Electrochemical corrosion behavior of HRB500 steel bar in Simulated Concrete Pore solutions

The electrochemical corrosion behavior of HRB500 steel bar in Simulated Concrete Pore (SCP) solutions contaminated by bicarbonate ions and (or) chloride ions was investigated by cyclic potentiodynamic polarization technique, and it was compared with that of HPB235 steel bar. The results show that the passivation and repassivation of HRB500 steel bar is remarkably in the conditions where pH is 12.5 and w(NaCl) is 0~0.1%, or pH is 11.5 and w(NaCl) is no more than 0.01%, or pH is 10.5 and w(NaCl) is less than 0.005%. These are almost similar to that of HPB235 steel bar. However, with the increase of the aggressivity of SCP solutions, the corrosion susceptibility of HRB500 to pH and chloride ions is greatly higher than that of HPB235. The threshold value of chloride ions is considerably decreased with the increase of carbonization. If the connection of HRB500 and HPB235 was exposed to the aggressive environments, HRB500 is anode which is corroded acceleratedly, and HPB235 steel bar is cathode.