Development of targeted chloride-responsive Ag/Ca-MoO₄-LDH for synergistic corrosion resistance

Layered double hydroxides (LDHs), as novel corrosion inhibitor in reinforced concrete, face instability in chloride consolidation due to sensitivity to environmental anions. This study explored the use of nano-Ag loaded on MoO4-intercalated CaAl-LDH (Ag/Ca-MoO4-LDH), based on isomorphic substitutes for cement hydration products (AFm), to target and stabilize chloride ion fixation in alkaline environments, thereby enhancing steel corrosion resistance. The mechanism of targeting and the enhancement of corrosion resistance were explored through comprehensive experimental and theoretical analyses. Results showed that Ag/Ca-MoO4-LDH enhanced chloride ion consolidation stability, increased the threshold of chlorides needed to trigger corrosion in simulated chloride-contaminated concrete pore (SCCP) solutions, and boosted steel's anti-corrosion effectiveness. Unlike direct application methods, Ag/Ca-MoO4-LDH released MoO42- in response to chloride presence, providing superior corrosion prevention. The study elaborated on the stability of Ag+ and Cl- interactions in SCCP solutions, the spontaneous exchange reactions between LDH-MoO4 and both LDH-OH and LDH-Cl, and various anticorrosion mechanisms, including the formation of protective oxide films on steel surfaces and the precipitation of CaMoO4.