Impact of fatigue-induced microcracks in concrete on the fluid ingress [Einfluss ermüdungsinduzierter Mikrorisse in Betonbauteilen auf den Eintrag flüssiger Medien]

Breitenbücher, R. and Przondziono, R.

Volume: 95 Pages: 844-849
DOI: 10.1002/bate.201800002
Published: 2018

Impact of fatigue-induced microcracks in concrete on the fluid ingress. The durability of concrete structures is sustainably impaired by the ingression of deleterious substances (carbon dioxide, chloride, acids, sulfates, alkalis, etc.) into the concrete microstructure. In order to minimize these processes, it is important to create a dense structure of the mortar matrix through an accordingly low water-cement ratio. If concrete structures are exposed to cyclic loading during their operating life, a degradation takes place within the concrete in the form of microstructural damages. These do not show macroscopically, but rather in the form of microcracks with widths from 5–15 Μm within the mortar matrix. These in turn promote the ingress of fluid media and thus deleterious substances. Typical examples are concrete traffic areas, that are exposed to cyclic loading through traffic on the one hand and alkaline de-icing agents during wintertime on the other hand. Such an external alkali supply promotes a deleterious alkali silica reaction (ASR) significantly. Similar conditions can be observed for offshore wind energy plants in alkaline seawater. The focus of the relevant investigations lay on the characterization of the degradation effects on a microstructural level as well as the transport behavior of fluid media in intact as well as pre-damaged concrete structures. © 2018, Ernst und Sohn. All rights reserved.

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