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Author Otie, M. ♦ Beushausen, H. ♦ Alexander, M.
Source SpringerLink
Content type Text
Publisher Springer Netherlands
File Format PDF
Copyright Year ©2012
Language English
Subject Domain (in DDC) Technology ♦ Engineering & allied operations
Subject Keyword Cover cracking ♦ Crack width ♦ Cover depth ♦ Corrosion rate ♦ Corrosion propagation ♦ Performance-based design ♦ Structural Mechanics ♦ Materials Science ♦ Theoretical and Applied Mechanics ♦ Operating Procedures, Materials Treatment ♦ Civil Engineering ♦ Building Materials
Abstract This paper advocates for the adoption of performance-based limiting crack widths with respect to steel corrosion in reinforced concrete structures. The authors argue that, from both durability and sustainability viewpoints, the practice of adopting a universal limiting crack width for a wide range of in-service exposure conditions and concrete cover conditions and quality is not valid. As new performance-based concrete design codes are being developed and/or improved, the influence of cover cracking on steel corrosion needs to be incorporated in these codes. An experimental set-up was designed to investigate the influence of cover cracking, cover depth and concrete quality on chloride-induced corrosion. Beam specimens (120 × 130 × 375 mm) were cast using five concretes made using two w/b ratios (0.40 and 0.55) and three binders (100 % CEM I 42.5 N (PC), 50/50 PC/GGBS and 70/30 PC/FA). Other variables in the experiments included cover depth (20 and 40 mm), crack width (0, 0.4 and 0.7 mm). A total of 105 beam specimens were cast and exposed to cyclic 3-days wetting (with 5 % NaCl solution) and 4-days air-drying in the laboratory (23 °C, 50 % relative humidity). Corrosion rate was monitored bi-weekly in the specimens. The results relevant to this paper are presented and discussed. For a given concrete quality and cover depth, corrosion rate increased with increasing crack width. If crack width and cover depth are kept constant, corrosion rate increases with decreasing concrete quality, and vice versa. A model framework that can be used to objectively select cover depth, concrete quality and crack width is proposed. Such a model can be improved into, for example, a nomograph and used in the design process for RC structures prone to corrosion. Performance-based crack width limits should be adopted in the design of RC structures prone to steel corrosion. These crack width limits should be dependent on a complex interaction of, inter alia, concrete quality, cover depth, crack characteristics and prevailing exposure conditions. This study showed the inter-relationship between crack width, cover depth and concrete quality in affecting chloride-induced corrosion rate. Accurate corrosion rate prediction models incorporating the influence of cover cracking on corrosion are a pre-requisite to implementing the influence of cover cracking in future concrete design codes.
ISSN 13595997
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2012-05-17
Publisher Place Dordrecht
e-ISSN 18716873
Journal Materials and Structures
Volume Number 45
Issue Number 12
Page Count 12
Starting Page 1805
Ending Page 1816

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Source: SpringerLink