Evaluation of the electrical resistivity of concrete as a parameter to calculation of the initiation period of corrosion induced by chlorids in concrete structures / Avaliação da resistividade elétrica do concreto como parâmetro para a previsão da iniciação da corrosão induzida por cloretos em estruturas de concreto

AUTOR(ES)

Lourdimine Santos

DATA DE PUBLICAÇÃO

2006

RESUMO

The electrical resistivity of concrete is a very sensitive parameter to its microstructural characteristics, especially in relation to the connectivity and the pore size distribution. This parameter is related to the resistance of the concrete to the penetration of liquids or gases and the moisture content present in the concrete pore network, and therefore, may furnish indicators in relation to its durability. The object of this paper is to evaluate the viability of using the electrical resistivity as a parameter to calculation of the initiation period of corrosion in structures subjected to the action of chloride ions. For this, the relationships existent between electrical resistivity and some of the factors that influence the duration of initiation period of the reinforcement were analyzed. The results obtained were used to evaluate the viability of using the model proposed by Andrade (2004) to predict the service life of reinforced concrete structures by their electrical resistivity. Concrete samples with a water/binder ratio of 0.4 and 0.5 were used, with different rates of silica fume (0% and 10%) as a replacement for cement. The results demonstrated the existence of a correlation between the electrical resistivity and the volume of pores with diameters between 0.05 m and 0.1m present in the concrete; a tendency of lower absorption capacity when there is a higher electrical resistivity in the concrete; and a correlation inversely proportionate to the ionic diffusivity. Furthermore, the existence of a correlation between the initial period obtained experimentally and the electrical resistivity of concrete was observed, which demonstrates the viability of using this parameter in the evaluation of its service life. However, the results also indicated that the application of this parameter in real structures, especially in concrete where silica fume has been used, requires consideration of the factors that influence the construction process.

ASSUNTO(S)

concreto armado - corrosão das armaduras construção civil cloretos resistividade elétrica previsão da iniciação da corrosão estruturas

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