scholarly journals Experimental and Empirical Time to Corrosion of Reinforced Concrete Structures under Different Curing Conditions

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ahmed A. Abouhussien ◽  
Assem A. A. Hassan
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Test ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Cell Potential ◽  
Accelerated Corrosion ◽  
Curing Conditions ◽  
Expected Time ◽  
Corrosion Initiation ◽  
Accelerated Corrosion Test

Reinforced concrete structures, especially those in marine environments, are commonly subjected to high concentrations of chlorides, which eventually leads to corrosion of the embedded reinforcing steel. The total time to corrosion of such structures may be divided into three stages: corrosion initiation, cracking, and damage periods. This paper evaluates, both empirically and experimentally, the expected time to corrosion of reinforced concrete structures. The tested reinforced concrete samples were subjected to ten alternative curing techniques, including hot, cold, and normal temperatures, prior to testing. The corrosion initiation, cracking, and damage periods in this investigation were experimentally monitored by an accelerated corrosion test performed on reinforced concrete samples. Alternatively, the corrosion initiation time for counterpart samples was empirically predicted using Fick’s second law of diffusion for comparison. The results showed that the corrosion initiation periods obtained experimentally were comparable to those obtained empirically. The corrosion initiation was found to occur at the first jump of the current measurement in the accelerated corrosion test which matched the half-cell potential reading of around −350 mV.

Experimental Investigation of Corrosion-Induced Cover Cracking in Reinforced Concrete Structures

2011 ◽  
Vol 197-198 ◽  
pp. 1690-1693
Author(s):  
Chun Hua Lu ◽  
Wei Liang Jin ◽  
Jiang Hong Mao
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Test ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Corrosion Products ◽  
Analytical Models ◽  
Reinforced Concrete Structures ◽  
Accelerated Corrosion ◽  
Cover Cracking ◽  
Accelerated Corrosion Test

Concrete cover cracking induced by reinforcement corrosion is an important problem in reinforced concrete structures. Several existing analytical models for cracking time are discussed, and it is found that the penetration of corrosion products into corrosion cracks is neglected in these models. Based on our study, a theoretical model that takes the ingress of rust into cracks into account is proposed to predict the cracking time. In order to analyze the amount of corrosion products deposited in cracks, an accelerated corrosion test was performed. Based on the experimental results, the parameter k, which deal with the ingress of corrosion products into cracks, is calibrated to be 0.1~0.3 for accelerated corrosion test. By comparing the predictions with the test results, it is found that the proposed model has high accuracy in analyzing the cracking time and that the mean absolute error between predictions and observations is about 9.4%.

scholarly journals The Study of Half-cell Potential Behaviour of Reinforced Concrete in Marine Environment

2021 ◽  
Vol 9 (VII) ◽  
pp. 128-131
Author(s):  
Shrabanee Giri
Keyword(s):  
Reinforced Concrete ◽  
Marine Environment ◽  
Concrete Structure ◽  
Corrosion Test ◽  
Reinforced Concrete Structure ◽  
Half Cell ◽  
Cell Potential ◽  
Accelerated Corrosion ◽  
Accelerated Corrosion Test ◽  
Potential Test

Corrosion of reinforcement in concrete affects the strength and durability of reinforced concrete structure. Monitoring and maintenance of concrete structure throughout the service life prevent the ingress of corrosion at the initial stage. Half-cell potential meter was developed and fabricated to monitor the corrosion potential of reinforcement in a M25 grade concrete. Half-cell potential test and accelerated corrosion test has been carried out in marine environment of 3.5% of NaCl solution. The potential behaviour of specimen subjected to accelerated corrosion is studied throughout the test period. The results were obtained in terms of current flow behaviour and weight loss. Obtained results has been analyzed graphically and a comparative analysis has been carried out to know the rate of corrosion occurred in the specimen by accelerated corrosion test and half-cell potential test. Obtained results clearly indicates that the potential behaviour value increases with increase in time from 160 mV on day 1 to 949 mV on day 5. In the other way the compressive strength value for corroded specimen is lesser than the controlled specimen subjected to accelerated corrosion.

Passive corrosion control and active corrosion prevention of the reinforced concrete structures by electrochemical chloride removal and inhibitors

2013 ◽  
Vol 61 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Guofu Qiao ◽  
Yi Hong ◽  
Tiejun Liu ◽  
Jinping Ou
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Corrosion Control ◽  
Cell Potential ◽  
Content Type ◽  
Chloride Removal ◽  
Active Corrosion

Purpose – The aim of this paper was to investigate the passive corrosion control and active corrosion protective effect of the reinforced concrete structures by electrochemical chloride removal (ECR) method and inhibitors approach, respectively. Design/methodology/approach – The concentration of aggressive chloride ion distributed from the reinforcing steel to the surface of the concrete cover was analyzed during the ECR processes. Besides, the half-cell potential, the concrete resistance R c , the polarization resistance R p and the capacitance of double layer C dl of the steel/concrete system were used to characterize the electrochemical performance of the concrete prisms. Findings – The effectiveness of ECR could be enhanced by increasing the amplitude of potential or prolonging the time. Inhibitor SBT-ZX(I) could successfully prevent the corrosion development of the reinforcing steel in concrete. Originality/value – The research provides the scientific basis for the practical application of ECR and inhibitors in the field.

Seismic Response for a Reinforce Concrete Specimen Considering Corrosive Hazards

2015 ◽  
Vol 764-765 ◽  
pp. 1124-1128 ◽  
Author(s):  
Wei Ting Lin ◽  
Yuan Chieh Wu ◽  
An Cheng ◽  
Tzu Ying Lee
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Response ◽  
Seismic Response ◽  
Corrosion Test ◽  
Natural Frequencies ◽  
Response Spectrum ◽  
Open Circuit ◽  
Reinforced Concrete Frame ◽  
Accelerated Corrosion ◽  
Accelerated Corrosion Test

This study is aim to evaluate the dynamic response variation of the scale-down reinforced concrete frame specimen under accelerated corrosion conditions. The specimens achieved the accelerated corrosion test by immersing in the accelerated corrosion test. Open circuit potential, corrosion rate, natural frequencies, displacements, accelerations and response spectral curves were tested and discussed. Test results presented that the corroded reinforced concrete specimens presented the changes in the dynamic response especially natural frequencies and response spectrum. This study provided further insight on the variation of seismic response behaviors in the deteriorated reinforced concrete structures and hoped to useful for structural assessments and appraisals applied to full-scale structures.

Ultrasonic C-Scan Imaging: Preliminary Evaluation for Corrosion and Void Detection in Posttensioned Tendons

2003 ◽  
Vol 1827 (1) ◽  
pp. 44-52 ◽  
Author(s):  
Shivprakash Iyer ◽  
Andrea J. Schokker ◽  
Sunil K. Sinha
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Corrosion Monitoring ◽  
Reinforced Concrete Structures ◽  
Preliminary Evaluation ◽  
Cell Potential ◽  
Impact Echo ◽  
Bridge Structures ◽  
Processing Techniques ◽  
User Friendly

Corrosion of the nation’s transportation infrastructure is a widespread and costly problem. The most prevalent durability issue in reinforced concrete structures is chloride-induced corrosion of the reinforcing steel. A reliable method of determining grout voids and corrosion levels in posttensioned bridge structures is needed. Traditional techniques of corrosion monitoring (e.g., half-cell potential and corrosion rate measurement) are problematic when used in this type of structure, as are standard nondestructive evaluation (NDE) methods, such as impact echo. C-scan imaging, an ultrasonic technique used primarily in the composites industry for detecting delamination, is examined as a method of evaluating grouted posttensioned tendons. This method exhibits many promising qualities: it can be used for internal or external tendons and on metal or plastic ducts; access to only one side of a specimen is required; strong imaging allows easy interpretation of results; the technique poses no risk to users or the environment; and the method has strong potential for development as a handheld field tool. The C-scan technique may be valuable for the investigation of not only posttensioning applications but other types of reinforced concrete structures as well. Results of preliminary investigations on lab specimens indicate that the C-scan technique holds promise. The ultimate goal of the research is to provide a user-friendly, robust system for the NDE of posttensioned tendons for voids, corrosion, and wire breaks. Recommendations for optimal acquisition and processing techniques as well as for the future development of the equipment as a field tool are proposed.

scholarly journals Study on the effects of green-based plant extracts and water-proofers as anti-corrosion agents for steel-reinforced concrete slabs

2021 ◽  
Vol 302 ◽  
pp. 02018
Author(s):  
Jagadeesh Bhattarai ◽  
Madan Somai ◽  
Nirmal Acharya ◽  
Ajaya Giri ◽  
Akash Roka ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Plant Extracts ◽  
Research Work ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Corrosion Properties ◽  
Cell Potential ◽  
Positive Direction ◽  
Reinforced Concrete Slabs ◽  
Corrosion Susceptibility

Widespread applications of reinforced concrete structures have been practiced since the 20th century because of their excellent properties despite their early corrosion degradation. For the control of such a problem, a design strategy of corrosion-resistant environments of the reinforced concrete structures is highly desirable for extending of a lifetime. The present research work was focused to investigate the effects of the green plant extract-based inhibitors from Vitex negundo and Catharanthus roseus leaves, and one waterproofing chemical (PtS) for controlling the corrosion susceptibility of concrete rebar using a half-cell potential method following the ASTM C876-91 standard. Both plant extracts have good anti-corrosion properties, and hence could be applied as green concrete additives to increase the corrosion resistance of the steel reinforcing bars. The anti-corrosion performance of the steel rebars in concrete is remarkably higher with the additions of 1000 and 2000 ppm plant extracts than the additions of waterproofing chemicals used, based on the shifting of corrosion potential (ϕcorr.) values to a more positive direction than −126 mV (SCE). The results agreed that both the plant extracts could be promising for the formulation of effective, ecofriendly anti-corrosion additives to delay the corrosion susceptibility of the concrete infrastructures.

scholarly journals Influence of Pore Networking and Electric Current Density on the Crack Pattern in Reinforced Concrete Test Due to Pressure Rust Layer at Early Ages of an Accelerated Corrosion Test

2019 ◽  
Author(s):  
Ángela M. Bazán ◽  
Encarnación Reyes ◽  
Jaime C. Gálvez
Keyword(s):  
Reinforced Concrete ◽  
Pore Size ◽  
Electric Current ◽  
Current Density ◽  
Corrosion Test ◽  
Electric Current Density ◽  
Rust Layer ◽  
Porous Network ◽  
Accelerated Corrosion ◽  
Accelerated Corrosion Test

Research on early stages of corrosion of steel bars, together with the formation and development of cracks induced in the surrounding concrete and caused by chloride penetration, is relevant in improving the durability of reinforced concrete structures. This paper uses integration of the analytical models examined in the published literature, combined with experimental research in corrosion induced at the concrete/steel interface, in estimating the time-to-crack initiation of reinforced concrete subjected to corrosion. This work studies the influence of the porous network and electric current density on the cracking process at early ages. The experimental campaign was performed by using an accelerated corrosion test on a conventional concrete (CC) and a concrete with silica fume (SFC) by submitting them to a current density of 50μA/cm2 and 100μA/cm2. Examination performed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) provided both qualitative and quantitative information on the penetration of the rust layer in the surrounding concrete porous network. Strain gauges were used to measure corrosion-induced deformations between steel and concrete matrices, as well as the formation of corrosion-induced cracks. A good correlation between the rate of penetration of the rust products in the surrounding pores  and the delay of the cracking pressure in concrete was observed from the experimental results. This phenomenon is incorporated into the analytical model by using a reduction factor, which mainly depends on the pore size of the concrete. The crack width obtained exhibited a significant dependency on electric current density at the beginning of the test, depending mainly on the pore size of the concrete later.

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