scholarly journals The Cover Depth Effect on Corrosion-Induced Deterioration of Reinforced Concrete Focusing on Water Penetration: Field Survey and Laboratory Study

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3478
Author(s):  
Shingo Asamoto ◽  
Junya Sato ◽  
Shinichiro Okazaki ◽  
Pang-jo Chun ◽  
Raktipong Sahamitmongkol ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Laboratory Study ◽  
Numerical Study ◽  
Steel Corrosion ◽  
Concrete Cover ◽  
Concrete Bridges ◽  
Water Penetration ◽  
Depth Effect ◽  
Cover Depth ◽  
Oxygen Penetration

Reinforced concrete bridges were visually surveyed in Japan, Thailand, and Vietnam to study the deterioration caused by internal steel corrosion under different climates, focusing on the concrete cover depth. Spalling or cracking arising from corrosion is likely where water is supplied. According to prior studies and our surveys, a concrete cover depth of more than 40 mm was found to prevent spalling, regardless of environmental conditions and structure age. Because water supply at steel is a key corrosion factor, it was hypothesised that under natural conditions, the water penetration in concrete would remain at a depth of approximately 40 mm. Our laboratory study examined water penetration under drying and wetting conditions. The results also suggested that under periodic rainfall conditions, the threshold of water penetration was not exceeded. The numerical study indicated maximum moisture evaporation to facilitate oxygen diffusion occurred at a depth of approximately 30–40 mm unless the concrete was exposed to continuous drying for more than one month. It was experimentally and numerically concluded that an adequate cover depth of greater than 40 mm could inhibit moisture and oxygen penetration at the steel, which supported the survey findings of cover depth effect on a high resistance to corrosion-induced deterioration despite an increase in service life.

scholarly journals Influence of Patching on the Shear Failure of Reinforced Concrete Beam without Stirrup

2021 ◽  
Vol 6 (7) ◽  
pp. 97
Author(s):  
Stefanus Adi Kristiawan ◽  
Halwan Alfisa Saifullah ◽  
Agus Supriyadi
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Numerical Study ◽  
Unsaturated Polyester ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Shear Capacity ◽  
Rc Beam ◽  
Shear Span ◽  
Shear Cracking

Deteriorated concrete cover, e.g., spalling or delamination, especially when it occurs at the web of a reinforced concrete (RC) beam within the shear span, can reduce the shear capacity of the beam. Patching of this deteriorated area may be the best option to recover the shear capacity of the beam affected. For this purpose, unsaturated polyester resin mortar (UPR mortar) has been formulated. This research aims to investigate the efficacy of UPR mortar in limiting the shear cracking and so restoring the shear capacity of the deteriorated RC beam. The investigation is carried out by an experimental and numerical study. Two types of beams with a size of 150 × 250 × 1000 mm were prepared. The first type of beams was assigned as a normal beam. The other was a beam with a cut off in the non-stirrup shear span, which was eventually patched with UPR mortar. Two reinforcement ratios were assigned for each type of beams. The results show that UPR mortar is effective to hamper the propagation of diagonal cracks leading to increase the shear failure load by 15–20% compared to the reference (normal) beam. The increase of shear strength with the use of UPR mortar is consistently confirmed at various reinforcement ratios.

scholarly journals Influence of Freeze-Thaw Damage on the Steel Corrosion and Bond-Slip Behavior in the Reinforced Concrete

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Fangzhi Zhu ◽  
Zhiming Ma ◽  
Tiejun Zhao
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structure ◽  
Steel Corrosion ◽  
Concrete Cover ◽  
Bond Slip ◽  
Freeze Thaw ◽  
Ordinary Concrete ◽  
Air Entrained Concrete

This paper mainly studies the behavior of steel corrosion in various reinforced concrete under freeze-thaw environment. The influence of thickness of concrete cover is also discussed. Additionally, the bond-slip behavior of the reinforced concrete after suffering the freeze-thaw damage and steel corrosion has also be presented. The results show that the freeze-thaw damage aggravates the steel corrosion in concrete, and the results become more obvious in the concrete after suffering serious freeze-thaw damage. Compared with the ordinary concrete, both air entrained concrete and waterproofing concrete possess better resistance to steel corrosion under the same freeze-thaw environment. Moreover, increasing the thicknesses of concrete cover is also an effective method of improving the resistance to steel corrosion. The bond-slip behavior of reinforced concrete with corroded steel decreases with the increase of freeze-thaw damage, especially for the concrete that suffered high freeze-thaw cycles. Moreover, there exists a good correlation between the parameters of bond-slip and freeze-thaw cycles. The steel corrosion and bond-slip behavior of reinforced concrete should be considered serious under freeze-thaw cycles environment, which significantly impact the durability and safety of concrete structure.

scholarly journals Numerical analysis of reinforced concrete beam subject to pitting corrosion

2022 ◽  
Vol 22 (1) ◽  
pp. 201-222
Author(s):  
Éverton Souza Ramos ◽  
Rogério Carrazedo
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Pitting Corrosion ◽  
Numerical Study ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Structural Element ◽  
Deterministic Models ◽  
Faraday’S Law ◽  
Parametric Analyses

Abstract This paper presents a numerical study about the effects of chloride-induced corrosion on the service life of structures. A two-dimensional geometrically nonlinear mechanical model based on Finite Element Method (FEM) was developed for reinforced concrete structures. The corrosion initiation stage was evaluated by Fick's diffusion laws. The corrosion propagation was carried out by deterministic models based on Faraday's law. Pitting corrosion was simulated in the reinforcements by pit elements, distributed longitudinally on the steel rebars, which degrade the physical properties over time. The service life was determined by the crack width.Two parametric analyses were performed. In the first analysis, five models were created with a variablecover thickness and water/cement ratio (w/c). In the second analysis, the reduction in yield stress due to corrosion was considered.The results showed that the concrete cover thicknessand the w/c ratio significantly influence the service life. The reduction of the cover thickness from 30 mm to 25 mm resulted in 21.26% reduction in service life, whilethe increase in the w/c ratio from 0.50 to 0.55 caused 32.98% reduction in service life of the structural element analyzed.

scholarly journals The Non-Destructive Test of Steel Corrosion in Reinforced Concrete Bridges Using a Micro-Magnetic Sensor

Sensors ◽  
2016 ◽  
Vol 16 (9) ◽  
pp. 1439 ◽  
Author(s):  
Hong Zhang ◽  
Leng Liao ◽  
Ruiqiang Zhao ◽  
Jianting Zhou ◽  
Mao Yang ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Steel Corrosion ◽  
Concrete Bridges ◽  
Magnetic Sensor ◽  
Destructive Test ◽  
Reinforced Concrete Bridges ◽  
Non Destructive

scholarly journals Mechanical Properties of Concrete After Chlorine Salt Extraction in Freeze-Thaw Environment

2014 ◽  
Vol 8 (1) ◽  
pp. 360-367 ◽  
Author(s):  
Liu Faming ◽  
Ye Shujin ◽  
Ma Jie
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Raw Materials ◽  
Steel Corrosion ◽  
Concrete Cover ◽  
Economic Losses ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Electrochemical Chloride Extraction

Steel corrosion caused by chlorine salt erosion, degrade performance of reinforced concrete structures. Lead to can't use or need to reinforce the maintenance structure, produce the huge economic losses. The research of this subject is also a worldwide difficult problem. The freeze-thaw damage of concrete is a complex process of physical change. The chlorine salt erosion is often accompanied by freezing and thawing process. Make concrete structure is in a very bad environment. According to different sources of chloride ion and adopt general international electrochemical chloride extraction testing method of concrete specimens after different freezing and thawing times, the effect of chloride extraction, compressive strength, permeability resistance are studied. It is concluded that the chloride extraction, the strength and durability of the concrete member after freezing and thawing has had certain improvement, especially the durability has a lot to improve. In addition, put forward to increase thickness of concrete cover, preferable high-performance concrete resistance to chloride, strictly control the content of chlorine ion in concrete raw materials, adding reinforcement rust and corrosion inhibitor, adopting concrete corrosion layer, special steel, cathodic protection and so on measures to prevent the chlorine salt erosion. For electrochemical chloride extraction technique in reinforced concrete hydraulic structure, the application of civil engineering in the marine environment which it is provided the theoretical foundation and promotion.

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 Parameters That Influence Corrosion Detection in Reinforced Concrete Based on Eddy Current Thermography

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Lu Liu ◽  
Dan Zheng ◽  
Jianting Zhou ◽  
Juan Yang ◽  
Hong Zhang
Keyword(s):  
Reinforced Concrete ◽  
Surface Temperature ◽  
Temperature Change ◽  
Eddy Current ◽  
Steel Corrosion ◽  
Concrete Cover ◽  
Quantitative Detection ◽  
Surface Temperature Change ◽  
Temperature Changes ◽  
Steel Bar

This study introduces an eddy current thermography technique that can be used to detect and evaluate steel corrosion in a reinforced concrete structure. The rate of surface temperature changes in reinforced concrete is proposed as a means to characterize the degree of steel bar corrosion. The rate of surface temperature changes increased gradually with an increase in the corrosion degree. The influence of structural parameters on the rate of the temperature change was analyzed in detail. The results indicated that the rate of surface temperature change increased with a decrease in the concrete cover depth and with an increase in the humidity of the concrete, and this was affected by the diameter of the internal steel bar. Concrete cover was the most significant factor that affected the rate of the surface temperature change, except for the corrosion degree. The variations in the surface temperature of reinforced concrete can be explained using the law of electromagnetic induction and the electrochemical property change of corroded steel bar. This research provides a reliable basis for real-world applications and is helpful to understand the application scope of eddy current thermography technology for the quantitative detection of steel corrosion.

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