Corrosion performance of steel reinforcement in concrete admixed with magnesium chloride and sulphate

2020 ◽  
Vol 67 (1) ◽  
pp. 106-118 ◽  
Author(s):  
Raghu Babu U. ◽  
Kondraivendhan B.
Keyword(s):  
Electrical Resistivity ◽  
Cementitious Material ◽  
Corrosion Mechanism ◽  
Aluminium Content ◽  
Water Reinforcement ◽  
Internal Source ◽  
Initiation Time ◽  
Content Type ◽  
Corrosion Initiation ◽  
Corrosion Initiation Time

Purpose Besides with a large amount of Na+ and Cl− ions in seawater, the presence of Mg+2 and SO4−2 ions builds more complex corrosion mechanism. This paper aims to investigate the corrosion of embedded reinforcement in concrete with the environment of both Cl− and SO4−2 anions associated Mg+2 cation. Design/methodology/approach The concrete specimens were prepared by using ordinary Portland cement (OPC), and OPC blended with metakaolin (MK) for water to cementitious material ratio (w/cm) 0.48 and 0.51. The concrete mixes were contaminated with the addition of MgCl2 alone and combined MgCl2 and MgSO4 in mix water. Reinforcement corrosion was evaluated by half-cell potential and corrosion current densities (Icorr) at regular intervals. Moreover, the influence of cementitious material type, salt type and w/cm ratio on electrical resistivity of concrete was also investigated. The statistical models were developed for electrical resistivity as a function of calcium to aluminium content ratio, compressive strength, w/cm ratio and age of concrete. Findings Although the corrosion initiation time increases in the concomitant presence of MgSO4 and MgCl2 as internal source compared to MgCl2, Icorr values are higher in both OPC and MK blended concrete. However, electrical resistivity decreased with addition of MgSO4. MK blended concrete performed better with increased resistivity, corrosion initiation time and decreased Icorr values. Originality/value This study reports statistical distributions for scattered Icorr of rebar in different concrete mixtures. Stepwise regression models were developed for resistivity by considering the interactions among different variables, which would help to estimate the resistivity through basic information.

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.

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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