Contribution of Red Mud in Alkali‐Activated Slag and Fly Ash Mortars to Corrosion Protection of Reinforcement

ABSTRACT The aim of this study is to assess the role of red mud addition to alkali‐activated materials (AAMs) on the corrosion resistance of steel in mortars. Microstructural properties, including total porosity and pore structure, are determined using (MIP). Resistance to chloride penetration is tested using accelerated chloride penetration (NT BUILD 443) and chloride migration (NT BUILD 492) test. Corrosion properties are evaluated by measuring corrosion potential, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) using two types of corrosion cell set up. In both cell set ups, steels embedded in alkali‐activated mortars with red mud exhibited better corrosion resistance than steels in alkali‐activated mortars without red mud. It is confirmed that the addition of red mud in AAMs contributes to pore refinement and chloride binding in the case of the slag‐based system and to the improvement of the properties of the passive film in the case of both the slag‐based and fly ash‐based systems.