Effect of the addition of red mud on the corrosion parameters of reinforced concrete

Red mud, the main waste generated in aluminum and alumina production by the Bayer process, is considered “hazardous” due to its high pH. The characteristic of high alkalinity associated with the presence of aluminosilicates facilitates the assimilation and formation of compounds by reaction with chloride ions. The high pH also provides greater protection of rebars, which is reflected in the low corrosion potential and high electrical resistivity (filler effect) of concrete. In this study, the chloride concentration was monitored by measuring the conductivity of the anolyte. Red mud proved to be a promising additive for concrete to inhibit the corrosion process. The corrosion potential was monitored by electrochemical measurements and the electrical resistivity was evaluated using sensors embedded in concrete test specimens. The results showed that the addition of red mud is beneficial to concrete, reducing its chloride migration rate (diffusion coefficients) and corrosion potential and increasing its electrical resistivity.