601 resultados para Nanopartícula de sílica


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

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Pós-graduação em Biologia Geral e Aplicada - IBB

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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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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 Biotecnologia Animal - FMVZ

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Pós-graduação em Odontologia - FOAR

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Pós-graduação em Odontologia Restauradora - ICT

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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