Permeabilidade ao gás em concreto com adições minerais e sua contribuição no campo dos indicadores de durabilidade

• Autor(a) principal: Macedo, Raquel Hellu
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/9430
• topic: Concreto; Durabilidade; Indicadores; Permeabilidade ao gás; CEMBUREAU; Concrete; Durability; Indicators; Gas permeability; CEMBUREAU; CONSTRUCAO CIVIL::MATERIAIS E COMPONENTES DE CONSTRUCAO

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.