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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

Estudo da aderência de concretos ativados alcalinamente à base de cinza da casca de arroz e metacaulim /

Guimarães, Paulo Victor Campos. January 2019 (has links)
Orientador: José Luiz Pinheiro Melges / Resumo: A indústria do cimento Portland é responsável direta por uma carga de poluentes de significativo dano ambiental. Os Concretos Ativados Alcalinamente (CAA) são matrizes compostas por um ativador alcalino e um aglomerante alternativo. O material comumente utilizado para a ativação alcalina é o silicato de sódio, cuja fabricação também se mostra como ambientalmente nociva. O silicato de sódio, junto ao cimento Portland, podem ser dispensados, uma vez que a produção do ativador pode se dar através de um composto rico em silício (materiais pozolânicos no geral), sendo a cinza da casca de arroz (CCA) o instrumento de estudo do trabalho apresentado, e a soda cáustica como fornecedora de sódio (meio alcalino). Os concretos CAA foram definidos conforme o parâmetro ξ (CAA-ξ), que representa a relação molar entre SiO2 e Na2O, com as variações ξ = 1,2, ξ = 1,6 e ξ = 2,0, esta última representando o concreto ativado alcalinamente com maior taxa de CCA. Este trabalho tem como intuito a avaliação das propriedades mecânicas dos concretos CAA, comparando-as, em seguida, com duas tipologias de concreto com cimento Portland CPV-ARI, com distintos fatores água cimento (0,45 e 0,55). A variação na relação a/c teve como intuito a análise de duas referências com valores diferentes de fck. Os resultados demonstram que a resistência à compressão axial e diametral (sete dias de cura) para os concretos CAA se encontraram na faixa de 25 a 30 MPa, e de 1,5 a 3,5 MPA, respectivamente. Não foram observados... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Portland cement industry is directly responsible for a load of pollutants of significant environmental damage. Alkali-Activated Concrete (AAC) is a matrix with prior activation and alternative binder. The catalyst material commonly used for prior activation is the sodium silicate, the manufacture of which is also environmentally harmful. Sodium silicate, together with Portland cement, can also be dispensed with, since the activator can be produced through a silicon-rich compound (pozzolanic materials in general), with the rice husk ash (RHA) being the instrument of study of the work presented, and caustic soda as a supplier of sodium. The AAC concretes were defined according to the parameter ξ (AAC- ξ), which represents the molar ratio of SiO2 and Na2O, with the variations ξ = 1.2, ξ = 1.6 and ξ = 2.0, the latter representing the AAC with higher RHA rate. This work intends to evaluate the mechanical properties of AAC, comparing them to two types of concrete with ordinary Portland cement with high early resistance, with different water cement factors (0.44 and 0.55). The variation in the water/binder mass ratio was intended to analyze two references with different values of compressive strength class. The results demonstrate that the axial and diametric compression strength (seven days cure) for the AAC concretes were in the range of 25 to 30 MPa, and of 1.5 to 3.5 MPA, respectively. There were no significant gains in the transition between the ages of 7 and 28 days, and 2... (Complete abstract click electronic access below) / Mestre
2

Análise do emprego de materiais alternativos no alto forno da Arcelormital Tubarão

Mosckem, Sergio Luis [UNESP] 02 July 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:30:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-07-02Bitstream added on 2014-06-13T20:39:47Z : No. of bitstreams: 1 mosckem_sl_me_guara.pdf: 1245042 bytes, checksum: 8a691aa6f65edd8f060ed9355bc9c3bd (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O trabalho de análise do uso de materiais alternativos no Alto Forno 1 da ArcelorMittal Tubarão estabelece uma taxa de substituição de cada material alternativo, plástico e pneu, em relação ao uso exclusivo do carvão mineral injetado no Alto Forno através das ventaneiras. A taxa de utilização de plástico e pneu é avaliada considerando o aporte de energia e dos agentes necessários para a reação química de redução do minério de ferro em ferro metálico. No presente trabalho são elaborados os balanços de massa e de energia de acordo com a configuração operacional vigente no segundo semestre de 2009 para o Alto Forno 1 e com os dados de produção do mês de julho de 2009. O resultado mostra a viabilidade técnica do uso de plástico ou pneu e estabelece as condições de uso de cada um em relação à quantidade, tipo e granulometria. A substituição energética decorrente do uso de plástico e pneu estabelece uma forma de aplicação segura e controlada deste resíduo, além de agregar valor a estes materiais normalmente descartados pela sociedade. Contribui também para amenizar os impactos ambientais decorrentes da falta de uma destinação regulamentada e eficaz para plásticos descartados e pneus inservíveis / The study of alternative fuel materials in the Blast Furnace 1 of ArcelorMittal Tubarão, establishes a rate of each material analyzed, waste plastics packaging and waste tires, in order to replace part of the pulverized coal that is usually injected in to the Blast Furnace through the tuyeres. The injection rate of waste plastic packaging and waste tires is analyzed considering the energy input and the necessary elements for the iron ore reduction chemical reaction. The mass and energy balance is done according to the operational configuration of the Blast Furnace 1 in the second semester of 2009 and operation data from July of 2009. The result of the study shows technical viability to use waste plastics packaging and waste tires and establish requirements for the injection, such as flow rate and particles size. The alternative energy provided from these waste materials builds a safety and controlled way to reach the best utilization for each one. Moreover, the environmental impact can be reduced due to its disposal is normally done in outdoor areas
3

Utilization and Impacts of Dredge Sediment and Other Alternative Materials on Concrete Compressive Strength

Needs, Andrew Douglas 14 May 2023 (has links)
No description available.
4

”Inget läromedel är ju fulländat” : En kvalitativ intervjustudie om sex lärares användning av alternativt material i religionskunskapsundervisningen i årskurs 4 – 6 / ”No teaching aid is perfect” : A qualitative interview study about six teachers’ use of alternative materials in Religious Education in grades 4 – 6

Hilding, Frida January 2019 (has links)
Studien är inriktad på ämnet religionskunskap i grundskolans årskurs 4 – 6. Det finns begränsat med tidigare forskning kring lärares användning av olika typer av material i religionskunskapsundervisning i en mellanstadiekontext. Dessutom visar forskning främst vilket material som används och mindre fokus ligger på hur och varför lärare använder olika typer av material. Syftet med studien är därför att undersöka lärares användning av alternativt material i religionskunskapsundervisningen i årskurs 4 – 6. Frågeställningarna handlar om vilket material som används samt varför lärare väljer att använda alternativt material. Med alternativt material menas, i denna studie, allt material som används utöver läroboken i religionskunskap. De didaktiska frågorna ”vad?”, ”hur?” och ”varför?” samt ett sociokulturellt perspektiv på lärande har varit betydande vid materialanalysen för att få syn på lärares didaktiska val och motiveringar när det kommer till alternativt material i religionskunskapsundervisningen. Resultatet är baserat på kvalitativa semistrukturerade intervjuer med sex lärare på olika skolor i två kommuner. Av resultatet framkommer att lärare använder olika typer av alternativt material när de upplever att läroboken inte räcker till, för att variera undervisningen så att det möter alla elevers olika behov och förutsättningar samt för att motivera och engagera. / The study is focused on the subject of religious education in the Swedish compulsory school’s grades 4 – 6. Previous research on teachers’ use of alternative materials in Religious Education in this context is limited. Furthermore, available research mainly show what materials are used and does not focus on how or why teachers use different kinds of materials. Therefore, the aim of this study is to investigate teachers’ use of alternative materials in Religious Education in grades 4 – 6. Moreover, the study aims to answer the questions of what material is used and why teachers choose to use alternative material. In this study, alternative material is used to describe every material that is used in addition to textbooks, in religious education. The didactical questions “what?”, “how?” and “why?” as well as a sociocultural perspective on learning have been important when analysing the material to distinguish teachers’ didactical choices when it comes to using alternative materials in Religious Education. The result is based on qualitative semi-structured interviews with six teachers in different schools in two municipalities. The result shows that teachers use different kinds of alternative materials when they feel that the textbook is insufficient and to vary their teaching to accommodate to every pupil’s needs and prerequisites. They also use alternative materials to motivate and engage the pupils.
5

Análise do emprego de materiais alternativos no alto forno da Arcelormital Tubarão /

Mosckem, Sergio Luis. January 2010 (has links)
Resumo: O trabalho de análise do uso de materiais alternativos no Alto Forno 1 da ArcelorMittal Tubarão estabelece uma taxa de substituição de cada material alternativo, plástico e pneu, em relação ao uso exclusivo do carvão mineral injetado no Alto Forno através das ventaneiras. A taxa de utilização de plástico e pneu é avaliada considerando o aporte de energia e dos agentes necessários para a reação química de redução do minério de ferro em ferro metálico. No presente trabalho são elaborados os balanços de massa e de energia de acordo com a configuração operacional vigente no segundo semestre de 2009 para o Alto Forno 1 e com os dados de produção do mês de julho de 2009. O resultado mostra a viabilidade técnica do uso de plástico ou pneu e estabelece as condições de uso de cada um em relação à quantidade, tipo e granulometria. A substituição energética decorrente do uso de plástico e pneu estabelece uma forma de aplicação segura e controlada deste resíduo, além de agregar valor a estes materiais normalmente descartados pela sociedade. Contribui também para amenizar os impactos ambientais decorrentes da falta de uma destinação regulamentada e eficaz para plásticos descartados e pneus inservíveis / Abstract: The study of alternative fuel materials in the Blast Furnace 1 of ArcelorMittal Tubarão, establishes a rate of each material analyzed, waste plastics packaging and waste tires, in order to replace part of the pulverized coal that is usually injected in to the Blast Furnace through the tuyeres. The injection rate of waste plastic packaging and waste tires is analyzed considering the energy input and the necessary elements for the iron ore reduction chemical reaction. The mass and energy balance is done according to the operational configuration of the Blast Furnace 1 in the second semester of 2009 and operation data from July of 2009. The result of the study shows technical viability to use waste plastics packaging and waste tires and establish requirements for the injection, such as flow rate and particles size. The alternative energy provided from these waste materials builds a safety and controlled way to reach the best utilization for each one. Moreover, the environmental impact can be reduced due to its disposal is normally done in outdoor areas / Orientador: José Antonio Perrella Balestieri / Coorientador: João Andrade de Carvalho Junior / Banca: Luiz Roberto Carrocci / Banca: Ricardo Dias Martins de Carvalho / Mestre
6

Avaliação de materiais alternativos como coberturas em instalações para produção animal visando o conforto térmico / Evaluation of alternative materials as coverings in installations for animal production aiming at the thermal comfort

Cardoso, Alaércio de Sousa 27 August 2010 (has links)
Made available in DSpace on 2015-03-26T13:23:32Z (GMT). No. of bitstreams: 1 texto completo.pdf: 832590 bytes, checksum: 366f1e8483b746bfb918ff8857b8e87b (MD5) Previous issue date: 2010-08-27 / Brazil, to remain competitive in agribusiness, the challenge is to continue production with low cost technologies in facilities with favorable environment conditions. In general, coverage due to represent much of the building, is the factor that has great influence on the environmental conditions for livestock. The efficiency is associated with the type of tiles material they are made, characterized by isolation, damping and thermal delay and associated with the superficial nature, characterized by radiant absorptivity and emissivity. Using the theory of similarity for the definition of 1:12 scale models, and thermal environmental indices, the objective of this research was to evaluate the conditions inside poultry or cattle sheds made with five types of alternative material roofs, namely: Tetra Pak, toothpaste tubes, Onduline with vegetable fiber and bitumen, Reciplac aluminized on the top and white on the bottom, Reciplac aluminized on the top and neutral on the bottom, compared with the tiling of clay, with and without the presence of an insulating undercoverage, under hot conditions. Considering the Black Globe Temperature and Humidity Index, the Radiant Thermal Load and Thermal Effectiveness enabled by coverage, in the birds and cattle level, it was found that in general there was similarity between the results, but with differences was amplified when the curtains were closed, and that during hot days, the best conditions were associated with coverage of clay. The worst results were associated with the coverage Onduline - vegetable fiber and asphalt - with and without under-coverage, Tetra Pak coverage - no under-coverage, Reciplac aluminized on the upper side and white on the bottom - with and without undercoverage, and Reciplac aluminized above and neutral below - with undercoverage. The use of an insulating undercoverage was unable to promote improvement in environmental thermal conditions, unless associated with the tiles of worse performance. It was estimated reduction in the initial cost of the roof, in comparison to the coverage of clay, at 47, 7% for Reciplac aluminized coated on the upper side and white on bottom, 45, 5% for Reciplac aluminized on the upper face and neutral at the bottom and 41, 2% for the roof made of Tetra Pak tiles. / O Brasil, para que continue competitivo no agronegócio, persiste o desafio da produção com tecnologias de baixo custo, em instalações com condições ambientais favoráveis. De forma geral, a cobertura por representar grande parte da envolvente, é o fator que tem grande influência sobre as condições do ambiente de galpões para a criação animal, sendo sua eficiência associada ao tipo do material constituinte das telhas, caracterizado pelo isolamento, amortecimento e retardo térmico, e associado à natureza superficial, caracterizado pela absortividade e emissividade radiante. Com a utilização da teoria de similitude, para definição de modelos reduzidos na escala 1:12, e de índices térmicos ambientais, o objetivo deste trabalho foi avaliar as condições no interior de galpões de avicultura ou bovinocultura, confeccionados com cinco tipos de coberturas de materiais alternativos, ou seja: embalagens Tetra Pak, tubos de pastas de dentes, Onduline com fibra vegetal e betume, Reciplac aluminizada na face superior e branca na inferior e Reciplac aluminizada na face superior e neutra na inferior, em comparação com a cobertura de telhas de barro, com e sem a presença de manta isolante subcobertura, em condições de calor. Considerando o Índice de Temperatura de Globo Negro e Umidade, a Carga Térmica Radiante e a Efetividade Térmica propiciados pelas coberturas, ao nível das aves e dos bovinos, verificou-se no geral que ocorreu semelhança entre resultados, porém com diferenças amplificadas quando as cortinas estavam fechadas, e que, no período quente do dia, as melhores condições estiveram associados à cobertura de barro. Os piores resultados estiveram associados com as coberturas Onduline fibra vegetal e betume - com e sem subcobertura, cobertura reciclada de Tetra Pak - sem subcobertura, cobertura Reciplac aluminizada na face superior e branca na inferior - com e sem subcobertura, e cobertura Reciplac aluminizada em cima e neutra por baixo - com subcobertura. O uso da manta isolante subcobertura não foi capaz de promover melhoria nas condições térmicas ambientais, a não ser quando associada a coberturas de pior desempenho. Estimou-se redução nos custos iniciais do telhado em comparação ao de cobertura de barro, em 47, 7% para o com cobertura Reciplac aluminizada na face superior e branca na inferior, 45, 5% para o com cobertura Reciplac aluminizada na face superior e neutra na inferior e 41, 2% para o com cobertura de material reciclado Tetra Pak.
7

Uso de experimentos, confeccionados com materiais alternativos, no processo de ensino e aprendizagem de Física: Lei de Hooke / Experiments use of made-up with alternative materials in the process of teaching and learning Physics: Hooke Law

Neves, João Henrique Moura [UNESP] 21 December 2015 (has links)
Submitted by JOÃO HENRIQUE MOURA NEVES null (jh120284@hotmail.com) on 2016-02-23T01:56:55Z No. of bitstreams: 1 DISSERTAÇÃO FINAL.pdf: 6988918 bytes, checksum: d199c0bfc0c5eff67276a97d4e0db62a (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-02-23T16:43:32Z (GMT) No. of bitstreams: 1 neves_jhm_me_prud.pdf: 6988918 bytes, checksum: d199c0bfc0c5eff67276a97d4e0db62a (MD5) / Made available in DSpace on 2016-02-23T16:43:32Z (GMT). No. of bitstreams: 1 neves_jhm_me_prud.pdf: 6988918 bytes, checksum: d199c0bfc0c5eff67276a97d4e0db62a (MD5) Previous issue date: 2015-12-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As atividades experimentais de Física proporcionam uma construção do conhecimento de forma qualitativa e quantitativa aos alunos, tanto das séries finais do Ciclo Básico, como das séries do Ensino Médio. Este trabalho propõe desenvolver atividades experimentais com materiais didáticos alternativos que permitam ao estudante uma reflexão sobre o aproveitamento de alguns materiais para estudo prático e, principalmente, de alguns conceitos básicos da Física Clássica neles envolvidos. O trabalho consiste em estudar a deformação elástica do tubo de látex, material usado em hospitais e para fabricar estilingues, conhecido como ‘soro’. Este material foi escolhido devido à sua flexibilidade e alta resistência à deformação, podendo ser utilizado para suspender uma grande quantidade de massas diferentes. O material de apoio contém um kit descrevendo os materiais utilizados nos experimentos, roteiro experimental e os resultados após a aplicação desta atividade. / The experimental activities in Physics provide a knowledge construction of qualitative and quantitative manner to students, both of the final series of the Basic Cycle, as the High School grades. This work proposes to develop experimental activities with alternative didactic material to enable the student to reflect on the use of some materials for practical study and mainly some basic concepts of Classical Physics involved therein. The work consists of studying the elastic deformation of latex tube, material used in hospitals and to make slingshots, known as 'sera'. This material was chosen because of its high flexibility and resistance to deformation and can be used to suspend a large amount of different masses. The support material contains a kit describing the materials used in the experiments, experimental script and the results after the application of this activity.
8

Emprego de EPS reciclado em blocos vazados de concreto para otimização do conforto térmico das edificações

Gonçalves, Paulo José Simão, 9299344-3501 06 February 2018 (has links)
Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-04-11T15:10:22Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação_Paulo J. S. Gonçalves.pdf: 7857623 bytes, checksum: 3677132bdb6d0d4f5c32c230cf3e630a (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-04-11T15:10:45Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação_Paulo J. S. Gonçalves.pdf: 7857623 bytes, checksum: 3677132bdb6d0d4f5c32c230cf3e630a (MD5) / Made available in DSpace on 2018-04-11T15:10:45Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação_Paulo J. S. Gonçalves.pdf: 7857623 bytes, checksum: 3677132bdb6d0d4f5c32c230cf3e630a (MD5) Previous issue date: 2018-02-06 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / The natural resources preservation and implementation of sustainable factor in projects are two of main concerns obeserved currently by researchers and engineers resident around world. The developed research seeked to make feasiable new concretes that incorporate these guidelines inserting expanded polystyrene, from mechanical recycling, in partial replacement of traditional coarse aggregate used in Amazonas. Firstly was carried out a physicochemical characterization in involved components to verify their uses on production of hollow concrete blocks. After that, the experimental dosage was obtained in association of Compressible Packaging Model with Tango´s adapted methodology for four concretes produced (with content ratios of 0, 5, 10 and 15% as partial volumetric replacement of coarse aggregate by recycled EPS) and w/c ratio of 0,5 was found for all concretes. The tests performed procedures to check physical and mechanical properties followed the NBR 12118:2013, and resulted in two classifications in terms of compressive strenght: referencial (0%) and 5% gravel’s parcial replacement by recycled EPS (defined as limit for employing this exchange according to NBR 6136:2014) attested their uses for structural applications, while 10 and 15% EPS’ partial replacement couldn´t be used because their compressive strenght were lower than minimum acceptance strenght. Regarding thermal analysis, it was verified that all blocks partially attented NBR 15575-4:2013, necessitating adjustments to ensure the minimum perfomance level required for that standard. The thermal comfort provided by referential blocks and blocks with 15% of recycled EPS presented similar results as a function of thermal transmittance and different radiant temperatures, became similar average heat flows in both specimens. However, at times when environment peak temperature were recorded, it was verified greater delay and thermal inertia in the masonry with recycled EPS, reducing heat transmition through the walls. / A preservação dos recursos naturais e a implantação do fator sustentável na concepção de projetos são duas das principais preocupações observadas atualmente por pesquisadores e engenheiros em todo mundo. A pesquisa desenvolvida buscou viabilizar uma nova elaboração de concretos que incorporassem estas diretrizes ao inserir o poliestireno expandido, oriundo da reciclagem mecânica, em substituição parcial ao agregado graúdo tradicional empregado no estado do Amazonas. Inicialmente, realizou-se a caracterização físico-química dos componentes envolvidos com o intuito de verificar o emprego destes na produção de blocos vazados. Após esta fase, obteve-se a dosagem experimental por meio da associação do Modelo de Empacotamento Compressível com a metodologia adaptada de Tango para os quatro tipos de concretos produzidos (com teores de substituição volumétrica de 0, 5, 10 e 15% do agregado graúdo por EPS reciclado), definindo um fator a/c igual a 0,5 para todos eles. Os ensaios executados para verificação das propriedades físicas e mecânicas seguiram as diretrizes da NBR 12118:2013, e resultaram em duas classificações quanto à resistência à compressão encontrada: os blocos referenciais (0%) e com 5% de substituição da brita pelo EPS reciclado (definido como o limite para empregar esta troca segundo a NBR 6136:2014) poderiam ser direcionados para fins estruturais, enquanto que os com 10 e 15% de substituição não atenderam a resistência mínima de aceitação. A respeito da análise térmica, verificou-se que os blocos atenderam parcialmente a NBR 15575-4:2013, necessitando de adequações para garantir o nível de desempenho mínimo exigido por esta norma. Os confortos térmicos proporcionado pelos blocos referenciais e com 15% de EPS apresentaram resultados semelhantes em função da transmitância térmica que, juntamente com as distintas temperaturas radiantes, equipararam os fluxos médios de calor em ambos exemplares. Contudo, no horário de pico da temperatura ambiente, verificou-se o maior atraso e inércia térmica na alvenaria com EPS reciclado, reduzindo da transmissão de calor entre as faces das paredes.
9

Durabilité des éco-bétons : impact d'additions cimentaires alternatives sur la corrosion des armatures dans les bétons armés / Durability of green concretes : impact of alternative cementitious materials on the corrosion of steel in reinforced concrete

Frohard, Fabien 15 December 2014 (has links)
L'utilisation de ressources locales est une des facettes importantes du développement durable dans le secteur de la construction. Plusieurs types de sous-produits sont aujourd'hui à l'étude pour une utilisation dans les bétons en tant qu'addition cimentaire, dans le but de développer des liants basés sur des ressources alternatives. La présente étude cherche à évaluer les performances de quatre types de sous-produits sur les propriétés des bétons armés vis-à-vis de la corrosion. La poudre de verre, les cendres volantes de papeterie, les cendres de boues d'épurations ou les sédiments calcinés présentent une nature minérale compatible avec un milieu cimentaire. Face à la problématique de corrosion des armatures, le béton constitue à la fois un milieu alcalin favorisant la passivité des aciers et une barrière de transport qui limite la pénétration de contaminants au sein de la matrice cimentaire (principalement les chlorures et le dioxyde de carbone). Les additions cimentaires doivent donc permettre aux aciers de développer un état passif et apporter à l'enrobage une densification afin de limiter la pénétration de contaminants jusqu'aux armatures. Les propriétés électrochimiques au contact des additions ont été caractérisées et les propriétés de transfert des bétons face aux chlorures et au dioxyde de carbone ont été étudiées. L'utilisation de ces matériaux n'influe pas particulièrement le comportement des aciers. Toutefois, l'enrobage est d'une importance particulière, à la fois vis-à-vis de la pénétration de chlorures et du dioxyde de carbone, mais aussi sur la cinétique de corrosion des armatures. La réactivité des additions impacte les propriétés de transfert qui contrôlent aussi bien la cinétique de contamination des bétons que le processus de corrosion des armatures dépassivées / The use of locally available resources is a major concern for construction sector when it comes to sustainable development. In the case of concrete, a variety of by-products is currently being investigated for use as cementitious materials so as to develop concrete made out of alternatives resources. The present study intends to assess the performance of four kinds of by-products on corrosion-related properties in reinforced concrete. Glass powder, paper mill fly ashes, sewage sludge ashes or calcined sediments exhibit a mineral nature compatible with the medium of concrete. In terms of corrosion concerns, the concrete act as an alkaline medium that enable steel passivity and as a transport barrier that limits deleterious elements ingress (mainly chlorides, carbon dioxide). Thus, the use of alternative cementitious materials should enable the passivation of steel and should also provide a densification to the cover in order to limit contaminants ingress toward steel vicinity. The electrochemical properties of steel in contact with cementitious additions were characterized and the transfer properties of concrete were investigated. The use of these materials has an insignificant impact on the behavior of steel. However, the concrete cover has significant influence on both chloride and carbon dioxide ingress as well as on the corrosion kinetic of reinforcement. The reactivity of the cementitious materials impacts the transfer properties which control the kinetic of contamination of concretes and the corrosion process of non-passive steel
10

Structural Testing of Compressed Earth Blocks and Straw Bale Panels

Tattersall, Graham 30 October 2013 (has links)
Globally, there is a need for alternative building materials that require less energy to produce than conventional materials. These alternative materials have gained popularity in recent years, however there is a need to better understand their physical properties in order to increase confidence in their use. As such, a testing program was undertaken to investigate the structural properties of some of these materials. A series of compressed earth blocks made from a mixture of earth and cement compressed to 8 - 12 MPa were tested for their compressive capacity in masonry prisms. The blocks had been weathered for one to two years. The blocks with no cement had a capacity of 2.22 MPa, while cement stabilized blocks had a capacity of 8.11 MPa. Weathering did not result in any significant reduction in the strength of the blocks. Bales of high density straw were tested both with and without cement plaster skins. Unplastered bales exhibited a stiffness between 0.3 - 0.7 MPa when oriented Flat, and 1.2 MPa on edge. The bales had a dilation ratio between 0.1 - 0.3 in the Flat orientation and averaging 3.5 in the Edge orientation. The high density bales plastered with cement plaster exhibited ultimate strengths averaging 171.2 kN/m. Capacity was heavily dependent on plaster strengths, and when normalized for plaster strengths, high density bales had capacities lower than those of regular density bales tested previously (34.1 kN/m/MPa compared to 44.3 kN/m/MPa). Three walls made of straw with cement plaster were constructed with pin-ended conditions to study the effects of buckling in straw bale walls. The average capacity was 12.8 kN/m/MPa when normalized for plaster strength. Pin ends resulted in plastic hinges forming more easily in the walls, and pin ended specimens had a 75% reduction in strength compared to previous tests of "standard" end conditions. Taller walls also resulted in reduced strengths. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-10-30 09:26:46.491

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