Numerical Analysis of the 2-Dimensional Diffusion Models of Choride Ions Based on the FDM with Alternating Direction Implicit Schemes

2014 ◽  
Vol 1020 ◽  
pp. 92-97
Author(s):  
Fei Hou ◽  
Yu Bai ◽  
Jun Dong
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Chloride Ion ◽  
Chloride Diffusion ◽  
Reinforced Concrete Structures ◽  
Two Dimensional ◽  
Ion Diffusion ◽  
Infinite Body ◽  
Diffusion Behavior ◽  
Coefficient Of Diffusion

Chloride ion etching is a significant reason for the damage of the reinforced concrete structures. Diffusion effect is considered to be the main form of which the chloride ion invades into the reinforced concrete structures. Assuming infinite diffusion medium, based on the Chlorine ion diffusion equation, and accounting for the effects of temperature and moisture, models of chloride diffusion in two-dimensional infinite body with consistent coefficient of diffusion and different coefficient of diffusion in both directions are formulated .Two-dimensional chloride ion diffusion behavior was simulated, which proved the diffusion coefficient has a larger effect on the diffusion behavior of the chloride ion. Through these comparisons, we can analysis that model with different coefficient of diffusion in both directions is more suitable for the actual conditions.

Use of Thermoplastic Polymer in Mortar Composites to Improve its Chloride Penetration Resistance

2016 ◽  
Vol 22 ◽  
pp. 33-44 ◽  
Author(s):  
M. Omrane ◽  
A.S. Benosman ◽  
M. Mouli ◽  
Y. Senhadji
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Portland Cement ◽  
Penetration Depth ◽  
Concrete Structures ◽  
Chloride Ion ◽  
Chloride Penetration ◽  
Partial Replacement ◽  
Total Charge ◽  
Reinforced Concrete Structures

This paper presents a study of the resistance to chloride penetration of blended Portland cement mortar containing thermoplastic waste polymer polyethylene terephthalate (TWPET). Composite TWPET-mortars are often presented as the materials of the future in reason of their potential for innovation and advantages that offer. In fact, the use of TWPET percentages as a cement substitution reduces energy costs; address problems related to environmental pollution by CO2 emissions and repairs various reinforced concrete structures. Blended Portland cement (CPJ) is partially replaced with TWPET at the amounts of 2%, 4% and 6% by weight of cementitious materials. Chloride penetration depth of full and partial immersions in 3% NaCl solution, rapid chloride permeability test (RCPT) after 28, 90 and 120 days, sorptivity, leaching test and flexural strength of thermoplastic-mortar composites (TMCs) were determined. Test results reveal that the resistance to chloride penetration of TMCs improves substantially with partial replacement of CPJ with TWPET and without significantly affecting the flexural strength in tap water. The chemical resistance is higher with an increase in the replacement level. So, sorptivity, the chloride ion penetration depth, apparent chloride ion diffusion coefficient, the total charge passed in coulombs and leached depth measurements of the TMCs are much smaller than those of reference mortar. The formations which appear such as different calcium salts were determined by X-ray diffraction. These results take into account the use of waste plastics in the manufacture of mortars modified which can be both recommended for preventing the chloride-induced corrosion of the steel in various reinforced concrete structures and participate greatly in the environment preservation.

Research on Chloride Diffusion Model of PC with Chloride Attack in Marine Atmosphere Zone

2014 ◽  
Vol 711 ◽  
pp. 481-484
Author(s):  
Yu Chen ◽  
Jie Xu ◽  
Rong Gui Liu ◽  
Su Bi Chen ◽  
Yuan Gao
Keyword(s):  
Prestressed Concrete ◽  
Concentration Distribution ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Ion Concentration ◽  
Chloride Diffusion ◽  
Marine Atmosphere ◽  
Ion Diffusion ◽  
Chloride Ion Diffusion

Based on the existing studies about chloride ion erosion in prestressed concrete structures, this paper intends to discuss the effects of the stress level and environment factors (including temperature and humidity, etc.) on chloride ion diffusion under marine atmosphere zone. The investigation from pre-stressed concrete crossbeams which service for 39 years in Lianyungang Port shows the chloride ion concentration distribution and chloride ion diffusion. According to the chloride ion concentration distribution, it finds that chloride ion concentration values in pre-concrete structures is Cmax,1> Cmax,2. In addition, the free chloride concentration distribution values go down smoothly after the second peak. Therefore, the result shows that the improved model can be used in marine atmosphere zone.

scholarly journals Autonomous Corrosion Assessment of Reinforced Concrete Structures: Feasibility Study

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6825
Author(s):  
Woubishet Zewdu Taffese ◽  
Ethiopia Nigussie
Keyword(s):  
Reinforced Concrete ◽  
Feasibility Study ◽  
Concrete Structures ◽  
Chloride Ion ◽  
High Sensitivity ◽  
Reinforced Concrete Structures ◽  
Corrosion Condition ◽  
Rc Structures ◽  
Corrosion Assessment ◽  
Use Of Internet

In this work, technological feasibility of autonomous corrosion assessment of reinforced concrete structures is studied. Corrosion of reinforcement bars (rebar), induced by carbonation or chloride penetration, is one of the leading causes for deterioration of concrete structures throughout the globe. Continuous nondestructive in-service monitoring of carbonation through pH and chloride ion (Cl−) concentration in concrete is indispensable for early detection of corrosion and making appropriate decisions, which ultimately make the lifecycle management of RC structures optimal from resources and safety perspectives. Critical state-of-the-art review of pH and Cl− sensors revealed that the majority of the sensors have high sensitivity, reliability, and stability in concrete environment, though the experiments were carried out for relatively short periods. Among the reviewed works, only three attempted to monitor Cl− wirelessly, albeit over a very short range. As part of the feasibility study, this work recommends the use of internet of things (IoT) and machine learning for autonomous corrosion condition assessment of RC structures.

scholarly journals Reliability algorithms applied to reinforced concrete structures durability assessment

2012 ◽  
Vol 5 (4) ◽  
pp. 440-450 ◽  
Author(s):  
C. G. Nogueira ◽  
E. D. Leonel ◽  
H. B. Coda
Keyword(s):  
Reinforced Concrete ◽  
Diffusion Process ◽  
Concrete Structures ◽  
Threshold Level ◽  
Concrete Cover ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Reinforced Concrete Structures ◽  
Reliability Method ◽  
Corrosion Time

This paper addresses the analysis of probabilistic corrosion time initiation in reinforced concrete structures exposed to ions chloride penetration. Structural durability is an important criterion which must be evaluated in every type of structure, especially when these structures are constructed in aggressive atmospheres. Considering reinforced concrete members, chloride diffusion process is widely used to evaluate the durability. Therefore, at modelling this phenomenon, corrosion of reinforcements can be better estimated and prevented. These processes begin when a threshold level of chlorides concentration is reached at the steel bars of reinforcements. Despite the robustness of several models proposed in the literature, deterministic approaches fail to predict accurately the corrosion time initiation due to the inherently randomness observed in this process. In this regard, the durability can be more realistically represented using probabilistic approaches. A probabilistic analysis of ions chloride penetration is presented in this paper. The ions chloride penetration is simulated using the Fick's second law of diffusion. This law represents the chloride diffusion process, considering time dependent effects. The probability of failure is calculated using Monte Carlo simulation and the First Order Reliability Method (FORM) with a direct coupling approach. Some examples are considered in order to study these phenomena and a simplified method is proposed to determine optimal values for concrete cover.

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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