Diffusivity Resistance of Concrete Systems in Chloride Rich Environment for Corrosion Protection of Embedded Steel Bars

2013 ◽  
Vol 831 ◽  
pp. 3-8
Author(s):  
Suad Khalid Al-Bahar ◽  
Safaa M. Abdul Salam ◽  
Adel M. Husain
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Steel Reinforcement ◽  
Mineral Admixtures ◽  
Chloride Ingress ◽  
Corrosion Initiation ◽  
Chloride Ion Penetration ◽  
Ion Penetration

Improving concrete performance and minimizing corrosion-induced deterioration of reinforced concrete structures are mandated Building Codes Practices and Specifications in arid regions such as the Arabian Gulf. Concrete structures resist corrosion due to the passivating properties of the hydrated cement around the steel reinforcement created by the high alkaline environment within the composite structure (pH > 12). However, the presence of chloride ions in the pore structure of the concrete destroys this passivating layer, which makes the steel reinforcement vulnerable to chloride-induced corrosion attack that accelerates degradation and deterioration of concrete structures. Corrosion activities-related tests such as Time-to-Corrosion Initiation (Modified ASTM G-109)6, and Corrosion Rate Test (Lollipop Test), can be effectively used to monitor the behavior of corrosion development, while chloride ingress characteristics tests such as Electrical Indication of Concretes Ability to Resist Chloride Ion Penetration ASTM C-1202-91)7, and the Resistance of Concrete to Chloride Ion Penetration (AASHTO T 259-80)8, are applied to evaluate the rate at which chloride ions can diffuse through concrete to onset the time-to-corrosion initiation, which will impact the structure service life and compromise its sustainability. Efforts have been made by scientists to develop mathematical simulation models that predict the service life of the structure based on Ficks Second Law for semi-finite diffusion of chloride ions, concentrated at different concrete depths. The study concluded that mineral admixtures have contributed to the enhancement of concrete performance and its resistance to chloride diffusivity, as well when in combination with corrosion-inhibiting admixture such as calcium nitrite.

Test Research of Chloride Ion Penetration in Concrete Tunnel Lining Structure

2012 ◽  
Vol 446-449 ◽  
pp. 3155-3159
Author(s):  
Zhong Li ◽  
Yan Peng Zhu ◽  
Xiao Yan Cui
Keyword(s):  
Service Life ◽  
Penetration Depth ◽  
Chloride Ion ◽  
Chloride Content ◽  
Chloride Ions ◽  
Tunnel Lining ◽  
Chloride Ion Penetration ◽  
Lining Structure ◽  
Erosion Environment ◽  
Ion Penetration

Chloride ion diffusion coefficient is an important indicator reflected the concrete durability in chloride erosion environment, and affects the service life of concrete structure directly. By the indoor test of chloride acceleration permeability, the chloride ions diffusivity is studied in the tunnel lining structure, and the variation law of the chloride content is tested with the change of penetration depth of different age specimen. Tests shows, with the increases of the penetration depth, the chloride content decrease gradually and finally tend to the initial chloride content of the specimen. Penetration time has a strong cumulative effect on the internal concentration of chloride ions in concrete, the high or low level of chloride ion concentration have a role of promotion or reduction for the chloride ion penetration in the concrete inside. The results provide an important basis for the predictions of service life of tunnel lining in chloride erosion environment.

scholarly journals Probability-Based Sensitivity of Service Life of Chloride-Attacked Concrete Structures with Multiple Cover Concrete Repairs

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Aruz Petcherdchoo
Keyword(s):  
Sensitivity Analysis ◽  
Service Life ◽  
Concrete Structures ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Expected Number ◽  
Probabilistic Data ◽  
Free Condition ◽  
Corrosion Initiation ◽  
Cover Concrete

This paper presents probabilistic and sensitivity analysis of service life (or time to repairs) for attaining corrosion-free condition of concrete structures under chloride attack. Four groups of probabilistic parameters are determined, i.e., (1) time-dependent chloride content, (2) mean and median of corrosion initiation and repair application times, (3) percent confidence of repairs, and (4) total expected number of repairs. To achieve this, this paper proposes a computational approach and probabilistic data. The proposed approach, which combined the Latin Hypercube technique with the Crank–Nicolson-based finite difference approach, is developed for predicting probabilistic chloride diffusion in concrete with repairs by cover concrete replacement. Probabilistic data of four governing random variables (surface chloride, diffusion coefficient, concrete cover depth, and critical chloride) and six repair strategies for corrosion-free condition are introduced. Numerical assessment is then shown. From the study, it is revealed that the reduction of the amount of chloride ions at the threshold depth due to using higher depth of cover concrete repairs is better than that using higher quality of repair materials. However, the excessive depth of repairs is not always recommended due to another control factor, such as the immediate amount of chloride ions at the repair depth, cost of repairs, etc. From the sensitivity analysis, the cover depth is found to be the most important parameter in the design of chloride-attacked concrete structures to extend the corrosion initiation and repair application times and to reduce the total expected number of repairs.

Penetration Behavior of Chloride Ions into Concrete in Coastal Areas

2006 ◽  
Vol 302-303 ◽  
pp. 584-590
Author(s):  
Yoshihiro Masuda ◽  
F.-R. Wu ◽  
S. Nakamura ◽  
S. Sato
Keyword(s):  
Chloride Ion ◽  
Concrete Specimen ◽  
Chloride Ions ◽  
Ion Content ◽  
Exposure Test ◽  
Total Chloride ◽  
Chloride Ion Penetration ◽  
Apparent Diffusion ◽  
Penetration Behavior ◽  
Ion Penetration

Exposure test on chloride ion penetration behavior into Concrete in coastal area was implemented. The distances between concrete specimens and coast were changed in the range from 50 to 150 meters, and water-cement ratios (W/C) were 45, 55, 60 and 65 %. The total chloride ion content at each different depth from surface of concrete specimen was measured at the age of 1, 2, 3, 5, 7, 8 and 10 years. In this paper, apparent diffusion coefficient (D) and chloride ion content on surface of concrete (C0) were calculated by inverse analyses from the measured total chloride ion content, and the chloride ion penetration behavior was simulated using the calculated D and C0. As a result, the chloride ion penetrated in concrete with a W/C of 60 % at a point 50 m from the sea for 10 years was estimated approximately 0.2 kg/m3.

scholarly journals Application of X-Ray Computed Tomography in Monitoring Chloride Ion Penetration Paths in Recycled Aggregate Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Yuan Zuo ◽  
Bing Qi ◽  
Jianming Gao ◽  
Weibin Li
Keyword(s):  
Computed Tomography ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
X Ray ◽  
Chloride Ion Penetration ◽  
X Ray Computed ◽  
Ion Penetration

The penetration paths of chloride ions in recycled aggregate concrete (RAC) are of significant interest and have not been well studied previously. This study used X-ray computed tomography (X-CT) as a novel approach to investigate chloride ion penetration paths in RAC. The results indicate that X-CT can be used for the constant monitoring of chloride ion penetration paths in RAC, and the influence of mix proportions on the chloride ion penetration can be understood through the X-CT visualization.

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