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.

Corrosion Rate Evolution in Concrete Structures with Hydrophobic Agents Exposed to the Marine Environment

2011 ◽  
Vol 374-377 ◽  
pp. 1320-1324
Author(s):  
Wei Qun Cao ◽  
Hong Fan ◽  
Tie Jun Zhao
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Marine Environment ◽  
Concrete Structures ◽  
Protective Layer ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Reinforced Concrete Structures ◽  
Chloride Diffusion Coefficient ◽  
Capillary Suction

In many cases, service life of reinforced concrete structures is severely limited by chloride penetration until the steel reinforcement. Today, concrete with high resistance with respect to chloride penetration can be produced by internal hydrophobic treatment. The aim of this study was to fill this gap in regards to reinforced concrete structures inserted in a marine environment. Results indicated the efficacy of the hydrophobic agents in cases where capillary suction is the mechanism of water penetration. However, when the transport mechanism is permeability this product is not advisable. Moreover, it was demonstrated that the chloride diffusion coefficient is reduced by the hydrophobic agents, and the corrosion rate of reinforcement could be well protected in the treated concrete with hydrophobic agents of silane. The durability of reinforced structures can be considerably increased and can be accurately designed by the application of an appropriate and optimized protective layer.

Passive corrosion control and active corrosion prevention of the reinforced concrete structures by electrochemical chloride removal and inhibitors

2013 ◽  
Vol 61 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Guofu Qiao ◽  
Yi Hong ◽  
Tiejun Liu ◽  
Jinping Ou
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Corrosion Control ◽  
Cell Potential ◽  
Content Type ◽  
Chloride Removal ◽  
Active Corrosion

Purpose – The aim of this paper was to investigate the passive corrosion control and active corrosion protective effect of the reinforced concrete structures by electrochemical chloride removal (ECR) method and inhibitors approach, respectively. Design/methodology/approach – The concentration of aggressive chloride ion distributed from the reinforcing steel to the surface of the concrete cover was analyzed during the ECR processes. Besides, the half-cell potential, the concrete resistance R c , the polarization resistance R p and the capacitance of double layer C dl of the steel/concrete system were used to characterize the electrochemical performance of the concrete prisms. Findings – The effectiveness of ECR could be enhanced by increasing the amplitude of potential or prolonging the time. Inhibitor SBT-ZX(I) could successfully prevent the corrosion development of the reinforcing steel in concrete. Originality/value – The research provides the scientific basis for the practical application of ECR and inhibitors in the field.

Nanoparticle Injection into Concrete Using Electromigration

2014 ◽  
Vol 1054 ◽  
pp. 6-10 ◽  
Author(s):  
Jiří Němeček ◽  
Yun Ping Xi
Keyword(s):  
Reinforced Concrete ◽  
Electric Field ◽  
Concrete Structures ◽  
Chloride Penetration ◽  
Reinforced Concrete Structures ◽  
Testing Chamber ◽  
Chloride Profile ◽  
Nanosilica Particles ◽  
Penetration Tests ◽  
Small Voltage

This paper aims at investigation of possibilities and effectiveness of chloride extraction from concrete and nanoparticle injection into existing reinforced concrete structures by means of electromigration technique. Concrete specimens are exposed to accelerated chloride penetration tests in order to simulate a natural chloride exposure. The developed chloride profile is removed by electroextraction by reversing the polarity in the testing chamber. In a similar manner, concrete specimens are injected with different concentrations of colloidal nanosilica particles. It was shown in the paper that chlorides can be effectively extracted from the concrete using small voltage lasting for several days. Higher concentration solutions of nanosilica can also be effectively transported into concrete via the electric field. Once injected nanosilica can act as microstructure densifier and further reduce chloride penetration as demonstrated by decreased diffusivity of the treated concrete.

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.

scholarly journals The Effect of Water Repellent Surface Impregnation on Durability of Cement-Based Materials

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Peng Zhang ◽  
Huaishuai Shang ◽  
Dongshuai Hou ◽  
Siyao Guo ◽  
Tiejun Zhao
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Concrete Structures ◽  
Chloride Penetration ◽  
Water Repellent ◽  
Reinforced Concrete Structures ◽  
Capillary Suction ◽  
Surface Impregnation ◽  
Cement Based Materials ◽  
Ft Ir

In many cases, service life of reinforced concrete structures is severely limited by chloride penetration until the steel reinforcement or by carbonation of the covercrete. Water repellent treatment on the surfaces of cement-based materials has often been considered to protect concrete from these deteriorations. In this paper, three types of water repellent agents have been applied on the surface of concrete specimens. Penetration profiles of silicon resin in treated concrete have been determined by FT-IR spectroscopy. Water capillary suction, chloride penetration, carbonation, and reinforcement corrosion in both surface impregnated and untreated specimens have been measured. Results indicate that surface impregnation reduced the coefficient of capillary suction of concrete substantially. An efficient chloride barrier can be established by deep impregnation. Water repellent surface impregnation by silanes also can make the process of carbonation action slow. In addition, it also has been concluded that surface impregnation can provide effective corrosion protection to reinforcing steel in concrete with migrating chloride. The improvement of durability and extension of service life for reinforced concrete structures, therefore, can be expected through the applications of appropriate water repellent surface impregnation.

scholarly journals Analysis of Chloride Penetration Into High Performance Concrete

2020 ◽  
Vol 3 (3) ◽  
pp. 295-305
Author(s):  
Silvija Mrakovčić ◽  
Natalija Bede ◽  
Ivan Ušić
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Chloride Penetration ◽  
Reinforced Concrete Structures ◽  
Wetting And Drying ◽  
Chloride Corrosion ◽  
Structure Degradation ◽  
Astm C1202

Corrosion of reinforcement is one of basic destruction mechanisms of reinforced concrete structures. In that sense, the most affected structures are those by the sea, especially their parts subjected to cycles of wetting and drying. Chlorides penetrate to concrete mostly by diffusion, faster if the concrete is more permeable, destructing reinforcement passive protection and causing its corrosion, reduction of reinforcement cross section and bearing capacity of the structure. Retardation of chloride corrosion that causes structure degradation in marine environment can be achieved by the usage of quality concrete with enhanced strength and permeability parameters in regards to ordinary concrete. Mixes of ordinary and high performance concrete with different ratio of silica fume have been made. Compressive strength and resistivity to chloride penetration have been tested on the specimens 28 days after mixing. The resistivity to chloride penetration has been determined by fast chloride penetration test according to ASTM C1202 standard, using appliance that measures electrical conductivity of concrete specimens. Based on test results, the suitability of building reinforced concrete structures by the sea using high performance concrete has been analysed.

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