Corrosion of steel in carbonated concrete: mechanisms, practical experience, and research priorities – a critical review by RILEM TC 281-CCC
Carbonation of concrete is generally assumed to lead to reinforcing steel corrosion. This mindset has long dictated the research priorities surrounding the developments towards new, low-emission binders. Here, by reviewing documented practical experience and scientific literature, we show that this widely held view is too simplistic. In fact, there are many cases from engineering practice where carbonation of the cementitious matrix surrounding the steel did not lead to noticeable corrosion or to corrosion-related damage at the level of a structure. The influencing factors that can, however, lead to considerable corrosion damage are identified as the moisture state, the microstructure of the carbonated concrete, various species that may be present – even in minor amounts – in the concrete pore solution, and the cover depth.
The circumstance that a reduced pH alone is not sufficient to lead to significant steel corrosion in concrete seriously challenges the established approach of assessing the durability performance based on carbonation testing and modeling. At the same time, this circumstance offers great opportunities for reducing the environmental impact of concrete structures with low-emission binders. To realize these opportunities, the focus in research and engineering should shift from studying carbonation to studying corrosion of steel in carbonated concrete.
Copyright (c) 2020 Ueli Angst, Fabrizio Moro, Mette Geiker, Sylvia Kessler, Hans Beushausen, Carmen Andrade, Jukka Lahdensivu, Arto Köliö, Kei-ichi Imamoto, Stefanie von Greve-Dierfeld, Marijana Serdar
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors retain copyright of the articles published in RILEM Technical Letters and grant the journal the right of first publication with open access. The work is simultaneously licensed under Creative Commons Attribution 4.0 International License (CC BY 4.0) that allows others to share and adapt the work under the following terms: 1) a proper attribution is given in a form of a reference to the original work's authorship and initial publication in RILEM Technical Letters (bibliographic record with the DOI link); 2) a link to the license is provided; 3) the changes (if any) are indicated.