MONITORING AND PROTECTION OF TIMBER-CONCRETE BRIDGES

The majority of timber bridges for ordinary road traffic are often made as timber-concrete composite structures. Concrete slab is something like as umbrella for timber. The reason for problems in timber-concrete bridges is nearly always poor detailing for durability and neglected maintenance. Mainly all aspects of timber protection and maintenance should therefore be considered even during the planning phase of bridge. Paper deals with evaluation of timber properties, system of opto-fiber sensors for monitoring and diagnostics of mechanical stress of timber-concrete bridges, and degradation of timber due to UV radiation, atmospheric conditions and biological agents after application of photocatalytic materials on surface

Quantitative three-dimensional local order analysis of nanomaterials through electron diffraction

Structure-property relationships in ordered materials have long been a core principle in materials design. However, the introduction of disorder into materials provides structural flexibility and thus access to material properties that are not attainable in conventional, ordered materials. To understand disorder-property relationships, the disorder – i.e., the local ordering principles – must be quantified. Local order can be probed experimentally by diffuse scattering. The analysis is notoriously difficult, especially if only powder samples are available. Here, we combine the advantages of three-dimensional electron diffraction – a method that allows single crystal diffraction measurements on sub-micron sized crystals – and three-dimensional difference pair distribution function analysis (3D-ΔPDF) to address this problem. In this work, we compare the 3D-ΔPDF from electron diffraction data with those obtained from neutron and x-ray experiments of yttria-stabilized zirconia (Zr0.82Y0.18O1.91) and demonstrate the reliability of the proposed approach

Quantitative three-dimensional local order analysis of nanomaterials through electron diffraction

Structure-property relationships in ordered materials have long been a core principle in materials design. However, the introduction of disorder into materials provides structural flexibility and thus access to material properties that are not attainable in conventional, ordered materials. To understand disorder-property relationships, the disorder – i.e., the local ordering principles – must be quantified. Local order can be probed experimentally by diffuse scattering. The analysis is notoriously difficult, especially if only powder samples are available. Here, we combine the advantages of three-dimensional electron diffraction – a method that allows single crystal diffraction measurements on sub-micron sized crystals – and three-dimensional difference pair distribution function analysis (3D-ΔPDF) to address this problem. In this work, we compare the 3D-ΔPDF from electron diffraction data with those obtained from neutron and x-ray experiments of yttria-stabilized zirconia (Zr0.82Y0.18O1.91) and demonstrate the reliability of the proposed approach

Study of inorganic matrix composites for FRP

Dlouhovláknovým kompozitům používaným ve stavebnictví prakticky po celou dobu od jejich uvedení do stavební praxe dominují jako pojivový materiál organické matrice. Přes své nesporné přednosti mají dva nedostatky: nízká odolnost proti ohni a proti vysokým teplotám. Z těchto důvodů se přistupuje k hledání alternativních materiálů schopných v plné míře nahradit organickou matrici. Přitom se hledá takové řešení, aby byly zachovány mechanické vlastnosti dlouhovláknových kompozitů s organickou matricí. Samozřejmostí je, že je kladen velký důraz na splnění standardů, které jsou kladeny na ekologický materiál. Anorganické matrice na bázi hlinitokřemičitanů těmto standardům vyhovují. Jsou nehořlavé, při styku s plamenem neuvolňují žádné toxické látky a jsou méně energeticky náročné na výrobu. Obsahem této práce je studium a analýza vybraných vstupních surovin, vliv jednotlivých vstupních surovin na výsledné reakční produkty vznikající v anorganické matrici a studium vlivu teploty na změnu struktury matrice. Součástí této práce je i návrh receptury anorganické matrice.During a whole period of time which fibre-reinforced polymers have been used in the building industry, in dominating bonding agent has been the organic resins. There is no doubt about their advantages, but at the same time, they have two weaknesses: they are not fire resistant and they have no resistance to high temperature. Those are the reasons why the research on alternative materials which could replace organic matrix has been undertaken. The goal of the work is to maintain mechanical properties of fibre-reinforced polymer with organic matrix. Of course, an emphasis is placed to fulfilling ecological standards which are required from ecological material. An aluminosilicate inorganic matrix can meet them all. It is non-flammable, does not produce any toxic matter in contact with fire and the energy consumption during production process is lower than in case of the organic matrix. This work includes study and analysis of selected raw materials as well as their influence and impact on final reaction products which are created in inorganic matrix. A part of this work is also a design of the inorganic matrix recipe.

Gothic green glazed tile from Malbork Castle: multi-analytical study

Abstract Looking at the façade of a historical building, it is often difficult to distinguish between the original decoration and later additions. One such building is the Holy Virgin Mary Church at the Malbork Castle (Northern Poland), built between 1276 and 1406. During the latest restoration works, ceramic tiles with some remnants of the green glaze, decorating the Holy Virgin Mary Church façade, were studied in situ using portable X-ray fluorescence spectrometry. Micro-samples were analyzed in laboratory by scanning electron microscopy with energy dispersive X-ray spectrometry (SEM–EDS) and wavelength-dispersive X-ray spectrometry (SEM–WDS), micro-Raman spectroscopy and powder X-ray micro-diffraction. We found that what was originally thought to be a paint layer was in fact a heavily deteriorated SiO2–PbO glaze. White, yellow and black pigments were found to have been added into the glaze as opacifiers and colorants. Copper and iron were used as glaze colorants. The originally added pigments were transformed into new phases, such as antimony-doped tin oxide. The technology used to produce the glazed tiles was identified. All the results collectively confirmed the medieval origin of the green glazed tiles. Graphical abstract Gothic green glazed tile from Malbork Castle: multi-analytical study

Synthesis of high dense yttrium-stabilised hafnia pellets for nuclear applications by spark plasma sintering

Dense yttrium–stabilised hafnia pellets (91.35 wt.% HfO2 and 8.65 wt.% Y2O3) were prepared by spark plasma sintering consolidation of micro-beads synthesised by the ‘‘external gelation’’ sol–gel technique. This technique allows a preparation of HfO2–Y2O3 beads with homogenous yttria–hafnia solid solution. A sintering time of 5 min at 1600 C was sufficient to produce high density pellets (over 90% of the theoretical density) with significant reproducibility. The pellets have been machined in a lathe to the correct dimensions for use as neutron absorbers in an experimental test irradiation in the High Flux Reactor (HFR) in Petten, Holland, in order to investigate the safety of americium based nuclear fuels.JRC.E.4-Nuclear Fuel Safet

Highly photoactive anatase foams prepared from lyophilized aqueouscolloids of peroxo-polytitanic acid

tPeroxo-polytitanic acid foams annealed at temperature above 500◦C lose volatile components and excessof oxygen providing anatase in the form of thin leaves consisting of intergrown nanocrystalline anataseparticles which transform at temperatures above 850◦C to rutile. The size and shape of the initialleaflets forming the foam is preserved up to ∼900◦C. We observed that the annealed material is highlyphotoactive, owing to highly anisotropic shape of anatase aggregates and their perfect crystallinity. Out-standing photocatalytic activity determined by measuring the kinetics of degradation of Methylene Blue(MB) and 4-chlorphenol (4-CP) as well as measuring the formation of hydroxyl radical spin adductsby EPR spectroscopy was observed. All three methods demonstrated significantly higher activity incomparison with the Degussa P25 photocatalyst. Both methods used for photoactivity tests providedsimilar results, the activity increased with increasing annealing temperature in order 500◦C < DegussaP25 < 600◦C < 850–950◦C. Results of measurement of formation of •OH radicals by EPR also confirmedthe unusually high activity of our materials. In comparison with the Degussa P25, the sample annealedat 950◦C showed significantly higher production of•OH radicals

Study of Interactions between Titanium Dioxide Coating and Wood Cell Wall Ultrastructure

Titanium dioxide (TiO2) is used as a UV light absorber to protect wood matter from photodegradation. In this paper, interactions between wood and TiO2 coating are studied, and the efficiency of the coating is evaluated. For the experiments, two wood species were chosen: beech (Fagus sylvatica) and pine (Pinus sylvestris). Molecular and physical modifications in coated and uncoated wood exposed to UV radiation were investigated with Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and transmission electron microscopy (TEM). UV-VIS spectroscopy was used to describe the absorption of UV light by the TiO2 planar particles chosen for the experiment. It was demonstrated that TiO2 coating protects wood against photodegradation to a limited extent. TEM micrographs showed fissures in the wood matter around clusters of TiO2 particles in beech wood

Water Vapor Diffusion and Adsorption of Sandstones: Influence of Rock Texture and Composition

The term sandstone is used for wide range of rocks containing quartz clasts which can be cemented by secondary precipitated quartz or calcite; moreover the space between clasts can be filled by matrix. These facts result in existence of numerous rocks having highly various properties. Sandstones have been used as construction materials due to their good accessibility and workability. Since most of sandstones are porous, water vapor can penetrate through sandstone constructions. The rate of water vapor diffusion, as well as the vapor sorption isotherm, was determined for range of sandstone types. The diffusion resistance factor was found to be dependent on the total porosity of sandstone but the sorption behavior was strongly influenced by nature of the particular sandstone; the specific surface area of stone and presence of clay matrix are determining its sorption isotherm. The published data enable estimating (i) diffusion resistance factor of a sandstone via knowledge of its total porosity and (ii) the sorption isotherm via knowledge of the stone’s nature and specific surface area. This approach can significantly reduce the time necessary to acquire vapor-related properties of a sandstone