Abstract
During the construction of the Copenhagen Metro from 1996 until the inauguration between 2002 and 2007 corrosion monitoring probes were installed and embedded in the concrete structures. One hundred and seventy sets of corrosion monitoring probes were installed each comprising 4 mild steel electrodes; a counter electrode (platinised titanium), reference electrode, temperature sensor and a reinforcement connection.
The overall objective of the installation is to have a prewarning system for corrosion in the concrete cover, so as to spot the onset of corrosion at reinforcement depth. This provides the basis for being able to apply preventive measures for corrosion protection, such as cathodic protection.
For the first three years the potential, zero resistance ammeter, temperature, impedance measurements were conducted manually. The metro trains have since commenced operating 24 hours a day, 7 days a week which made manual data collection unpractical. For this reason and also in order to have continuous monitoring, the Metroselskabet developed a data collection system, where each corrosion probe is connected to a measuring board and data is being collected on a regular basis and transferred to a server using databus cables and fibre optics. A software system controls the measurements being conducted and presents the data. This article describes the monitoring system and results from the pilot installation.
