Effect of Steel-Concrete Interface on Reinforcement Corrosion in Marine Environment

2011 ◽  
Vol 250-253 ◽  
pp. 1311-1314
Author(s):  
Rui Jin Zhang
Keyword(s):  
Corrosion Rate ◽  
Environmental Conditions ◽  
Concrete Cover ◽  
Reinforcement Corrosion ◽  
Interface Quality ◽  
Corrosion Initiation ◽  
Concrete Members ◽  
Chloride Threshold ◽  
Interface Defects ◽  
Concrete Interface

This paper dealt with the influence of the steel-concrete interface quality and environmental conditions on reinforcement corrosion. High size concrete members were cast to get different interface quality decreased with the height of rebar due to the top-bar effect. Five groups of specimen with two concrete covers have subjected to different exposed programs. The experimental results showed that the concrete cover significantly influenced corrosion initiation and corrosion rate by blocking the penetration of aggressive agents. The height of rebar affected the corrosion initiation because of the variation of concrete porosity, interface defects and chloride threshold. The existence of defects at the interface was more important than the size of defect for corrosion initiation.

Which Rust Deposition Model Should Be Used in Predicting Concrete Cover Cracking due to Reinforcement Corrosion?

2012 ◽  
Vol 468-471 ◽  
pp. 1000-1004 ◽  
Author(s):  
Roger Zou ◽  
Frank Collins
Keyword(s):  
Predictive Model ◽  
Concrete Cover ◽  
Zone Model ◽  
Reinforcement Corrosion ◽  
Rust Layer ◽  
Rc Structures ◽  
Cover Cracking ◽  
Porous Zone ◽  
Walled Cylinder ◽  
Concrete Interface

The critical amount of corroded steel that causes concrete cover cracking can be readily calculated based on thick-walled cylinder theory. However, the results may vary significantly depending on how the rust deposition is considered. There are several rust deposition hypothesis proposed in the literature for modelling concrete cover cracking of RC structures due to reinforcement corrosion. Among them, three are considered representative ones and have been widely cited in the literature. They are: (i) assumes a certain amount of rust product carried away from the rust layer and deposited within the open cracks proposed by Pantazopoulou and Papoulia; (ii) assumes all of the rust products build up around the bar and all of them are responsible for the expansive pressure proposed by Bazant; (iii) assumes certain amount of rust products deposited into a porous zone around the bar/concrete interface proposed by Liu and Weyers. In this paper, all three rust deposition hypotheses were examined for the critical amount of corrosion to induce cover cracking. When compared to the test data available from the literature, it showed that the porous zone model proposed by Liu and Weyers gives the best predictions. Thus it may be concluded that assuming a porous zone around the steel/concrete interface would be reasonable and may be adopted in developing concrete cover cracking predictive model.

Influence of steel–concrete interface quality on reinforcement corrosion induced by chlorides

2003 ◽  
Vol 55 (2) ◽  
pp. 151-159 ◽  
Author(s):  
A. Castel ◽  
T. Vidal ◽  
R. François ◽  
G. Arliguie
Keyword(s):  
Reinforcement Corrosion ◽  
Interface Quality ◽  
Concrete Interface

scholarly journals Propagation of reinforcement corrosion: principles, testing and modelling

2018 ◽  
Vol 52 (1) ◽  
Author(s):  
Carmen Andrade
Keyword(s):  
Corrosion Rate ◽  
Large Scale ◽  
Galvanic Corrosion ◽  
Steel Corrosion ◽  
Electrical Signal ◽  
Guard Ring ◽  
Concrete Durability ◽  
Reinforcement Corrosion ◽  
Chloride Threshold ◽  
Corrosion Zone

Abstract Reinforcement corrosion is the risk most frequently cited to justify concrete durability research. The number of studies specifically devoted to corrosion propagation, once the object of most specialised papers, has declined substantially in recent years, whilst the number addressing initiation, particularly where induced by chlorides, has risen sharply. This article briefly describes the characteristics of steel corrosion in concrete that need to be stressed to dispel certain misconceptions, such as the belief that the corrosion zone is a pure anode. That is in fact seldom the case and as the zone is also affected by microcells, galvanic corrosion accounts for only a fraction of the corrosion rate. The role of oxygen in initiating corrosion, the scant amount required and why corrosion can progress in its absence are also discussed. Another feature addressed is the dependence of the chloride threshold on medium pH and the buffering capacity of the cement, since corrosion begins with acidification. Those general notions are followed by a review of the techniques for measuring corrosion, in particular polarisation resistance, which has proved to be imperative for establishing the processes involved. The inability to ascertain the area affected when an electrical signal is applied to large-scale elements is described, along with the concomitant need to use a guard ring to confine the current or deploy the potential attenuation method. The reason that measurement with contactless inductive techniques is not yet possible (because the area affected cannot be determined) is discussed. The method for integrating corrosion rate over time to find cumulative corrosion, P corr, is explained, together with its use to formulate the mathematical expressions for the propagation period. The article concludes with three examples of how to use corrosion rate to assess cathodic protection, new low-clinker cements or determine the chloride threshold with an integral accelerated service life method.

Bond Models for FRP Bars Anchorage in Concrete Slabs under Fire

2011 ◽  
Vol 82 ◽  
pp. 533-538 ◽  
Author(s):  
Emidio Nigro ◽  
Antonio Bilotta ◽  
Giuseppe Cefarelli ◽  
Gaetano Manfredi ◽  
Edoardo Cosenza
Keyword(s):  
Experimental Tests ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Concrete Slabs ◽  
Concrete Members ◽  
Reinforced Polymer ◽  
In Fire ◽  
External Loads ◽  
Frp Bars ◽  
Concrete Interface

Experimental tests were recently performed to evaluate resistance and deformability of nine concrete slabs reinforced with Fiber Reinforced Polymer (FRP) bars in fire situation by varying (a) external loads in the range of the service loads, (b) concrete cover in the range of usual values (30-50mm), (c) bar end shape (straight or bent) and its length at the end of the concrete members, namely in the zone not directly exposed to fire (250-500mm). Experimental results showed the importance of concrete cover in the zone directly exposed to fire for the protection provided to FRP bars, due to its low thermal conductivity. Moreover, the length of the FRP bars in the zone of slab not directly exposed to fire and its shape at the end of the members was crucial to ensures slab resistance once the resin softening reduced the adhesion at the FRP-concrete interface in the fire exposed zone of slab. In particular the anchorage obtained simply by bending bars at the end of member in a short zone (250mm) allowed attaining a good structural behavior in case of fire equivalent to that showed by slabs characterized by a large anchoring length (500mm). Tests results are briefly compared and discussed in this paper, whereas the behavior of the bar anchorage is carefully examined based on both the results of numerical thermal analysis and the predictions of a bond theoretical model adjusted for fire situation.

Electrochemical Studies on the Corrosion of Steel Bar in Concrete in Chloride Environment

2013 ◽  
Vol 631-632 ◽  
pp. 776-781
Author(s):  
Rui Jin Zhang ◽  
Hui Lin Yang ◽  
Da Yong Ye
Keyword(s):  
Electrochemical Impedance ◽  
Interface Quality ◽  
Linear Polarization Resistance ◽  
Corrosion Initiation ◽  
Impedance Response ◽  
Steel Bar ◽  
Chloride Environment ◽  
Corrosion Of Steel ◽  
Concrete Interface

This paper deals with the influence of the steel-concrete interface quality on the steel bar corrosion. Electrochemical methods including linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) were comparatively used to monitor the corrosion process of reinforcing steel in cement mortar. Experimental results show that a good quality of steel-concrete interface can significantly delay the corrosion initiation and reduces the corrosion rate. The results highlight the reasonable correlation between the impedance response and the Rp values by LPR method, but the corrosion rates obtained by EIS are lower than those results of LPR.

The Corrosion of Steel Reinforcement in Carbonated Concrete Under Different Humidity Regimes

1994 ◽  
Vol 370 ◽  
Author(s):  
Anastasia G. Constantinou ◽  
Karen L. Scrivener
Keyword(s):  
Corrosion Rate ◽  
Concrete Cover ◽  
Interfacial Region ◽  
Reinforcing Bars ◽  
Electrochemical Monitoring ◽  
Corrosion Of Steel ◽  
Curing Regimes ◽  
Linear Polarisation ◽  
Concrete Interface ◽  
Microstructural Examination

AbstractIn this investigation, four concretes (two mix designs and two curing regimes), containing reinforcing bars at covers 11 mm and 20 mm were carbonated fully in 100% CO2 and 65% relative humidity (RH). They were then placed in two different humidity environments (65% RH and 90% RH). The progress of the corrosion of the samples was followed electrochemically (using the linear polarisation technique) and microscopically (using a scanning electron microscope).Electrochemical monitoring of the corrosion rate showed that corrosion started very soon after placement in the humidity regimes and generally increased with time. The water/cement ratio, the concrete cover of the reinforcement and the curing of the concrete had a significant effect the length of time taken to carbonate the specimens. However, the effect of these variables on the corrosion rate was negligible. In addition, the corrosion rate showed no dependance on the humidity regimes.Microstructural examination of the samples revealed the existence of corrosion products at the steel/concrete interface after 6 months in the humidity regimes. There was more corrosion product in the samples at 90% RH. The samples with the low w/c showed more extensive cracking in the interfacial region.

Thermal effect on fiber reinforced polymer reinforced concrete slabs

2008 ◽  
Vol 35 (3) ◽  
pp. 312-320 ◽  
Author(s):  
A. Zaidi ◽  
R. Masmoudi
Keyword(s):  
Thermal Effect ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Concrete Slabs ◽  
Fiber Reinforced ◽  
Reinforced Concrete Slabs ◽  
Reinforced Polymer ◽  
Frp Bar ◽  
Frp Bars ◽  
Concrete Interface

The difference between the transverse coefficients of thermal expansion of fiber reinforced polymer (FRP) bars and concrete generates radial pressure at the FRP bar – concrete interface, which induces tensile stresses within the concrete under temperature increase and, eventually, failure of the concrete cover if the confining action of concrete is insufficient. This paper presents the results of an experimental study to investigate the thermal effect on the behaviour of FRP bars and concrete cover, using concrete slab specimens reinforced with glass FRP bars and subjected to thermal loading from –30 to +80 °C. The experimental results show that failure of concrete cover was produced at temperatures varying between +50 and +60 °C for slabs having a ratio of concrete cover thickness to FRP bar diameter (c/db) less than or equal to 1.4. A ratio of c/db greater than or equal to 1.6 seems to be sufficient to avoid splitting failure of concrete cover for concrete slabs subjected to high temperatures up to +80 °C. Also, the first cracks appear in concrete at the FRP bar – concrete interface at temperatures around +40 °C. Comparison between experimental and analytical results in terms of thermal loads and thermal strains is presented.

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