1000 resultados para Concreto. Resíduo. Scheelita. Sustentabilidade


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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As autoras discutem a questão da sustentabilidade a partir da reportagem de um casamento realizado na Avenida Paulista e definido como ecologicamente correto. Elas demonstram como esse acontecimento está contido numa escala mais ampla. Argumentam que a racionalidade capitalista presente na lógica da competitividade e do desperdício é a mesma no comando do ideário da sustentabilidade do movimento ambientalista. Munidas de um conjunto de dados referentes à ação de grupos legais e ilegais, mostram como a prática da sustentabilidade abre novas e lucrativas frentes de acumulação enquanto contribui para o agravamento dos danos irreversíveis ao meio-ambiente. Concluem que, além da impossibilidade do modelo capitalista deter o atual processo de destruição das condições de vida no planeta, somente a associação internacional dos movimentos sociais emancipadores poderá criar ações para uma radical mudança de rumo.

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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O trabalho tenta discutir a relação entre crescimento urbano e sustentabilidade a partir da experiência de Maringá, cidade de porte médio do norte do Paraná com características únicas. Concebida por um engenheiro urbanista para ser uma espécie de cidade-jardim inglesa em solo brasileiro, a cidade teve seu projeto implantado por uma companhia colonizadora privada (cuja antecessora era britânica), o qual foi relativamente preservado pelos vários planos urbanísticos subsequentes. Desse modo, apesar do inexorável empobrecimento da qualidade urbana e ambiental - condição comum às cidades brasileiras - Maringá continua próxima, urbanisticamente, de um equilíbrio dinâmico entre crescimento e sustentabilidade, que ainda pode ser plenamente atingido. Sobrepondo fatos a teorias, o autor discute as razões que levaram à curva descendente de qualidade urbana e a consequente desigualdade no acesso à tão almejada cidade verde em Maringá, os perigos que rondam esta quase utopia e os possíveis caminhos para alcançá-la. Muito oportuno, o texto pode servir de referência para novos estudos sobre a paisagem urbana brasileira, ampliando o debate entre disciplinas e áreas de atuação e possibilitando novas abordagens para a questão da sustentabilidade

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The soil is one of the main C pools in terrestrial ecosystem, capable of storing significant C amounts. Therefore, understanding the factors that contribute to the loss of CO2 from agricultural soils is critical to determine strategies reducing emissions of this gas and help mitigate the greenhouse effect. The purpose of this study was to investigate the effect of soil tillage and sugarcane trash on CO2 emissions, temperature and soil moisture during sugarcane (re)planting, over a study period of 15 days. The following managements were evaluated: no-tillage with crop residues left on the soil surface (NTR); without tillage and without residue (NTNR) and tillage with no residue (TNR). The average soil CO2 emission (FCO2) was lowest in NTR (2.16 µmol m-2 s-1), compared to the managements NTNR (2.90 µmol m-2 s-1) and TNR (3.22 µmol m-2 s-1), indicating that the higher moisture and lower soil temperature variations observed in NTR were responsible for this decrease. During the study period, the lowest daily average FCO2 was recorded in NTR (1.28 µmol m-2 s-1), and the highest in TNR (6.08 µmol m-2 s-1), after rainfall. A loss of soil CO2 was lowest from the management NTR (367 kg ha-1 of CO2-C) and differing significantly (p<0.05) from the managements NTNR (502 kg ha-1 of CO2-C) and TNR (535 kg ha-1 of CO2-C). Soil moisture was the variable that differed most managements and was positively correlated (r = 0.55, p<0.05) with the temporal variations of CO2 emission from NTR and TNR. In addition, the soil temperature differed (p<0.05) only in management NTR (24 °C) compared to NTNR (26 °C) and TNR (26.5 °C), suggesting that under the conditions of this study, sugarcane trash left on the surface induced an average rise in the of soil temperature of 2 ºC.

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There is a huge debate surrounding the sustainability issues, especially urban sustainability. This article seeks to establish a critique of models of sustainable cities and postmodern city structured by dispersed city model produced by the logic of capital, it is an effort to confront methodological theoretical models of two cities, the capitalist model of production space and model sustainable city, the dispersed city model against a model of the compact city. For example it was used as environmental certifications for building a label denoting sustainable building when actually articulate a series of symbols that mask and reaffirm their production processes from the perspective of capital cities

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This paper investigated the influence of the amount of superplasticizer and mineral adding - silica fume and basaltic filer - in plastic shrinkage and cracking of self-compacting concrete (SCC) mortars. Initially analysis was performed of the rheological behavior of cement paste and mortars phases of the compositions of SCC. Then the deformations of mortars were measured by the effect of shrinkage and evaluation of cracking. On plastic shrinkage and cracking, the composition with silica fume showed superior results, independent of wind and superplasticizer content, relative to the composition with addition of basalt filler. However, the composition with silica fume showed superior results only in the tests with imposed ventilation at vertical plastic deformation. The rheological behavior affected directly the plastic shrinkage and cracking at early ages, fact confirmed by the analysis of capillary pressures of mortars tested.

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The bond between steel and concrete is essential for the existence of reinforced concrete structures, as both materials act together to absorb structural strain. The bond phenomenon is considered to be complex regarding many factors that affect it. Several types of bond tests have been proposed over years. One is the modified proposed of pull-out test, which was elaborated by Lorrain and Barbosa [1] called APULOT test (Appropriete pull-out-test). Based on experimental results obtained by Vale Silva[2] either by conventional pull-out tests, or by modified pull-out test, APULOT, seeks to know the numeric behavior of bond steel-concrete through a numerical simulation using a calculation code ATENA which is based on the Finite Element Method (FEM). The numerical simulation provided better evaluate the stress distribution and cracking that occurs during the test, thereby becoming a valuable tool to support the experimental project that aims to validation, validation partially or not recommend the modified bond test steel-concrete - APULOT test - as quality control test of structural concrete. The numerical results showed good representation compared to experimental results.

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Since the Seventies, there has been a growing degradation of concrete structures in Brazil. For that reason, much research has been made on the durability of those structures, aiming at contributing towards quality improvement and reduction of maintenance and repair costs. This study evaluates the behavior of the durability of high-performance concrete with additions, replacing part of the cement and aggregates with rice husk ash and tire rubber, respectively. Durability tests were carried out in which concrete was subjected to several degradation processes, such as the action of water, temperature, salts and acid solution. The results indicated that the addition of active silica or rice husk ash, both with tire rubber did not worsen the durability of concrete. In fact, rubber proved to be very effective in preventing the action of chemical agents, high temperatures and the penetration of water. Rice husk ash, despite the larger diameter of particles, had similar results to that of the active silica.

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Pós-graduação em Engenharia Mecânica - FEG

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Pós-graduação em Agronomia - FEIS

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Pós-graduação em Engenharia Civil - FEIS

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)