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Corrosion under Combined Actions



Author(s):
Paper category: Bibliography
Book title: Publications on Durability of Reinforced Concrete Structures under Combined Mechanical Loads and Environmental Actions: An Annotated Bibliography
Editor(s): Yao Yan, Wang Ling, Wittmann Folker
Print ISBN: 978-3-942052-03-0
Publisher: Aedificatio Publishers
Pages: 95 - 104
Total Pages: 10
Language: English


Abstract: 
Service life of reinforced concrete structures is seldom jeopardized by deterioration of concrete properties but in most cases in practice by initiation of corrosion and time-dependent further development of corrosion of steel reinforcement. Historical concrete structures built without steel reinforcement have survived thousands of years without major problems. Many research projects were focused on different details of corrosion of steel in concrete in the past. In most cases, however, one single parameter has been studied as for instance the time to reach a critical chloride concentration in the surrounding of the steel bars in concrete or the influence of inhibitors. But it may be anticipated that the time to reach the conditions for initiation of corrosion and the rate of corrosion both depend on a combination of different processes and parameters such as humidity content and temperature.

So far few results on the influence of combined mechanical load and environmental actions are available in the literature. Recent papers dealing with this subject are compiled in this chapter. Reinforced concrete structures are nearly always load bearing structures. As a consequence structural elements may be damaged by micro-crack formation or they have real cracks in the tensile zone. In several papers it could be shown that chloride penetration is accelerated in the presence of cracks and hence service life is shortened, if predicted on diffusion parameters determined in laboratory on specimens without applied mechanical load. As papers on service life of cracked structural elements are rare literature reviews have been published recently (see for example 8.7).

Chloride migration is not only accelerated by an applied mechanical load and induced damage or crack formation but also by leaching. It could also be shown that the rate of carbonation is significantly increased by leaching. So far few papers only describe the influence of self-healing on the durability and service life under combined actions. This topic must be considered to be an urgent research area in the near future.

It will be impossible to predict service life of reinforced concrete structures under combined actions in aggressive environment just by simple equations containing a number of parameters, which can be determined in laboratories according to standards or recommendations. The different migration processes and their interaction and before all the influence of combined actions on migration of ions are too complex. For this reason an increasing number of numerical models are described in recent publications. These numerical models will have to be developed in close co-operation with colleagues who run the corresponding experiments.

The papers collected in this section clearly show that service life of reinforced concrete structures can be reduced significantly by combined actions, but at the same time it has to be recognized that this branch of durability studies is still in its infancy.


Online publication: 2014
Publication Type: full_text
Public price (Euros): 0.00