scholarly journals Mechanism analysis and model calculation of chloride ion diffusion in reinforced concrete structure

2020 ◽  
Vol 198 ◽  
pp. 01035
Author(s):  
Faqiang Yu ◽  
Weiwei Gao ◽  
Wenchao Liu
Keyword(s):  
Reinforced Concrete ◽  
Diffusion Mechanism ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Cumulative Distribution ◽  
Reinforced Concrete Structures ◽  
Mechanism Analysis ◽  
Reinforced Concrete Structure

Chloride-induced corrosion of steel in reinforced concrete structures is one of the major causes of their deterioration over time. The analysis and research on the diffusion mechanism of chloride ions in reinforced concrete structures is still insufficient, and it is necessary to calculate the path of chloride ions based on theoretical models. In this paper, the fick’s second law was used to describe the free chloride concentration evolution in concrete. The Monte Carlo simulation was used to predict the cumulative distribution of corrosion initiation of reinforcing steel.The results show that the calculated results of the established model are in good agreement with the measured results.

scholarly journals Experimental study of the influence of crack width due to corrosion behaviour using different measurement methods and different exposures

2019 ◽  
Vol 289 ◽  
pp. 08005
Author(s):  
Martin Schneider ◽  
Georg Gardener
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Corrosion Behaviour ◽  
Concrete Strength ◽  
Concrete Structures ◽  
Chloride Ions ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Surface Corrosion ◽  
Potential Mapping

Corrosion of reinforcing steel has a great influence in reducing the lifetime of concrete structures; Carbonation of the concrete pore solution causes surface corrosion on the steel and diffusion of chloride ions through the capillary system of the concrete cover causes pitting corrosion on the steel surface. Corrosion of metals is highly dependent on the environmental conditions. Exposure to chloride ions can be critical to the service life of reinforced concrete structures. The durability of reinforced concrete structures exposed to deicing salt or marine environments can be affected by impact of chloride ions. Detection methods for the rate of corrosion of non-destructive and destructive procedures were analysed. The potential mapping applied on the concrete surface was discussed as a standard method for corrosion detection and will be explained in detail including the application boundaries of the method. It is assumed that the corrosion behaviour of reinforcing steel depends on crack widths. To analyse that, 8 coated and 8 uncoated test samples with different concrete strength classes were used. The concrete objects were exposed to a 3% sodium chloride solution. The corrosion behaviour of reinforcing steel is analysed by using potential mapping with different reference electrodes (Ag/AgCl and Cu/CuSO4). The results show a significant correlation between crack size and protection system on the surface. The maximum crack width with a low indication of corrosion was found to be 0.1 mm.

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 Modeling Blast Loading on Buried Reinforced Concrete Structures with Zapotec

2008 ◽  
Vol 15 (2) ◽  
pp. 137-146 ◽  
Author(s):  
Greg C. Bessette
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structure ◽  
Explosive Charge ◽  
High Explosive ◽  
Concrete Structures ◽  
Blast Loading ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure ◽  
Solution Approach ◽  
Coupling Algorithm

A coupled Euler-Lagrange solution approach is used to model the response of a buried reinforced concrete structure subjected to a close-in detonation of a high explosive charge. The coupling algorithm is discussed along with a set of benchmark calculations involving detonations in clay and sand.

scholarly journals COMBINED EFFECT OF CARBONATION AND CHLORIDE AGGRESSION: DEG-RADATION OF REINFORCED CONCRETE STRUCTURES

2018 ◽  
Author(s):  
L.V. KIM ◽  
E.E. SHALYI ◽  
S.N. LEONOVICH ◽  
N.A. BUDREVICH
Keyword(s):  
Reinforced Concrete ◽  
Ph Value ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Protective Layer ◽  
Sharp Decrease ◽  
Threshold Concentration ◽  
Steel Reinforcement ◽  
Reinforced Concrete Structures ◽  
Cross Sectional

Corrosion reinforcement marine hydraulic structures due to chloride aggression and carbonization of concrete leads to a sharp decrease in the safety of the structure. The steel reinforcement will be subjected to a so-called depassivation process, once the chloride concentration on surface exceeds a certain threshold concentration, or the pH value in the protective layer of concrete decreases to a threshold value due to carbonation. Electrochemical reactions begin to occur with the formation of corrosion products with the penetration of oxygen on the steel reinforcement surface. This leads to cracking of the protective layer of concrete. It should also be taken into account that, due to corrosion mechanisms, the cross-sectional area of the reinforcement also decreases. The article suggests a method for predicting the complex degradation of reinforced concrete structures, taking into account various mechanisms of corrosion wear, which will allow developing effective ways to improve the durability and maintainability of structures operated in the marine environment.

Fuzzy uncertainty and its applications in reinforced concrete structures

2020 ◽  
Vol 18 (5) ◽  
pp. 1175-1191
Author(s):  
Utino Worabo Woju ◽  
A.S. Balu
Keyword(s):  
Reinforced Concrete ◽  
Material Properties ◽  
Concrete Structure ◽  
Concrete Structures ◽  
Fuzzy Relation ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure ◽  
Intermediate Grades ◽  
Content Type ◽  
Degree Of Membership

Purpose The aim of this paper is mainly to handle the fuzzy uncertainties present in structures appropriately. In general, uncertainties of variables are classified as aleatory and epistemic. The different sources of uncertainties in reinforced concrete structures include the randomness, mathematical models, physical models, environmental factors and gross errors. The effects of imprecise data in reinforced concrete structures are studied here by using fuzzy concepts. The aim of this paper is mainly to handle the uncertainties of variables with unclear boundaries. Design/methodology/approach To achieve the intended objective, the reinforced concrete beam subjected to flexure and shear was designed as per Euro Code (EC2). Then, different design parameters such as corrosion parameters, material properties and empirical expressions of time-dependent material properties were identified through a thorough literature review. Findings The fuzziness of variables was identified, and their membership functions were generated by using the heuristic method and drawn by MATLAB R2018a software. In addition to the identification of fuzziness of variables, the study further extended to design optimization of reinforced concrete structure by using fuzzy relation and fuzzy composition. Originality/value In the design codes of the concrete structure, the concrete grades such as C16/20, C20/25, C25/30, C30/37 and so on are provided and being adopted for design in which the intermediate grades are not considered, but using fuzzy concepts the intermediate grades of concrete can be recognized by their respective degree of membership. In the design of reinforced concrete structure using fuzzy relation and composition methods, the optimum design is considered when the degree of membership tends to unity. In addition to design optimization, the level of structural performance evaluation can also be carried out by using fuzzy concepts.

Research on Factors Affecting Durability and Improvements for FRP Reinforced Concrete Structures

2011 ◽  
Vol 189-193 ◽  
pp. 847-852 ◽  
Author(s):  
Lei Tan ◽  
Xi Jun Liu ◽  
Ming Qiao Zhu
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structure ◽  
Civil Engineering ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure ◽  
Factors Affecting ◽  
Related Research ◽  
Durability Of Concrete ◽  
At Home

With wide applications of FRP in civil engineering, it is necessary to study the durability of FRP reinforced concrete structure. Based on the related research both at home and abroad, the factors affecting durability of FRP reinforced concrete structures and the corresponding improvements have been put forward by analyzing the durability of concrete, FRP materials and reinforced structures, respectively.

scholarly journals Increase of fire resistance of reinforced concrete structures with polypropylene microfiber

2018 ◽  
Vol 245 ◽  
pp. 03005 ◽  
Author(s):  
Marina Gravit ◽  
Elena Golub
Keyword(s):  
Reinforced Concrete ◽  
Fire Resistance ◽  
Concrete Structures ◽  
Point Of View ◽  
Reinforced Concrete Structures ◽  
Fibrous Materials ◽  
Reinforced Concrete Structure ◽  
Explosive Spalling ◽  
High Rise ◽  
Concrete Mix

The increase in the construction of high-rise, technically complex buildings and structures is a prerequisite for the widespread use of structures of heavy concrete. In this work, a special type of destruction of this type of concrete is considered in the fire action explosive spalling. One method of protection is polypropylene microfiber, the objective of which is to increase the fire resistance of concrete and reinforced concrete structures. The fire resistance tests of the reinforced concrete structure with the use of microfiber and without it have been carried out. It is shown that polypropylene microfiber can completely prevent explosive spelling of concrete. In addition, the introduction of additives in the form of fibrous materials into the concrete mix is the most optimal from the point of view of labor intensity and material costs.

Fire Resistance of Non-Crack Resistant Flexural Reinforced Concrete Elements

2015 ◽  
Vol 725-726 ◽  
pp. 15-20
Author(s):  
Vyacheslav Belov ◽  
Valery Morozov
Keyword(s):  
Reinforced Concrete ◽  
High Temperature ◽  
Fire Resistance ◽  
Concrete Structures ◽  
National Income ◽  
Developed Countries ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure ◽  
Actual Problem ◽  
Concrete Elements

In developed countries only loss of property because of fire makes annually up to 2% of their national income [9, 15]. The bearing capacity of reinforced concrete structures at high temperature impact is lost within several dozens of minutes [1, 3, 5, 10, 12, 18, 25]. Disappointing statistics of increase of both the number of fires and the scope of damage due to them aggravates the actual problem of determination of reinforced concrete structures fire-endurance. The main problems and methods of evaluation of reinforced concrete structure fire resistance are stated. Within the framework of block approach to evaluation of strain of flexural reinforced concrete elements with cracks, design model of reinforced concrete thermo-force resistance is made. Extended nomenclature of influences of high temperature at fire on decrease of performance of bearing reinforced concrete structures is considered. Empirical dependencies of strength and strain characteristics of concrete and reinforcement on high temperatures are used. Proposals on specification of evaluation of fire resistance of statically indeterminate reinforced concrete structures are formulated.

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