Zn–Al–NO2 layered double hydroxide as a controlled-release corrosion inhibitor for steel reinforcements

Abstract

Zn–Al–NO2 layered double hydroxide (LDH) is proposed as a controlled-release inhibitor for steel reinforcements in chloride-contaminated concrete. The cumulative amount of nitrite released from LDH is sensitive to the chloride concentration in the solution. Compared with NaNO2, Zn–Al–NO2 LDH increased the chloride threshold value from 0.15 to 0.25 M and simultaneously decreased the critical [NO2−]/[Cl−] molar ratio from 0.09 to 0.02. In conclusion, the Zn–Al–NO2 LDH exhibits considerably higher inhibiting performance due to the on-demand release of NO2–.