Made available in DSpace on 2016-03-15T19:36:43Z (GMT). No. of bitstreams: 1 Cindy Yuri Ueki Peres.pdf: 14079358 bytes, checksum: e18673ab8406f72692d9a0a35b414328 (MD5) Previous issue date: 2014-06-09 / Fundo Mackenzie de Pesquisa / This work aims to evaluate the concrete with addition of hollow glass microspheres . The specific objectives of this work is to evaluate the influence of the addition of hollow glass microspheres with different combinations of dosage in concrete concerning resistance and workability. It was proved that in other studies glass microspheres may influence the workability of the concrete , because due to its geometry, the balls can roll on each other and on the other solid components of the concrete. In view of the foregoing, it becomes important to study the effect of varying the dosage of these glass microspheres in the concrete properties, such as fluidity, strength and compactn ess. Tests are carried out Workability Slump in each dosage of concrete , and in every age of curing of concrete , the bodies of the test piece was be submitted to ultrasound and axial strength test . we used the Weibull to compare the results. With the results obtained in the tests, the comparative analysis of the variation of each factor chosen were performed. The analysis of the results shows that for some formulations, the addition of hollow glass microspheres imparts high mechanical strength to compressive strength above 30MPa at all periods analyzed. Importantly, the workability of the concrete had to be substantially reduced, showing no improvement in workability due to the addition of hollow glass microsphere / Este trabalho tem como objetivo avaliar o concreto com adição de microesferas ocas de vidro. O objetivo específico deste trabalho é avaliar a influencia da adição de microesferas ocas de vidro com diferentes combinações de dosagem no concreto, em relação à resistência e à trabalhabilidade. Foi provado em outros trabalhos que as microesferas de vidro podem influenciar na trabalhabilidade do concreto, pois, devido a sua geometria, as esferas podem rolar umas sobre as outras e sobre os demais componentes sólidos do concreto. Em virtude do exposto, torna-se importante estudar a influência da variação da dosagem dessas microesferas de vidro nas propriedades do concreto, como fluidez , resistência e compacidade. Foram realizados ensaios de trabalhabilidade ou Slump em cada dosagem de concreto, e em cada idade de cura do concreto, os corpos-de-prova foram submetidos ao ultrassom e ao ensaio de resistência axial, utilizou-se o método de Weibull para comparar os resultados de resistência a compressão. Com os resultados obtidos nos ensaios, foram realizadas as análises comparativas da influência da variação de cada fator escolhido. A análise dos resultados obtidos mostra que para algumas formulações, a adição das microesferas ocas de vidro confere alta resistência mecânica de compressão do concreto, acima de 30MPa, em todos os períodos de cura analisados. Importante destacar qu e a trabalhabilidade do concreto apresentou-se substancialmente reduzida, não apresentando qualquer melhora de trabalhabilidade devido à adição da microesfera oca de vidro.

For many metal components the presence of hard, non-metallic inclusions such as oxides lowers the impact toughness by acting as fracture initiation points and easing crack propagation. In components produced by powder metallurgy hot isostatic pressing (PM HIP), oxides often form a continuous network of small, spherical inclusions after consolidation at the prior particle boundaries (PPB). It is therefore of great importance to reduce surface oxides before consolidation in order to improve mechanical properties. In this work, oxides were attempted to be reduced directly prior to the consolidation of one tool steel and one low-alloy steel by introducing H2 into sealed PM HIP capsules. The two H2-carriers were hollow glass microspheres and the compound ammonia borane (H3NBH3). The H2-carriers were placed separately from the metal powder. Microspheres were filled at 300 °C with a gas mixture at 675 bar resulting in a storage capacity of 0.16 wt%. Gaseous species released from the H2-carriers during heating were analysed by mass spectrometry. Results showed that the microspheres only release H2 while ammonia borane in addition releases other nitrogen and boron containing species. Impact testing as well as chemical and microstructural analysis were performed on the two consolidated materials with samples retrieved from different vertical and radial positions. Both H2-carriers had leaked into the material resulting in decreased impact toughness compared to the reference. Further from the source of the contaminants, oxygen content was reduced and impact toughness was improved. Microspheres showed overall better reduction ability even though they release less hydrogen compared to ammonia borane. Impact toughness was not improved as much with ammonia borane even though similar oxygen levels were achieved. Ammonia borane’s decomposition products likely obstruct the oxide reduction or introduce new inclusions lowering the impact toughness. / Det är för många metallkomponenter viktigt att så mycket som möjligt undvika hårda, icke metalliska inneslutningar. Detta eftersom de sänker slagsegheten genom sprickinitiering men även genom att underlätta spricktillväxt. Ytoxider i komponenter tillverkade genom pulvermetallurgisk het-isostatisk pressning (PM HIP) bildar ofta ett kontinuerligt nätverk av små, sfäriska inneslutningar efter konsolidering vid de tidigare partikelgränserna. Det är därför viktigt att reducera ytoxider före konsolidering för att förbättra de mekaniska egenskaperna av komponenter tillverkade genom PM HIP. I detta examensarbete har ytoxider reduceras direkt före konsolidering av ett låglegerat stål och ett verktygsstål genom att tillsätta H2 i de förseglade PM HIP kapslarna. Två vätgasbärare testades, ihåliga mikrosfärer av glas och ammoniak boran (H3NBH3). Vätgasbärarna var placerade i ett område avskilt från metallpulvret. Mikrosfärerna fylldes med en gasblandning vid 675 bar och 300 °C vilket resulterade i en lagringskapacitet på 0.16 vikt%. Gaser som frigjordes från vätgasbärarna vid uppvärmning analyserades med en masspektrometer. Resultatet visade att mikrosfärerna bara frigör H2 medan ammoniak boran också frigör andra ämnen innehållande kväve och bor. Slagprovning och analys av mikrostruktur samt syre- och kvävehalter utfördes på de två konsoliderade materialen med prover från olika vertikala och radiella positioner. Båda vätgasbärarna hade läckt in i materialet vilket resulterade i minskad slagseghet jämfört med referensmaterialet. Längre från vätgasbärarnas ursprungsposition var slagsegheten bättre och syrehalten lägre. De vätgasfyllda mikrosfärerna uppvisade överlag bättre förmåga att minska syrehalten trots att de innehöll mindre H2 jämfört med ammoniak boran. Slagsegheten förbättrades inte lika mycket med ammoniak boran trots att liknade syrenivåer uppmättes. Ammoniak boranets pyrolysprodukter förhindrar möjligtvis oxidreduktionen eller introducerar nya inneslutningar som resulterar i en försämrad slagseghet.