scholarly journals Effect of Ultrasonic Parameters on Electrochemical Chloride Removal and Rebar Repassivation of Reinforced Concrete

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2774 ◽  
Author(s):  
Qingyang Liu ◽  
Zijian Song ◽  
Huanchun Cai ◽  
Aiping Zhou ◽  
Wanyi Wang ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Ultrasonic Waves ◽  
Work Time ◽  
Environment Friendly ◽  
Steel Bar ◽  
Ultrasonic Assisted ◽  
Chloride Removal ◽  
Ultrasonic Parameters

Electrochemical chloride removal (ECR) from reinforced concrete can be considered as an environment-friendly technique since it can reduce the environmental issues arising from demolition and reconstruction. In this study, we used ultrasonic waves to promote the ECR efficiency without increasing the current density so as to shorten the overall power-on time, lowering the power consumption and electricity-induced material damage. Rebar-embedded cement mortar specimens were prepared and a set of ultrasonic-assisted ECR test devices was designed. For obtaining the optimal parameters, different ultrasonic frequencies and powers were adopted to conduct the ECR test. After that, the discharged and residual chloride ion amounts were detected to characterize the ECR efficiency. The corrosion behavior of rebar was characterized by electrochemical method. It was found that ultrasonic waves can not only promote the discharge of chloride ions, but also promote the passivation process of steel bar. For this investigation, the ultrasonic waves with a frequency of 40 Hz and a power of 60 W had the best auxiliary effect and could reduce the work time by 64%. It is considered that the ultrasound-assisted method has potential to promote the application possibilities of the ECR technique.

scholarly journals The Effect of a Corrosion Inhibitor on the Rehabilitation of Reinforced Concrete Containing Sea Sand and Seawater

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1480 ◽  
Author(s):  
Chonggen Pan ◽  
Xu Li ◽  
Jianghong Mao
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Inhibitor ◽  
Control Experiment ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Maximum Value ◽  
Steel Bar ◽  
Sea Sand ◽  
Chlorine Ions ◽  
Electrochemical Chloride Extraction

Concrete made with sea sand and seawater is rich in chlorine ions which are the main factors that induce corrosion of the reinforcement. In this study, an innovative method to rehabilitate reinforcement is presented; the concentrations of chloride ions and the corrosion inhibitor in concrete were measured. Electrochemical chloride extraction (ECE) was applied as a control experiment via using saturated Ca(OH)2 solution as an external electrolyte. Bidirectional electromigration (BIEM)technology combined with the corrosion inhibitor could not only remove the chloride ions but also protect the steel bar in concrete, and animidazoline inhibitor mixed in concrete is more effective than thetriethylenetetramine inhibitor due to the specific molecular structure. It was found that the optimum ratio of N/Cl reached the maximum value 3.3, when the concentration of inhibitor was 1. Meanwhile, the experimental results also revealed that the corrosion inhibitor and chloride ion concentrations reached necessary levels on the surface of the steel, and the corrosion inhibitor migrated effectively. Overall, the contents of imidazoline and triethylenetetramine inhibitor in seawater concrete are0.75% and 1%, respectively. The results demonstrate that the addition of the corrosion inhibitor and the application of bidirectional electromigration would effectively improve the durability of reinforced concrete containing sea sand and seawater.

An Experimental Corrosion Investigation of Coupling Chloride Ions with Stray Current for Reinforced Concrete

2012 ◽  
Vol 166-169 ◽  
pp. 1987-1993 ◽  
Author(s):  
Mengcheng Chen ◽  
Kai Wang ◽  
Quanshui Wu ◽  
Zhen Qin
Keyword(s):  
Reinforced Concrete ◽  
Chloride Ion ◽  
Current Strength ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Test Time ◽  
Light Rail ◽  
Stray Current ◽  
Concrete Deterioration ◽  
Two Stages

According to the service environment of light rail transit and subway structures, in this paper experiments on the corrosion characteristics of reinforced concrete under single corrosion environment of stray current, single corrosion environment of chloride ions and joint corrosion environment of stray current and chloride ions were respectively carried out. Loading direct current electric field was used to simulate the stray current. The experimental results showed that, the corrosion growth process of the rebar in reinforced concrete under single environment of chloride ions was slow and stable, while that under single environment of stray current being separated two stages, i.e., rapidly increasing stage and stably varying stage. In addition, the rebar of reinforced concrete in stray current alone environment was corroded faster than that in chloride ion alone environment did; when stray current and chloride ion coexist, the stray current speeded up the chloride ion transportation, which gave rise to the increase of the corrosion rate of the rebar of reinforced concrete; the corrosion degree of the rebar depended on the chloride ion concentration, stray current strength and test time. The stronger the stray current strength, the longer the stray current corrosion period and the heavier the chloride ion concentration, the more the corrosion products of the rebar and thus the more serious the reinforced concrete deterioration.

scholarly journals Durability Investigation of Carbon Fiber Reinforced Concrete under Salt-Freeze Coupling Effect

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6856
Author(s):  
Yongcheng Ji ◽  
Wenchao Liu ◽  
Yanmin Jia ◽  
Wei Li
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Coupling Effect ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Fiber Reinforced Concrete ◽  
Ion Concentration ◽  
Fiber Reinforced ◽  
Ion Distribution ◽  
Carbon Fiber Reinforced

In order to study the durability behavior of CFRP (carbon fiber reinforced polymer) reinforced concrete, three category specimens (plain, partially reinforced, and fully reinforced) were selected to investigate its performance variation concerning chlorine salt and salt-freeze coupled environment, which included the microscopic examination, the distribution of chloride ion concentration, and the compressive properties. By observing the microscopic of the specimens, the surface and cross-section corrosion deterioration was examined with increasing exposure time, and the physical behavior of CFRP and core concrete were discussed. The chloride ion diffusion test exerted that the chloride ion concentration in plain specimens is at least 200 times higher than that of fully reinforced specimens. Therefore, the effectiveness of CFRP reinforcement will be proved to effectively hinder the penetration of chloride ions into the core section. The formula of the time-dependent effect of concrete diffusivity with salt-freeze coupling effect was presented and its accuracy verified. A time-varying finite element model of chloride ion distribution was established by using ABAQUS software. It can be seen from the axial compression test that the strength loss rate of three categories of specimens was varied when subjected to the corrosion environment. Therefore, it is proved that CFRP reinforcement can effectively reduce the deterioration of the specimen’s mechanical properties caused by the exposure environment. The research results can provide technical reference for applying the CFRP strengthened concrete in a severe salt-freeze environment.

REDUCTION OF CHLORIDE ION INGRESS INTO REINFORCED CONCRETE USING A HYDROPHOBIC ADDITIVE MATERIAL

2017 ◽  
Vol 79 (2) ◽  
Author(s):  
Agus Maryoto ◽  
Buntara S. Gan ◽  
Han Aylie
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Calcium Stearate ◽  
Corrosion Attack ◽  
Reinforced Concrete Member ◽  
Load Carrying ◽  
Compressive Strength Test ◽  
Infiltration Test

Reinforced concrete structures located in areas near the coast are exposed to potential corrosion attack. Corrosion attack can occur because of the infiltration of chloride ions into concrete. At the initiation of the corrosion process, the load-carrying capacity of a reinforced concrete member will be affected negatively as a function of time. Infiltration of chloride ions into the concrete could be avoided by improving the micro-concrete properties. Enhancement of these properties can be achieved by use of an additive in the concrete. Calcium stearate is a hydrophobic material that can improve the properties of concrete. To determine the optimum contribution in concrete, laboratory experiments were conducted. Calcium stearate was added in varying contents of 0, 0.2, 0.9, and 1.9% of the cement weight. Four types of tests were performed to analyse the contribution of calcium stearate, namely the compressive strength test, absorption test, chloride ion infiltration test, and corrosion test. The results show that an optimum value of the compressive strength of concrete is obtained through the addition of calcium stearate. Besides that, the absorption, chloride ion infiltration, and corrosion value decrease significantly when a higher amount of calcium stearate is added to the concrete.  

Investigation on Inhibitor Electromigration Anticorrosion Technology for Reinforced Concrete Structure

2009 ◽  
Vol 79-82 ◽  
pp. 1025-1028
Author(s):  
Jun Wu Tang ◽  
Shu Ang Han ◽  
Chang Hong Huang ◽  
Sen Lin Li
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structure ◽  
Polarization Resistance ◽  
Steel Surface ◽  
Chloride Ion ◽  
Passive State ◽  
Reinforced Concrete Structure ◽  
Technical Parameters ◽  
Chloride Removal ◽  
Effective Component

Based on measuring inhibitor effective component N content, chloride removal efficiency and steel polarization resistance, influences of technical parameters of concrete and electric charge amount on the inhibitor electromigration anticorrosion efficiency were described. The results indicated that inhibitor electromigration anticorrosion technology could remove chloride ion, and inhibitor group could move to steel surface so rapidly that corrosive steel could return into passive state, to meet the anticorrosion aim for steel.

scholarly journals Mechanism analysis and model calculation of chloride ion diffusion in reinforced concrete structure

2020 ◽  
Vol 198 ◽  
pp. 01035
Author(s):  
Faqiang Yu ◽  
Weiwei Gao ◽  
Wenchao Liu
Keyword(s):  
Reinforced Concrete ◽  
Diffusion Mechanism ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Cumulative Distribution ◽  
Reinforced Concrete Structures ◽  
Mechanism Analysis ◽  
Reinforced Concrete Structure

Chloride-induced corrosion of steel in reinforced concrete structures is one of the major causes of their deterioration over time. The analysis and research on the diffusion mechanism of chloride ions in reinforced concrete structures is still insufficient, and it is necessary to calculate the path of chloride ions based on theoretical models. In this paper, the fick’s second law was used to describe the free chloride concentration evolution in concrete. The Monte Carlo simulation was used to predict the cumulative distribution of corrosion initiation of reinforcing steel.The results show that the calculated results of the established model are in good agreement with the measured results.

scholarly journals Bayesian Assessment of the Effects of Cyclic Loads on the Chloride Ingress Process into Reinforced Concrete

2020 ◽  
Vol 10 (6) ◽  
pp. 2040 ◽  
Author(s):  
Henriette Marlaine Imounga ◽  
Emilio Bastidas-Arteaga ◽  
Rostand Moutou Pitti ◽  
Serge Ekomy Ango ◽  
Xiao-Hui Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Bayesian Networks ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Chloride Ingress ◽  
Rc Structures ◽  
Corrosion Initiation ◽  
Static And Cyclic Loading

Chloride-induced corrosion and load induced concrete cracking affect the serviceability and safety of reinforced concrete (RC) structures. Once these phenomena occur simultaneously, the prediction of RC structures’ lifetimes becomes a major challenge. The objective of this paper is to propose a methodology to evaluate the effect of loading and cracking on the mechanism of chloride ion penetration in concrete. The proposed methodology will be based on Bayesian networks. Bayesian networks are useful to update the lifetime assessment based on experimental data as well as to characterize the uncertainties of the input parameters of a chlorination model including a chloride diffusion acceleration factor. The proposed methodology is illustrated with experimental data coming from tests on RC beams subjected to static and cyclic loading before being in contact with a solution containing chloride ions. The characterized parameters are then used to evaluate the effect of these two loading conditions (static and cyclic) on the corrosion initiation time and the corrosion initiation probability. The results obtained indicate that the proposed methodology is capable of integrating loading and chlorination test data for the determination of the probabilistic parameters of a model in a comprehensive way.

scholarly journals Experimental Study and Simulation Calculation of the Chloride Resistance of Concrete under Multiple Factors

2021 ◽  
Vol 11 (12) ◽  
pp. 5322
Author(s):  
Yang Ding ◽  
Tong-Lin Yang ◽  
Hui Liu ◽  
Zhen Han ◽  
Shuang-Xi Zhou ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Penetration Depth ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Chloride Ions ◽  
Finite Element Software ◽  
Chloride Resistance ◽  
Simulation Calculation ◽  
Marine Concrete ◽  
Resistance Performance

Cement is widely used in marine concrete, and its resistance to chloride ion corrosion has been widely considered. In this paper, based on a laboratory test, the influence of different hydrostatic pressures, coarse aggregate contents and w/c ratios on the chloride resistance performance is analyzed. Based on COMSOL finite element software, a two-dimensional cementitious materials model is established, and the simulation results are compared with the experimental results. The results show that the penetration depth of chloride ions in cement increases with the increase of the w/c ratio. Under the hydrostatic pressure of 0 MPa, when the w/c ratio is 0.35, the penetration depth of chloride ions is 7.4 mm, and the simulation result is 8.0 mm. When the w/c ratio is 0.45, the penetration depth of chloride ions is 9.3 mm, and the simulation result is 9.9 mm. When the w/c ratio is 0.55, the penetration depth of chloride ions is 12.9 mm, and the simulation result is 12.1 mm. Under different hydrostatic pressures, the penetration depth of chloride ions obviously changes, and with the increase in hydrostatic pressure, the penetration depth of chloride ions deepens. Under the w/c ratio of 0.35, when the hydrostatic pressure is 0.5 MPa, the penetration depth of chloride ions is 11.3 mm, and the simulation result is 12.1 mm. When the hydrostatic pressure is 1.0 MPa, the penetration depth of chloride ions is 16.2 mm, and the simulation result is 17.5 mm.

scholarly journals Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec ◽  
Patryk Włodarczyk
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Spectroscopy ◽  
Low Frequency ◽  
Chloride Ion ◽  
Ion Source ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Broadband Dielectric Spectroscopy ◽  
Free Chloride ◽  
Structure Rebuilding

AbstractThe dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [Bi2O2]2+ layers and their growth, which increased the intensity of the (101) diffraction peak. The electrical conductivity and dielectric permittivity were related to the movement of chloride ions between plates (in the low-frequency region), the interplanar motion of Cl− ions at higher frequencies, vibrations of these ions, and charge carrier hopping at frequencies above 10 kHz. The influence of the free chloride ion concentration on the electrical conductivity was also described. Structure rebuilding was associated with a lower concentration of free chloride ions, which significantly decreased the conductivity. According to the analysis, the BiOCl plate conductivity was related to the movement of Cl− ions, not electrons.

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