Detalhes bibliográficos
| Ano de defesa: |
2022 |
| Autor(a) principal: |
Fagundes, Rayane Campos Lopes
 |
| Orientador(a): |
Oliveira, Andrielli Morais de
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| Banca de defesa: |
Oliveira, Andrielli Morais de,
Faria, Tulio Honorio de,
Cascudo, Helena Carasek,
Matos, Oswaldo Cascudo |
| Tipo de documento: |
Dissertação
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| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Universidade Federal de Goiás
|
| Programa de Pós-Graduação: |
Programa de Pós-graduação em Geotecnia, Estruturas e Construção Civil (EEC)
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| Departamento: |
Escola de Engenharia Civil e Ambiental - EECA (RMG)
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| País: |
Brasil
|
| Palavras-chave em Português: |
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| Palavras-chave em Inglês: |
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| Área do conhecimento CNPq: |
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| Link de acesso: |
http://repositorio.bc.ufg.br/tede/handle/tede/12741
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Resumo: |
In a contemporary engineering context, a performance approach and the design of more durable, sustainable and efficient structures are required. Corrosion of reinforcement is one of the main mechanisms of degradation of reinforced concrete structures, especially in the marine environment, and can lead to its collapse if there is no intervention. To meet this approach, predictive models have been developed, with the objective of predicting the useful life of structures, considering different degradation mechanisms; among them, the corrosion of the reinforcements. Thus, the objective of this work is to study different parameters of chloride transport in concrete with three water/cement – w/c ratios (0.40; 0.55 and 0.70) for application in prediction models of service life. For that, four different test methodologies were used to evaluate the transport of chlorides, over four months. Two migration tests were then considered – NT Build 492: 1999 (in non-steady state); LMDC test (steady state) – and a nonsteady state diffusion test: NT Build 443: 1995, carried out in two different ways, according to the standard (exclusive diffusion mechanism, with the concrete continuously submerged) and by means of weekly cycles of wetting and drying (hybrid mechanism, containing capillary absorption in the convection layer and diffusion in the deeper saturated layers). The results of the experimental program, as expected, showed a tendency for the coefficients to increase with increasing w/c ratio and a decrease in these parameters with increasing maturity of the cement matrix (age effect). Despite having different principles, the coefficients obtained by different methods showed good correlations: with the results of the NT Build 492 and NT Build 443 standards being close to each other and about 10 to 16 times greater than the effective coefficient (steady state) obtained by the LMDC test. The application of prediction models indicated the importance of a more assertive definition of the input parameters of these models, especially the diffusion coefficient used. Among the methods studied, the use of the effective diffusion coefficient (LMDC test) as an input parameter resulted in service lives more in line with reality. Among the models applied, Life-365 stood out for considering different influential factors and getting closer to reality. Regardless of the model applied or the coefficient considered as an input parameter, the w/c ratio strongly influenced the calculated service life: it reduced, on average, 40% of concrete with w/c ratio 0.40 for concrete with w/c ratio c 0.55, reduced by 50% when the w/c ratio increased from 0.55 to 0.70 and 70% from 0.40 to 0.70. |
