Condition assessment of reinforced concrete systems with fusion-bonded epoxy-coated rebars

Field Investigation ◽

Test Methods ◽

Coated Steel ◽

Cell Potential ◽

Rc Structures ◽

Eis Technique ◽

The Difference ◽

Corrosion assessment of reinforced concrete (RC) structures with fusion-bonded-epoxy (FBE) coated steel rebars is a challenge because the common inspection methods and data cannot be applied or interpreted in the same way as that for the systems with uncoated rebars. If corrosion detection tools based on techniques such as half-cell potential (HCP), linear polarization resistance (LPR), or electrochemical impedance spectroscopy (EIS) are used for the assessment of systems with FBE coated steel rebars without considering the difference in the electrochemical conditions between coated and uncoated systems, then, the interpretation can result in the inability to detect ongoing corrosion. Therefore, the objective of this paper is to examine the suitability of these inspection methods and data to be applied to the RC systems with FBE coated steel rebars. For this, the suitability of test methods on HCP, LPR, and EIS for assessing corrosion conditions of RC structures was assessed using laboratory specimens and field structures. Field investigation using HCP shows that the HCP could not detect corrosion of FBE rebars unless the coating was severely disbonded due to corrosion of steel rebars. Also, the suitability of test methods based on HCP, LPR, and EIS was assessed by additional laboratory specimens. Although complex, only the EIS technique could reliably detect the corrosion conditions of the FBE coated steel rebars embedded in concrete. Therefore, a way forward to assess RC structures using EIS technique is proposed.

Effect of Sunlight/Ultraviolet Exposure on the Corrosion of Fusion-Bonded Epoxy (FBE) Coated Steel Rebars in Concrete

CORROSION ◽

10.5006/3588 ◽

2020 ◽

Vol 76 (9) ◽

pp. 843-860 ◽

Cited By ~ 1

Author(s):

Deepak K. Kamde ◽

Radhakrishna G. Pillai

Keyword(s):

Service Life ◽

Adverse Effects ◽

Steel Corrosion ◽

Uv Exposure ◽

Ultraviolet Rays ◽

Prolonged Storage ◽

Coated Steel ◽

Railway Bridges ◽

Currently, highway/railway bridges are designed for the service life of more than 100 y. In such reinforced concrete structures, fusion-bonded epoxy (FBE) coated steel rebars are being used in anticipation of delayed initiation of reinforcement corrosion. However, the FBE steel rebars get exposed to sunlight/ultraviolet rays during prolonged storage and delayed/staged construction. This paper presents microanalytical and electrochemical data (Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersion x-ray diffraction, and electrochemical impedance spectroscopy) and shows the adverse effects of sunlight/UV exposure on the corrosion resistance of FBE-coated steel reinforcement in concrete construction. Based on tests on steel-mortar specimens, the mechanisms of UV-induced chemical changes, shrinkage, and cracking of FBE coating, and the resulting steel corrosion mechanisms are proposed. Also, the adverse effects of sunlight/UV exposure on chloride threshold and reduction in the service life of FBE-coated steel in cementitious systems are presented. The paper recommends to minimize the exposure of FBE-coated steel rebars to sunlight/UV rays to less than one month.

DETECTING CORROSION RESISTANCE OF COATED STEEL REBARS BY ELECTROCHEMICAL TECHNIQUE (EIS)

Surface Review and Letters ◽

10.1142/s0218625x06008293 ◽

2006 ◽

Vol 13 (04) ◽

pp. 345-349 ◽

Cited By ~ 2

Author(s):

J. RYOU ◽

S. SHAH

Keyword(s):

Corrosion Resistance ◽

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Materials Science ◽

Electrochemical Techniques ◽

Electrochemical Technique ◽

Coated Steel ◽

Coating Materials ◽

Electrochemical impedance spectroscopy (EIS) is one of the electrochemical techniques used in materials science. The present measurements are used to evaluate the corrosion resistance of new types of coated steel rebar used in reinforced concrete. In this study, Si -based coating materials are used and evaluated, because adding Si to metals and alloys, including steel, generally increases their corrosion, oxidation, and erosion resistance. The result suggests that electrochemical impedance spectroscopy may be useful for monitoring corrosion activity on coated steel rebars. Based upon impedance changes, it appears that the silicon powder coating bonds well to the steel, and that the coating has a good performance.

Temperature Stress Analysis of Super-Long Frame Structures Accounting for Differences in the Linear Expansion Coefficients of Steel and Concrete

Processes ◽

10.3390/pr9091519 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1519

Author(s):

Yigang Jia ◽

Liangjian Lu ◽

Guangyu Wu ◽

Bo Zhang ◽

Huibin Wang

Keyword(s):

Reinforced Concrete ◽

Stress Analysis ◽

Temperature Stress ◽

Linear Expansion ◽

Frame Structures ◽

Reinforced Concrete Structure ◽

Rc Structures ◽

Design Elements ◽

Expansion Coefficients ◽

The Difference

Temperature stress analysis is of prime importance to ensure the adequate servicing of super-long frame structures during their service life. The existing design codes and recommendations for reinforced concrete (RC) structures provide methodologies for the reinforcement of design elements that neglect differences in the linear expansion coefficients of steel and concrete. In this paper, we present a numerical method based on a degenerated three-dimensional solid virtual laminated element for simulating and analyzing the temperature stress of a two-layer super-long frame reinforced concrete structure subjected to allover cooling action, whereby the difference in the linear expansion coefficients of steel and concrete are taken into consideration. The results show that the difference in the linear expansion coefficients of steel and concrete, with different constraints, affects the temperature stress experienced by each material in the structure, and this difference adversely affects attempts to avoid structure cracking.

Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

The Scientific World JOURNAL ◽

10.1155/2014/957904 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 16

Author(s):

Sanjeev Kumar Verma ◽

Sudhir Singh Bhadauria ◽

Saleem Akhtar

Keyword(s):

Reinforced Concrete ◽

Reinforcement Corrosion ◽

Early Failure ◽

Cell Potential ◽

Premature Failure ◽

Rc Structures ◽

Steel Bars ◽

Inspection And Maintenance ◽

Corrosion Of Steel ◽

Corrosion State

Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion.

Degradation Monitoring in Reinforced Concrete with 3D Localization of Rebar Corrosion and Related Concrete Cracking

Applied Sciences ◽

10.3390/app11156772 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6772

Author(s):

Charlotte Van Steen ◽

Els Verstrynge

Keyword(s):

Reinforced Concrete ◽

Degradation Mechanism ◽

Heterogeneous Material ◽

Corrosion Damage ◽

Corrosion Process ◽

Internal Damage ◽

Rc Structures ◽

Degradation Monitoring ◽

Rebar Corrosion ◽

Width Measurements

Corrosion of the reinforcement is a major degradation mechanism affecting durability and safety of reinforced concrete (RC) structures. As the corrosion process starts internally, it can take years before visual damage can be noticed on the surface, resulting in an overall degraded condition and leading to large financial costs for maintenance and repair. The acoustic emission (AE) technique enables the continuous monitoring of the progress of internal cracking in a non-invasive way. However, as RC is a heterogeneous material, reliable damage detection and localization remains challenging. This paper presents extensive experimental research aiming at localizing internal damage in RC during the corrosion process. Results of corrosion damage monitoring with AE are presented and validated on three sample scales: small mortar samples (scale 1), RC prisms (scale 2), and RC beams (scale 3). For each scale, the corrosion process was accelerated by imposing a direct current. It is found that the AE technique can detect damage earlier than visual inspection. However, dedicated filtering is necessary to reliably localize AE events. Therefore, AE signals were filtered by a newly developed post-processing protocol which significantly improves the localization results. On the smallest scale, results were confirmed with 3D micro-CT imaging, whereas on scales 2 and 3, results were compared with surface crack width measurements and resulting rebar corrosion levels.

A Practical Finite Element Modeling Strategy to Capture Cracking and Crushing Behavior of Reinforced Concrete Structures

Materials ◽

10.3390/ma14030506 ◽

2021 ◽

Vol 14 (3) ◽

pp. 506 ◽

Cited By ~ 1

Author(s):

Alexandre Mathern ◽

Jincheng Yang

Keyword(s):

Finite Element ◽

Reinforced Concrete ◽

Constitutive Relations ◽

Fe Analysis ◽

Rc Beams ◽

Cracking Behavior ◽

Concrete Cracking ◽

Rc Structures ◽

Nonlinear Fe Analysis ◽

Modeling Strategy

Nonlinear finite element (FE) analysis of reinforced concrete (RC) structures is characterized by numerous modeling options and input parameters. To accurately model the nonlinear RC behavior involving concrete cracking in tension and crushing in compression, practitioners make different choices regarding the critical modeling issues, e.g., defining the concrete constitutive relations, assigning the bond between the concrete and the steel reinforcement, and solving problems related to convergence difficulties and mesh sensitivities. Thus, it is imperative to review the common modeling choices critically and develop a robust modeling strategy with consistency, reliability, and comparability. This paper proposes a modeling strategy and practical recommendations for the nonlinear FE analysis of RC structures based on parametric studies of critical modeling choices. The proposed modeling strategy aims at providing reliable predictions of flexural responses of RC members with a focus on concrete cracking behavior and crushing failure, which serve as the foundation for more complex modeling cases, e.g., RC beams bonded with fiber reinforced polymer (FRP) laminates. Additionally, herein, the implementation procedure for the proposed modeling strategy is comprehensively described with a focus on the critical modeling issues for RC structures. The proposed strategy is demonstrated through FE analyses of RC beams tested in four-point bending—one RC beam as reference and one beam externally bonded with a carbon-FRP (CFRP) laminate in its soffit. The simulated results agree well with experimental measurements regarding load-deformation relationship, cracking, flexural failure due to concrete crushing, and CFRP debonding initiated by intermediate cracks. The modeling strategy and recommendations presented herein are applicable to the nonlinear FE analysis of RC structures in general.

Performance of coatings containing treated silica fume in the corrosion protection of reinforced concrete

Pigment & Resin Technology ◽

10.1108/prt-08-2017-0076 ◽

2018 ◽

Vol 47 (4) ◽

pp. 350-359 ◽

Cited By ~ 4

Author(s):

Nivin M. Ahmed ◽

Mostafa G. Mohamed ◽

Reham H. Tammam ◽

Mohamed R. Mabrouk

Keyword(s):

Reinforced Concrete ◽

Silica Fume ◽

Corrosion Protection ◽

Electrochemical Techniques ◽

Dual Function ◽

Core Shell ◽

Protection Efficiency ◽

Content Type ◽

Anticorrosive Pigments

Purpose This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent silica fume (core) with 10-20 per cent phosphates (shell) previously, to play dual functions simultaneously as anticorrosive pigments in coating formulations and as an anticorrosive admixture in concrete even if it is not present in the concrete itself. Two comparisons were held out to show the results of coatings on rebars containing core-shell pigments in concrete, and concrete admixtured with silica fume can perform a dual function as anticorrosive pigment and concrete admixture. The evaluation of corrosion protection efficiency of coatings containing core-shell pigments and those containing phosphates was performed. Design/methodology/approach Simple chemical techniques were used to prepare core-shell pigments, and their characterization was carried out in a previous work. These pigments were incorporated in solvent-based paint formulations based on epoxy resin. Different electrochemical techniques such as open-circuit potential and electrochemical impedance spectroscopy were used to evaluate the anticorrosive efficiency of the new pigments. Findings The electrochemical measurements showed that concrete containing coated rebars with core-shell pigments exhibited almost similar results to that of concrete admixtured with silica fume. Also, the anticorrosive performance of coatings containing Si-Ph pigments offered protection efficiency almost similar to that of phosphates, proving that these new pigments can perform both roles as anticorrosive pigment and concrete admixture. Originality/value Although the new Si-Ph pigments contain more than 80 per cent waste material, its performance can be compared to original phosphate pigments in the reinforced concrete.

Statistical and Reliability Study on Shear Strength of Recycled Coarse Aggregate Reinforced Concrete Beams

Materials ◽

10.3390/ma14123321 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3321

Author(s):

Hyunjin Ju ◽

Meirzhan Yerzhanov ◽

Alina Serik ◽

Deuckhang Lee ◽

Jong R. Kim

Keyword(s):

Reinforced Concrete ◽

Concrete Beams ◽

Construction Material ◽

Safety Margin ◽

Shear Capacity ◽

Reinforced Concrete Beams ◽

Construction And Demolition Waste ◽

Demolition Waste ◽

Rc Structures ◽

Coarse Aggregates

The consumption of structural concrete in the construction industry is rapidly growing, and concrete will remain the main construction material for increasing urbanization all over the world in the near future. Meanwhile, construction and demolition waste from concrete structures is also leading to a significant environmental problem. Therefore, a proper sustainable solution is needed to address this environmental concern. One of the solutions can be using recycled coarse aggregates (RCA) in reinforced concrete (RC) structures. Extensive research has been conducted in this area in recent years. However, the usage of RCA concrete in the industry is still limited due to the absence of structural regulations appropriate to the RCA concrete. This study addresses a safety margin of RCA concrete beams in terms of shear capacity which is comparable to natural coarse aggregates (NCA) concrete beams. To this end, a database for reinforced concrete beams made of recycled coarse aggregates with and without shear reinforcement was established, collecting the shear specimens available from various works in the existing literature. The database was used to statistically identify the strength margin between RCA and NCA concrete beams and to calculate its safety margin based on reliability analysis. Moreover, a comparability study of RCA beams was conducted with its control specimens and with a database for conventional RC beams.

Corrosion of Steel Rebars in Anoxic Environments. Part I: Electrochemical Measurements

Materials ◽

10.3390/ma14102491 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2491

Author(s):

Elena Garcia ◽

Julio Torres ◽

Nuria Rebolledo ◽

Raul Arrabal ◽

Javier Sanchez

Keyword(s):

Corrosion Rate ◽

Electrochemical Techniques ◽

Chloride Content ◽

Offshore Platforms ◽

Anoxic Conditions ◽

Current Limit ◽

Anoxic Environments ◽

Corrosion Of Steel ◽

The number of reinforced concrete structures subject to anoxic conditions such as offshore platforms and geological storage facilities is growing steadily. This study explored the behaviour of embedded steel reinforcement corrosion under anoxic conditions in the presence of different chloride concentrations. Corrosion rate values were obtained by three electrochemical techniques: Linear polarization resistance, electrochemical impedance spectroscopy, and chronopotenciometry. The corrosion rate ceiling observed was 0.98 µA/cm2, irrespective of the chloride content in the concrete. By means of an Evans diagram, it was possible to estimate the value of the cathodic Tafel constant (bc) to be 180 mV dec−1, and the current limit yielded an ilim value of 0.98 µA/cm2. On the other hand, the corrosion potential would lie most likely in the −900 mVAg/AgCl to −1000 mVAg/AgCl range, whilst the bounds for the most probable corrosion rate were 0.61 µA/cm2 to 0.22 µA/cm2. The experiments conducted revealed clear evidence of corrosion-induced pitting that will be assessed in subsequent research.

Experimental testing of medium scale GFRP reinforced concrete frames

MATEC Web of Conferences ◽

10.1051/matecconf/201928904004 ◽

2019 ◽

Vol 289 ◽

pp. 04004

Author(s):

George Hopartean ◽

Ted Donchev ◽

Diana Petkova ◽

Costas Georgopoulos ◽

Mukesh Limbachiya ◽

...

Keyword(s):

Reinforced Concrete ◽

Experimental Testing ◽

Control Sample ◽

Concrete Frames ◽

Reinforced Concrete Frames ◽

Reinforced Polymers ◽

Rc Structures ◽

Gfrp Bars ◽

Glass Frp ◽

Reversed Cyclic

Fibre reinforced polymers (FRP) have been used as strengthening for existing RC structures for many decades. Lately, there has been a lot of interest in using FRP as internal reinforcement in beams, slabs and columns. One potential area of application could be reinforced concrete frames internally reinforced with GFRP bars. With limited research in this direction, the objective of this publication is to assess the behaviour of glass FRP (GFRP) reinforced concrete frames under reversed cyclic lateral in plane loading and to analyse the seismic performances of such elements. For the purpose of this paper, experimental testing of two 1/3 scaled down frames is conducted in displacement-controlled mode with the loading history according to ACI 374.1-05. The control sample is reinforced with conventional steel reinforcement and the results obtained are compared with the sample reinforced with GFRP bars. In summary, observations on the sample behaviour at specified drift ratio such as load-displacement behaviour, envelope curves and energy dissipation are presented.