Self-assembly of corrosion inhibitors-intercalated layered double hydroxides (LDHs) in cementitious systems

Abstract

This work investigates the self-assembly of corrosion inhibitor-intercalated layered double hydroxides (LDHs) in cementitious systems. The impacts of inorganic and organic corrosion inhibitors (i.e., sodium nitrite, sodium benzoate, and sodium molybdate) on the intercalation chemistry and chloride-induced transformation of LDHs in ordinary Portland cement (OPC) and limestone calcined clay cement (LC3) pastes are revealed. The results show that direct admixing of inorganic or organic inhibitors results in spontaneous formation of inhibitors-intercalated LDHs (i.e., NO2-AFm, C6H5COO-AFm, and MoO4-AFm), regardless of binder chemistry. The sequestrated anodic inhibitors in cementitious systems are released upon exposure to chloride, accompanied by simultaneous formation of Friedel's salts (Cl-AFm). The incorporation of anodic inhibitors has little influence on the chloride binding capacity of OPC and LC3 pastes, but impacts their chloride resistance via pore structure modification. This research advances our understanding of the physicochemical roles of admixed anodic inhibitors in cementitious systems.