Permeabilidade ao gás em concreto com adições minerais e sua contribuição no campo dos indicadores de durabilidade
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2018-11-29
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Universidade Federal de Goiás
Resumo
There is a continuing concern in scientific-technical environment regarding concrete durability
considering that Brazilian standards are based on a prescriptive approach, resulting only in
specifications concerning water/ binder ratio and cover thickness values. In this context, this study
is focused on the durability indicator of concrete gas permeability, making use of the most used
method in the world, CEMBUREAU, in order to contribute to the measurement of the permeability
coefficient (to the gas) applied to local and regional concretes. Three different study proportions
were elaborated, each one containing respectively, 9% of active silica in composition with 1% of
nanosilica, 5% of a high fineness metakaolin in composition with 5% of a metakaolin a little less
fine, both with high pozzolanicity and a proportion containing exclusively 10% of metakaolin of
higher fineness, along with a reference proportion, all of them with two water/binder ratio, two
spots for analysis (covering and interior) and two situations of relative humidity (75% and oven
dried). The specimens were tested with CEMBUREAU permeameter, the object of this study,
using the AFREM-AFPC method to measure the gas permeability coefficient. Next, an analysis of
variance (ANOVA) was performed to verify if the chosen variables were influential in the gas
permeability values. All the chosen variables, namely: mineral addition, water/binder ratio,
extraction spot, inlet pressure, and relative humidity were influential in the concrete gas
permeability. The results from the permeability coefficients were compared with those from
literature and submitted to criteria. Straight after, correlations among durability properties were
tested with a previous study (MALAGONI, 2016) which used the same concrete proportioning of
this research. It is concluded that the additions used modified significantly the gas permeability
coefficient, the water/binder is also influential in this values, what is repeated to the sample
extraction spot and relative humidity. For correlations with durability properties, good values were
tested and found to compressive strength, elasticity modulus, capillary absorption and air
permeability (Figg). Therefore, the AFREM-AFPC test methodology was investigated to national
validation and is ready for study and conception of a national standard related to the gas
permeability indicator.
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MACEDO, R. H. Permeabilidade ao gás em concreto com adições minerais e sua contribuição no campo dos indicadores de durabilidade. 2018. 178 f. Dissertação (Mestrado em Geotecnia, Estruturas e Construção Civil) - Universidade Federal de Goiás, Goiânia, 2018.