Corrosion performance of blended concretes exposed to different aggressive environments

The research study presented herein evaluates the corrosion behaviour of the reinforcing steel in blended concretes using two pozzolanic additives-metakaolin (MK) and silica fume (SF)-at 10% replacement of cement weight. They are exposed to CO2 and chlorides. The corrosion process was followed by monitoring of open-circuit potential (OCP), polarisation resistance (Rp) and electrochemical impedance spectroscopy (EIS). Electrochemical measurements show that the addition of MK and SF enhances corrosion resistance exposed to chlorides, however under accelerated carbonation these concretes show higher corrosion rates. In the simultaneous exposition to carbon dioxide and chlorides, SF-concrete shows a decrease of corrosion rate.