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.

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.

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 INVESTIGATING THE CORROSION INITIATION PROCESS IN REINFORCED CONCRETE STRUCTURES UNDER THE IMPACT OF CLIMATE CHANGE

2021 ◽  
Vol 6 (2) ◽  
pp. 37-44
Author(s):  
Tran Ngoc-Long ◽  
◽  
Phan Van-Phuc ◽  
Valeriy Morozov ◽  
◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
Temperature Rise ◽  
Concrete Structures ◽  
Chloride Penetration ◽  
Initiation Time ◽  
Corrosion Initiation ◽  
Corrosion Initiation Time ◽  
The Impact

Introduction: Climate change (temperature rise and sea level rise) has a considerable influence on the behavior of concrete structures over time. All concrete degradation processes are connected to climate variables and the effects of climate change. The RCP8.5 (Representative Concentration Pathway) scenario, which is part of the report on climate change and level rise scenarios for Vietnam, predicts that the beginning of the 21st century will see an average annual increase in temperature between 0.8 and 1.1°C. In the mid-21st century, the temperature will likely increase by 1.8–2.3°C, with the temperature in the north likely increasing by 2.0–2.3°C and in the south by 1.8–1.9°C. In marine environments, the degradation of concrete structures can occur rapidly due to chloride-induced reinforcement corrosion. Furthermore, sea level rise is going to reduce the distance from the coastline to the structures and lead to increased surface chloride concentration. Methods: The evaluation of chloride penetration was based on the ASTM C1202 test (ASTM, 2012). The cylinder specimens (d = 100 mm, h = 200 mm) used for a rapid chloride penetration test (RCPT) were immersed in water for 28 days in a water-curing tank. Results: This study proposes a predictive model for analyzing the impact of climate change on the service life of concrete structures on Vietnam’s North Central Coast. The corrosion initiation time decreases by 16.5% when the effects of both temperature rise and sea level rise are taken into consideration. When only temperature rise is taken into consideration, the rate of reduction is approximately 9.0%. These results reaffirm that climate change has a significant effect on the corrosion initiation time of concrete structures located in a marine environment.

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.

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.

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