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.

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 Effect of Imidazoline Inhibitor on the Rehabilitation of Reinforced Concrete with Electromigration Method

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 398 ◽  
Author(s):  
Chonggen Pan ◽  
Jianghong Mao ◽  
Weiliang Jin
Keyword(s):  
Reinforced Concrete ◽  
Extraction Efficiency ◽  
Corrosion Potential ◽  
Steel Bar ◽  
Chloride Migration ◽  
Significant Difference ◽  
Steel Bars ◽  
Novel Method ◽  
Electrochemical Chloride Extraction ◽  
High Chloride

Steel bars embedded in reinforced concrete are vulnerable to corrosion in high chloride environments. Bidirectional electromigration rehabilitation (BIEM) is a novel method to enhance the durability of reinforced concrete by extracting chloride out of concrete and introducing an inhibitor to the surface of the steel bar under the action of an electric field. During the migration process, a higher ionization capacity of the inhibitor with a symmetrical molecular structure was introduced. A new imidazoline inhibitor was, therefore, employed in this study due to its great ionization capacity. The effect of imidazoline and triethylenetetramine inhibitor on chloride migration, corrosion potential, and strength of concrete were explored. The research results showed that the effect of chloride extraction and electrochemical chloride extraction made no significant difference on the surface of the concrete, where chloride extraction efficiency was more than 70%, and the chloride extraction efficiency was more than 90% around the location of the steel. while a dry-wet cycle test, the potential of concrete increased by about 200 mV by mixing imidazoline inhibitor. The imidazoline inhibitor was found to be effective at facilitating chloride migration and ameliorating corrosion, meanwhile, it had a negligible impact on the concrete’s strength.

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.

scholarly journals Effect of cations on the removal rate of chloride ions and mechanism analysis in high-salt wastewater

2021 ◽  
Author(s):  
Kangning Gao ◽  
Jie Lu ◽  
Xi Wang ◽  
Dengxin Li ◽  
Shihong Xu
Keyword(s):  
Removal Rate ◽  
Low Cost ◽  
Chloride Ion ◽  
Chloride Ions ◽  
High Salt ◽  
Cuprous Chloride ◽  
Mechanism Analysis ◽  
Chlorine Gas ◽  
Chlorine Ions ◽  
Chlorine Removal

Abstract Precipitation dechlorination has the advantage of being a simple process with a low cost. However, there are few reports on the effect of cations on dechlorination. In this study, we investigated the effect of cations in high-salt wastewater on the removal of chlorine ions by cuprous chloride precipitation and analysed the corresponding mechanism. A series of investigations revealed that Fe3+ could oxidise sulphite, thereby reducing the removal rate of chlorine ions. The reaction between magnesium and sulphite results in precipitation, which has a slightly adverse effect on the removal of chloride ions. Hexavalent chromium oxidises the chloride ion, resulting in the formation of chlorine gas, which improves the removal rate. Ferrous and manganese, however, do not have a notable effect on chlorine removal.

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.  

The Life-Span Prediction of Reinforcing Bars Corrosion of Self-Compacting Concrete

2011 ◽  
Vol 189-193 ◽  
pp. 4318-4324
Author(s):  
Yue Li ◽  
Chao Yan ◽  
Xiu Li Du ◽  
Yong Zhang ◽  
Qiao Lei
Keyword(s):  
Reinforced Concrete ◽  
Prediction Model ◽  
Life Span ◽  
Chloride Ion ◽  
Test Results ◽  
Reinforcing Bars ◽  
Prediction Formula ◽  
Self Compacting Concrete ◽  
Corrosion Condition ◽  
Chlorine Ions

Self-compacting concrete (SCC) has been used widely. However, the study of life-span prediction of self-compacting reinforced concrete is not enough under chloride ion corrosion condition， For the reinforcing bars corrosion that chlorine ions invade into SCC，the life-span prediction of Self-Compacting Concrete is the key issue. In this paper, the life-span prediction model of SCC structure under chloride ion corrosion condition is established and used to analyze the life-span prediction of SCC samples. Prediction results matched the test results very well, which shows the rationality of this prediction formula.

scholarly journals The electrochemical performance and modification mechanism of the corrosion inhibitor on concrete

2021 ◽  
Vol 28 (1) ◽  
pp. 352-562
Author(s):  
Meiyan Hang ◽  
Minghui Jiang ◽  
Junwei Xu ◽  
Teng Cheng ◽  
Hao Wang ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Electrochemical Performance ◽  
Corrosion Inhibitor ◽  
Electrode Potential ◽  
Concrete Structures ◽  
Corrosion Damage ◽  
Chloride Ions ◽  
Reinforced Concrete Structures ◽  
Chloride Corrosion ◽  
Chloride Environment

Abstract The purpose of this study was to solve the chloride corrosion damage problems of the rebar in reinforced concrete structures under the chloride environment. The effects of 1.0% triethanolamine (abbreviated as 1.0% TEA), 1.0% Ca(NO2)2, and 0.5% TEA + 0.5% Ca(NO2)2 (abbreviated as 1.0% composite corrosion inhibitor) on the electrochemical performance and modification mechanism of the mortar specimens were investigated by combining macro experiment and microanalysis. The results showed that the electrode potential of the rebar was effectively improved by incorporating the 1.0% composite corrosion inhibitor. This composite corrosion inhibitor displayed the ability to stabilize the electrode potential of the rebar; it also formed a passive film on the surfaces of the rebar, protected the rebar from chloride attack, and achieved satisfactory electrochemical performance. In addition, it could also effectively improve the strength of the mortar specimens and possessed the strong ability to bind chloride ions, thus signifying that it could promote cement hydration and accelerate the formation of cement to form AFt crystals. Therefore, the results of this investigation confirmed that this composite corrosion inhibitor could be effectively used in practical engineering to prevent the corrosion of reinforced concrete structures.

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 Study on the potential change of corroded reinforced concrete in ECE with MPC-CFRP as anode

2020 ◽  
Vol 319 ◽  
pp. 06005
Author(s):  
Yue Li ◽  
Xiuhu Zhang ◽  
S.M.Ali S. Hejazi
Keyword(s):  
Composite Material ◽  
Reinforced Concrete ◽  
Current Density ◽  
Good Effect ◽  
Steel Bar ◽  
Steel Bars ◽  
Cfrp Composite ◽  
Current Densities ◽  
Electrochemical Chloride Extraction ◽  
Corrosion Of Steel

Aiming at the rust removal requirements of reinforced concrete, the MPC-CFRP composite material was used as the external anode, and the Electrochemical chloride extraction (ECE) method was used to test the polarization curve of the steel bar under different ECE current densities, and the potential changes of the steel bar at different times were analyzed. The results show that the ECE system with MPC-CFRP as the external anode has a good effect of reducing the corrosion rate and the risk of corrosion of steel bars. The current density of 3A/m2is higher than that of 1A/m2in dechlorination efficiency. After 28 days of ECE, the current density of 1A/m2and 3A/m2can re passivate the reinforcement.

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