Corrosion resistance of commercial metallic materials in contact with mortar

The objective of the present work is to examine the corrosion behaviour of the following materials: copper, lead, aluminium, zinc, stainless steel (AISI 304) and carbon steel (SAE 1040), when they are in contact with mortar, with and without the addition of chloride ions. Mortar specimens containing bars of these materials have been made. In addition, these specimens have been contaminated with chloride ions in different concentrations: 0, 0.3 % and 1 % (chloride ion mass by mass of cement). These specimens have been exposed to different conditions: laboratory, with a relative humidity (RH) of 45 %; curing chamber (98% RH) and immersed in a solution of 3.5 wt.% NaCl. The electrochemical parameters normally used to characterize the corrosion behaviour of reinforcing steel in concrete have been monitored periodically. These parameters include the corrosion potential (Ec), the polarization resistance (Rp) and the electrical resistivity of mortar (rho). Also, the carbonation rate was determined in order to evaluate the resistance of the mortar to the ingress of carbon dioxide. Among the materials studied, the stainless steel has hitherto presented the best behaviour against corrosion, in all conditions tested. Specimens made with aluminium bars and contaminated with 1% chloride ion presented cracks and partial mortar cover detachment due to the effect of voluminous aluminium corrosion products. (C) 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of SAM/CONAMET 2011, Rosario, Argentina.