scholarly journals The Influence of Impressed Current on Residual Bond Strength of Corroded Structure

2015 ◽  
Vol 773-774 ◽  
pp. 984-989 ◽  
Author(s):  
Sallehuddin Shah Ayop ◽  
John J. Cairns
Keyword(s):  
Bond Strength ◽  
Significant Influence ◽  
Experimental Work ◽  
Crack Width ◽  
Corrosion Process ◽  
Accelerated Corrosion ◽  
Current Densities ◽  
Impressed Current ◽  
Type Bond ◽  
Bar Diameter

An experimental work was carried out to study the influence of impressed current on residual bond strength of corroded specimens. In accelerated corrosion process, two different current densities 0.08 mA/cm2 and 0.4 mA/cm2 were used which identified as ‘slow’ and ‘fast’ current. Beam end type bond specimens reinforced with 10 mm and 16 mm bar diameter were prepared for the bond test. Stirrups were provided along the main bar. Corrosion level of the main reinforcement was limited to 8% theoretical section loss. Other parameter such as the location of the test bar (corner and centre location) was also considered. The results indicate a significant influence of impressed current on the crack width with the ‘fast’ current tended to have wider crack than the ‘slow’ current. The influence on bond strength and other related parameters are being discussed.

Review on Experimental Study on Effect of Corrosion In Reinforced Concrete Fly-Ash Beam

2020 ◽  
pp. 92-96
Author(s):  
Shubham N. Dadgal ◽  
Shrikant Solanke
Keyword(s):  
Fly Ash ◽  
Bond Strength ◽  
Structural Damage ◽  
Pullout Test ◽  
Partial Replacement ◽  
Structural Members ◽  
Accelerated Corrosion ◽  
Resistivity Method ◽  
Electrical Resistivity Method ◽  
Structural Failures

In modern days for structures in coastal areas it has been observed that the premature structural failures are occurs due to corrosion of the reinforcements of the designed structural member. The corrosion causes the structural damage which in turn leads to reduction in the bearing capacity of the concerned structural members. The aim of this study was to study the effect of partial replacement of fly ash to minimize the corrosion effect. Beams were designed and corroded by using artificial method known accelerated corrosion method. The beams were then tested for flexural and bond strength. Also the weight loss of the reinforced bars was been determined using electrical resistivity method. The fly ash will replace by 10% and 15%.The strength will calculate at varying percentage of corrosion at 10% and 15%. Beams will cast at M25 grade concrete. The flexural strength will test by using UTM and the bond strength will calculate using pullout test.

Influence of Nd:YAG Laser Irradiation on an Adhesive Restorative Procedure

2006 ◽  
Vol 31 (5) ◽  
pp. 604-609 ◽  
Author(s):  
M. Franke ◽  
A. W. Taylor ◽  
A. Lago ◽  
M. C. Fredel
Keyword(s):  
Statistical Analysis ◽  
Bond Strength ◽  
Laser Irradiation ◽  
Significant Influence ◽  
Nd:Yag Laser ◽  
Deleterious Effect ◽  
Adhesive System ◽  
High Energy ◽  
Low Energy ◽  
Adhesive Penetration

Clinical Relevance Statistical analysis of the results obtained in this study shows that Nd:YAG laser irradiation on the adhesive system has a significant influence on bond strength to dentin. Bond strength is improved by better adhesive penetration when low energy is applied; whereas, high energy densities have a deleterious effect on the procedure.

The Effect of Cracks on Chloride Penetration into Concrete

2007 ◽  
Vol 348-349 ◽  
pp. 769-772 ◽  
Author(s):  
In Seok Yoon ◽  
Erik Schlangen ◽  
Mario R. de Rooij ◽  
Klaas van Breugel
Keyword(s):  
Service Life ◽  
Crack Length ◽  
Significant Influence ◽  
Crack Width ◽  
Chloride Transport ◽  
Crack Depth ◽  
Chloride Penetration ◽  
Critical Crack ◽  
Chloride Migration ◽  
Migration Testing

This study is focused on examining the effect of critical crack width in combination with crack depth on chloride penetration into concrete. Because concrete structures have to meet a minimum service-life, critical crack width has become an important parameter. Specimens with different crack width / crack length have been subjected to rapid chloride migration testing (RCM). The results of this study show a critical crack width of about 0.012 mm. Cracks smaller than this critical crack width are considered not to have a significant influence on the rate of chloride transport inwards, while chloride penetration does proceed faster above this critical crack width.

Bond behaviour of chemically prestressed textile reinforced concrete

2019 ◽  
Author(s):  
Katarzyna Zdanowicz ◽  
Boso Schmidt ◽  
Hubert Naraniecki ◽  
Steffen Marx
Keyword(s):  
Reinforced Concrete ◽  
Bond Strength ◽  
Crack Width ◽  
Research Programme ◽  
Textile Reinforced Concrete ◽  
Self Compacting Concrete ◽  
Bond Behaviour ◽  
Bond Slip ◽  
Laser Sensors ◽  
Pull Out

<p>The bond behaviour of concrete specimens with carbon textile reinforcement was investigated in the presented research programme. Pull-out specimens were cast from self-compacting concrete with expansive admixtures and in this way chemical prestress was introduced. The aim of the research was to compare bond behaviour between prestressed specimens and non-prestressed control specimens. During pull-out tests, the pull-out force and notch opening were measured with a load cell and laser sensors. Further, bond - slip and pull-out force - crack width relationships were drawn and compared for prestressed and non-prestressed specimens. Chemically prestressed specimens reached 24% higher bond strength than non-prestressed ones. It can be therefore concluded, that chemical prestressing positively influences the bond behaviour of concrete with textile reinforcement and thus better utilisation of its properties can be provided.</p>

Effects of Fatigue Damage on Bond Behavior between Corroded Rebar and Concrete

2019 ◽  
Author(s):  
Yunpeng Zhang ◽  
Weiping Zhang ◽  
You Hu
Keyword(s):  
Bond Strength ◽  
Fatigue Damage ◽  
Current Method ◽  
Fatigue Loading ◽  
Repeated Loading ◽  
Relative Slip ◽  
Pull Out ◽  
Bond Degradation ◽  
Impressed Current ◽  
Different Levels

Bond degradation due to rebar corrosion and fatigue loading may affect the serviceability and even safety of reinforced concrete (RC) bridges. 15 specimens confined with stirrups were cast for eccentric pull-out tests, and 12 of them were corroded with the target mass loss of 0.03 by the impressed current method. Monotonic pull-out tests were conducted on three corroded and three uncorroded specimens. Wavy descending branch was found in bond stress-slip test curves of uncorroded specimens attributed to stirrup confinement, however it disappeared in those curves of the corroded specimens due to the corrosion loss of rebar transverse ribs. Based on the tested monotonic bond strength, the other nine corroded specimens of different fatigue damages were obtained through repeated loading with different levels and cycles before undergoing monotonic pull-out tests. It is observed that the relative slip increases with a gradually decreasing rate as the loading cycles increase. The monotonic tests of specimens with fatigue damage show that the bond strength increases to a certain value and then decreases with the increase of fatigue loading cycles. Moreover, the higher the loading level is, the fewer cycles are needed to reach the maximum bond strength. In addition, the peak slip corresponding to bond strength decreases with the increase of fatigue loading cycles.

Polarization Studies of Aluminum Alloys In Water at 200 C and 300 C

CORROSION ◽  
1963 ◽  
Vol 19 (4) ◽  
pp. 146t-155t ◽  
Author(s):  
J. H. GREENBLATT ◽  
A. F. McMILLAN
Keyword(s):  
Anodic Polarization ◽  
Cathodic Polarization ◽  
Oxidation Potential ◽  
Electronic Conduction ◽  
Film Resistance ◽  
Applied Current ◽  
Weight Gain Data ◽  
Current Densities ◽  
Polarization Studies ◽  
Impressed Current

Abstract Specimens of commercial 2S aluminum and two special alloys containing iron and nickel were polarized anodically and cathodically at a number of different current densities at 200 C and 300 C. Weight gains were obtained and the potentials relative to the stainless steel autoclave were measured by an interrupter method. The weight gain data indicated that the polarizing current is being carried by electronic conduction. The potential-time curves for anodic polarization indicate differences between 2S aluminum and the alloys in that greater polarization is obtained with the latter. These curves also indicate that the impressed current decreases the film resistance. In all cases the potential reached a plateau value with time and this time was shorter for the alloys. The potential-time curves for cathodic polarization also show plateau values but the rise to a plateau value is in the opposite sense to the applied current. With increasing cathodic polarization the plateau values occur at more negative values of the potential. This latter trend is in the same direction as the applied polarizing current. This apparently is explained in terms of the build-up of the aluminum oxidation potential which acts in a sense opposite to the applied current. Again the time to reach plateau values was shorter for the alloys. Voltage current curves were also obtained on specimens left overnight (approximately 17 hours) at two different anodic polarizing currents. These curves indicated differences between 2S aluminum and the alloys; these differences are discussed in terms of the semi-conducting properties of the oxide film. The observations made on the differences in the properties of the oxide films on the materials examined as revealed by potential and polarization curves are discussed as to their significance in determining corrosion resistance.

On Comparison between Reinforcement Electricity Accelerated Corrosion and Natural Corrosion of Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 676-679 ◽  
Author(s):  
Sen Li ◽  
Jun Yin Yan ◽  
Xiao Gang Wang
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Experimental Research ◽  
Comparative Research ◽  
Corrosion Process ◽  
Common Method ◽  
Corrosion Mechanism ◽  
Accelerated Corrosion ◽  
Electric Flux ◽  
Natural Corrosion

Electricity accelerated corrosion is a common method to obtain corroded reinforced concrete specimens in current experimental research, and it has some relevance and differences with natural corrosion. The paper undertakes a detailed comparative research on the relevance and differences of the two corrosion conditions from the corrosion mechanism, the corrosion process, the corrosion rate, the electric flux and corrosion features, and this provide a better understanding of the research achievements based on accelerated corrosion.

Influence of transverse crack width on reinforcement corrosion initiation and propagation in mortar beams

2008 ◽  
Vol 35 (3) ◽  
pp. 236-245 ◽  
Author(s):  
Mustafa Şahmaran ◽  
İ. Özgür Yaman
Keyword(s):  
Diffusion Coefficient ◽  
Effective Diffusion Coefficient ◽  
Crack Width ◽  
Effective Diffusion ◽  
Reinforcing Bars ◽  
Nacl Solution ◽  
Accelerated Corrosion ◽  
Corrosion Initiation ◽  
Initiation And Propagation ◽  
Crack Widths

This paper discusses the relationship between crack widths, chloride diffusivity, and corrosion rate of cracked mortar beams. Flexural loads are introduced to generate crack widths ranging from 29 to 390 µm. The specimens were subjected to accelerated corrosion by immersion in a 5% NaCl solution and a constant voltage of 12 V. In addition, salt ponding tests were conducted to determine the chloride ion transport properties. The results showed that as the crack width increased, the effective diffusion coefficient (corrosion initiation) and mass loss of steel reinforcing bars due to the accelerated corrosion (corrosion propagation) also increased. For crack widths less than about 135 µm, the effect of crack width on the effective diffusion coefficient and mass loss of steel reinforcing bars embedded in mortar specimens was found to be marginal when compared with the virgin specimens. Therefore, it was concluded that the effect of crack width on the corrosion initiation and propagation period was more pronounced when the crack width is greater than about 135 µm. Moreover, a significant amount of self-healing was observed for the cracks that have widths below 50 µm when subjected to the NaCl solution exposure.

scholarly journals Bond Effects between Concrete and Steel Bar Using Different Diameter Bars and Different Initial Crack Width

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Papa Niane Faye ◽  
Yinghua Ye ◽  
Bo Diao
Keyword(s):  
Crack Width ◽  
Chloride Content ◽  
Initial Crack ◽  
Bond Performance ◽  
Pull Out ◽  
Steel Bar ◽  
Service Conditions ◽  
Concrete Casting ◽  
Initial Cracks ◽  
Bar Diameter

The importance of an accurate simulation of service conditions in the bond performance of reinforced concrete structures in coastal regions is highlighted. Four widths of initial crack of 0, 80, 150, and 210 microns were artificially made by inserting slice into bond specimens during concrete casting. Three bar diameters of 10 mm, 14 mm, and 18 mm were selected. At 28 days, the bond specimens were exposed to the environment of wet-dry cycles of seawater and atmosphere for another 90 days. The pull-out test was then conducted and chloride contents were tested at crack area along 40 mm depth. Results show that, for the specimen with 10 mm bar diameter, cracks width of less than 80 microns vanished rapidly during wet-dry cycles; for other specimens, cracks width of 100–150 microns decreased slightly. However the cracks of width more than 200 microns increased gradually; the chloride content decreased along the depth of concrete, and the chloride content increased as the widths of initial cracks increased or as the bar diameters increased. The ductility of bond specimens decreased as the diameter increased.

scholarly journals Regression Analysis of Bond Parameters between Corroded Rebar and Concrete Based on Reported Test Data

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
H. J. Zhou ◽  
Y. F. Zhou ◽  
Y. N. Xu ◽  
Z. Y. Lin ◽  
F. Xing ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Bond Strength ◽  
Crack Width ◽  
Experimental Tests ◽  
Test Results ◽  
Bond Slip ◽  
Regression Effect ◽  
Pull Out ◽  
Maximum Crack ◽  
Best Fit

Reinforcement corrosion is a major cause of degradation in reinforced concrete structures. The fragile rust layer and cracking and spalling of the cover caused by splitting stress due to rust expansion can alter bond behaviors significantly. Despite extensive experimental tests, no stochastic model has yet incorporated randomness into the bond parameters model. This paper gathered published experimental data on the bond-slip parameters of pull-out specimens and beam-end specimens. Regression analysis was carried out to identify the best fit of bond strength and the corresponding slip value in the context of different corrosion levels from the recollected test results. An F-test confirmed the regression effect to be significant. Residual data were also analyzed and found to be well described by a normal distribution. Crack width data of the tested specimens were also collected. A regression analysis of the bond strength and maximum crack width was carried out given the comparative simplicity of measuring crack width versus rebar area loss. Results indicate that maximum crack width can also be used to predict bond strength degradation with similar variation magnitude.

Sign in / Sign up

Export Citation Format

Share Document