Electrochemical behaviour of iron in chlorinated alkaline media. The effect of slurries from granite processing

Abstract

Porriño is a well known zone of quarry and stone working of the SW of Galicia, Spain. In granite's working processes 3 × 105 ton year-1 of granite powder are generated in this area, causing an important environmental problem. This dust has proved to be an efficient addition to high-strength concrete to improve mechanical properties. Nevertheless, no works have been published concerning the effect of this admixture in the passivation of steel reinforcements. The objective of the present work is to analyze the electrochemical behaviour of iron and carbon steel electrodes in alkaline solutions resulting from these slurries. The growth and evolution of the passive layers formed on the tested electrodes are studied by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. Scanning Electron Microscopy and X-ray powder Diffraction have been used for the morphological and chemical characterisation of the generated passive films. The effect of the presence of Cl- ions is also considered. ©2007 Sociedade Brasileira de Química.