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A reinforcement of concrete structures is needed because of the low tensile strength of concrete. Corrosion of the usually used steel reinforcments cause issues during time. Therfore, alternative reinforcements produced from non-corosive materials - like polymer fibers - become more interesting. A polymer fiber has to reach high mechanical properties and a good bonding ability to concrete. Both properties can be influenced by the selection of polymer and the used production process. Two polymers, polypropylene and aliphatic polyketone are tested within this study. First mono-material fibers of each material are produced and tested, later the materials are combined in a core-shell fiber. All fibers are produced by standard extrusion or coextrusion and a later drawing process. The mechanical properties are determined by tensile tests. The calculation of interfacial shear strength from single fiber pull-out tests allows an evaluation of the bonding ability. Additionally, fiber surface before and after pull-out is examined using reflected light microscopy. Contact angle measurements are done to evaluate possible influences of the surface energy and polarity. Density measurements are used to compare weight potential of the different mono-material and core-shell fibers. The results show good mechanical properties for all fiber materials. The interfacial shear strength is ≈ 2-3 times higher for fibers with polyketone compared to the ones with polypropylene at the fibers surface, which can be explained by higher surface energy and polarity of the polyketone compared to polypropylene and different surface deformation during pull-out. Lower densities are reached by fibers containing polypropylene.
Stable isotope data from hypogene (i.e., below the line of weathering) iron oxides and gangue minerals from BIF-hosted iron ore deposits in Australia, South Africa, and Brazil have significantly assisted in constraining different hydrothermal fluid sources and fluid flow models during the upgrade of BIF to iron ore. The δ18O values on iron oxides from BIF and different paragenetic stages of enrichment display a consistent decrease from unenriched BIF (4–9‰) to as low as −10‰ for high-grade iron ore. This large shift in oxygen isotope values is interpreted as evidence for enormous incursion of ‘ancient’ meteoric water into fault and fracture zones at the time of iron enrichment during the Archean and Paleoproterozoic time. The δ18Ofluid values of paragenetically early iron oxides of > 4‰ suggest the involvement of magmatic fluids in greenstone belt-hosted Carajás-type iron ore deposits, and basinal brines in basin-hosted Hamersley-type deposits. In contrast, the paragenetically late stage iron oxides in the metamorphosed, basin hosted iron ore deposits of the Quadrilátero Ferrífero display δ18Ofluid values > 6‰. This reflects the renewed deep crustal, hypogene (metamorphic or magmatic) fluid influx. Carbon and oxygen isotope data on carbonates in BIF and hydrothermally altered iron ore indicate that carbon in the latter is not derived from BIF units, but represents either magmatic carbon in the case of the Carajás-type deposits or carbon within the underlying basin stratigraphy as in the case of the Hamersley-type iron deposits. The systematic decrease of δ18O values in iron oxides from the early to late paragenetic stages and from the distal to proximal alteration zone, including the ore zone, may be used as a geochemical vector. In this case, oxygen isotope analyses on iron oxides provide a potential exploration tool, particularly for targeting the extension of iron ore bodies or entirely concealed high-grade iron ore deposits, in which hematite/magnetite are frequently the only mineral that can be readily analysed.
Large-scale, hypogene iron mineralization systems developed recurrently in the São Francisco craton in association with two orogenies. During the ca. 2.1–2.0 Ga Trans-Amazonian orogeny, low-temperature and low-to-moderate-salinity metamorphic fluids resulted in carbonatization-related iron enrichment of the early Paleoproterozoic Cauê Iron Formation (IF) of the Minas Supergroup (MSG) as well as short-distance iron mobilization. Monazite from the iron-oxide veins yielded a SHRIMP 232Th/208Pb date corresponding to fluid circulation coeval with the migmatization of the Archean tonalite-trondhjemite-granodiorite crust. During the Ediacaran to Cambrian Brasiliano orogeny, when the São Francisco craton was consolidated in its present configuration, hydrothermal fluids repeatedly mineralized the Cauê IF and the younger IFs of the lower Espinhaço Supergroup. Far-field hydrothermal alteration associated with distinct Fe mineralization episodes widely affected Meso- to Neoproterozoic sequences as well as Archean to Paleoproterozoic terranes of the cratonic core. Circulation of hydrothermal fluids during the Brasiliano orogeny caused desilicification, iron mobilization, and widespread alteration of the rocks. The alteration events are dated with monazite and xenotime intergrown with hematite, anatase, and recrystallized rims of detrital zircons from interlayered quartzites and of igneous zircons from pegmatites, granites, acidic volcanic rocks, and orthogneisses, yielding U-Pb dates between 542 and 493 Ma. U-Pb dates point to five Cambrian hydrothermal events from the waning stages to the aftermath of the Brasiliano orogeny. These hydrothermal fluid circulation events correspond to the emplacement ages of four granite suites and pegmatites that lasted from the final stages of the collision to the collapse of the Araçuaí-West Congo orogen. Episodic circulation of fluids continued for approximately 2 billion years after IF deposition on the eastern São Francisco craton with the formation of high-grade iron ore deposits and resetting of the IF trace-element inventory.
Der Artikel behandelt die Nachweisführung zum Feuerwiderstand von Mauerwerks-Bauteilen. Es werden die möglichen bauaufsichtlichen Anforderungen an Standsicherheit und/oder Raumabschluss im Brandfall, die mögliche Nachweisführung über Bauarten als technische Baubestimmungen oder Bauarten mit Anwendbarkeitsnachweis, die Zuordnung der bauaufsichtlichen Anforderungen zu den Leistungsangaben in den Nachweisen und die Grundlagen der brandschutztechnischen Bemessung von Mauerwerksbauteilen diskutiert.
Der Artikel beschreibt die Änderungen der Zuordnungstabellen für das Brandverhalten von Baustoffen bei Klassifizierung nach EN 13501-1, speziell aus dem Blick der Technischen Isolierung. Hierbei ist insbesondere zwischen "linearen Rohrdämmstoffen" und Dämmstoffen als "sonstige Bauprodukte" zu unterscheiden.
Der Beitrag behandelt den Umgang mit sogenannten "nichttragenden Brandwänden" im deutschen Bauordnungsrecht. Mit der Umstellung von der früheren Bauregelliste (BRL) auf die (Muster) Verwaltungsvorschrift Technische Baubestimmungen (MVV TB) wurde diesen die Grundlage für die Erteilung allgemeiner bauaufsichtlicher Prüfzeugnisse und die erforderliche Zuordnung der bauaufsichtlichen Anforderungen zu Leistungsangaben in Anwendbarkeitsnachweisen entzogen. Es wird die Möglichkeit der "Verzichtserklärung" der obersten Bauaufsichtsbehörden vorgestellt.
Der Artikel stellt die tatsächlichen Änderungen der Zuordnungstabellen für das Brandverhalten von Baustoffen bei Klassifizierung nach EN 13501-1 seit MVV TB 2023/1 vor. Insbesondere wird auf die neue Begrenzung des Wertes TSP 600s bei Klassifizierung auf Grundlage von EN 13823 Ausgabe 2020 oder jünger bei den bauaufsichtlichen Anforderungen "nichtbrennbar" oder "schwerentflammbar und geringer Rauchentwicklung" eingegangen.
Der Vortrag betont die zentrale Rolle von Holz in der Bioökonomie für die notwendige Transformation unserer Lebens- und Wirtschaftsweise. Der Fokus liegt dabei auf der ganzheitlichen Betrachtung der Wertschöpfungskette Forst-Holz und möglichen Beschleunigern für eine bioökonomische Transformation: Interdisziplinäre Lösungskompetenz ist gefragt, um Holz als Rohstoff für zukunftsfähige Produkte zu etablieren, Holzarten, -sortimente und -qualitäten optimal den verschiedenen Verwendungen zuzuführen und die Kreislaufwirtschaft als Schlüssel zur Ressourceneffizienz umzusetzen.
Der Vortrag wurde im Rahmen des Stuttgarter Nachhaltigkeitsstammtisch gehalten.