Corrosion of steel reinforcement is one of the primary causes of deterioration in concrete infrastructure. While corrosion inhibiting admixtures (CIAs) are widely used, the molecular-level mechanisms by which they enhance steel passivation remain poorly understood. In this study, we explore how different types of CIAs interact with steel at the molecular level, with the goal of understanding which functional groups are most effective in promoting passive film formation. Three compounds were selected - dimethylethanolamine (DMEA), glutamine, and benzoate - each carrying distinct functional groups: amine, amino acid, and carboxylate, respectively. Using classical molecular dynamics simulations in LAMMPS, we model how these molecules behave near steel surfaces in environments similar to concrete pore solutions. The simulations help in understanding their influence on passive film stability. Also, electrochemical tests such as potentiodynamic polarization and electrochemical impedance spectroscopy measurements were done to observe how each inhibitor performs in real cementitious systems. Together, the computational and experimental results provide a clearer picture of how molecular structure impacts corrosion protection. This work not only identifies which functional groups are more effective but also helps build a framework for designing better CIAs for use in concrete, ultimately contributing to more durable and sustainable infrastructure.
