scholarly journals Chloride-Induced Corrosion of Steel in Concrete: An Overview on Chloride Diffusion and Prediction of Corrosion Initiation Time

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Muhammad Umar Khan ◽  
Shamsad Ahmad ◽  
Husain Jubran Al-Gahtani
Keyword(s):  
Diffusion Models ◽  
Chloride Diffusion ◽  
Second Law ◽  
Chloride Ingress ◽  
Initiation Time ◽  
Chloride Binding ◽  
Rc Structures ◽  
Corrosion Initiation ◽  
Corrosion Initiation Time ◽  
Corrosion Of Steel

Initiation of corrosion of steel in reinforced concrete (RC) structures subjected to chloride exposures mainly depends on coefficient of chloride diffusion, Dc, of concrete. Therefore, Dc is one of the key parameters needed for prediction of initiation of reinforcement corrosion. Fick’s second law of diffusion has been used for long time to derive the models for chloride diffusion in concrete. However, such models do not include the effects of various significant factors such as chloride binding by the cement, multidirectional ingress of chloride, and variation of Dc with time due to change in the microstructure of concrete during early period of cement hydration. In this paper, a review is presented on the development of chloride diffusion models by incorporating the effects of the key factors into basic Fick’s second law of diffusion. Determination of corrosion initiation time using chloride diffusion models is also explained. The information presented in this paper would be useful for accurate prediction of corrosion initiation time of RC structures subjected to chloride exposure, considering the effects of chloride binding, effect of time and space on Dc, and interaction effect of multidirectional chloride ingress.

CORROSION INITIATION TIME FOR REINFORCED CONCRETE MEMBERS ALONG INDIAN COASTS: EFFECTS OF TEMPERATURE AND RELATIVE HUMIDITY — A PROBABILISTIC APPROACH

2008 ◽  
Vol 15 (06) ◽  
pp. 539-553
Author(s):  
SATISH B. ALLAMPALLEWAR ◽  
A. SRIVIDYA
Keyword(s):  
Diffusion Coefficient ◽  
Relative Humidity ◽  
Probabilistic Approach ◽  
Chloride Concentration ◽  
Threshold Value ◽  
Chloride Ingress ◽  
Initiation Time ◽  
Corrosion Initiation ◽  
Concrete Members ◽  
Corrosion Initiation Time

Corrosion initiation time of steel reinforcement for partially saturated concrete members subjected to chloride ingress is investigated at five places along Indian coasts using simplified probabilistic analysis and sensitivity of the parameters to reinforcement corrosion is studied. Previously proposed diffusion based chloride ingress model for constant surface chloride concentration and variable diffusion coefficient is used. Corrosion is initiated when the chloride concentration on steel reinforcement exceeds a threshold value. The various input parameters considered in the model are surface chloride concentration (Cs), chloride threshold value (Cth), Concrete cover (X), reference diffusion coefficient (Dref), age (t), reference age (tref), diffusion decay index (m) and monthly temperature and relative humidity correction factors f(T) and f(h) respectively; to reference diffusion coefficient. For prediction of corrosion initiation time temperature and relative humidity data collected by India metrological Department is used and all other parameters are assumed same. A large variation in corrosion initiation time is found and therefore it becomes necessary to consider the temperature and relative humidity data in a region. Life-365 considers fully saturated condition of concrete and thus underestimates the corrosion initiation time of a reinforced concrete member. The deterministic approach uses mean values of the parameters and provides a 50% probability of corrosion initiation but the probabilistic approach provides expected time of first corrosion for chosen risk of corrosion and also gives sensitivity of parameters to probability of corrosion. Corrosion initiation time in ascending order is found at Colaba, Kanyakumari, Santacruz, Chennai and Vishakhapatnam. Corrosion initiation time is useful for owner, designer, or to an organization to take decision in time of priority of repairs, repair strategy, corrosion protection in order to optimize maintenance planning and budgeting. Planned maintenance at the optimum time is the safest and most cost effective approach.

scholarly journals The Effect of Shape on Chloride Penetration of Circular Reinforcement Concrete Columns and Its Durability Design

2020 ◽  
Vol 10 (2) ◽  
pp. 459
Author(s):  
Gu Yin ◽  
Li Pan
Keyword(s):  
Diffusion Model ◽  
Chloride Diffusion ◽  
Model Parameters ◽  
Geometrical Shape ◽  
Initiation Time ◽  
Minimum Thickness ◽  
Corrosion Initiation ◽  
Durability Design ◽  
Corrosion Initiation Time ◽  
The Impact

The reinforced concrete (RC) circular element is usually simplified as slab one on the issue of chloride diffusion simulation, without considering the effect of the geometrical shape. In the paper, a modified slab diffusion model is proposed for circular section. A formulation for estimating the error caused by neglecting the effect of shape on chloride diffusion is derived. The formulation demonstrates that radius significantly affect the error. When shape is neglected, the effects of model parameters, including the diffusion coefficient, radius, cover concrete thickness and age factor, on the corrosion initiation time are investigated. The result shows the radius has a slight effect on calculating the corrosion initiation time compared with other model parameters. Furthermore, the influence of shape on estimating on reliability index for different service time is also discussed. A guideline is proposed for properly using the modified slab diffusion model instead of the original one to predict service life. Finally, the impact of the shape of the RC circular column on the durability design against chloride corrosion is studied. The design result when the column is simplified as a slab element indicates a lower required minimum concrete cover thickness. The minimum thickness should be improved by 5 mm as a conservative choice based on the result of the slab element.

Time-Variant Seismic Performance of Offshore RC Bridge Columns with Uncertainty

2018 ◽  
Vol 18 (12) ◽  
pp. 1850149
Author(s):  
Hong-Nan Li ◽  
Hu Cheng ◽  
Dong-Sheng Wang
Keyword(s):  
Seismic Performance ◽  
Bridge Columns ◽  
Column Height ◽  
Seismic Fragility ◽  
Initiation Time ◽  
Rc Structures ◽  
Material Parameters ◽  
Corrosion Initiation ◽  
Corrosion Initiation Time ◽  
Rc Bridge Columns

To establish a framework for evaluating the time-variant seismic performance of deteriorated reinforced concrete (RC) structures with uncertainty, offshore RC bridge columns exposed to marine environments are studied in this paper. The uncertainties from the material parameters, corrosion initiation time and earthquake ground motions are taken into account. Due to the different corrosion characteristics in various zones (i.e. the submerged zone, splash and tidal zone, and atmospheric zone) along the column height, corrosion-induced damages in each zone are considered separately, and the geometric mean of the yield displacements of the three zones is used to define the structural capacity (limit state). Meanwhile, the time-variant limit states are determined based on nonlinear static analyses, which reflect the current state of deteriorating RC columns. A total of four cases are studied using the Latin hypercube sampling (LHS) technique based on the probability distributions of the material parameters and corrosion initiation time, including the effects of statistical correlations among the material parameters. The results reveal that the seismic fragility is underestimated by a deterministic numerical model. The uncertainty in the corrosion initiation time influences the seismic fragility less significantly than that in the structural material parameters whether or not anti-corrosion measures are implemented. It is suggested that probabilistic methods should be used for seismic evaluation of deteriorating RC structures to consider the uncertainty involved.

scholarly journals Reinforced Concrete Structure Performance in Marine Structures: Analyzing Durability Indexes to Obtain More Accurate Corrosion Initiation Time Predictions

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7662
Author(s):  
Mauricio Arreola-Sanchez ◽  
Elia M. Alonso-Guzman ◽  
Wilfrido Martinez-Molina ◽  
Andres A. Torres-Acosta ◽  
Hugo L. Chavez-Garcia ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Chloride Concentration ◽  
Pulse Velocity ◽  
Chloride Diffusion ◽  
Void Content ◽  
Chloride Diffusion Coefficient ◽  
Initiation Time ◽  
Reinforced Concrete Structure ◽  
Corrosion Initiation ◽  
Corrosion Initiation Time

This paper presents a comparison of six index properties collected during durability inspections of five Mexican seaports. Typical durability indicators such as compressive strength, saturated electrical resistivity, ultrasonic pulse velocity, percent total void content, capillary porosity, and chloride concentration profiles were analyzed to obtain empirical correlations with the non-steady-state chloride diffusion coefficient. These indices were compared to determine correlation coefficients that are the most important for obtaining better corrosion initiation forecasting. Two models of corrosion initiation time (ti) were used: Fick’s second law of diffusion and the reported UNE-83994-2 (Spanish Association for Standardization, UNE) in which electrical resistivity was used to calculate concrete service life. The data from both models were cleaned using correlated variables, and the initial variables were compared with ti. The main result achieved was the verification of the feasibility of using correlations of variables to clean unnecessary data in order to calculate ti. Additionally, electrical resistivity was identified as one of the main durability indexes for in-service concrete structures exposed to marine environments. This is important because electrical resistivity is a non-destructive and reliable test that can be measured both in the laboratory and in the field very easily.

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.

Corrosion initiation time of steel reinforcement in a chloride environment—A one dimensional solution

1997 ◽  
Vol 39 (4) ◽  
pp. 739-759 ◽  
Author(s):  
P. Arora ◽  
B.N. Popov ◽  
B. Haran ◽  
M. Ramasubramanian ◽  
S. Popova ◽  
...  
Keyword(s):  
Steel Reinforcement ◽  
Initiation Time ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Corrosion Initiation ◽  
Corrosion Initiation Time ◽  
Chloride Environment

Probability Model of Corrosion Initiation Time of Steel in Concrete Structure in Chloride Environment

2011 ◽  
Vol 243-249 ◽  
pp. 5632-5636
Author(s):  
Ya Li Ma ◽  
Ai Lin Zhang
Keyword(s):  
Sensitivity Analysis ◽  
Probability Distribution ◽  
Probability Model ◽  
Chloride Concentration ◽  
Initiation Time ◽  
Distribution Law ◽  
Corrosion Initiation ◽  
Corrosion Initiation Time ◽  
Chloride Environment ◽  
Distribution Type

Probability distribution law of corrosion initiation time of steel in concrete under chloride environment is discussed. Based on the Fick’s second law, by Monte Carlo, frequency distribution, distribution type and probability density is analyzed. The statistic parameters of the factors influencing the probability distribution of corrosion initiation time are studied and the expression for sensitivity analysis of corrosion initiation time is deduced. By sensitivity analysis can know, corrosion initiation time is found to be more sensitive to cover than the diffusion coefficient, and more sensitive to surface chloride concentration than the critical chloride level. The analysis of the paper perfects the methods of predicting the corrosion initiation time.

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