Evaluation of the effectiveness of electrochemical re-alkalization repair techniques for reinforced concrete structures of historical buildings: A case study

Electrochemical re-alkalization technique is an effective method for non-destructive restoration of carbonized reinforced concrete structures in historic buildings. In this paper, 21 groups of reinforced concrete specimens were designed for re-alkalization tests. The effects of different parameters such as energization time, current density, electrolyte solution type and concentration on the repair effect and safety were analyzed. A safety assessment was also carried out to address the possible problems of alkali aggregate reaction and bond strength degradation that may arise from the current electrochemical 2 technology. The test results show that when the energization time is 14d and the current density is 3A/m2, the natural corrosion potential change of rebar after re-alkalization has a larger positive shift, and the bond strength between rebar and concrete is larger and the bond performance is better. On this basis, extend the energization time to 21d, the re-alkalization depth is maximum, the pore liquid phase pH value after re-alkalization is maximum 10.89, the alkaline restoration effect is better, currently, the lowest cementite alkali content within the concrete, and the risk of alkali aggregate reaction is low. This technology can effectively repair the carbonization corrosion of reinforced concrete in ancient buildings without the risk of alkaline aggregate reaction, which provides a reference for the protection of cultural relics.