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.

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.

Service Life Extension and CO2 Emission due to Silane Treatment on Chloride-Exposed Concrete Structures

2017 ◽  
Vol 728 ◽  
pp. 384-389
Author(s):  
Aruz Petcherdchoo ◽  
Chotima Ongsopapong
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Treatment Strategies ◽  
Life Extension ◽  
Chloride Diffusion ◽  
Silane Treatment ◽  
Free Service ◽  
Before And After ◽  
Chloride Attack ◽  
Service Life Extension

This study presents assessment of the environmental impact in terms of the CO2 due to silane treatment for extending corrosion-free service life of concrete structures under chloride attack. To achieve this, there are two issues to be addressed; prediction of corrosion-free service life extension, and assessment of the amount of CO2 emission. In predicting the corrosion-free service life extension, the behaviors of chloride diffusion before and after time-based silane treatment are considered. Then, the cumulative CO2 due to silane treatment is accordingly calculated. The ratio of the corrosion-free service life extension to the cumulative CO2 is defined as the effectiveness of silane treatment, and used to compare different silane treatment strategies.

New Composite Materials that Reduce the Effect of Reinforcement Corrosion

2013 ◽  
Vol 837 ◽  
pp. 265-270 ◽  
Author(s):  
Vasile Constantinescu ◽  
Gheorghe Veniamin Bogus ◽  
Rares George Taran ◽  
Ioan Carcea
Keyword(s):  
Carbon Dioxide ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Service Life ◽  
Concrete Structures ◽  
Reinforcing Steel ◽  
Reinforcement Corrosion ◽  
Corrosion Initiation ◽  
Deicing Salts ◽  
The World

Concrete is a complex material of construction that enables the high compressive strength of natural stone to be sed in any configuration. In tension, however, concrete can be no stronger than the bond between the cured cement and the surfaces of the aggregate. This is generally much lower than the compressive strength of the concrete. Concrete is therefore frequently reinforced, usually with steel. When a system of steel bars or a steel mesh is incorporated in the concrete structure in such a way that the steel can support most of the tensile stresses and leave the immediately surrounding concrete comparatively free of tensile stress, then the complex is known as reinforced concrete. Corrosion of reinforcing steel in concrete leads to the premature failure of many structures exposed to harsh environments. Rust products form on the bar, expanding its volume and creating stress in the surrounding concrete. This leads to cracking and spalling, both of which can severely reduce the service life and strength of a member. Corrosion of reinforcing steel in concrete structures is one of the most expensive problems facing civil engineers in the world. The structural integrity of many bridges, overpasses, parking garages, and other concrete structures has been impaired by corrosion, and repairs are urgently required to ensure public safety. Corrosion-induced deterioration of reinforced concrete can be modelled in terms of three component steps: (1) time for corrosion initiation; (2) time, subsequent to corrosion initiation, for appearance of a crack on the external concrete surface (crack propagation); and (3) time for surface cracks to progress into further damage and develop into spalls, to the point where the functional service life, is reached. The two most common causes of reinforcement corrosion are: (i) localized breakdown of the passive film on the steel by chloride ions and (ii) general breakdown of passivity by neutralization of the concrete, predominantly by reaction with atmospheric carbon dioxide. Sound concrete is an ideal environment for steel but the increased use of deicing salts and the increased concentration of carbon dioxide in modern environments principally due to industrial pollution, has resulted in corrosion of the rebar becoming the primary cause of failure of this material. The scale of this problem has reached alarming proportions in various parts of the world. Corrosion in reinforced concrete structures is causing deterioration of our infrastructure. Structures in or near marine environments and transportation structures on which deicing salts are used are especially vulnerable. A widely promoted method for repairing damaged structures or for protecting structures in corrosive environments is the application of fiber-reinforced composite wraps over the surface of the structures elements.

Service Life Checking Calculation of Marine Reinforced Concrete Structures Based on Monte Carlo Method

2013 ◽  
Vol 788 ◽  
pp. 663-669
Author(s):  
Gui Hong Dong ◽  
Zhi Hong Fan ◽  
Jian Bo Xiong
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Service Life ◽  
Marine Environment ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Chloride Diffusion ◽  
Distribution Model ◽  
Chloride Diffusion Coefficient ◽  
Design Life

Checking some apparent chloride diffusion coefficient of concrete in the marine environment meets the requirements of design life based on Monte Carlo method. Through the project investigations, laboratory test data, statistical analysis and to determine random distribution model of the critical chloride concentration, the surface chloride concentration ,using computer program simulation 5000 random groups critical chloride concentration, surface chloride concentration into the life value calculation model, And obtain the derived distribution of the concrete structures service life, in order to determine Compliance with the design life of concrete structures. For the concrete durability design and service life checking provide the effective analysis under the marine environment.

scholarly journals A Thermo-Hygro-Coupled Model for Chloride Penetration in Concrete Structures

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Nattapong Damrongwiriyanupap ◽  
Suchart Limkatanyu ◽  
Yunping Xi
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Chloride Ions ◽  
Chloride Penetration ◽  
Heat Diffusion ◽  
Chloride Diffusion ◽  
Actual Condition ◽  
Reinforced Concrete Structures ◽  
Coupled Transport ◽  
Governing Equations

Corrosion damage due to chloride attack is one of the most concerning issues for long term durability of reinforced concrete structures. By developing the reliable mathematical model of chloride penetration into concrete structures, it can help structural engineers and management agencies with predicting the service life of reinforced concrete structures in order to effectively schedule the maintenance, repair, and rehabilitation program. This paper presents a theoretical and computational model for chloride diffusion in concrete structures. The governing equations are taking into account the coupled transport process of chloride ions, moisture, and temperature. This represents the actual condition of concrete structures which are always found in nonsaturated and nonisothermal conditions. The fully coupled effects among chloride, moisture, and heat diffusion are considered and included in the model. The coupling parameters evaluated based on the available material models and test data are proposed and explicitly incorporated in the governing equations. The numerical analysis of coupled transport equations is performed using the finite element method. The model is validated by comparing the numerical results against the available experimental data and a good agreement is observed.

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