Correlation of Surface Cracks of Concrete due to Corrosion and Bond Strength (between Steel Bar and Concrete)

The current experimental study presents the results of bond strength loss (steel bar concrete) due to the corrosion damage of steel bar specimens, semiembedded in concrete, at various times of exposure to corrosive environment. In this case, a correlation was made between the width of the surface cracks of concrete caused by reinforcing steel corrosion and bond strength for different distances between stirrups and different cover thickness of concrete. The study indicates close relationship between the width of surface cracking, the percentage mass loss of embedded reinforcing bar, the distance between stirrups, and the cover thickness. In addition, mathematical predictive models of bond strength loss of corroded specimens were proposed. The model outcomes showed that the cracking development on concrete surface up to a width of 1.6 mm is accompanied by an exponential reduction of bond strength loss between steel reinforcement and concrete. Furthermore, the investigation has shown that the increase of transverse reinforcement (stirrups) percentage and the cover thickness play a significant role in durability of reinforced concrete elements and in bond strength maintenance between rebar and concrete.

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Corrosion Effect on Bond Loss between Steel and Concrete

10.5772/intechopen.94166 ◽

2020 ◽

Author(s):

Charis Apostolopoulos ◽

Konstantinos Koulouris

Keyword(s):

Reinforced Concrete ◽

Structural Integrity ◽

Steel Corrosion ◽

Strength Loss ◽

Reinforcing Bar ◽

Concrete Members ◽

Cover Concrete ◽

Gradual Development ◽

Corrosion Of Steel ◽

Bond Mechanism

This chapter is devoted to the effects of steel corrosion on bond relationship between steel and concrete. One of the basic assumptions in design of reinforced concrete members is the perfect steel - concrete bond mechanism, so that strain of reinforcing bar is the same as that of the surrounding concrete and these two different materials act as one. However, corrosion of steel reinforcement consists one of the main durability problems in reinforced concrete members, downgrade the bond behavior and therefore their structural integrity. Corrosion degrades the reinforcement itself, reducing the initial cross-section of the steel bar and its mechanical properties. Furthermore, tensile stresses in surrounding concrete caused due to oxides on the corroded reinforcement, lead to the gradual development of tensile field to the surrounding concrete, with spalling of the cover concrete and loss of bond mechanism as a consequence. In this chapter, an overview of damage of reinforced concrete due to steel corrosion is given, focused on the bond mechanism; factors that play key role in the degree of bonding and, also, proposed models of bond strength loss in correlation with the surface concrete cracking due to corrosion are indicated. To conclude, the ongoing research in this area of interest is presented, based on recent scientific studies.

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Finite element analysis on the bond behavior of steel bar in salt–frost-damaged recycled coarse aggregate concrete

REVIEWS ON ADVANCED MATERIALS SCIENCE ◽

10.1515/rams-2021-0063 ◽

2021 ◽

Vol 60 (1) ◽

pp. 853-861

Author(s):

Tian Su ◽

Ting Wang ◽

Haihe Yi ◽

Rui Zheng ◽

Yizhe Liu ◽

...

Keyword(s):

Bond Strength ◽

Concrete Cover ◽

Bond Slip ◽

Bond Behavior ◽

Steel Bar ◽

Calculation Results ◽

Cover Thickness ◽

Bar Diameter ◽

Good Agreement ◽

Ultimate Bond Strength

Abstract In this article, the ABAQUS finite element software is used to simulate the bond behavior of the steel bar in salt–frost-damaged recycled coarse aggregate concrete, and the influence of the steel bar diameter and the concrete cover thickness on the bond strength is investigated. The result shows that the calculated bond–slip curve is in good agreement with the experimental bond–slip curve; the mean value of the ratio of the calculation results of ultimate bond strength to the experiment results of ultimate bond strength is 1.035, the standard deviation is 0.0165, and the coefficient of variation is 0.0159, which proves that the calculation results of the ultimate bond strength are in good agreement with the experimental results; with the increase of steel bar diameter and the concrete cover thickness, the ultimate bonding strength of RAC and steel increases; the calculation formulas for the ultimate bond strength of specimens with different steel bar diameters (concrete cover thickness) after different salt–frost cycles are obtained.

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Bond Strength Modelling of Corroding Steel Reinforcement in Concrete

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.757 ◽

2011 ◽

Vol 255-260 ◽

pp. 757-761 ◽

Cited By ~ 1

Author(s):

Roger Zou ◽

Ahmad Shayan ◽

Frank Collins

Keyword(s):

Bond Strength ◽

Bearing Capacity ◽

Analytical Model ◽

Experimental Test ◽

Concrete Structure ◽

Concrete Cover ◽

Simple Analytical Model ◽

Load Bearing Capacity ◽

Steel Bar ◽

Cover Thickness

Corrosion of reinforcement can significantly affect the bond strength between the steel bar and the surrounding concrete thus greatly reducing the load bearing capacity of the concrete structure. In this paper, a simple analytical model is proposed to evaluate the maximum bond strength of corroded concrete with varying rebar diameters and concrete cover thickness. Predicted results compared well with experimental test data.

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Characterizing Steel Corrosion in Different Alkali-Activated Mortars

Materials ◽

10.3390/ma14237366 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7366

Author(s):

Nina Gartner ◽

Miha Hren ◽

Tadeja Kosec ◽

Andraž Legat

Keyword(s):

Electrochemical Impedance ◽

Steel Corrosion ◽

Corrosion Damage ◽

Corrosion Properties ◽

Reinforcing Bar ◽

Wide Range ◽

Steel Bars ◽

Computed Microtomography ◽

Eis Measurements ◽

Alkali Activated

Alkali-activated materials (AAMs) present a promising potential alternative to ordinary Portland cement (OPC). The service life of reinforced concrete structures depends greatly on the corrosion resistance of the steel used for reinforcement. Due to the wide range and diverse properties of AAMs, the corrosion processes of steel in these materials is still relatively unknown. Three different alkali-activated mortar mixes, based on fly ash, slag, or metakaolin, were prepared for this research. An ordinary carbon-steel reinforcing bar was installed in each of the mortar mixes. In order to study the corrosion properties of steel in the selected mortars, the specimens were exposed to a saline solution in wet/dry cycles for 17 weeks, and periodic electrochemical impedance spectroscopy (EIS) measurements were performed. The propagation of corrosion damage on the embedded steel bars was followed using X-ray computed microtomography (mXCT). Periodic EIS measurements of the AAMs showed different impedance response in individual AAMs. Moreover, these impedance responses also changed over the time of exposure. Interpretation of the results was based on visual and numerical analysis of the corrosion damages obtained by mXCT, which confirmed corrosion damage of varying type and extent on steel bars embedded in the tested AAMs.

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Experimental Research on Interfacial Bond Performance in Rock Anchor with High-Performance Grouting Medium

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.517.932 ◽

2012 ◽

Vol 517 ◽

pp. 932-938 ◽

Cited By ~ 2

Author(s):

Zhi Fang ◽

Hong Qiao Zhang

Keyword(s):

Rock Mass ◽

Bond Strength ◽

High Performance ◽

Interfacial Bond ◽

Interfacial Bond Strength ◽

Bond Performance ◽

Pull Out ◽

Steel Bar ◽

Reactive Powder ◽

Ground Anchor

There exist the problems such as low bond strength and bad durability in the ordinary grouting slurry of the ground anchor system at present. The high-performance grouting mediums RPC (Reactive Powder Concrete) and DSP (Densified Systems containing homogeneously arranged ultrafine Particles) would become the potential replacement of grouting medium in ground anchor resulting from their high compressive strength, durability and toughness. Based on a series of pull-out tests on ground anchors with different high-performance grouting medium of RPC and DSP , different bond length in the construction field, the bond performance on the interfaces between anchor bolt (deformed steel bar) and grouted medium as well as between grouted medium and rock mass was studied. The results indicate that the interfacial bond strength between RPC or DSP and deformed steel bolt ranges within 23-31Mpa, far greater than that (about 2-3MPa) between the ordinary cementitious grout and deformed steel bar. Even though the interfacial bond strength between the grouted medium and rock mass of limestone was not obtained in the test since the failure mode was pull-out of those steel bar rather than the interface shear failure between grouted medium and rock mass, the bond stress on the interface reached 6.2-8.38 MPa, also far greater than the bond strength (about 0.1-3MPa) between the ordinary cementitious slurry and rocks.

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Experimental study on the effect of concrete strength and corrosion level on bond between steel bar and concrete

Transport and Communication Science Journal ◽

10.47869/tcsj.72.4.9 ◽

2021 ◽

Vol 72 (4) ◽

pp. 498-509

Author(s):

Vuong Doan Dinh Thien ◽

Hung Nguyen Thanh ◽

Hung Nguyen Dinh

Keyword(s):

Compressive Strength ◽

Bond Strength ◽

Concrete Strength ◽

Concrete Block ◽

Bond Stress ◽

Concrete Compressive Strength ◽

Pull Out ◽

Steel Bar ◽

Stress Degradation ◽

Slip Displacement

Corrosion of the steel reinforcement bars reduces the area of the steel bar and the bond stress between the steel bars and around concrete that decreases the capacity of concrete structures. In this study, the bond stress between steel bar with a diameter of 12mm and concrete was examined with the effect of different corrosion levels and different concrete grades. A steel bar was inserted in a concrete block with a size of 20×20×20cm. The compressive strength of concrete was 25.6MPa, 35.1MPa, and 44.1MPa. These specimens were soaked into solution NaCl 3.5% to accelerate the corrosion process with different corrosion levels in the length of 60mm. The pull-out test was conducted. Results showed that the bond strength of the corroded steel bar was higher than that predicted from CEB-FIP. Slip displacement and the range of slip displacement at the bond strength were reduced when the concrete compressive strength was increased. The rate of bond stress degradation occurred faster with the increment of the corrosion level when the concrete compressive strength was increased.

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