Contribuição ao estudo da durabilidade e do transporte de fluidos em concretos contendo adições minerais
Nenhuma Miniatura disponível
Data
2016-09-21
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
Brazil's current water crisis, generated by the low level of reservoirs, has threatened the national
energy production. Faced with this problem, the wind towers present themselves as a viable
solution. It is known that these towers are constructed in regions of high aggressiveness and
therefore, it is necessary to develop high performance concretes that are able to withstand
environmental action to which they are submitted, so that these structures reach the lifespan
previously defined in project, ensuring the viability of the towers. In this sense, the present study
evaluates the mass transport mechanisms (permeability and absorption) that takes place inside the
concrete containing mineral pozzolanic admixtures of high performance, in order to evaluate the
influence of the presence of these additions in these properties. Three different study mixes were
prepared containing, respectively, 9% of silica fume in composition with 1% of nanossílica, 5% of
a metakaolin with high fineness in composition with 5% of a metakaolin slightly less fine, both
with high pozzolanic activity, a mix containing only 10% of the metakaolin with higher fineness,
and a reference proportioning. The analysis presented in this work involve the scanning electron
microscope (SEM) to characterize the internal structure of the material, the trace reconstruction test
to analyze the aggregate/binder ratio in the regions of the cover and the interior of concrete, and the
analyzes related to the mass transport: water absorption by immersion and capillarity and the air
permeability obtained by the Figg’s method, in addition to the mechanical characterization. The
concrete with addition of pozzolanic admixtures showed significant improvements in compressive
strength, in the modulus of elasticity, in the air permeability and in the refinement of pores.
Furthermore, the evaluation of the microstructure by scanning electron microscope showed that the
use of mineral admixtures may cause an improvement in the adhesion and in the densification of
the transition zone between aggregate and cement paste. The trace reconstitution test showed that
the concrete cover has lower ratio aggregate/binder, which corroborates the results of the capillary
absorption test in which it was found that the cover of concrete presents a mean capillarity
absorption lower than the interior region. Thus, it was concluded that the incorporation of the
different mineral admixtures studied in this work significantly alter the properties of concrete, with
positive emphasis on the properties related to the durability, in which the benefits of using mineral admixtures is more pronounced and, in addition, it was also concluded that the concrete cover
presents itself more favorable to the durability than the interior region.
Descrição
Palavras-chave
Citação
ALMEIDA, Marina Augusta Malagoni de. Contribuição ao estudo da durabilidade e do transporte de fluidos em concretos contendo adições minerais. 2016. 176 f. Dissertação (Mestrado em Geotecnia, Estruturas e Construção Civil) - Universidade Federal de Goiás, Goiânia, 2016.