Employing sodium alginate to improve corrosion protection of phytic acid conversion coating for steel in chloride-contaminated concrete pore solution

Sodium alginate (SA) was used to modify phytic acid conversion coating (PACC) for reinforcing steel . The corrosion protection performance of the modified PACC was examined in chloride-contaminated concrete pore solution through electrochemical measurements and surface characterization techniques. Results show that the modified PACC significantly enhances the corrosion resistance of carbon steel . The modification effect progressively intensifies as the dosage of SA increases from 0.2 % to 0.8 %. The modified PACC on the steel surface displays the highest inhibition efficiency of 93.5 % at the dosage of 0.8 % SA. After prolonged exposure to chloride, the corrosion rate of steel with the modified PACC is 2.17 μm/a, marking a 72.8 % reduction compared to the unmodified PACC. The presence of SA effectively fills natural cracks in PACC and facilitates the formation of the modified PACC with a complex bilayer structure. • SA is used to modify natural PACC layer to improve its anti-corrosion performance. • The modified PACC significantly reduces corrosion rate vs. the natural one. • The modified PACC with a complex bilayer structure acts as a physical barrier.