Protection of reinforcement steel corrosion by phenylphosphonic acid pre-treatment PART II: Tests in mortar medium

A pre-treatment of steel reinforcement in mortar by a 72 h immersion in 0.1 M phenyl-phosphonic acid (C6H5P(O)(OH)2; PPA) was investigated. Then effectiveness of this procedure for protection against the corrosion of steel bars embedded in pre- or post-addition of sodium chloride mortar was evaluated by electrochemical impedance spectroscopy, visual inspection, SEM, and EDS analyses. The results showed that for non-treated steel reinforcement, the charge transfer resistance (Rt) decreases considerably with time indicating a very advanced state of corrosion after 54 months corrosion test. In contrast, for pre-treated steel rebar, this resistance remains high reflecting the effectiveness of the pre-treatment method against corrosion. The corrosion rate evaluated from the charge transfer resistance at 54 months corrosion in chloride containing medium was 0.5 μm year−1.