Residual capacity of corroded reinforcing bars

doi:10.1680/MACR.2005.57.3.135

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Residual capacity of corroded reinforcing bars

Journal Article•DOI•

Residual capacity of corroded reinforcing bars

01 Apr 2005-Magazine of Concrete Research (Thomas Telford Ltd)-Vol. 57, Iss: 3, pp 135-147

TL;DR: In this article, the authors investigated the influence of type and diameter of reinforcement on the residual strength of corroded reinforcing bars and found that the residual cross-section of a corroded bar is no longer round and varies considerably along its circumference and its length.

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Abstract: This paper presents an experimental investigation into the residual capacity of corroded reinforcing bars. By performing both accelerated and simulated corrosion tests on bare bars and on bars embedded in concrete, the mechanism of the reduction of the capacity of corroded reinforcement was investigated. The influence of type and diameter of reinforcement on its residual capacity is discussed. The experimental results show that, due to local attack penetration, the residual cross-section of a corroded bar is no longer round and varies considerably along its circumference and its length. Although the force–extension curves of corroded bars are similar to those of non-corroded bars for up to 16% corrosion, their residual yield and ultimate forces decrease more rapidly than their average cross-sectional area and, therefore, their residual strength decreases significantly. Even though the residual capacity of corroded small diameter and/or plain bars reduces more than that of large diameter or ribbed ones, di...

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Journal Article•

Corrosion of steel by concrete

[...]

A C Smith

01 Jan 1982-Civil Engineering

TL;DR: In this paper, the authors examined the reactions of various concretes on steel reinforcement and concluded that the most significant influences on the corrosion of prestressing wire in concrete are: the presence of chloride, presence of nitrates, the composition of concrete, the degree of carbonation of the concrete; concrete compaction and chlorides and sulphates should be used as far as possible when steel is embedded.

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Abstract: The author details the reactions of various concretes on steel reinforcement. Although portland cements, slag cements and high alumina cements are all hydraulic binders, each possess special properties which are examined. The discussion of causes and methods of preventing the corrosion of steel reinforcement covers such aspects as galvanised steel reinforcement, effects of concrete composition, corrosion of steel reinforcments in concrete and prestressed reinforcement. It is concluded that the most significant influences on the corrosion of prestressing wire in concrete are: the presence of chloride; the presence of nitrates; the composition of the concrete; the degree of carbonation of the concrete; concrete compaction and, chlorides and sulphates should be used as far as possible when steel is embedded. (TRRL)

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621 citations

Journal Article•DOI•

Chloride-induced corrosion of steel reinforcement – Mechanical performance and pit depth analysis

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Charis Apostolopoulos¹, Sotiris Demis¹, Vagelis G. Papadakis²•Institutions (2)

University of Patras¹, University of Western Greece²

01 Jan 2013-Construction and Building Materials

TL;DR: In this article, the effects of chloride-induced corrosion, in terms of mechanical properties and pit depths, are evaluated on B500c steel bars embedded in concrete (embedded samples) and directly exposed (bare samples), immersed in a salt spray chamber.

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228 citations

Cites background or result from "Residual capacity of corroded reinf..."

...Recently [22–24,26–28], it was demonstrated that steel bars subjected to corrosion (salt-spray) may suffer a relatively modest loss of strength but a significant loss of ductility....
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...It should be mentioned at this point that, the modest loss of strength and more important, the significant loss of ductility observed on the steel samples exposed directly to the corrosive medium, is in accordance with results from other studies in the literature [14,24,26–28]....
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...Such type of damage can have significant effects on strength [3,4,14,16,17,21–26] and ductility of reinforced concrete elements [19,23–25,27]....
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...Given the above, apart a few valid efforts [4,14,16,17,19,21–27], investigations on the effects of corrosion on the mechanical performance of reinforcing steel bars remains rare....
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...Conclusions, also observed in other studies [14,26–28,39–41], explained due the level of influence the concrete environment entails on the electrochemical nature of the chloride induced corrosion process....
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Journal Article•DOI•

Pitting corrosion and structural reliability of corroding RC structures : Experimental data and probabilistic analysis

[...]

Mark G. Stewart¹, Ali Al-Harthy²•Institutions (2)

University of Newcastle¹, Sultan Qaboos University²

01 Mar 2008-Reliability Engineering & System Safety

TL;DR: It was found that the maximum corrosion loss in a reinforcing bar conditional on beam collapse was no more than 16%, which shows the importance of considering spatial variability in a structural reliability analysis for deteriorating structures, particularly for corroding RC beams in flexure.

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228 citations

Journal Article•DOI•

Mechanical behaviour of pitting corrosion of flexural and shear reinforcement and its effect on structural reliability of corroding RC beams

[...]

Mark G. Stewart¹•Institutions (1)

University of Newcastle¹

01 Jan 2009-Structural Safety

TL;DR: In this article, a spatial and time-dependent reliability model was developed for a RC beam subject to corrosion-induced pitting corrosion, for shear and flexural limit states.

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213 citations

Cites background from "Residual capacity of corroded reinf..."

...There is sufficient evidence to suggest that yield stress reduces linearly with corrosion loss such that [23]:...
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...[23] recommend that ay = 0....
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Journal Article•DOI•

Effect of corrosion on ductility of reinforcing bars

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Yingang Du, L. A. Clark, Andrew Chan

01 Sep 2005-Magazine of Concrete Research

TL;DR: In this paper, the effect of corrosion on the ductility of steel reinforcement is investigated and a set of simple empirical equations is proposed to assess the ductile of corroded reinforcement in practice.

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Abstract: An experimental investigation into the effect of corrosion on the ductility of steel reinforcement is reported. Both accelerated and simulated corrosion tests were conducted on bare bars and on bars embedded in concrete. The mechanism and degree of the reduction of ductility of reinforcement due to corrosion were examined. The influence of bar type and diameter on ductility of corroded reinforcement is discussed. The experimental results indicate that, since local attack penetration results in a significant variation of residual cross-section along its length, corrosion significantly reduces ductility of reinforcement. Although the strength ratio, elastic modulus and hardening strain only vary with bar type rather than corrosion level, the elongation, ultimate strain and ductile area of corroded reinforcement reduce much more significantly than do those of their yield and ultimate strengths. There is concern regarding bar ductility since about 10% corrosion may possibly decrease the ultimate strain of reinforcement below the minimum requirement specified in CEB Model Code 90 for class S reinforcement. Even though the elongation, ultimate strength and ductile area parameter of corroded small diameter and/or plain bars reduce more than those of large diameter and/or ribbed ones, such differences are not significant and can be neglected. Finally, a set of simple empirical equations is proposed to assess the ductility of corroded reinforcement in practice.

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202 citations

Cites background or methods from "Residual capacity of corroded reinf..."

...In the authors’ opinion, the reason for such contradictory results is the use of different types of bar and different testing techniques.(4) An extensometer with the 60 mm gauge length used by Andrade et al....
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...Hence, when corrosion reduces bar section, the yield and ultimate strengths are reduced by similar amounts and the strength ratio is largely unaffected.(4) Furthermore, the hardening strain and elastic modulus of a reinforcing bar are dependent on their chemical composition and manufacturing process....
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...ported in a previous paper.(4) Hence, only a brief description is given here....
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...The reductions in these various measurements of ductility are greater than those of yield and ultimate strength which have been reported previously by the authors.(4) (c) The ductility of bars corroded whilst embedded in concrete decreases more significantly than that of bare bars....
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...A proof stress was not used because corrosion was found not to change the shape of the stress–strain curve.(4)...
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References

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Open Access

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Book•

Corrosion of Steel in Concrete: Understanding, investigation and repair

[...]

John P. Broomfield

01 Dec 1996

TL;DR: In this paper, the authors present a survey and assessment methodology for corrosion assessment of reinforced concrete, including a detailed survey of available techniques for inspection and characterization of steel in concrete.

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Abstract: Preface Acknowledgements Glossary Introduction Corrosion of steel in concrete: The corrosion process Black rust Pits, stray current and bacterial corrosion Electrochemistry, cells and half cells Conclusions Causes and mechanisms of corrosion and corrosion damage in concrete: Carbonation Chloride attack Corrosion damage Vertical cracks, horizontal cracks and corrosion The synergistic relationship between chloride attack, chloride binding and release Condition evaluation: Preliminary survey Detailed survey Available techniques Visual inspection Delamination Cover Half cell potential measurements Carbonated depth measurement Chloride determination Resistivity masurement Corrosion rate measurement Other useful tests for corrossion assessment Survey and assessment methodology Monitoring Special conditions: coated rebars and prestressing Physical and chemical repair and rehabilitation techniques: Concrete removal and surface preparation Patches Coating, sealers, membranes and barriers Encasement and overlays Sprayed concrete Corrosion inhibitors Electrochemical repair techniques: Basic principles of electrochemical techniques Cathodic protection The components of an impressed current cathodic protection system Cathodic protecton system design Control criteria System installation Cathodic protection of prestressed concrete Cothodic protection of epoxy coated reinforcing steel Cathodic protection of structures with ASR Chloride removal Realkalisation Comparison of techniques Rehabilitation methodology: Technical differences between repair options Repair costs Cabonation options Summary of options for carbonation repairs Chloride options Summary Understanding and calculating the corrosion of steel in concrete: Initiation time To, carbonation induced corrosion Chloride ingress rates (initiation) Rate of depassivation (activation) Deterioration and corrosive rates Corrosion without spalling Pitting corrosion Cracking and spalling rates, condition indices and end of functioning service life Summary of methodology to determine service life Building for durability: Cover, concrete and design Fusion bonded epoxy coated rebars Waterproofing membranes Penetrating sealers Galvinized rebar Stainless steel reinforcement Corrosion inhibitors Installing cathodic protestion in new structures Durable buildings Conclusions Future developments Appendix A: Bodies involved in corrosion and repair of reinforced concrete Appendix B: Stategic highway research program: published reports on concrete and structures (concrete and the corrosion of steel in atmospherically exposed reinforced concrere bridge componants suffering from chloride induced corrosion) Appendix C: Strategic highway research program: unpublished reports on concrete and structures (concrete and the corrosion of steel in atmospherically exposed reinforced concret

...read moreread less

637 citations

Journal Article•

Corrosion of steel by concrete

[...]

A C Smith

01 Jan 1982-Civil Engineering

...read moreread less

621 citations

Journal Article•DOI•

Effect of reinforcement corrosion on bond strength

[...]

A. A. Almusallam¹, A. S. Al-Gahtani¹, Abdur Rauf Aziz¹, Rasheeduzzafar¹•Institutions (1)

King Fahd University of Petroleum and Minerals¹

01 Mar 1996-Construction and Building Materials

TL;DR: In this article, the effect of reinforcement corrosion on the bond strength between steel and concrete was investigated, including the ultimate bond strength, free-end slip, and the modes of failure in precracking, cracking and postcracking stages.

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461 citations

"Residual capacity of corroded reinf..." refers background in this paper

...The amount of corrosion used in equations (6) and (7) can be determined from such measured values by using equations (12) and (13):...
[...]
...Hence, the residual forces and strengths of reinforcements in concrete can also be determined by equations (6) and (7)....
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...In accordance with equations (6) and (7), the force and strength of corroded reinforcement can be expressed generally as...
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...Hence, it is suggested that, in practice, equation (6) can be employed to predict the residual forces of all corroded plain and ribbed reinforcement with different diameters....
[...]
...Hence, the further regression analyses performed on both sets of test data suggested that the residual capacity of corroded bare reinforcement could be determined by equations (6) and (7)...
[...]

Journal Article•

Corrosion of steel

[...]

Wilhelm Schwenk

01 Jan 1969-Stahl Und Eisen

TL;DR: An extensive literature review as discussed by the authors covers environmental corrosion of mild steel and low alloy steels, pitting, interand transcryst, and corrosion at high temp. stress corrosion cracking of stainless steels and austenitic Mn steels.

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Abstract: An extensive literature review, covering environmental corrosion of mild steel and low alloy steels, pitting, interand transcryst. stress corrosion cracking of stainless steels and austenitic Mn steels, and corrosion at high temp. A short section on corrosion prevention is included. The discussion gives a comprehensive review of the corrosion of welds in CrNi steels, with reference to heat treatment and delta-ferrite content. 266 references. -- AATA

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203 citations

Journal Article•DOI•

Mechanical Response of Corroded Steel Reinforcement of Abandoned Concrete Bridge

[...]

Ragnar Palsson, M. Saeed Mirza

01 Mar 2002-Aci Structural Journal

TL;DR: In this paper, the ductility of steel reinforcing bars from the abandoned, deteriorated Dickson Bridge in Montreal, Canada, were tested in tension to establish how the mechanical properties are affected by corrosion.

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Abstract: In this research, samples of undamaged and corroded steel reinforcing bars from the abandoned, deteriorated Dickson Bridge in Montreal, Canada, were tested in tension to establish how the mechanical properties are affected by corrosion. The study found that the ductility of the reinforcing bars decreased dramatically as a result of severe corrosion.

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129 citations