Influência e uso do inibidor nitrito de sódio no combate à corrosão na armadura do concreto

Abstract

The influence of sodium nitrite on the process of corrosion inhibition of steel inserted in concrete was studied. Steel contents (relative to cement mass) used in this work were 0, 4, 6, 8, 10%. Marine atmosphere was mimicked by immersing the samples in 3,5% aqueous NaCl Solutions. The inhibitor effect a the compressive strength, water uptake, electrical resistivity, and Tafel parameters was monitored. Regarding corrosion analysis, Tafel parameters were obtained for test specimens with all the mentioned inhibitor contents by simulation. In the case ofiCOr, it enabled one to verifv what was the inihibitor contribution to the corrosion kinetics. It was found that the effectiveness of inhibition increases when inhibitor concentration was increased, being 6% the limit concentration for corrosion inhibition in this particular case. Water uptake and electrical resistivity were independent onthe amount of inhibitor. Conversely, compression strength decreased 30% for test specimens with 6% ofinhibitor. It was concluded that the addition ofNaNCh to concrete can be a simple altemative for retarding corrosion caused by chloride ions, improving structure durability, provided that, in conjunction with the inhibitor, additives which enhance compression strength are used. Measurements ofi^ from potentiostatic polarization were reprodulible, as long as the analyzed test specimens underwent conditioning to laboratory environment and were adequately protected.