Development of an electrochromic device triggered by the macrocell current in chloride-induced corrosion of steel-reinforced concrete

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 (Formula presented.) = 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.