Coeficiente de difusão aparente de oxigênio e o controle da corrosão de armaduras revestidas com primers

The present work evaluates the influence of five different types of coatings applied on the rebar on apparent diffusion coefficient of oxygen (Dap (O₂)) and on the corrosion intensity (Icorr) in comparison with a reference coating composed of a cement-sand mortar. Oxygen flow (J (O₂)) until the rebar was measured by potenciostático method in the steady state and the corrosion intensity (Icorr) was monitored by the Polarization Resistance technique (Rp). Evaluations for porosity of coatings were made through magnifying glasses, optical microscopy and SEM. The primers that represent barrier protection systems were, under the conditions tested, less permeable to oxygen. The apparent diffusion coefficient values (Dap (O₂)) ranged from 2.1 x 10-6 cm²/s to 4 x 10-9 cm²/s, causing variations in the corrosion intensity measurements (Icorr), due to the cathodic corrosion process control.