AVALIAÇÃO DO DESEMPENHO DE CONCRETOS COM ADIÇÕES MINERAIS QUANTO À CORROSÃO DAS ARMADURAS INDUZIDA POR CLORETOS
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Data
2007-08-29
Autores
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Universidade Federal de Goiás
Resumo
The present work aims to study the performance of concrete with regard to the action
of chloride ions, evaluating the influence of both mineral additions and water/binder ratio
(w/b), considering kinetic and thermodynamic aspects of the corrosive phenomenon.
A experimental research was carried out considering the following variables: the
presence of mineral additions in partial substitution to the cement weight (10% of silica fume;
25% of fly ash; 10%, 20% and 30% of metakaolin) and the water/binder ratio (0,40 and
0,55). Thus, cubic concrete test specimens were produced, in addition to cylindrical test
specimens for concrete characterization in relation to the compressive strength, specific mass,
void ratio and capillary water absorption. After 645 days of casting, the cubic concrete test
specimens were submitted to the chlorides attack during 308 days, totality 44 weekly cycles
of immersion in chlorides aggressive solution. They were monitored, throughout this period,
by means of techniques, such as: the concrete electric resistivity, the half-cell potential, the
polarization resistance and the electrochemical impedance spectroscopy. At the end of the
experiment, visual inspections of reinforcing steels allowed to observe their superficial
aspects after attack.
As general result, it was gotten that the incorporation of mineral additions to the
concretes promoted significant profits in all the evaluated properties, evidencing the
beneficial effect of these additions in concretes exposed to aggressive conditions, specially in
those in which there are chloride ions. In this direction, the statistical analysis has shown
evidences that concretes with silica fume and metakaolin achieved the best results of
electrical resistivity. In relation to the half-cell potentials, the reference concrete (without
mineral additions) presented the worst performance, with an indication of despassivation in
the reinforcing steels accentuated fall in the values of resistance of polarization with the time,
proving the susceptibility of these systems to the action of chlorides. The concrete with
mineral additions did not present depassivation of the reinforcing steels meaning that these
systems possess great durability and service life in relation to those without mineral additions
Descrição
Palavras-chave
concreto , adições minerais , sílica ativa , metacaulim , armadura , corrosão , cloretos , técnicas eletroquímicas , concrete , mineral additions , silica fume , metakaolin , reinforcing steel , corrosion , chlorides , electrochemical techniques , 1. Concreto - Adição mineral Avaliação 2. Corrosão de
armaduras
Citação
OLIVEIRA, Andrielli Morais de. Performance evaluation of concretes content with mineral additions in
relation to the reinforcing steels corrosion induced by chlorides. 2007. 276 f. Dissertação (Mestrado em Engenharias) - Universidade Federal de Goiás, Goiânia, 2007.