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Du er her: DBR > Non-destructive Electrochemical Methods for Monitoring of Reinforcement Corrosion

Non-destructive Electrochemical Methods for Monitoring of Reinforcement Corrosion

Title:
Non-destructive Electrochemical Methods for Monitoring of Reinforcement Corrosion

Type of project:
PhD.-project

Responsible part:
DTU, Dept. of Civil Engineering

Description:
Corrosion of the steel reinforcement in concrete structures is often referred to as the main cause of damage.

Most owners of large concrete structures use investigation and assessment as a tool for planning of maintenance, repair, and replacement. Information on the condition of the reinforcement is important for limitation of expensive repairs and the risk of collapse without warning as has been experienced in a few structures affected by chloride induced corrosion. In this connection reliable non-destructive techniques for assessment of the corrosion risk and rate of reinforcement are required. Half-cell potential measurements are typically used for the indication of corrosion risk; however, the method needs calibration due to the qualitative nature. Quantitative information on the corrosion rate can be obtained from measurements of the polarisation resistance of the embedded reinforcement steel. Three techniques for measuring the polarisation resistance exists – the Linear Polarisation Resistance technique, the Galvanostatic Pulse technique and Electrochemical Impedance Spectrography. Based on the two first techniques instruments for non-destructive on-site measurement of the reinforcement corrosion rate has been developed. However, none of these instruments give correct results for reinforcement in neither the passive nor active corrosion state. The main reason for this is claimed to be the confinement techniques used for focusing the current applied to the reinforcement from the concrete surface.

This study addresses the electrochemical as well as the confinement techniques used for measuring the corrosion rate of the reinforcing steel in concrete structures. The studies will be performed through experimental investigations and numerical simulations. Based on the outcome of the studies recommendations for a next generation corrosion rate meter will be given.

Furthermore, through a large experimental program the effect of temperature and relative humidity on the corrosion rate of steel undergoing passive, general, and pitting corrosion will be investigated. In these experiments the polarisation resistance (and hence the corrosion rate) is measured with the traditional linear polarisation resistance technique and two galvanostatic pulse techniques. The effect of polarisation time and current on the polarisation resistances determined with the three technique is also evaluated and calibrated against gravimetric measurements.

Project period:
August 2004 – July 2007

Participants:
DTU, Dept. of Civil Engineering
DTU, Dept. of Management Engineering
FORCE Technology

Link:
www.byg.dtu.dk

Relation to the Danish Concrete Counsel focus areas:
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