materials, the advantages that they have in comparison with traditional stone and concrete, and the great possibilities of obtaining a variety of structures and facade plastics have been analyzed.

Abstract: The electronic structure of lithium pyrophosphates (Li₄P₂O₇) and sodium (Na₄P₂O₇) was calculated by the density functional theory method. The calculations were performed for ordered (crystalline) and disordered (corresponding to glassy) structural states of lithium and sodium pyrophosphates. The disordering of the structure is simulated by ab initio molecular dynamics from crystal state with the same atomic basis as used for ideal crystal electronic calculations.

Abstract: This paper presents data on the mixed alkali effect in two fundamentally different systems: chalcogenide and oxide (phosphate). In the first system (Ag – Cu)_0.44AsSe_1.5, the predominantly ionic conductivity of silver-containing glasses is replaced by purely electronic in copper-containing, in the second - 0.5(Li₂O-Na₂O) – 0.4P₂O₅ – 0.1Nb₂O₅ carriers of electric current are alkaline ions and the extreme dependences of the electrical parameters associated with their joint migration.

Abstract: Ionic Seebeck effect has been investigated in Li (Na,K)₂O‐Nb₂O₅‐P₂O₅ glasses. Ionic Seebeck coefficients and heats of ion transfer have been measured. Soret coefficients have been calculated for glasses being studied. Temperature dependence and content of Nb₂O₅ dependence of Soret coefficients have been analyzed. Hypotheses of coefficients of self-diffusion and thermodiffusion ratio when temperature and content of Nb₂O₅ change have been proposed.

Abstract: Within several research projects and with the aim to optimize structural performance, energy efficiency and ecological characteristics of structural building components the Department of Structural Design and Timber Engineering (ITI) at the Vienna University of Technology (TU Wien) developed several wood-based composite systems, which combine timber products with other conventional building materials and components. As a representative example for these developments, this paper illustrates the results of the joint research project “Wood-based concrete: building construction with composite elements of wood-concrete compounds and timber (WooCon)”. The objective of the research project “WooCon” is to develop a multi-layer wall system composed of wood lightweight concrete (WLC), connected timber sections, textile reinforcement as well as glass layers on the exterior to gain and use advantages of each used material - lightweight, structural, thermal storage and insulation, ecological and economic benefits - to name the most important ones. In order to assess the structural physical properties of wood-based composite wall elements, in a first step measurements of the thermal properties with respect to thermal-insulating properties and thermal storage capacity are carried out. In following step, the results obtained are used further to simulate the thermodynamic and hygrothermal building behavior. The aim of the simulations is to investigate the effect of the wood-based composite wall elements to the annual heating demand as well as to the operative room temperature of a typical south-orientated living space.

Abstract: 60CaO-30P₂O₅-(10 ̶ x)Nb₂O₅-xTiO₂ (x = 0 ~ 10, mol%) glasses were prepared in order to obtain biomaterials with high chemical durability and therapeutic ions releasability. Dissolution test of these glasses using Tris buffer solution showed the controlled release of niobate ions from Nb₂O₅-containing glasses and the formation of calcium titanate in some of them. These behavior might induce positive effects for bone regeneration.

Abstract: The Dy³⁺-doped glasses of the M₂O₃:CaO:SiO₂:B₂O₃ (M₂O₃ = Y₂O₃ and La₂O₃) materials have been successfully fabricated with the 0.5 % mol of the Dy₂O₃ concentration, and thoroughly investigated based on the physical, optical, photo- and radioluminescence properties. The developed glass materials were prepared from the compositions of 25M₂O₃:10CaO:10SiO₂:(55-x)B₂O₃:0.5Dy₂O₃ by the conventional melt-quenching technique at 1,400°C. The clear sample of the doped La₂O₃ glass demonstrated higher density and the molar volume than those of the doped Y₂O₃ glass. From the spectrophotometry, the absorption peaks of the Dy³⁺ ions were clearly observed in both glasses. The photoluminescence (PL) spectra of the developed glasses indicated two-colors with two strongest peaks at 577 nm (⁴F_9/2®⁶H_13/2) and 482 nm (⁴F_9/2®⁶H_15/2). In addition, the emission spectra from the radioluminescence (RL) were identical to those from the PL measurements. From the results of the PL and RL measurements, the Y₂O₃ glass had higher emission in the intensity than the La₂O₃ glass. The X-ray absorption near edge spectroscopy (XANES) with the synchrotron radiation was carried out in fluorescent-yield mode to determine the average oxidation number of the Dy ions dispersed in the glass matrices. The DyL₃-edge XANES spectra of both developed glasses were nearly identical with the sharp white line at 7795.5 eV and the edge energy of 7793 eV. Compared to the XANES spectrum of the pure Dy₂O₃ standard, both glasses showed the difference smaller than 0.5 eV, and therefore confirmed the oxidation number of the Dy ions of 3+.

Abstract: In order to promote the recycling of the one way glass bottles, the impact fracture by using the pulse power underwater shock-wave with micro bubble was examined. It is reported that the pressure of underwater shock-wave with micro-bubble increases. From the experimental result, the glass bottle‘s crushed experiment was executed in the water with micro-bubble. As a result, the small glass fragments (Cullet) increased and it was shown that the micro-bubble in the water promoted the bottle fracture.

Abstract: The spherical indentation combined with acoustic emission was used to evaluate the local strength of glass, which is a nondestructive testing approach. However, stress time effect on the local strength of glass during spherical indentation has not been studied before. In the present work, stress time effect was investigated by examining the local strength of unstrengthened and strengthened glass at different loading rates. It is discovered that the local strength of glass increased greatly with the loading rate, which confirmed the time dependence of the fracture on glass. As a typical brittle material, the discreteness of strength date of glass measured by spherical indentation was also analyzed to evaluate the strength of glass correctly.

Abstract: This study presents results of an experimental investigation conducted to investigate the mechanical properties of sisal and glass fiber reinforced concrete. Four basic concrete mixes were considered: 1) Plain concrete (PC) containing ordinary natural aggregates without any fibers, 2) sisal fiber reinforced concrete (SFRC), 3) sisal and glass fiber reinforced concrete (SGFRC), 4, glass fiber reinforced concrete (GFRC). Investigated properties were compressive strength, splitting tensile strength, flexural tensile strength and workability. The results of fiber reinforced concrete mixes were compared with plain concrete to investigate the effect of fibers on the mechanical properties of fiber reinforced concrete. It was determined that addition of different kinds of fibers (natural and synthetic) is very useful to produce concrete. The addition of fibers was resulted into higher compressive strength, splitting and tensile strength. However, the workability of the fiber reinforced concrete was found lower than the plain concrete due to the addition of fibers in the concrete.