Effect of Simulated Concrete Pore Solution Chemistry, Chloride Ions, and Temperature on Passive Layer Formed on Steel Reinforcement

2014 ◽  
Vol 111 (4) ◽  
Author(s):  
Abdulrahman Alhozaimy ◽  
Raja Rizwan Hussain ◽  
Abdulaziz Al-Negheimish ◽  
Rajeh Al-Zaid ◽  
D. D. N. Singh
Keyword(s):  
Pore Solution ◽  
Passive Layer ◽  
Chloride Ions ◽  
Steel Reinforcement ◽  
Solution Chemistry

Study of the semi-conductive behavior of the passive film on carbon steel in simulated concrete pore solution under stress

2015 ◽  
Vol 62 (6) ◽  
pp. 363-370 ◽  
Author(s):  
Yujie Zhang ◽  
Amir Poursaee
Keyword(s):  
Passive Film ◽  
Design Methodology ◽  
Pore Solution ◽  
Passive Layer ◽  
Chloride Ions ◽  
Content Type ◽  
Ring Model ◽  
Different Types ◽  
Different Levels ◽  
Chloride Contaminated

Purpose – This paper aims to clarify the semi-conductive behavior of the passive layer formed in concrete environment without and with presence of chloride ions under different loading conditions. Passivation and depassivation of steel play an essential role in the subsequent stages of the corrosion process. Due to the nature of passive films on metals, they show electrochemical properties of a semi-conductor. Design/methodology/approach – A C-ring model was proposed in this experiment to induce stress on the specimens. Specimens under different levels of compressive and tensile loadings were exposed to chloride-free and chloride-contaminated solutions and their semi-conductive behavior was investigated using Mott–Schottky technique. Findings – Irrespective of the type and magnitude of the applied load, the passive film on rebars in simulated concrete pore solution is a highly disordered n-type semi-conductor. In all specimens, the presence of chloride ions decreases the slope of the Mott-Schottky plots, the donor density and the space charge layer thickness, which leads to a thinner passive film. Results indicate that steel specimens immersed in chloride-free pore solution under tensile loadings passivate more rapidly compared to those under compressive loadings. However, the situation in chloride-contaminated solution is different, and steel under tensile stress exhibits more corrosion than steel under compressive stress or under no load. Originality/value – Reinforced concrete structures inevitably experience variable mechanical loads, and continuous degradation from aggressive environments. Therefore, it is imperative to study the synergic impact of different types of mechanical loadings and exposure to chloride ions on this process. This paper fulfils this need.

scholarly journals Protection of Carbon Steel Rebars by Epoxy Coating with Smart Environmentally Friendly Microcapsules

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 113
Author(s):  
Jacob Ress ◽  
Ulises Martin ◽  
Juan Bosch ◽  
David M. Bastidas
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Corrosion Protection ◽  
Corrosion Potential ◽  
Electrochemical Impedance ◽  
Pore Solution ◽  
Control Sample ◽  
Chloride Ions ◽  
Epoxy Coating ◽  
Transfer Resistance

The protection of mild steel by modified epoxy coating containing colophony microencapsulated corrosion inhibitors was investigated in this study. The corrosion behavior of these epoxy coatings containing colophony microcapsules was studied by electrochemical analysis using cyclic potentiodynamic polarization and electrochemical impedance spectroscopy. The microcapsule coating showed decreased corrosion current densities of 2.75 × 10−8 and 3.21 × 10−8 A/cm2 along with corrosion potential values of 0.349 and 0.392 VSCE for simulated concrete pore solution and deionized water with 3.5 wt.% NaCl, respectively, indicating improved corrosion protection in both alkaline and neutral pH. Electrochemical impedance spectroscopy analysis also showed charge transfer resistance values over one order of magnitude higher than the control sample, corroborating the electrochemical corrosion potential and current density testing results. Overall, the use of colophony microcapsules showed improved corrosion protection in simulated concrete pore solution and DI water solutions containing chloride ions.

Experimental Study on the Interaction Effect of Sulfate Ions and Chloride Ions on Reinforcement Corrosion in Marine Environment

2017 ◽  
Author(s):  
Yi Huang ◽  
Yunze Xu ◽  
Xiaona Wang ◽  
Shide Song ◽  
Lujia Yang
Keyword(s):  
Passive Film ◽  
Pore Solution ◽  
Construction Materials ◽  
Chloride Ions ◽  
Localized Corrosion ◽  
Test Results ◽  
Reinforcement Corrosion ◽  
Marine Structures ◽  
Sulfate Ions ◽  
Corrosion Risk

Reinforced concrete is one of the most widely used construction materials for marine structures. Due to the abundance of the aggressive ions such as chloride ions and sulfate ions in the seawater, the reinforcement exposed to the marine and costal environment are exposed to a high corrosion risk. Localized corrosion will occur once the passive film on the rebar is damaged. In this work, the corrosion behavior of the steel in the simulated pore solution containing with both sulfate ions and chloride ions are studied by using cyclic potentialdynamic polarization methods and the corrosion morphologies observed using scanning electron microscope (SEM). The test results show that the initial rebar corrosion is caused by the absorption of the chloride ions in the passive film. The sulfate ions nearly had no effect on the corrosion of the rebar in pore solution and it can further mitigate the pitting corrosion in chloride containing pore solution.

scholarly journals Detection, Protection, Repair and Rehabilitation of Corroded Prestressed Concrete Structures

2021 ◽  
Author(s):  
Md Khorshed Alam Khan
Keyword(s):  
Mild Steel ◽  
Prestressed Concrete ◽  
Chloride Ions ◽  
Steel Reinforcement ◽  
Cross Sectional Area ◽  
Cold Climate ◽  
Tensile Failure ◽  
Sectional Area ◽  
Cross Sectional ◽  
Prestressing Steel

Corrosion is a natural and unavoidable process and its control is a global challenge. The civil engineers of 21st century are facing a major problem for corrosion of prestressed concrete as they maintain an aging infrastructure. It affects various public and private economic sectors including infrastructure, transportation, production, manufacturing and utilities. Corrosion of prestressing steel is much more severe than corrosion of mild steel reinforcement. This is due to higher strength of the prestressing steels, and the high level of stressing in the steel. Usually prestressing steels are stressed about 70%-80% of their ultimate strength which is much lower in mild steel reinforcement. The loss of cross-sectional area of the reinforcing steel due to corrosion is likely lead to tensile failure. The cross-sectional area of prestressing steel is less than mild steel reinforcement due to its higher strength. As a result, the loss of one prestressing strand or bar will have a tremendous effect on the capacity of the member than the loss of an equivalent size mild steel bar. The corrosion of prestressing steel in concrete is an electrochemical reaction that is influenced by various factors including chloride-ion content, pH level, concrete permeability, and availability of moisture to conduct ions within the concrete. Normally steels in concrete are protected from corrosion by a passive film of iron oxides resulting from the alkaline environment of the concrete. For the corrosion process to be initiated, the passive oxide film on the prestressing steel must be destroyed. Passivation of the steel may be destroyed by the carbonation or by the presence of the chloride ions. In Canada, one of the reasons of this problem is due to the huge amount of deicing chemicals to combat the cold climate. Once corrosion occurs, the corrosion products occupy up to six times as much volume as steel, leading to cracking and disruption of the concrete. The ACI limit on chloride in prestressed concrete members is half of that for conventionally reinforced concrete. Prestressing steel is also more inclined to other forms of corrosion related deterioration that do not occur in mild steel reinforcement. These forms are stress corrosion cracking, hydrogen embrittlement, fretting fatigue and corrosion fatigue. These types of deterioration are very difficult to detect, and can lead to brittle failure with little or no sign of warning. This report presents the mechanisms, causes and effects of corrosion in North American design and construction and the proper detection and protection systems.

Study on the Concrete in Chloride Environment Based on Electrochemical Impedance Spectroscopy

2019 ◽  
Vol 34 (06) ◽  
pp. 2059017
Author(s):  
Fengjiao Jiang ◽  
Jinxin Gong ◽  
Jichao Zhu ◽  
Huan Wang
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Electric Double Layer ◽  
Electrochemical Impedance ◽  
Pore Solution ◽  
Salt Water ◽  
Chloride Ions ◽  
Double Layer Capacitance ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Electric Double Layer Capacitance

In this paper, the effect of water-cement ratio and chloride ions on the concrete meso-structure was studied. Three kinds of concrete cubes with different water-cement ratios were immersed in fresh water and salt water, respectively. Then, the Electrochemical Impedance Spectroscopy (EIS) analysis of various test cubes were carried out by using electrochemical workstation. The results show that the salt water can improve electric double layer capacitance in the test cubes with the same water-cement ratio, but it can reduce some other parameters such as resistance of pore solution, resistance to transfer the hydrated electron, coefficient of diffusion impedance of concreter, which shows that the chloride ions diffused into the concrete in salt water and increase the ionic concentration in pore solution and C-S-H gel. However, the phase angle index is constant whether in fresh water or salt water, which shows chloride ions cannot affect the concrete meso-structure even though they can improve the ion concentration of pore structure. For the concrete test cubes which has different water-cement ratio in salt water, with the reduction of water-cement ratio, the electric double-layer capacitance of concrete remains unchanged, which indicates when the water-cement ratio becomes smaller, the porosity becomes lower, and the internal structure of concrete becomes denser.

scholarly journals Cement-based materials destruction under the action of deicing salts

2019 ◽  
Vol 298 ◽  
pp. 00053 ◽  
Author(s):  
Ekaterina Potapova ◽  
Ivan Korchunov
Keyword(s):  
Aqueous Solution ◽  
Pore Solution ◽  
Colorimetric Method ◽  
Chloride Ions ◽  
Cement Matrix ◽  
Chloride Solutions ◽  
Deicing Salts ◽  
Cement Based Materials ◽  
Destructive Processes

The results of chloride ions with aqueous solution penetrating into the cement structure were determined with the colorimetric method. Some tendencies of chloride solutions migration in different conditions were established. The article suggests the possible ways of the prevention of destructive processes occur during the excessive pore solution saturation in cement matrix with chloride ions.

Einfluss der elektrochemischen Doppelschicht auf die Sorption und den Transport von Chlorionen im Zementstein / Influence of the electrochemical double layer on sorption and transport of chlorides in hardened cement paste

2000 ◽  
Vol 6 (4) ◽  
pp. 415-428
Author(s):  
O. Wowra ◽  
M.J. Setzer
Keyword(s):  
Double Layer ◽  
Cement Paste ◽  
Building Materials ◽  
Pore Solution ◽  
Chloride Ions ◽  
Transport Processes ◽  
Cement Matrix ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Electrochemical Double Layer

Abstract Besides the formation of Friedel salt the transport and binding of chlorides in concrete is mainly defined by the electrochemical double layer at the interface between cement matrix and pore solution. Due to the alkaline pore solution the surface of hardened cement paste is negatively charged which may change to positive values by the potential regulating calcium ions. Inverting of the surface charge leads to an attraction of anions and therefore, to an adsorption of chloride ions in the diffuse part of the electrochemical double layer. Influence from outside like sulphates and carbon dioxide may lead to a decomposition of Friedel salt. Apart from these effect temperature, pH-value and certain environmental conditions affects the electrochemical double layer as well. The chloride equilibrium is mainly controlled by adsorbed ions in the electrochemical double layer. The model presented here is relevant for the assessment of ion transport processes in mineral building materials. Continuing investigations may lead to optimize transport models and a better evaluation of the critical chloride threshold value in reinforced concrete.

Sign in / Sign up

Export Citation Format

Share Document