Design verification using corrosion monitoring systems indicating time-to-corrosion

Title: Design verification using corrosion monitoring systems indicating time-to-corrosion
Author(s): Michael Raupach, Joost Gulikers
Paper category : conference
Book title: 2nd International Symposium on Service Life Design for Infrastructures
Editor(s): K. van Breugel, Guang Ye, Yong Yuan
Print-ISBN: 978-2-35158-096-7
e-ISBN: 978-2-35158-097-4
Publisher: RILEM Publications SARL
Publication year: 2010
Pages: 985 - 994
Total Pages: 10
Nb references: 1
Language: English

Abstract: During recent years durability of marine and coastal concrete structures has become an important issue due to the problem of reinforcement corrosion, especially when the design service life is relatively high, e.g. 100 a. Several approaches have been developed to prevent premature corrosion of steel in concrete to occur, e.g. by the use of stainless steels, epoxycoated rebars, inhibitors or electrochemical methods like cathodic prevention and protection.
However, in practice for most large concrete structures exposed to sea water the following approach is preferred: the resistance of the concrete cover against chloride ingress has been increased as much as possible to achieve a maximum corrosion protection effect for the embedded reinforcement by ensuring a high cover thickness (typically between 5 and 7 cm) and a concrete with a low chloride diffusion coefficient. In addition, often sensors are installed to monitor the ingress of the critical chloride front as design verification as well as early warning system.
Most of these sensors, like the so-called Anode-Ladder, consist of a number of electrically isolated steel sections acting as sensors, each section being located at well-defined distances from the exposed concrete surface. Such a sensor system may comprise 6 steel sections using a fixed depth interval of approximately 1 cm, the exact interval being dependent on the actual thickness of the concrete cover. These sensors will reveal the depth of the critical chloride content and the depth of the carbonation front initiating corrosion. This information is used to determine the time-to-corrosion, enabling the owners of structures to anticipate on preventive protection measures before extensive cracking and spalling will occur, i.e. before the costs for repair measures increase over-proportionately. This paper focuses on the principles of the measurement of the time-to-corrosion using embedded sensors.

Online publication: 2011-04-20
Publication type : full_text
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