avaliação de inibidores de corrosão para estruturas de concreto armado

Abstract

Concrete reinforcement corrosion is one of the most important problems that diminish the durability of con-crete structures, and it is often caused by the carbonation process and chloride ion attack in aggressive and marine environments. It is estimated that 90% of pathological problems affecting concrete structures world-wide lead to reinforcement corrosion. The research for materials with resistance to this deterioration process is fundamental to improve the durability and efficiency of concrete structures. In this context, the effect of three chemical additives, a commercial one based on nitrite salts, sodium molybdate (MoNa2O4) and sodium tungstate (Na2O4W.2H2O), used in contents of 1% and 2% in relation to the cement mass. Cylindrical, steel embedded, mortar samples (30 MPa strength class) were submitted to the potentiodynamic polarization test. The use of commercial additive was not efficient in reducing corrosion rates, but the effect of curing time reduced the mean corrosion rate from 4.7 mm/year at 60 days to 1.6 mm/year, at 90 days. The best results were obtained for the tungstate and molybdate additives, in which the addition of 1% of molybdate additive presented an efficiency rate of 50%, while 2% of tungstate additive presented an efficiency rate of 29%.