Development of an electrochromic device triggered by the macrocell current in chloride‐induced corrosion of steel‐reinforced concrete†. (13th July 2017) - Juraschek, Thomas
Abstract: This article presents the development and characterisation of an electrochromic device and its application to detect steel corrosion in reinforced concrete. Steel corrosion inflicts an enormous annual economic damage, which could be reduced by the installation of appropriate monitoring devices. These should be simple, reliable, long lasting, and should not require service or maintenance. The present electrochromic device is constructed in such a way that it uses the macrocell current in an active, chloride‐induced corrosion element as power supply to trigger the colour change. This way, the system stays inactive until corrosion occurs. The device consists of diheptyl viologen in a liquid polymer electrolyte made from LiClO4 and poly(ethylene glycol) with M ¯ w = 400 g mol −1 . The addition of viologen lowers the resistance but causes no further changes in the electrochemical properties of the polymer electrolyte. Impedance spectra indicate ion transport rather than capacitance effects to dominate the electrochemical properties. Experiments using direct current in the microampere range show electrochromic switching times of several minutes, which is sufficient for the intended monitoring application. Abstract : An electrochromic device is presented in which the colour change is successfully triggered by the weak electrical currents occurring during steel corrosion in reinforced concrete. The device consists of diheptyl viologen in a LiClO4 ‐poly(ethylene glycol) electrolyte sandwiched between an ITO‐coated PET sheet and a copper plate. It is simple, easy to construct, and requires little to no service or maintenance throughout the service life. As part of corrosion monitoring systems, it is therefore an ideal component of a sustainable infrastructural development.