Electrochemical anti-corrosion method
1. Overview
The electrochemical anti-corrosion method involves passing direct current through the concrete, using the steel material inside the concrete as the cathode and an anode placed near the concrete surface, in order to inhibit steel corrosion. The electrochemical anti-corrosion method includes a galvanic protection method, desalination method and re-alkalinization method, with the method being used depending upon factors such as structural location.
2. Key Features
- The desalination method is a method which electrochemically extracts salt from inside the concrete, where it contributes to deterioration. The electrification period is approximately eight weeks (current density*: 1.0A/m2), after which electrification is unnecessary. The desalination system is comprised of two methods: a panel method, which achieves desalination of repair members that have been immersed in an electrolytic solution, and a fiber method, which achieves desalination of concrete surfaces that have been sprayed with cellulose fiber sprayed/impregnated with an electrolytic solution. The desalination method not only removes elements which contribute to deterioration, it permeates the interior of the concrete with alkaline ions in an electrolytic solution to perform re-alkalinization, which also repassivates the rebar and, when combined with a surface coating method applied afterward, helps to ensure greater durability.
*Current density: Amount of electricity flowing per unit time in a direction perpendicular to a unit area
- The galvanic protection method includes an impressed current system and a galvanic anode system (sacrifice anode placement method). The impressed current system uses a DC power supply to directly supply protection current to the rebar, and it is necessary to continue supplying current for the service life of the structure. The galvanic anode system replaces the power supply with a metal possessing a lower potential than the rebar, and this metal is attached to the existing rebar, allowing the galvanic action created by the difference in the two materials’ electric potential to supply continuous protection current.
3. Our Construction
- Benten-ohashi Bridge salt damage repair work
- Koyurugi Viaduct (2) repair work
4. Catalogs & Technical Reports
- No.10 Electrochemical Desalination Method
- No.11 Galvanic Protection Method
- No.22 Sacrifice Anode Placement Method