Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2016. / Submitted by Aline Mequita (alinealmeida@bce.unb.br) on 2016-11-21T13:08:47Z No. of bitstreams: 1 2016_DivinoGabrielLimaPinheiro.pdf: 4477306 bytes, checksum: 878e66ee435ef0980d2aae41549b721b (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2017-01-26T15:50:52Z (GMT) No. of bitstreams: 1 2016_DivinoGabrielLimaPinheiro.pdf: 4477306 bytes, checksum: 878e66ee435ef0980d2aae41549b721b (MD5) / Made available in DSpace on 2017-01-26T15:50:52Z (GMT). No. of bitstreams: 1 2016_DivinoGabrielLimaPinheiro.pdf: 4477306 bytes, checksum: 878e66ee435ef0980d2aae41549b721b (MD5) / A cinza da casca de arroz (CCA) é uma adição mineral pozolânica ao cimento Portland que vem sendo cada vez mais estudada nos últimos anos. Quando produzida com processo de queima controlada e finamente moída, apresenta alto teor de sílica amorfa e é classificada como pozolana altamente reativa, com propriedades similares à da sílica ativa. Porém, devido ao seu alto poder calorifico, a casca de arroz, na maioria das vezes, é utilizada como combustível em alguns processos industriais. Quando a CCA é gerada sem queima controlada, é chamada de CCA residual, que tem como característica principal um menor teor de sílica amorfa, quando comparada a CCA produzida de forma controlada. Cordeiro et al. (2009),Sensale (2010), Rêgo et al. (2014, 2015), já comparam CCAs com alto e baixo teor de sílica amorfa, tanto em relação às suas propriedades pozolânicas quanto quando incorporadas em pastas de cimento. Contudo, não existem trabalhos com valores intermediários de sílica amorfa para investigar e avaliar o efeito da granulometria no grau de atividade pozolânica. Neste sentido, neste trabalho foram utilizadas amostras de CCAs com valores intermediário, alto e baixo de sílica amorfa. As três CCAs geradas após o processo de calcinação, foram moídas originando, cada uma delas, seis amostras diferentes de acordo com o tempo de moagem. Foram executados ensaios relacionados a finura, caracterização física e ensaios de atividade pozolânica dessas CCAs. Assim, foi possível determinar relações entre a finura, quantidade de sílica amorfa e atividade pozolânica nas amostras de CCA com baixo, intermediário e alto teor de sílica amorfa. Foi observado que a atividade pozolânica da CCA com teor intermediário de sílica amorfa apresentou um aumento substancial das suas propriedades mecânicas e consumo de hidróxido de cálcio com a diminuição do tamanho da partícula. Desta forma, pode-se constatar que a cinza intermediária estudada apresenta potencial para sua utilização como adição mineral altamente reativa ao cimento Portland. / The rice husk ash (RHA) is a pozzolanic mineral addition to Portland cement that has been more studying in the last years. When produced with controlled burning process and finely ground, it shows a high amorphous silica content and is classified as highly reactive pozzolan, with similar properties to silica fume. However, due to your high calorific power, the rice husk, is usually used as fuel in some industrial processes. When RHA is produced without controlled burning, it is called residual RHA, that has like main feature a smaller content of amorphous silica if compared to RHA produced in a controlled manner. Cordeiro et al. (2009), Sensale (2010), RÊGO et al. (2014, 2015), as compared RHAs with high and low content of amorphous silica, both in relation to their pozzolanic properties as when incorporated into cement pastes. However, there are no studies with intermediate values of amorphous silica to investigate and evaluate the effect of particle size on the degree of pozzolanic activity. So, in this work were used RHAs samples with intermediate values, high and low amorphous silica to investigate RHAs as mineral additions. For this study were analyzed three temperatures of calcination that showed differents levels of amorphous silica in the samples of RHA produced. TheRHAs generated after the calcination process at each one of these temperatures were milled and it produced six different samples according with the grinding time, thus, the calcination and grinding influenced in your pozzolanic activity. Tests were performed related to thinness, physical characterization and pozzolanic activity assays of these RHAs. Then, it was possible to determine relations between the fineness, the amount of amorphous silica and pozzolanic activity in RHA samples with low, intermediate and high content of amorphous silica. At the end of this search, after to analyzed the samples it was possible to evaluate the influence of grain fineness and amorphous silica content in the pozzolanic activity of RHA. It was observed that the pozzolanic activity of the RHA with intermediate content of amorphous silica presented a substantial increase with the reduction of the particle size that enables their use as a mineral addition highly reactive to Portland cement.

No description available.

O presente trabalho apresenta os resultados de estudos mineralógicos de seis clinqueres de cimento Portland produzidos comercialmente por indústrias nacionais, com matérias primas domésticas. Esses seis exemplos representam, em verdade, uma seleção de numerosos produtos analisados, por se prestarem melhor às diagnoses dos tipos, condições de preparação e cuidados no controle de matéria prima, bem como dos processos de clinquerização de resfriamento. A parte fundamental deste estudo é desenvolvida por microscopia óptica. Para esse fim são descritas, minuciosamente, as técnicas de amostragem e de preparação das amostras (seções polidas), assim como o uso de reagentes seletivos (\"spot test\") para identificação das fases presentes: Alita - silicato tricálcico (3CaO.Si\'O IND.2\'); Belita - silicato bicálcico (2CaO.Si\'O IND.2\'); Celita - fase intersticial, que pode ser diferenciada em aluminato tricálcico (3CaO.\'Al IND.2\'\'O IND.3\') e ferroaluminato tetracálcico (4CaO.\'Al IND.2\'\'O IND.3\'.\'Fe IND.2\'\'O IND.3\'); componentes secundários - Cal livre (CaO), Periclásio (MgO), fase métalica - metal e seus óxidos e sulfetos. O presente estudo é corroborado por análises químicas, que constituem base para a determinação da composição \"mineralógica\" normativa através dos cálculos propostos por Bogue. Baseados nos conceitos termodinâmicos de equilíbrio entre as fases presentes nos clínqueres, aliados a conceitos mineralógicos-cristalográficos (difusão iônica, reações de estado sólido, soluções sólidas, crescimento cristalino, etc) e a critérios petrográficos (estrutura e textura), o estudo microscópico fornece informações sobre: composição granulometria e homogeneidade da matéria prima (calcáreo e argila); temperatura e tempo de clinquerização; e velocidade de resfriamento do clinquer. É feita uma comparação entre a análise modal obtida por microscopia e a análise normativa calculada a partir das análises químicas, evidenciando as vantagens diagnósticas do método microscópico para definir a composição do clinquer. Conclue-se que: 1. As análises químicas são imprescindíveis no controle rotineiro da matéria prima, permitindo correções imediatas na sua composição. Elas definem ainda, supondo-se um processamento industrial adequado, os módulos de hidraulicidade, de sílica e de fundentes do clinquer. 2. A microscopia, através do estudo das relações paragenéticas e texturais do estabelecimento de uma composição modal, constitui um excelente método de semi-rotina para o controle da fabricação industrial do clinquer, fornecendo, implicitamente, recomendações para melhorar a sua qualidade. / Not available.

O concreto normalmente oferece um alto grau de proteção contra a corrosão ao aço, devido à formação de uma fina película protetora na sua superfície, causada pela alta alcalinidade do concreto. Entretanto, essa película pode ser rompida tanto pela diminuição do pH da solução dos poros do concreto (por carbonatação, por exemplo) ou pela penetração de íons agressivos (como cloretos, por exemplo) até a superfície do aço. O presente trabalho tem por objetivo comparar o desempenho de concretos feitos com diferentes tipos de cimento Portland normalizados no Brasil frente à ação de íons cloreto provenientes de fontes externas. O programa experimental foi realizado com cinco diferentes tipos de cimento (CPII-E, CPII-F, CPIV, CPV ARI e CPV ARI-RS), com e sem adições, e cinco relações água/aglomerante (0,30; 0,35; 0,45; 0,60 e 0,80) em ensaios acelerados de despassivação por cloretos, por meio de ciclos de imersão e secagem dos corpos-de-prova em solução contendo 3,5% de cloreto de sódio. O método de Potencial de Eletrodo foi utilizado para monitorar a corrosão ao longo do tempo. Paralelamente foram realizados ensaios de resistência à compressão do concreto aos 28 dias, de perda de massa da armadura e de teor de cloretos livres no cobrimento da armadura. Os resultados obtidos mostraram que a escolha do tipo de cimento tem influência tanto na resistência à compressão simples quanto na resistência à corrosão das armaduras, verificada através dos ensaios de potencial de eletrodo, de perda de massa gravimétrica da armadura e de teor de cloretos livres. No entanto não houve um tipo de cimento que apresentasse os melhores resultados para todos os tipos de ensaio. / Concrete usually provides a high level of protection against steel corrosion, due to the formation of a fine protecting film on its surface, caused by concrete alkalinity. However, this film can be torn both as a result of the decrease in the pH of the solution of the concrete pores (by carbonation, for example) or as a result of the penetration of aggressive ions (such as chlorides, for example) up to the surface of the steel. The present work has the objective of comparing the performance of concrete made with different kinds of Portland cement regulated in Brazil before the action of chloride ions derived from external sources. The experimental program was performed with five different types of cement (CPII-E, CPII-F, CPIV, CPV ARI and CPV ARI-RS), with and without additions, and five water/agglomerative relations (0.30; 0.35; 0.45; 0.60 and 0.80) in acceleration assays of inactivation by chlorides, by means of immersion cycles and drying of proof bodies in a solution contained 3.5% of sodium chloride. The method of Electrode Potential was used to monitor corrosion over time. Concomitantly, resistance tests were performed as to the compression of the concrete at 28 days, from the loss of mass of the armature and content of free chlorides in the armature coating. The results obtained showed that the selection of the kind of cement has an impact both on the simple compression resistance and on the resistance to armature corrosion, verified through tests of electrode potential, of armature gravimetric mass loss and free chloride content. However, there was not a kind of cement presenting the best results for all types of assay.

Orientador : Gladis Camarini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil / Made available in DSpace on 2018-07-28T20:36:45Z (GMT). No. of bitstreams: 1 DeMilito_JoseAntonio_M.pdf: 10481944 bytes, checksum: a714bee8c0079194a2c251118b5dc6fe (MD5) Previous issue date: 2001 / Resumo: O uso crescente de revestimento de gesso nas edificações tem sido uma alternativa prática e econômica. O gesso tem a vantagem de endurecer rapidamente e proporcionar um acabamento fino, mas está limitado ao uso interno devido à sua sensibilidade a água. Por outro lado, o cimento Portland é um aglomerante que resiste bem em contato permanente com a água. Além disso, com a presença da sílica ativa, suas propriedades são ainda mais favorecidas. Neste sentido, o objetivo deste trabalho foi o de observar as propriedades de pastas das misturas de gesso-cimento Portland-sílica ativa aplicadas em painéis de alvenaria de bloco de concreto submetidos a duas condições: ambiente interno, protegido das intempéries e em ambiente externo sujeito às variações ambientais. Realizaram-se ensaios fisicos, químicos e fisico-químicos. Dos resultados obtidos observou-se que a adição de sílica ativa na mistura reduz a formação de etringita, especialmente nos revestimentos sujeitos à umidade. Da mesma forma, houve melhoria à abrasão e menor perda de massa ao longo do tempo nas misturas com adição de cimento e, após 180 dias de sua aplicação, não houve o aparecimento de fissuras ou gretamento visíveis na superficie dos revestimentos. Assim, os resultados obtidos permitem concluir uma possível coexistência de sucesso entre o gesso e o cimento / Abstract: The growing use of plaster in the constructions has been a practical and economical alternative. The plaster has the advantage of to harden quickly and to provide a fme fmish, but limited to the internal use due to its water sensibility. In other hand, Portland cement is a hydraulic binder and have an excellent behaviour in water. Besides that, silica fume improves its properties. So, the aim of this work was to observe the properties of pastes made from the mixture of plaster-Portland cement-silica fume in concrete block walls. These pastes were submitted to two kinds of expositions: internal and external walls. These pastes were submitted to several tests: physical, chemical and physico-chemical. From these results it was observed that the addition of silica fume diminished the ettringite formation in the walls subjected to humidity. The plaster-Portland cement had the abrasion resistance improved and the weight loss was also diminished. The panels are until now with the same aspects-from the fIrst day of the paste application and there were not observed cracks on them. In this way, its is possible to conclude that the mixture of plaster and Portland cement can be a reality / Mestrado / Edificações / Mestre em Engenharia Civil

Orientadores: Maria Izabel Maretti Silveira Bueno, Ronei Jesus Poppi, Patricio G. Peralta-Zamora / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-01T08:22:06Z (GMT). No. of bitstreams: 1 Nagata_Noemi_D.pdf: 5455307 bytes, checksum: 1ff60be7df11cbbd263f81d1e43b24f3 (MD5) Previous issue date: 2001 / Doutorado

Orientador: Wesley Jorge Freire / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-07-20T10:13:04Z (GMT). No. of bitstreams: 1 Grandi_LuizAlfredoCotini_D.pdf: 4235109 bytes, checksum: f7566b6ef336d7cdd2a5b6abe78eaaa6 (MD5) Previous issue date: 1995 / Doutorado / Construções Rurais / Doutor em Engenharia Agrícola

Portland has a rich, active, and fluid music culture which is constantly being (re)created and (re)defined by a loose network of local musicians who write, record, produce, promote, distribute, and perform their music locally (and sometimes regionally, nationally, and internationally) and local residents, or audiences, who engage in local musical practices. Independent ("indie") local music making in Portland, which is embedded in DIY (do it yourself) values, creates alternative cultural places and landscapes in the city and is one medium through which some people represent themselves in the community. These residents not only perform, consume, promote, and distribute local music, they also (re)create places to host musical expressions. They have built alternative and democratic cultural landscapes, or culturescapes, in the city. Involved Portlanders strive to make live music performances accessible and affordable to all people, demonstrating through musical practices that the city is a shared space and represents a diversity of people, thoughts, values, and cultural preferences. Using theoretical tools from critical research about the economic, spatial, and social role of cultures in cities, particularly music, and ethnographic research of the Portland music scene, including participant observations and in-depth interviews with Portland musicians and other involved residents, this research takes a critical approach to examining ways in which manifestations of independent music are democratic cultural experiences that influence the city's cultural identity and are a medium through which a loosely defined group of Portlanders represent their cultural values and right to the city. In particular, it focuses on how local musical practices, especially live performances, (re)create alternative spaces within the city for musical expressions and influence the city's cultural landscapes, as well as differences between DIY independent music in Portland and its commodified forms and musicians and products produced by global music industry.

Social worker stress and burnout are pervasive problems that harm workers, organizations, and clients. Past research has identified burnout, a psychological response to work stress, as an important predictor of intent to leave and ultimate turnover. An emerging body of research has examined work engagement, considered to be the opposite of burnout, as a predictor of retention. The problem of burnout and turnover within organizations employing social workers has been addressed in the literature for many years. This dissertation responded to a call in the literature for a greater emphasis on burnout prevention and enhancement of workforce engagement and retention. The three goals of the study were: (1) to measure levels of work engagement; (2) to examine the psychometric properties of two new instruments that measure burnout and engagement; and (3) to use the Job Demands-Resources model to test a hypothesized model of the unique relationships between job demands, resources, burnout, engagement and intent to leave. Survey data were collected from 243 public child welfare workers employed with Oregon's Department of Human Services, Children, Adult and Families Division, Service Delivery Area 2 serving Multnomah County. Findings revealed that half of the workers were highly engaged and that engagement explained 18% of the variance of intent to remain employed. An alternative measure of burnout, the Oldenburg Burnout Inventory, demonstrated good internal consistency, convergent validity with the MBI, and explained 26% of the variance of intent to leave. A series of path analyses indicated support for a partially-mediated model. The findings demonstrate that burnout and engagement mediate the effects that demands and resources have on intent to leave. Supervisor support exerted both direct and indirect effects on intent to leave. The results support the inclusion of work engagement in burnout research, demonstrate the psychometric soundness of two new instruments to measure engagement and burnout, and support the applicability of the Job Demands Resources Model to a sample of social service workers employed in public child welfare. The findings indicate that job demands and resources play an important role in worker intent to leave. Research, education, policy, and practice implications are addressed.

The research problem in this thesis can be briefly stated as a study of a general population to test certain demographic variables, in particular those of income, age and education, which may or may not have a significant relationship to an expressed willingness to care for foster children; and to further examine whether certain special characteristics of a child, in particular those of increased age, physical handicap, minor emotional problems or mental retardation, further increase unwillingness to care for foster children. The sample was selected by a two- stage cluster sampling taken from the Southeast catchment area of metropolitan Portland, Oregon. From this sample of 787individuals, the survey was conducted by trained interviewers, using a questionnaire and personal interview. The data used in this research project were then extracted from the larger survey, and computed to determine the relationship of age, income and education to willingness to care for foster children. The data were extracted on the basis of the chosen variables of income, age and education and five questions relating specifically to willingness to care for foster children. As had been anticipated, the findings showed that the general population is not willing to care for foster children. However, certain significant findings were related to willingness to care for foster children. A significant relationship was found between income and willingness to care for foster children in that those respondents with incomes between $4,000-$20,000 expressed the most willingness to care for foster children while there was significant underrepresentation in both the highest and lowest income groupings to express a willingness to care for foster children with an almost lineal relationship of decreasing age with increasing willingness to care for foster children. There is no significant relationship, it was found, between education of the respondent and willingness to care for foster children. There is a lineal relationship of increasing willingness to care for foster children with increasing age of the foster child. Of those individuals expressing a willingness to care for foster children, there is no significant decrease in willingness because of physical disability, minor emotional problems or mental retardation. The results of this study have certain implication for recruitment and selection of foster parents. The findings indicate the need for further research to explore why more individuals in the population do not express a willingness to care for foster children, how such an interest can be encouraged and what criteria can be used in recruitment and selection.