Modeling of Chloride Concentration Effect on Reinforcement Corrosion (original) (raw)
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Probabilistic Modeling of Steel Corrosion in RC Structures
The corrosion of reinforcement leads to a decrease in the effective area of the steel. The growth of rust products leads to concrete cracking, and later, the spalling of concrete cover, thus affecting the durability and reliability of a RC structure. The rate of reinforcement corrosion is governed by the availability of water, oxygen and chlorides on the steel surface. Durability limit states are explained, followed by a relevant model for degradation processes based on steel corrosion. Efficient design software is introduced which enables the probabilistic durability assessment of concrete structures. The development of the concentration of chlorides at the vicinity of the rebar surface is solved by a specific technique using cellular automata which is explained and then applied in an illustrative example showing the ingress of chlorides into a reinforced concrete cross section and the corresponding drop in the rebar's diameter due to corrosion.
Journal of Infrastructure Systems, 2013
Maintaining an adequate safety level in concrete bridges under gradual degradation, due to traffic and environmental actions, is not only an expensive task, but also filled with some level of uncertainty. Degradation in itself is not easily quantifiable because numerous aspects reduce the load bearing capacity of a concrete bridge. Furthermore, the effects of preventive maintenance and rehabilitation actions are difficult to predict. Chloride ion ingress is an important aspect of durability design and maintenance, especially in regions where winter salt is commonly applied for traffic safety. This paper introduces a feasible approach to analyze the effects of chloride induced deterioration on the overall safety level, which is validated by the application to a real highway bridge, which was demolished after 38 years of service. Concrete samples were extracted from this bridge and chemical analyses were performed to determine the chloride concentration profile in the concrete. Once the present chloride levels were determined, an inverse analysis of chloride ion ingress, based on the Cellular Automata technique, provided information regarding the temporal and spatial development of the chloride concentration. This data serves as basis for a probabilistic prognosis of the corrosion processes during the planned service life of the structure, which accounts for uncertainties in the experimental investigations. The prediction of non-visible
Probabilistic failure modelling of reinforced concrete structures subjected to chloride penetration
International Journal of Advanced Structural Engineering, 2012
Structural durability is an important criterion that must be evaluated for every type of structure. Concerning reinforced concrete members, chloride diffusion process is widely used to evaluate durability, especially when these structures are constructed in aggressive atmospheres. The chloride ingress triggers the corrosion of reinforcements; therefore, by modelling this phenomenon, the corrosion process can be better evaluated as well as the structural durability. The corrosion begins when a threshold level of chloride concentration is reached at the steel bars of reinforcements. Despite the robustness of several models proposed in literature, deterministic approaches fail to predict accurately the corrosion time initiation due the inherent randomness observed in this process. In this regard, structural durability can be more realistically represented using probabilistic approaches. This paper addresses the analyses of probabilistic corrosion time initiation in reinforced concrete ...
Engineering Failure Analysis, 2017
In this paper, from the mesoscopic point of view, under the assumption of metal corrosion damage evolution being a diffusive process, the cellular automata (CA) method was proposed to simulate numerically the uniform corrosion damage evolution of the outer steel tube of concrete filled steel tubular columns subjected to corrosive environment, and the effects of corrosive agent concentration, dissolution probability and elapsed etching time on the corrosion damage evolution were also investigated. It was shown that corrosion damage increases nonlinearly with increasing elapsed etching time, and the longer the etching time, the more serious the corrosion damage; different concentration of corrosive agents had different impacts on the corrosion damage degree of the outer steel tube, but the difference between the impacts was very small; the heavier the concentration, the more serious the influence. The greater the dissolution probability, the more serious the corrosion damage of the outer steel tube, but with the increase of dissolution probability, the difference between its impacts on the corrosion damage became smaller and smaller. To validate the present method, corrosion damage measurements for concrete filled square steel tubular columns (CFSSTCs) sealed at both their ends immersed fully in a simulating acid rain solution were conducted, and Faraday's law was used to predict their theoretical values. Meanwhile, the proposed CA mode was applied for the simulation of corrosion damage evolution of the CFSSTCs. It was shown by the comparisons of results from the three methods aforementioned that they were in good agreement, implying that the proposed method used for the simulation of corrosion damage evolution of concrete filled steel tubular columns is feasible and effective. It will open a new approach to study and evaluate further the corrosion damage, loading capacity and lifetime prediction of concrete filled steel tubular structures.
Modelling reinforcement corrosion in concrete
A physio-chemical model for the simulation of reinforcement corrosion in concrete structures was developed. The model allows for simulation of initiation and subsequent propagation of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold is reached causing the formation of anodic and cathodic regions along the reinforcement. Critical chloride thresholds, randomly distributed along the reinforcement surface, link the initiation and propagation phase of reinforcement corrosion.
Journal of Building Pathology and Rehabilitation
The performance-based design of reinforced concrete structures, which focuses on the compliance with durability limit state and service life design of reinforced concrete structures, has received much interest nowadays. Concrete reinforcement corrosion has been identified to be a primary source of lack of resilience and long-term disintegration in the structure. Chloride ingress and carbonation has been identified as the root cause of corrosion of steel embedded in concrete. The development of models for predicting the service life of concrete has been ongoing for many years. This project work reviews service life prediction, and modelling of reinforced concrete structures subjected to chloride ingress. A comparative study of the four existing models is done, identifying the advantages and limitations of them followed by computer simulation of these models using MATLAB. The models considering free chloride concentration as the driving force and those considering the effect of chloride binding on diffusion coefficient, predicts higher service life while the models based on total chloride concentration give conservative results.
Numerical Simulation of Concrete Degradation due to Chloride-Induced Reinforcement Corrosion
2018
Concrete structures built in marine environment are susceptible to attack by chemicals such as chloride which diffuses into concrete structures and attack the reinforcements embedded in reinforced structures and break down the reinforcement protective layer. This paper presents the use of Abaqus Finite Element Analysis software in Analyzing the processes involved in concrete structure degradation from chloride diffusion to concrete cracking. Mass diffusion, Faraday's law and the Extended Finite Element Method (XFEM) were used to simulate chloride diffusion, mass loss from steel corrosion and corrosion product expansion and concrete cover cracking simultaneously, while the pressure due to the tensile stress generated by corrosion product was idealized as radial displacements. Obtained results show an increasing chloride concentration with time, but reduction with depth of penetration, while an obvious crack pattern was obtained.
Cement and Concrete Composites, 2012
Concrete structures are subjected to chloride-induced corrosion that can lead to shortened service life. Reliable predictions of life cycle performance of concrete structures are critical to the optimization of their life cycle design and maintenance to minimize their life cycle costs. This paper presents two simplified semi-analytical probabilistic models based on the first-and second-order reliability methods to model the uncertainty of the key parameters including surface chloride concentration, chloride threshold, cover depth and diffusion coefficient, which govern the chloride ingress into concrete and corrosion of reinforcing steel. A case study of a reinforced concrete highway bridge deck is used to illustrate the capability and efficiency of these simplified probabilistic models in modeling the uncertainty and predicting the time-dependent probability of corrosion. The models enable to quantify the impact of the different governing parameters on probability of corrosion and service life, which can be used to develop costeffective management strategies.
European Journal of Environmental and Civil Engineering
Chloride ingress and carbonation are the main factors leading to corrosion initiation of reinforced concrete (RC) structures. Lifetime assessment and maintenance optimization of these deteriorating structures has been based for several practical applications on analytical predictive models. The literature review shows that there are numerous analytical models of chloride ingress and carbonation. It was also found that comprehensive lifetime assessment requires that the selected models be able to propagate uncertainties in a correct manner. Thus, this paper proposes a methodology for probabilistic sensitivity analysis of analytical models for chloride ingress and carbonation. Given that di↵erent parameter notations were found for each model, a homogenization of notations and generic forms are first proposed. The sensitivity analysis is based on the following indicators: elasticity coe cient, Pearson coe cient, bias of the mean and standard deviation of the response of the model. The results highlighted which parameters are influential for each model by considering three concrete types. Overall results indicated a higher e↵ect of the nonlinearity of the models on the sensitivity indicators. It was found that the level of influence of each parameter depends also on the concrete type and the duration of the exposure to chlorides or carbon dioxide.