Effectiveness of concrete inhibitors in retarding rebar corrosion

The effect of inhibitors on the corrosion of steel reinforcements in concrete was evaluated by using anodic polarization, electron spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy (AES). The reinforcement corrosion in uncontaminated concrete specimens was evaluated by impressing +4 V anodic potential for accelerated corrosion of the steel bar and measuring the time-to-cracking of the concrete specimens. The effectiveness of the inhibitors in retarding reinforcement corrosion in the contaminated concrete specimens was evaluated by measuring the corrosion potentials and corrosion–current density. Results indicated that the time-to-cracking in uncontaminated concrete specimens incorporating inhibitors M2 and R2 was higher than that in the control concrete specimens. While the increase in the time-to-cracking in the concrete specimens incorporating M2 was marginal, a significant improvement in the corrosion-resisting characteristics of concrete incorporating R2 was indicated over the control specimens. The data on time-to-cracking in the uncontaminated concrete specimens and the corrosion rate of steel in the contaminated concrete specimens indicated the usefulness of corrosion inhibitor R2 in retarding reinforcement corrosion. The electrochemical test results and surface analysis results using ESCA and AES techniques showed the better performance of inhibitor R2 compared to inhibitor M2 in retarding corrosion of steel in an environment of saturated calcium hydroxide in the presence of chloride ions.