scholarly journals Low durability of concrete elements due to steel corrosion – cases wherein the steel reinforcing bars acted as an internal clock bomb

2017 ◽  
Vol 5 ◽  
pp. 139-146
Author(s):  
Lino Maia ◽  
Sérgio Alves
Keyword(s):  
Steel Corrosion ◽  
Internal Clock ◽  
Reinforcing Bars ◽  
Concrete Elements ◽  
Durability Of Concrete

The Summary of the Durability of Concrete Parameters Calculation Models

2011 ◽  
Vol 71-78 ◽  
pp. 937-944
Author(s):  
Ping Jie Cheng ◽  
Han Zhou Hu ◽  
Shu Guang Hu
Keyword(s):  
Environmental Effects ◽  
Concrete Structure ◽  
Civil Engineering ◽  
Steel Corrosion ◽  
Type Model ◽  
Model Parameters ◽  
Source Type ◽  
Important Field ◽  
Parameters Calculation ◽  
Durability Of Concrete

The durability of concrete structure has become an important field of civil engineering at home and abroad, and how to determine the environmental effects of typical durability of concrete structure key parameters become the key. Proposed by different domestic and foreign scholars to study durability parameters of concrete structure of different models, different models are different in the source, type, model parameters and applicable conditions. In this paper, some typical models are reviewed and analyzed from two major aspects of the durability of concrete, the deterioration of concrete and the steel corrosion.

Effect of Chloride-Induced Steel Corrosion on Working Life of Concrete Structures

2018 ◽  
Vol 272 ◽  
pp. 226-231 ◽  
Author(s):  
Ivan Hollý ◽  
Juraj Bilčík
Keyword(s):  
Pore Solution ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
Radial Pressure ◽  
Concrete Cover ◽  
Transport Infrastructure ◽  
Reinforcing Bars ◽  
Volume Increase ◽  
Volumetric Expansion ◽  
High Alkalinity

The reinforcing steel embedded in concrete is generally protected against corrosion by the high alkalinity (pH = 12.5 to 13.5) of the concrete pore solution. The structural degradation of concrete structures due to reinforcement’s corrosion has an impact on the safety, serviceability and durability of the structure. The corrosion of reinforcements in the construction of a transport infrastructure (especially bridges), parking areas, etc., is primarily initiated by chlorides from de-icing salts. When corrosion is initiated, active corrosion results in a volumetric expansion of the corrosion products around the reinforcing bars against the surrounding concrete. Reinforcement corrosion causes a volume increase due to the oxidation of metallic iron, which is mainly responsible for exerting the expansive radial pressure at the steel–concrete interface and development of hoop tensile stresses in the surrounding concrete. When this tensile stress exceeds the tensile strength of the concrete, cracks are generated. Higher corrosion rates can lead to the cracking and spalling of the concrete cover. Continued corrosion of reinforcement causes a reduction of total loss of bond between concrete and reinforcement.

scholarly journals Analysis of Chloride Deterioration and Structural Safety Evaluation of Bridge Barriers

2021 ◽  
Vol 21 (6) ◽  
pp. 177-184
Author(s):  
Koog Hun Kim ◽  
Joo Ha Lee
Keyword(s):  
Safety Evaluation ◽  
Structural Safety ◽  
Reinforcing Bars ◽  
Concrete Barriers ◽  
The Status ◽  
Deicing Agents ◽  
Durability Of Concrete

Recently, there has been an increase in the chloride deterioration of bridges on urban highways owing to the excessive usage of deicing agents in winter, thus necessitating repair and maintenance measures to ensure the durability of concrete. In this study, the status of the damages occurring in the concrete barriers, such as walls and median partitions, of bridges on urban highways in Seoul was investigated. After collecting a total of 306 cores from various sites, a chloride analysis test was performed on a total of 918 samples obtained by dividing each core into three parts. The results were analyzed using the depth, upper and lower parts of the barrier, damage conditions, and route. In addition, the safety of the structure was evaluated in the case of repair by removing the corroded reinforcing bars (main reinforcing bars and spacers) directly exposed to chloride.

scholarly journals Ultimate Flexural Capacity of Reinforced Concrete Elements Damaged by Corrosion

Buildings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 160 ◽  
Author(s):  
Bossio ◽  
Imperatore ◽  
Kioumarsi
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Case Studies ◽  
Steel Corrosion ◽  
Experimental Results ◽  
Reinforced Concrete Structures ◽  
Flexural Capacity ◽  
Static Behavior ◽  
Fem Model ◽  
Concrete Elements

Worldwide, steel corrosion is one of the greatest deterioration problems for reinforced concrete structures. Comparing some experimental results from literature with a complex FEM model, the present paper points out the principal aspects that characterize the static behavior of reinforced concrete (RC) elements damaged by corrosion. Moreover, the nondimensional abaci defined for some specific case studies finalized to the evaluation of the residual flexural strength of corroded elements highlight the dangerousness of the corrosion degradation if the failure of the element is governed by the steel.

scholarly journals Assessment of corrosion-induced bond deterioration in reinforced concrete: towards a splitting crack-based approach

2021 ◽  
Author(s):  
Michele Win Tai Mak ◽  
Janet M. Lees
Keyword(s):  
Reinforced Concrete ◽  
Bond Strength ◽  
Steel Corrosion ◽  
Concrete Bridges ◽  
Reinforcing Bars ◽  
Accelerated Corrosion ◽  
General Validity ◽  
Safety Risks ◽  
Infrastructure Network ◽  
Residual Capacity

<p>Reinforced concrete structures are subjected to several sources of deterioration that can reduce their load-resisting capacity over time. This has significant consequences for the management of infrastructure, leading to high costs of maintenance, repair, strengthening and premature decommissioning. Assessing the residual capacity of structures is challenging but paramount to manage the infrastructure network effectively. Corrosion of the internal steel reinforcement is among the main causes of deterioration in reinforced concrete bridges. The subsequent reduction in steel-to-concrete bond strength is difficult to evaluate with accuracy. There is no unified theory of general validity. Most existing models adopt measures of the level of corrosion as the key parameter to evaluate the bond reduction. In this paper, a different approach is investigated. Corrosion-induced splitting crack widths are used as the fundamental indicator of bond strength reduction, irrespective of the associated degree of steel corrosion. Available experimental results on deformed steel bars embedded in concrete subjected to either natural or accelerated corrosion, with or without transverse reinforcement, are analysed and compared with a different perspective. The analysis indicates that this new splitting crack-based approach can lead to more accurate predictions. This contributes to a better understanding of the fundamental principles underlying bond of corroded reinforcing bars. Enhanced assessment strategies can lead to a reduction of the safety risks, maintenance costs and environmental footprint of the infrastructure network.</p>

scholarly journals Micromechanical modeling of tension stiffening in FRP-strengthened concrete elements

2018 ◽  
Vol 52 (19) ◽  
pp. 2577-2596
Author(s):  
Bahman Ghiassi ◽  
Masoud Soltani ◽  
Sara Rahnamaye Sepehr
Keyword(s):  
Crack Spacing ◽  
Fiber Reinforced Polymer ◽  
Parameter Study ◽  
Crack Plane ◽  
Average Response ◽  
Fiber Reinforced ◽  
Reinforcing Bars ◽  
Tension Stiffening ◽  
Reinforced Polymer ◽  
Concrete Elements

This article presents a micromodeling computational framework for simulating the tensile response and tension-stiffening behavior of fiber reinforced polymer–strengthened reinforced concrete elements. The total response of strengthened elements is computed based on the local stress transfer mechanisms at the crack plane including concrete bridging stress, reinforcing bars stress, FRP stress, and the bond stresses at the bars-to-concrete and fiber reinforced polymer-to-concrete interfaces. The developed model provides the possibility of calculating the average response of fiber reinforced polymer, reinforcing bars, and concrete as well as the crack spacing and crack widths. The model, after validation with experimental results, is used for a systematic parameter study and development of micromechanics-based relations for calculating the crack spacing, fiber reinforced polymer critical ratio, debonding strength, and effective bond length. Constitutive models are also proposed for concrete tension stiffening and average response of steel reinforcing bars in fiber reinforced polymer–strengthened members as the main inputs of smeared crack modeling approaches.

ANALYSIS OF DETERIORATION IN REINFORCED CONCRETE BRIDGE GIRDERS DAMAGED BY CHLORIDE DETERIORATION AND FATIGUE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
H. Honda ◽  
T. Shimozato ◽  
Y. Arizumi
Keyword(s):  
Visual Inspection ◽  
Steel Corrosion ◽  
Chloride Ion ◽  
Reinforcing Bars ◽  
Loading Test ◽  
Reinforcing Bar ◽  
Reinforced Concrete Bridge ◽  
Internal Loss ◽  
Static Loading Test ◽  
Girder Bridge

The subject of this research was a concrete T-girder bridge which had been exposed for 40 years to the sub-tropical archipelago environment off the east coast of Okinawa, with large amounts of windblown salt, high temperatures and high humidity, a harsh environment for salt damage and steel corrosion. It had suffered damage in the forms of 1) concrete spalling due to reinforcing bar corrosion, 2) internal loss of cross section and severance in internal reinforcing bars, and was therefore removed. Various tests and inspections were applied to analyze the state of deterioration of a real salt-damaged bridge, with the aim of providing technical reference material of use in formulating appropriate maintenance management methods. Distant visual inspection was performed prior to removal of the girder. After the removal, close visual inspection and non-distractive inspections were performed. Compressive strength, elastic modulus and chloride ion content of the concrete were measured. Corrosion of reinforcing bar was observed after chipping the concrete. Chloride-induced deterioration inside the concrete and competence of non-destructive inspection for the deterioration were studied. Static loading test and fatigue-test were performed.

Possibilities of Increasing the Durability of Concrete Products by Technologies Based on Surface Hardening

2018 ◽  
Vol 272 ◽  
pp. 197-202
Author(s):  
Adam Hubáček ◽  
Lucia Ťažká
Keyword(s):  
Surface Hardening ◽  
Current Knowledge ◽  
Side Surface ◽  
Slip Resistance ◽  
Resistance To Wear ◽  
Concrete Elements ◽  
Durability Of Concrete

Requirements of the quality of surface have increased recently for vibro-pressed concrete elements. As a consequence, there are new concrete products available with specially treated visual side - surface is coated with an impregnating paint and then hardened by infrared or ultraviolet light.The paper summarizes current knowledge of vibro-pressed concrete elements with surface treated in mentioned way. The focus is on description and effectiveness of individual methods, hardening principles and further possible treatments of surface of concrete aiming at higher durability of concrete. Observed parameters and properties of vibro-pressed concrete elements include resistance of surface to water and chemical de-icers, water absorbing capacity, resistance to wear, slip resistance and reduction of risk of efflorescence.

scholarly journals The effect of synthetic zeolite admixture on the durability of concrete paving blocks

2016 ◽  
Vol 11 (3) ◽  
pp. 215-221 ◽  
Author(s):  
Giedrius Girskas ◽  
Džigita Nagrockienė ◽  
Gintautas Skripkiūnas
Keyword(s):  
Synthetic Zeolite ◽  
Test Results ◽  
Absorption Increase ◽  
Splitting Strength ◽  
Aluminium Fluoride ◽  
Tensile Splitting Strength ◽  
The Baltic ◽  
Stone Concrete ◽  
Concrete Elements ◽  
Durability Of Concrete

Concrete paving blocks that were started to be used in the last century have become very popular. They became an alternative to the natural stone. Concrete paving blocks are used for the paving of pedestrian and vehicle zones. Durability is one of the main characteristics in the production of high-quality concrete paving blocks in the Baltic region climate zone. The article describes tests with concrete paving blocks, the top layer of which contains 5% of synthetic zeolite admixture obtained by means of low temperature synthesis in laboratory conditions. This zeolite admixture is obtained from aluminium fluoride production waste. The durability of concrete paving blocks was tested according to abrasion resistance, tensile splitting strength, absorption and frost resistance. The test results revealed that 5% of zeolite admixture added to the top layer of concrete paving blocks reduce the absorption, increase the tensile splitting strength by more than 10%, and decrease abrasion by 6.5%. The zeolite admixture used in concrete paving blocks reduces the scaling about 4 times after 28 freeze-thaw cycles when 3% NaCl is used as the freezing solution. The tests revealed that synthetic zeolite admixture can be used in concrete elements production by means of vibropressing (pavement elements) to increase their durability.

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