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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Concreto auto-adensável, de alta resistência, com baixo consumo de cimento Portland e com adições de fibras de lã de rocha ou poliamida / High strength self-consolidating concrete, with low content of cement Portland and addition of polyamide or rock wool fibers

Pereira, Tobias Azevedo da Costa 28 April 2010 (has links)
O objetivo deste trabalho é apresentar uma metodologia que possibilita a obtenção de uma linha de concretos auto-adensáveis de alta resistência, econômicos e com reduzido impacto ambiental quando comparados com os concretos correntes. Para atingir estes resultados foram estabelecidos critérios de dosagem e de produção visando à sinergia entre os materiais constituintes do concreto. Foram pesquisados métodos de empacotamento dos agregados e adições minerais, estudada a interação entre o aditivo superplastificante e os materiais cimentícios e a incorporação de fibras de lã-de-rocha ou poliamida. Os concretos com matriz densa sob efeito de temperaturas elevadas tendem a sofrer lascamentos explosivos. Diante disso foi verificado o comportamento de corpos de prova e os resultados indicaram a importância da adição da fibra de poliamida nessa condição, onde o concreto resistiu a uma temperatura de 400ºC. Ensaios de resistência à abrasão indicaram que a fibra de lã-de-rocha melhora essa propriedade do concreto e, como esperado, essa adição não inibe o lascamento explosivo do concreto. Também foram determinadas as propriedades mecânicas dos concretos e concluiu-se que é possível o emprego de um concreto estrutural auto-adensável com consumo de cimento Portland da ordem de 325 kg/\'M POT.3\', fc7 = 53 MPa, fc28 = 71 MPa e Ec28 = 43 GPa. Devido à ação das adições minerais, estes concretos atingiram uma grande reserva de resistência à compressão após a idade de referência de 28 dias, obtendo-se 89 MPa aos 131 dias de idade. A densificação da pasta hidratada, a melhoria da zona de interface desta com os agregados, além da fissuração reduzida decorrente do baixo consumo de cimento e da adição de fibras indicam que este material tem desempenho superior ao prescrito pela NBR 6118 para as diversas classes de agressividade ambiental e de resistência. / The aim of this work is to show a methodology that allows to realize a set of high strength self-consolidating concrete, economic and with lower environmental impact when compared with current concretes. To get these results, criteria for production and mix design had been established aiming at to synergy between constituent materials of the concrete. Methods of particles packing (aggregates and mineral additions), the interaction between the superplasticizer and cementitious materials and the fiber incorporation were researched. The concretes with dense matrix under effect of high temperatures are susceptible to explosive spalling. In this situation, concretes were evaluated by testing cylindrical specimens and results evidenced the importance of the polyamide fiber when the concrete supported 400ºC. Tests of abrasion resistance indicated a good application for the wool-of-rock fiber, but this material not avoids explosive spalling. The mechanical properties of the concretes were determined and show that is possible to product a self consolidate concrete with low cement content (325 kg/\'M POT.3\'), fc7 = 53 MPa, fc28 = 71 MPa and Ec28 = 43 GPa. Due to action of the mineral additions, these concretes had a great reserve of compressive strength after the age of reference of 28 days and achieved 89 MPa at 131 days of age. The high density cement paste, the improvement of the matrix-aggregate interfacial zone and the reduced cracking due to the low cement content and the fibre addition indicate that these materials has superior performance to those prescribed for the NBR 6118 for diverse strength classes and aggressive environmental exposure.
2

Concreto auto-adensável, de alta resistência, com baixo consumo de cimento Portland e com adições de fibras de lã de rocha ou poliamida / High strength self-consolidating concrete, with low content of cement Portland and addition of polyamide or rock wool fibers

Tobias Azevedo da Costa Pereira 28 April 2010 (has links)
O objetivo deste trabalho é apresentar uma metodologia que possibilita a obtenção de uma linha de concretos auto-adensáveis de alta resistência, econômicos e com reduzido impacto ambiental quando comparados com os concretos correntes. Para atingir estes resultados foram estabelecidos critérios de dosagem e de produção visando à sinergia entre os materiais constituintes do concreto. Foram pesquisados métodos de empacotamento dos agregados e adições minerais, estudada a interação entre o aditivo superplastificante e os materiais cimentícios e a incorporação de fibras de lã-de-rocha ou poliamida. Os concretos com matriz densa sob efeito de temperaturas elevadas tendem a sofrer lascamentos explosivos. Diante disso foi verificado o comportamento de corpos de prova e os resultados indicaram a importância da adição da fibra de poliamida nessa condição, onde o concreto resistiu a uma temperatura de 400ºC. Ensaios de resistência à abrasão indicaram que a fibra de lã-de-rocha melhora essa propriedade do concreto e, como esperado, essa adição não inibe o lascamento explosivo do concreto. Também foram determinadas as propriedades mecânicas dos concretos e concluiu-se que é possível o emprego de um concreto estrutural auto-adensável com consumo de cimento Portland da ordem de 325 kg/\'M POT.3\', fc7 = 53 MPa, fc28 = 71 MPa e Ec28 = 43 GPa. Devido à ação das adições minerais, estes concretos atingiram uma grande reserva de resistência à compressão após a idade de referência de 28 dias, obtendo-se 89 MPa aos 131 dias de idade. A densificação da pasta hidratada, a melhoria da zona de interface desta com os agregados, além da fissuração reduzida decorrente do baixo consumo de cimento e da adição de fibras indicam que este material tem desempenho superior ao prescrito pela NBR 6118 para as diversas classes de agressividade ambiental e de resistência. / The aim of this work is to show a methodology that allows to realize a set of high strength self-consolidating concrete, economic and with lower environmental impact when compared with current concretes. To get these results, criteria for production and mix design had been established aiming at to synergy between constituent materials of the concrete. Methods of particles packing (aggregates and mineral additions), the interaction between the superplasticizer and cementitious materials and the fiber incorporation were researched. The concretes with dense matrix under effect of high temperatures are susceptible to explosive spalling. In this situation, concretes were evaluated by testing cylindrical specimens and results evidenced the importance of the polyamide fiber when the concrete supported 400ºC. Tests of abrasion resistance indicated a good application for the wool-of-rock fiber, but this material not avoids explosive spalling. The mechanical properties of the concretes were determined and show that is possible to product a self consolidate concrete with low cement content (325 kg/\'M POT.3\'), fc7 = 53 MPa, fc28 = 71 MPa and Ec28 = 43 GPa. Due to action of the mineral additions, these concretes had a great reserve of compressive strength after the age of reference of 28 days and achieved 89 MPa at 131 days of age. The high density cement paste, the improvement of the matrix-aggregate interfacial zone and the reduced cracking due to the low cement content and the fibre addition indicate that these materials has superior performance to those prescribed for the NBR 6118 for diverse strength classes and aggressive environmental exposure.
3

Life cycle assessment of the semidetached passive house "Röda lyktan" in northern Sweden : A comparison between the construction phase and the use phase / Livscykelanalys av det tvådelade passivhuset "Röda lyktan" i norra Sverige : En jämförelse mellan konstruktionsfasen och användningsfasen

Svensson, Michelle January 2013 (has links)
This report is a life cycle assessment of a relatively newly built semidetached passive house/low energy house located in Östersund/Jämtland. The analysis concentrates on the building materials in the construction phase and the energy in the use phase for 50 years. The construction phase include frame, foundation, interior and exterior walls, ceiling and roof, middle floor structure, floor coverings, interior and exterior doors, windows, interior staircase with banisters, stove and FTX-ventilation system. The inventory to obtain the volume of each material has been made with the help of blueprints and interviews. The inventory of the use phase has been made using measurements from a parallel study by Itai Danielski of the energy use in the house (Danielski, Svensson & Fröling, 2013). The database Ecoinvent has been used to get a result for the volume and energy values. The inventory data is allocated and the characterization methods GWP, CED (cumulative energy demand) and USEtox are used. The aim of this study was to compare the construction phase with the use phase to see which phase that has the highest energy values ​​and environmental impact. Another goal was to examine which materials in the construction phase that has the highest embodied energy and environmental impact. The result shows that in a comparison between the construction phase and the use phase, and when considering the parameters included in this study, the use phase has the highest values for global warming potentials (around 54 %), cumulative energy demand (around 80 %), ecotoxicity (around 56 %), human non-carcinogenic toxicity (around 77 %) and total human toxicity (around 75 %). The construction phase has the highest values for human carcinogenic toxicity (around 57 %). Even if the use phase has the highest values in most categories the construction phase also has high values. As buildings become more energy efficient and with increasing use of renewable energy, the construction phase becomes more important from an environmental perspective. This means that the material choices which are made in passive houses become increasingly important if passive houses should be considered to be environmentally friendly also in the future. The study also shows that the FTX-ventilation system, some of the insulation materials (with cellular plastic sheets and rock wool in top), metals (with sheet metal roofing of steel in top), glued laminated timber and wood fiber boards  have some of the highest values of environmental impact and the highest embodied energy. These materials should in future buildings be considered, if possible, to be replaced with materials with less environmental impact. / Den här rapporten är en livscykelanalys av ett relativt nybyggt passivhus/lågenergihus som också är ett parhus (ett hus delat i två separata lägenheter) beläget i Östersund/Jämtland. Analysen koncentrerar sig på byggnadsmaterialen i konstruktionsfasen och energin i användningsfasen under 50 år. Konstruktionsfasen inkluderar stomme, grund, inner- och ytterväggar, inner- och yttertak, mellanbjälklag, golvbeklädnader, inner- och ytterdörrar, fönster, invändig trappa med trappräcke, kamin och FTX-ventilationssystem. Inventeringen för att få fram volymen på varje material har gjorts med hjälp av ritningar och intervjuer. Inventeringen av användningsfasen har gjorts med hjälp av mätvärden från en parallell studie av Itai Danielski på energianvändningen i huset (Danielski, Svensson & Fröling, 2013). Databasen Ecoinvent har sedan använts för att få fram ett resultat för volym- och energivärdena. Inventeringsdatan är allokerad och karaktäriseringsmetoderna GWP (globalt uppvärmingspotential), CED (kumulativt energibehov) och USEtox (toxicitet) har använts. Målet med studien är att jämföra konstruktionsfasen med användningsfasen för att kunna se vilken fas som har högst energivärden och miljöpåverkan. Målet är också att undersöka vilka material i konstruktionsfasen som har högst förkroppsligad energi och miljöpåverkan, i syftet att eventuellt kunna byta ut vissa material till miljövänligare alternativ, för att få ett miljövänligare hus i framtida liknande byggnationer. Resultaten visar att i en jämförelse mellan konstruktionsfasen och användningsfasen, och med hänsyn till de parametrar som ingår i studien, att användningsfasen har de högsta värdena för globalt uppvämingspotential (runt 54 %), kumulativt energibehov (runt 80 %), ekotoxicitet (runt 56 %), human icke-cancerogen toxicitet (runt 77 %) och total human toxicitet (runt 75 %). Konstruktionsfasen har högst värden för human cancerogen toxicitet (runt 57 %). Även om användningsfasen har högst värden i de flesta kategorierna så har även konstruktionsfasen höga värden. Ju mer energieffektiva husen blir och med en ökad användning av energi från förnyelsebara källor, desto viktigare blir konstruktionsfasen ur ett miljöperspektiv. Det betyder att materialvalen som görs i huset blir väldigt viktiga om passivhus ska fortsätta anses som miljövänliga även i framtiden. Denna studie visar också att FTX-ventilationssystemet, några av isoleringsmaterialen (med cellplasten och stenullen i topp), metallerna (med plåttaket av stål i topp), limträbalkar och träfiberskivor har några av de högsta värdena av miljöpåverkan och den högsta förkroppsligade energin. Dessa material borde i framtida byggnationer övervägas att om möjligt ersättas med andra material med mindre miljöpåverkan.

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