Determination of the time-to-corrosion of concrete structures

Different sensor systems have been developed to monitor the time-to-corrosion of the reinforcement, designed to be installed directly into the concrete during construction or afterwards into drilled holes of existing structures. Most of these sensors as the so-called Anode-Ladder or the Expansion-Ring-System consist of different single sensors in defined distances from the concrete cover, e.g. of 6 steps, each of about 1 cm width, depending on the thickness of the concrete cover. These sensors indicate the depth of the critical chloride content and the depth of the carbonation front initiating corrosion: The time-to-corrosion can be determined, enabling the owners of buildings to initiate preventive protection measures before cracks and spalling occur, i.e. before the costs for repair measures increase over-proportionately. This paper shows the principles and some practical examples of the measurement of the corrosion behaviour of the reinforcement under on-site-conditions.