Effect of Recycled Brick Powder on Corrosion of Reinforced Concrete under the Action of Chloride or Carbonation

The mechanism of steel corrosion in recycled brick powder (RBP)-incorporated concrete remains unclear considering the potential utilization of active RBP for low-carbon design in engineering structures. This study aimed to point the influence of RBP on the corrosion behavior of reinforced concrete under the action of chloride or carbonation. Mortar containing RBP (RBPM) was used in this study to concentrate on the effect of RBP and limit the effect of coarse aggregate. The mechanical, chloride penetration, and carbonation properties of RBPM were first investigated. Then the steel corrosion in reinforced RBPM under the action of chloride or carbonation was evaluated by different electrochemical tests. The underlying mechanisms were elucidated by the chemical composition, pH value, and pore structures of RBPM. The results showed that the compressive strength of mortar decreased 21.7% when 30% RBP was used. The addition of RBP reduced the chloride ion permeability but increased the carbonation depth of RBPM. The corrosion caused by chloride penetration in reinforced RBPM was reduced with a higher corrosion potential and lower corrosion current density, which resulted in an approximately 20% lower mass loss with 30% RBP. However, compared with normal concrete, RBPM suffered an increase in corrosion after carbonation. The corrosion current density and mass loss were greatly increased with increasing the RBP content. When the replacement ratio of RBP was 20%, the mortar was in low corrosion state after carbonation curing for 56 days. This was because a combination of the pozzolanic, filling, and nucleation effect of RBP contributed to a 16.28% lower cumulative pore volume and lower pH of RBPM. Considering the effect of RBP on the mechanical properties and corrosion of reinforce mortar, this study suggested a utilization ratio of 20% for RBP in the practical project.