Improvement in the anti-corrosion property of marine concrete using layered double hydroxides and polyvinylpyrrolidone

Abstract

Chloride induce corrosion destroys the structure of marine concrete, thereby shortening its actual service life. In this study, Fe-based layered double hydroxides (LDHs), including CaFe-NO3 and CaFeAl-NO3 LDHs, and polyvinylpyrrolidone (PVP), were added to increase the anti-corrosion property of mortar. Electrochemical tests and chloride penetration resistances of the samples were conducted, and the corresponding micro-mechanisms were investigated. The samples that were immersed short-term (5 d) exhibited similar electrochemical characteristics and corrosion tendencies compared to the 7 d samples. With increasing immersion time, all the samples were corroded, whereas the LDHs-PVP composites still exhibited higher resistances and impedance, larger arc radius, and a lower corrosion current density and corrosion rate than the other samples due to the synergistic effect via the formation of a passive film by PVP, the increased compactness and adaptability by Fe-based LDHs, and promotion of uniform dispersion of LDHs in slurry by PVP. Further, the work function of the LDHs-PVP composites was lower than that of the control, indicating that the addition of LDHs and PVP decelerated the corrosion reaction of steel. Thus, the LDHs-PVP composites exhibited high anti-corrosion property; the rapid chloride migration coefficient and total charge passed decreased by 17.5% and 4.9% compared to those of the control, respectively, highlighting the potential of this composite as effective inhibitors for marine concrete corrosion.