Statistical Variations of Rebar Placement and Its Effect on Service Life
Publication: Practice Periodical on Structural Design and Construction
Volume 23, Issue 3
Abstract
Significant attention is given to the transport properties of the concrete covering the reinforcing bars (covercrete) while neglecting the statistical characteristic of its thickness resulting from variations in rebar placement. A statistics-based model was developed to evaluate the effect of variations in covercrete thickness on the equivalent service life of a structure. It was demonstrated that service life can diminish by ∼30% when the standard deviation of the covercrete thickness reaches 15 mm (0.6 in.), as sometimes observed in practice. Field investigation of covercrete thickness in five infrastructure projects identified two sources of errors: (1) error in the average covercrete thickness, which indicates poor control of the specified thickness, and (2) standard deviation of thickness that ranges from 7.3 to 16.4 mm (0.29 to 0.65 in.). As a result, the projects' equivalent service life ranged from 0.40 to 0.99, where higher values were obtained in projects in which the mean concrete cover thickness was much greater than specified.
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Acknowledgments
The author gratefully acknowledges the National Road Company’s partial support of this research and extends his thanks to Engs. Eli Gamernick and Ronen Brown for their devotion in carrying out the experimental work.
References
ACI (American Concrete Institute). 2008. Building code requirements for structural concrete. ACI 318M-08. Farmington Hills, MI: ACI.
Alexander, M. G., Y. Ballim, and K. Stanish. 2008. “A framework for use of durability indexes in performance-based design and specifications for reinforced concrete structures.” Mater. Struct. 41 (5): 921–936. https://doi.org/10.1617/s11527-007-9295-0.
Andrade, C., M. Prieto, P. Tanner, F. Tavares, and R. d’Andrea. 2013. “Testing and modelling chloride penetration into concrete.” Constr. Build. Mater. 39: 9–18. https://doi.org/10.1016/j.conbuildmat.2012.08.012.
Bentur, A., S. Diamond, and N. S. Berke. 1997. Steel corrosion in concrete—Fundamentals and civil engineering practice. Boca Raton, FL: CRC.
BSI (British Standards Institute). 1988. Testing concrete. Recommendations on the use of electromagnetic covermeters. BS 1881-204:1988. London, UK: BSI.
CEN (European Committee for Standardization). 2004. Design of concrete structures, part 1.1. Eurocode 2. Brussels, Belgium: CEN.
Clark, L. A., M. Shammas-Toma, D. E. Seymour, P. F. Pallet, and B. K. Marsh. 1997. “How can we get the cover we need?” Struct. Eng. 75 (17): 289–296.
Conciatori, D., H. Sadouki, and E. Brühwiler. 2008. “Capillary suction and diffusion model for chloride ingress into concrete.” Cem. Concr. Res. 38 (12): 1401–1408. https://doi.org/10.1016/j.cemconres.2008.06.006.
Ehlen, M. A. 1999. “Life-cycle costs of fiber-reinforced-polymer bridge decks.” J. Mater. Civ. Eng. 11 (3): 224–230. https://doi.org/10.1061/(ASCE)0899-1561(1999)11:3(224).
Ehlen, M. A., and H. E. Marshall. 1996. The economics of new-technology materials: A case study of FRP bridge decking. Rep. No. 5864. Gaithersburg, MD: National Institute of Standards and Technology.
Epaarachchi, D. C., and M. G. Stewart. 2004. “Human error and reliability of multistory reinforced-concrete building construction.” J. Perform. Constr. Facil. 18 (1): 12–20. https://doi.org/10.1061/(ASCE)0887-3828(2004)18:1(12).
European Concrete Platform ASBL. 2008. Commentary to Eurocode 2. Edited by J.-P. Jacobs. Brussels, Belgium: European Concrete Platform ASBL.
fib (International Federation for Structural Concrete). 2006. Model code for service life design. Lausanne, Switzerland: fib.
ISO (International Organization for Standardization). 2006. Environmental management—Life cycle assessment—Principles and framework. ISO 14040:2006. Geneva, Switzerland: ISO.
Katz, A. 2004. “Environmental impact of steel and fiber–reinforced polymer reinforced pavements.” J. Compos. Constr. 8 (6): 481–488. https://doi.org/10.1061/(ASCE)1090-0268(2004)8:6(481).
Luco, L. F., M. Fischli, and J. Podvoiskis. 2007. “Transport mechanisms and reference tests.” Non-destructive evaluation of the penetrability and thickness of the concrete cover—State-of-the-art report of RILEM Technical Committee 189-NEC, edited by R. Torrent and L. F. Luco, 133–155. Bagneux, France: RILEM.
Marosszeky, M., and M. Chew. 1990. “Site investigation of reinforcement placement on buildings and bridges.” Concr. Int. 12 (4): 59–70.
Mirza, S. A., and J. G. MacGregor. 1979. “Variation in dimension of reinforced concrete members.” J. Struct. Div. 105 (4), 751–766.
Morgan, P. R., T. E. Ng, N. H. M. Smith, and G. D. Base. 1982. “How accurately steel be placed?” Concr. Int., 4 (4): 54–65.
Neville, A. M. 1998. “Concrete cover to reinforcement—Or cover up?” Concr. Int. 20 (11): 25–29.
Neville, A. M. 2011. Properites of concrete. London: Pearson.
Nganga, G., M. Alexander, and H. Beushausen. 2013. “Practical implementation of the durability index performance-based design approach.” Constr. Build. Mater. 45: 251–261. https://doi.org/10.1016/j.conbuildmat.2013.03.069.
Schiessl, P., C. Gehlen, and G. Kapteina. 2004. “Assessment and service life updating of existing tunnels.” In Proc., 1st Int. Symp. on Safe and Reliable Tunnels: Innovative European Achievements, 189–197. Gouda, Netherlands: Centre for Civil Engineering Research and Codes.
Seymour, D., M. Shammas-Toma, and L. Clark. 1997. “Limitation of the use of tolerances as a means of stating quality requirements in reinforced concrete.” In Lean construction, edited by L. Alarcon, 471–491. Rotterdam, Netherlands: A. A. Balkema.
SII (Standards Institute of Israel). 2003. Concrete code: General principles. SI 466-1. Tel Aviv, Israel: ISI.
Stewart, M. G., and D. V. Rosowsky. 1998. “Time-dependent reliability of deteriorating reinforced concrete bridge decks.” Struct. Saf. 20 (1): 91–109. https://doi.org/10.1016/S0167-4730(97)00021-0.
Torrent, R., and L. F. Luco, eds. 2007. Non-destructive evaluation of the penetrability and thickness of the concrete cover—State-of-the-art report of RILEM Technical Committee 189-NEC. Bagneux, France: RILEM.
Information & Authors
Information
Published In
Practice Periodical on Structural Design and Construction
Volume 23 • Issue 3 • August 2018
Copyright
© 2018 American Society of Civil Engineers.
History
Received: Sep 11, 2017
Accepted: Jan 8, 2018
Published online: May 7, 2018
Published in print: Aug 1, 2018
Discussion open until: Oct 7, 2018
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