222 / 2022-06-10 18:19:57

Numerical study on electrochemical rehabilitation methods for reinforced concrete damaged by various factors

Electrochemical rehabilitation,Reinforced concrete structures,Mechanical cracking,Multi-species transport,Crack repair,Numerical model

Reinforced concrete (RC) structures have been widely constructed in harsh environments where the resultant durability problems can lead to serious deterioration in carrying capacity and thus limiting the designed service life. In recent years, various electrochemical rehabilitation methods for RC structures have been proposed including electrochemical chloride removal (ECR) and electrochemical realkalization (ER) which have been proved to be effective in rehabilitating RC structures damaged by chloride induced corrosion. However, RC structures are commonly exposed in the combined attack of various durability problems, and the previously mentioned rehabilitation methods with single targeted durability issues cannot prevent multiple deterioration factors at the same time. Therefore, it is necessary to find comprehensive electrochemical rehabilitation methods with multiple advantages in mitigating various durability issues and healing cracks so as to better prolong the service life.



In this study, a mesoscopic numerical model has been developed for promising electrochemical rehabilitation methods of electrochemical deposition method (EDM), and improved electrochemical chloride removal method. In addition to traditional functions such as chloride removal and realkalization, advantages including alkali silica reaction (ASR) mitigation and cracking repairing can also be achieved by migrating lithium and magnesium ions respectively into the damaged concrete. The entire process involved in the life cycle of reinforced concrete structures was represented by three sub-models: concrete mechanical damage model, multi-ionic transport model, and electrochemical rehabilitation model. The local mechanical variations of multiphase concrete have been considered in the mechanical damage model. The interaction among various ionic species was also quantitively expressed by the multi-ionic transport model. In addition, mitigation effectiveness on ASR affected concrete and dynamic crack closure status were also successfully reproduced by the proposed electrochemical rehabilitation model.



After validation against the third-party experimental data, a detailed parametric analysis has also been conduced to explore and discuss the potential influence factors on the efficiency of electrochemical rehabilitation treatment. Results showed that although large current density can facilitate the migration of lithium ions and removal of chloride ions, the crack closure rate is negatively affected because the previously formed deposition products will block the subsequent supply of magnesium ions. Increasing ambient temperature is beneficial to the overall improvement of electrochemical rehabilitation efficiency. Meanwhile, crack distribution pattern has an obvious influence on the crack closure status, and for ASR induced more discrete cracks distribution, it is recommended to arrange all exposure surface as working anodes to ensure a better repairing effect.