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Stavební průzkum a hodnocení stavu konstrukce / Building survey and evaluating the state constructionNguyen, Martin January 2017 (has links)
This diploma thesis deal with the building survey and evaluating the state of existing constructions. In theoretical part are described the types of civil engineering surveys and diagnostic methods for conducting a survey of reinforced concrete structures. The practical part deal with describes the structural and technical survey of the production hall in the industrial area Fatra Napajedla, evaluating the strength of concrete on the existing structure through donations cores and verification of compliance with the reinforcement according to project documentation. The last part is focused on a static assessment of selected supporting elements of the structure.
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Experimentální ověření modulu pružnosti v tlaku jemnozrnných kompozitů na bázi silikátových pojiv / The experimental verification of modulus of elasticity of fine grained composites based on silicate bindersHoduláková, Michaela January 2017 (has links)
Since their inception, building materials are constantly improving. New ways to explore and improve the material's properties are constantly investigated (especially to improve the mechanical and deformation characteristics of the materials). This thesis is focused on identifying and comparing values of the modulus of elasticity of fine-grained composites. These features are compared with respect to water cement ratio, ageing and compressive strength of the investigated materials. Afterwards, the values of the modulus of elasticity are studied in the relation to the tested materials.
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Evaluation of the geochemical and mineralogical transformation at an old copper mine tailings dump in Musina, Limpopo Province, South AfricaThobakgale, Rendani 18 September 2017 (has links)
MENVSC / Department of Ecology and Resource Management / Historically, mining activities have generated vast quantities of abandoned tailings dumps in several regions of South Africa and throughout the world. The management and disposal of huge volumes of tailings dumps has constituted a major challenge to the environment. The current study aims to establish the physicochemical properties and mineralogical characterization of the old copper tailings dump in Musina, to reveal the mobility patterns and attenuation dynamics of potentially toxic or heavy metal species as a function of depth, with a view of assessing their potential environmental impact with respect to surface and ground water systems. This information is crucial in the beneficial utilization of copper tailings in the development of sustainable construction materials as part of reuse approach management system. About twelve tailings samples were collected into polyethylene plastic bags from three established tailings profiles drilled by a hand auger. The collected tailings samples were characterized using standard analytical procedures i.e., X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS). The transfer of potentially toxic or heavy metal species from tailings to water was evaluated using the standardized batch leaching test (EN 12457) and speciation-equilibrium calculations on the aqueous extracts performed by MINTEQA2. The leachate concentration of cations in the collected tailings samples was determined by inductively coupled mass spectrometry (ICP-MS) and the leachate concentration of anions was determined by ion chromatography (IC).
A modified sequential extraction scheme was applied on the selected tailings samples of the drilled tailings profiles to further understand the mode of occurrence, the geochemical partitioning and distribution, real mobility, and environmental bioavailability of potentially toxic or heavy metal species in the tailings and tailings-soil interface. The extracted fractions or phases from sequential scheme were as follows: (F1) water-soluble fraction, (F2) exchangeable fraction, (F3) carbonate fraction, (F4) iron and manganese hydroxide associated fraction, (F5) organic matter and secondary sulphide associated fraction, (F6) primary sulphide bound fraction, and (F7) residual or silicate fraction. The results obtained from the seven steps sequential extraction scheme were validated by the determination
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of percentage recoveries from pseudo-total digestion or total metal content of the original sample. The distribution of major elements and potentially toxic or heavy metal species in different leachate fractions obtained after each step of sequential extraction of the selected tailings samples was determined by inductively coupled plasma mass spectrometry (ICP-MS). The appraised data was used to reveal the impact of atmospheric oxygen and infiltrating rain-water on the chemistry of copper tailings dump by depth profiles.
Macroscopic properties revealed that the abandoned Musina copper tailings are fine to medium coarse grained, and range in color from light/dark gray at the upper or shallow depth of the tailings, to dark reddish-brown at the deeper zone where the tailings are mixed with the underlying soil or soil-interface. The drilled respective tailings profiles were uniform and slightly varied in both mineralogical and bulk chemical compositions with tailings depth. Mineralogical analysis showed the following order of mineralogical composition within the respective tailings profiles: quartz> epidote> chlorite> muscovite> calcite> hematite. Chalcopyrite was the only sulphide mineral observed by optical microscopy, although not identified or quantified by XRD and SEM-EDS analysis. The observed discrete chalcopyrite grains were attributed to the primary mined ore (i.e., chalcopyrite, chalcocite and bornite) during past copper mining activities in Musina. The tailings profiles were characterized by a medium alkaline pH (7.97-8.37) that corresponds very well with the tailings leachates or pore-water pH (8.36-8.46). This pH was constant and slightly varied with tailings depth in the respective tailings profiles. The high abundance of alumino-silicate minerals and traces of carbonates as calcite coupled with low sulphide mineral content, suggested a high neutralization capacity of the tailings which was in common agreement with an alkaline nature of the copper tailings dump. The chemical composition of major elements within the respective tailings profiles followed the order: Si>Al>Fe>Ca>Mg>K>Na, and corresponds very well with the mineralogical composition of the tailings, whereby alumino-silicates were the most abundant minerals in the tailings samples. Nevertheless, the solid-phase concentration of metals decreases with increasing tailings depth as Cu>Sr>Zr>Ni>Zn and was incongruent with the mineralogical composition within the respective tailings profiles. The main secondary minerals were calcite and hematite, and their proportion increased with increasing tailings
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depth. In addition, hematite formed coatings on the rims and corners of chlorite as observed from optical microscopy, and retained relatively high amounts of potentially toxic or heavy metals (up to 862 ppm of Cu, up to 36 ppm of Ni, and up to 25 ppm of Zn) at the upper and shallow depth of the respective tailings profiles, where bulk density was high and low porosity.
Based on batch leaching tests, the amounts of potentially toxic or heavy metal species released into solution were low (0.27-0.34 μg/L Pb, 0.54-0.72 μg/L Ni, 0.88-1.80 μg/L Zn, and 20.21-47.9 μg/L Cu) and decreases with increasing tailings depth, indicating that, presently, the tailings have a minor impact on heavy metals load transported to the receiving surface and groundwater systems. The low concentration of potentially toxic or heavy metal species in solution is primarily due to their retention by secondary Fe oxide phases (i.e., hematite) and the prevailing medium alkaline pH condition of the tailings leachate or pore-water. The observations are consistent with MINTEQA2 speciation calculations, which predicted the precipitation of secondary phase cuprite (Cu2O) as the main solubility-controlling mineral phase for Cu, Zn, and Ni. Primary factors influencing aqueous chemistry at the site are neutralization and dissolution reactions as a function of pH, precipitation, and sorption into hydrous oxides (hematite and cuprite).
Based on sequential extraction results, the leachable concentration of potentially toxic or heavy metal species in the water-soluble, exchangeable and carbonate fractions of the respective tailings profiles was relatively low, except for Cu and Mn. For instance, the leachable concentration of Cu and Mn reached 10.84 mg/kg and 321.7 mg/kg at the tailings-soil interface (3 m) in tailings profile C, respectively. The low concentration of potentially toxic or heavy metal species (Cr, Co, Ni, Zn, Cd, and Pb) in these fractions could be due to the low solubility of minerals bearing these trace elements caused by variations in pore-water pH in the respective tailings profiles. The high concentration of Cu and Mn in these fractions suggests their high mobility and therefore most available for uptake in the environment.
Except for Cu>Mn>Cr, the contents of potentially toxic or heavy metal species in the Fe and Mn oxides and organic matter or sulphides bound fractions was low, due to the low
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quantity of these fractions in the tailings, despite their high affinity and sorption capacity for potentially toxic or heavy metal species. Likewise, the residual fraction of the respective tailings profiles contained the highest proportion of potentially toxic or heavy metal species. Although the highest potentially toxic or heavy metal species content was in fractions with limited mobility, care must be taken since any geochemical change or shift in the tailings pH or acidic conditions may cause them to be displaced to more mobile fractions, thereby increasing their mobility and environmental bioavailability. Therefore, physicochemical properties of the tailings including pH and mineralogical composition of the tailings samples were the main substrate controlling the geochemical partitioning and distribution, potential mobility, and environmental bioavailability of potentially toxic or heavy metal species by tailings depth. The knowledge of mobility and eco-toxicological significance of tailings is needed when considering tailings dump disposal or reuse in the environment.
The addition of copper tailings at 3 and 28 days successfully improved the compressive strength of cement mortar mixtures incorporating tailings at C5 (5%) and C10 (10%) respectively, although with small margin relative to the control mixture (C0). The maximum strength was 31.15 Mpa attained after 28 curing days, and slightly varied when compared with other compressive strength on copper blended cement mortars mixtures in other countries, used for the development of sustainable construction materials. The chemical composition, physical properties and improved compressive strength on cement mortars mixtures incorporating copper tailings, implies that copper tailings are suitable for the development of sustainable construction materials, thereby ensuring job creation, availability of land for development usage, and the reduction of environmental pollution induced by the abandoned copper tailings dumps.
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Inverkan av delmaterialensvariationer på betongensegenskaper / Effect of variations in the constituents on the properties of concreteGhafori, Abbas, Estrada Bernuy, Gabriel January 2015 (has links)
Vid betongframställning förekommer det spridningar i delmaterialens egenskaper som påverkar den färskaoch hårdnande betongen. Spridningarna i betongens delmaterial har studerats hos tre av Skanskas betongfabriker(Göteborg, Luleå och Norrköping), genom provuttag som analyserats hos Cementa Research.Provuttag har gjorts en gång per månad under ett års tid från fabrikerna. Delmaterialen som har analyseratsär ballast, cement, flytmedel och kalkfiller (endast hos Göteborg och Norrköping). Siktning av ballast0-8 mm har utförts med den traditionella siktningen. För kornstorlekar mindre än 0,25 mm, cement samtkalkfiller har lasersiktning använts.För att få en överskådlig bild över spridningarna hos delmaterialen har en analys utförts som illusteraravvikelserna med exakta siffror. Analysen har visat att den traditionella siktingen har mindre spridningjämfört med lasersiktning. Dessutom visar analysen att sättmåttet har större spridning jämfört med hållfastheten.För ballast 0-8 mm har minst spridning visats hos Luleå och störst hos Norrköping, däremot så har Luleåvisat störst spridning i ballast < 0,25 mm, cement, kalkfiller flytmedel och hållfasthet samtidigt som Göteborgvisat minst spridning i dessa och istället störst spridning i sättmått.För att få en överskådlig bild över vilka egenskapsförändringar som förväntas i betongen om respektivedelmaterial förändrats åt något håll har deskriptiv analys tillämpats parallellt med teoretisk analys. Dendeskriptiva analysen har avgränsats genom att undersöka hur förändringar i delmaterialen ballast, cement,kalkfiller och flytmedel påverkar sättmåttet och hållfastheten.Resultaten från den deskriptiva analysen har visat att en utökad mängd grövre ballast 0-8 mm ger upphovtill större sättmått och en utökad mängd finare ballast 0-8 mm ger högre hållfasthet för majoriteten avproverna. För ballast 0-8 mm < 0,25 mm har analysen visat att finare ballast < 0,25 mm ger upphov tillstörre sättmått. Hos Göteborg visar dessutom majoriteten av proverna högre hållfasthet för finare ballast< 0,25 mm.Prover från Göteborg har visat att grövre kalkfiller ger högre hållfasthet. Hos Norrköping visar dessutommajoriteten av proverna större sättmått för finare kalkfiller och högre hållfasthet för grövre kalkfiller.För cementet har analysen visat att majoriteten av proverna hos Luleå har gett upphov till större sättmåttför finare cement och högre hållfasthet för grövre cement. Hos Norrköping har analysen visat sammagällande hållfasthet, däremot tvärtom för sättmåttet, d.v.s. grövre cement har gett upphov till större sättmått.För flytmedel har majoriteten av proverna hos Luleå visat att högre torrhalt gett upphov till större sättmåttoch lägre torrhalt resulterat till högre hållfasthet. / During concrete production, property variations of the constituents occur that affect the fresh and hardenedconcrete. The variation in the constituents has been studied at three of Skanska’s concrete plants(Gothenburg, Luleå and Norrköping) through the samples analyzed at Cementa Research. Sampling atthese factories took place once per month over a one year period. The constituents that have been analyzedare aggregates, cement, superplasticizers and limestone filler (only in Gothenburg and Norrköping).Sieving of aggregates 0-8 mm has been conducted with traditional sieving. For grain sizes smaller than0.25 mm, cement and limestone filler laser sieving has been used.To get a clear picture of the variations in the constituents an analysis was performed that illustrated theexact figures of the discrepancies. Analyses show that the traditional sieving has less variation compared tolaser sighting. Moreover, the analysis shows that the slump has larger variations than the compressivestrength.Luleå showed the least variation for aggregates 0-8 mm while the largest variation was apparent at Norrkoping.However, Luleå has shown the largest variation in aggregates < 0.25 mm, cement, limestone filler,superplasticizers and compressive strength. Gothenburg on the other hand showed least variationamongst these while showing the largest variation in the slump.To better understand the property changes that are expected in the concrete of the respective the constituentsin either direction, both descriptive and theoretical analysis are applied simultaneously. The descriptiveanalysis has been limited to explore how changes in aggregates, cement, limestone fillers andsuperplasticizers affect the slump and compressive strength.The results of the descriptive analysis has shown that an increased amount of coarse aggregates 0-8 mmgives rise to larger slump and an increased amount of finer aggregates 0-8 mm gives greater compressivestrength to the majority of the samples. For aggregates 0-8 mm < 0.25 mm analysis has shown that fineraggregates < 0.25 mm give rise to greater slump. Analysis in Gothenburg also shows that the majority ofthe samples have higher compressive strength for the finer aggregates < 0.25 mm.Samples from Gothenburg have shown that coarser limestone filler provides higher compressive strength.Majority of the samples at Norrköping show greater slump for fine limestone filler and higher compressivestrength for coarse limestone filler.Analyses of cement have shown that the majority of the samples in Luleå have given rise to greater slumpfor finer cements and higher compressive strength for coarser cement. In Norrköping, the analysisdemonstrated the same compressive strength, however, to the contrary coarse cement has given rise togreater slump.Analysis of superplasticizers in Luleå show that the majority of the samples at higher dry content resultedin greater slump and at lower dry content resulted in higher compressive strength.
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Diagnostika železobetonových konstrukcí / Diagnostics of reinforced concrete structuresNápravník, Petr January 2022 (has links)
This thesis deals with the structural-technical survey of beam bridge no. 204c - M1, located in Bystřice pod Hostýnem. The theoretical part of the thesis is devoted to general characteristics of bridges, load capacity of bridges, beam bridges, concrete reinforcement, concrete, diagnosis of reinforced concrete structures, and laboratory evaluation. The practical part deals with carrying out a structural-technical survey on the bridge mentioned above, its evaluation and assessment, recalculation of the load capacity, and design of the necessary rehabilitation to maintain the functionality of the bridge.
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Stavební průzkum a diagnostika železobetonové konstrukce / Survey and Diagnostics of Reinforced Concrete StructureRichterová, Dominika January 2022 (has links)
The main theme of this diploma thesis is a building survey and diagnostics of a reinforced concrete construction. In the first, theoretical part the focus lies on a description of each method for testing constructions and their evaluation. The second, practical part focuses mainly on finding of material characteristics and reinforcement of particular parts of the construction. On basis of obtained information, the final part of this paper focuses on static assessment of chosen parts of the construction.
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Využití recyklátů z vozovek do pozemních komunikací / The utilization of the pavement waste materials to roadsFurdaničová, Alice Unknown Date (has links)
The diploma thesis deals with the use of recycled asphalt with aggregate in a hydraulically bound mixtures. The mixture is determined in the base or sub-base course of the pavement. The theoretical part of the diploma thesis describes the base course of the pavement, the production of recyclates from construction demolition waste, the acquisition and processing of recycled asphalt, the road reuse and recycling. The thesis is enriched by a contribution from the implementation of recycled asphalt laying into the base course of the communication company SKANSKA a.s. and ČNES a.s. The next chapter describes detailed experiences with recycling abroad. The thesis also contains a description of laboratory tests, which are important for evaluating the properties of mixtures with recycled asphalt. The practical part verifies the suitability of the mixture of recycled asphalt and aggregate for the road surface by testing the transverse tensile strength, compressive strength and frost and water resistance. The mixtures used are found to be suitable for pavement base course.
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Nerve guides manufactured from photocurable polymers to aid peripheral nerve repairPateman, C.J., Harding, A.J., Glen, A., Taylor, C.S., Christmas, C.R., Robinson, P.P., Rimmer, Stephen, Boissonade, F.M., Claeyssens, F., Haycock, J.W. 2015 February 1914 (has links)
Yes / The peripheral nervous system has a limited innate capacity for self-repair following injury, and surgical intervention is often required. For injuries greater than a few millimeters autografting is standard practice although it is associated with donor site morbidity and is limited in its availability. Because of this, nerve guidance conduits (NGCs) can be viewed as an advantageous alternative, but currently have limited efficacy for short and large injury gaps in comparison to autograft. Current commercially available NGC designs rely on existing regulatory approved materials and traditional production methods, limiting improvement of their design. The aim of this study was to establish a novel method for NGC manufacture using a custom built laser-based microstereolithography (muSL) setup that incorporated a 405 nm laser source to produce 3D constructs with approximately 50 mum resolution from a photocurable poly(ethylene glycol) resin. These were evaluated by SEM, in vitro neuronal, Schwann and dorsal root ganglion culture and in vivo using a thy-1-YFP-H mouse common fibular nerve injury model. NGCs with dimensions of 1 mm internal diameter x 5 mm length with a wall thickness of 250 mum were fabricated and capable of supporting re-innervation across a 3 mm injury gap after 21 days, with results close to that of an autograft control. The study provides a technology platform for the rapid microfabrication of biocompatible materials, a novel method for in vivo evaluation, and a benchmark for future development in more advanced NGC designs, biodegradable and larger device sizes, and longer-term implantation studies.
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Vlastnosti betonů s přídavkem plazmatem upravených polypropylenových vláken / Properties of concrete with the addition of plasma modified polypropylene fibersVorel, Pavel January 2013 (has links)
Master‘s thesis focuses on concrete combined with polypropylen fibres produced commercially, fibres without surface modifications and fibres modificated by plasma. Most important topic of the thesis is experimental verification of influence of plasma modificated fibres on attributes of fresh concrete and physical-mechanical attributes of solidified concrete. Based on the results of the tests perfomed on examin units compares results and anylyses applicability of different fibre surface modifications.
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Herstellung und Eigenschaften neuartiger, metallischer PolyederzellstrukturenReinfried, Matthias 01 November 2010 (has links) (PDF)
Das Ziel der vorliegenden Arbeit ist es, die technologischen Schritte für die Herstellung eines geschlossenzelligen metallischen Werkstoffs aus Stahl zu untersuchen. Das Eigenschaftsbild dieses neuartigen zellular aufgebauten Werkstoffs soll umfassend beschrieben und mit bereits existierenden Werkstoffkonzepten verglichen werden.
Die Grundidee für die Herstellung einer geschlossenzelligen Struktur bildet die Kombination der Technologie zur Herstellung von metallischen Hohlkugeln und Hohlkugelstrukturen mit dem Herstellungsprozesses für Partikelschäume aus expandierbarem Polystyrol (EPS).
Dazu ist es notwendig zunächst Grünkugeln herzustellen, wie bei der Technologie der Hohlkugeln, wobei jedoch ein treibmittelhaltiges EPS zum Einsatz kommt, das mit einer Beschichtung aus Metallpulver und Binder versehen wird. Anschließend sollen die Grünkugeln in einer geschlossenen Form zum expandieren gebracht werden. Dazu wird, wie bei der Partikelschaumtechnologie für Teile aus expandierbarem Polystyrol (EPS), Wasserdampf verwendet. Der durch den Temperaturanstieg und das Treibmittel der EPS-Partikel in den Grünkugeln entstehende Innendruck führt zum Aufschäumen und zur Expansion jeder Grünkugel. In der Folge ändert jede Kugel ihre Form so lange, bis sie mit allen Nachbarn einen flächigen, stabilen Kontakt bildet. Der auf diesem Weg erzeugte Grünkörper kann dann entformt und getrocknet werden. Wie bei der Hohlkugeltechnologie muss nachträglich das EPS durch die thermische Entbinderung entfernt und das Metallpulverskelett zu dichten Zellwänden gesintert werden.
Für die Umsetzung dieser Idee ist es erforderlich, ein geeignetes Bindersystem für die Metallpulver-Binder-Beschichtung zu entwickeln, welches die Formänderung während des Schäumprozess unbeschädigt übersteht, sowie den Schäumprozess entsprechend anzupassen.
Damit wäre die Möglichkeit gegeben, einen geschlossenzelligen metallischen Werkstoff herzustellen. Er würde die Vorteile einer geschlossenzelligen Struktur und die Materialvielfalt der pulvermetallurgischen Technologie der Hohlkugelherstellung (insbesondere in Bezug auf Stähle und andere höherschmelzende Werkstoffe) miteinander verbinden.
In Vorversuchen wurde bereits gezeigt, dass die der Arbeit zugrunde liegenden Ideen realisierbar sind. Mit der vorliegenden Arbeit wird jedoch erstmals die vollständige Kette der technologischen Schritte hinsichtlich der relevanten Einflussgrößen untersucht, wobei großen Wert auf eine Umsetzbarkeit auch im industriellen Maßstab gelegt wird.
Für den praktischen Einsatz des geschlossenzelligen Metallschaums sind seine mechanischen Kennwerte, sowie die sie beeinflussenden Herstellungsparameter von grundlegender Bedeutung. Dazu soll die Charakterisierung der zellularen Struktur und des Gefüges des Zellwandmaterials erfolgen. Hauptsächlich soll das Verformungsverhalten mit Hilfe von Druckversuchen untersucht werden. Die Festigkeitskennwerte, das Energieabsorptionsvermögen und die Steifigkeit des zellularen Werkstoffes sind weitere zu untersuchende Kenngrößen. Anhand der Ergebnisse wird eine Einordnung gegenüber dem Stand der Technik der Metallschäume vorgenommen.
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