Macrocell Corrosion Formation in Concrete Patch Repairs - A Laboratory Study

2016 ◽  
Vol 711 ◽  
pp. 68-75
Author(s):  
Choorackal A. Eldho ◽  
Ominda Nanayakkara ◽  
Jun Xia ◽  
Stephen W. Jones
Keyword(s):  
Field Application ◽  
Patch Repair ◽  
Steel Bar ◽  
Repair Materials ◽  
Steel Bars ◽  
Patch Repairs ◽  
Macrocell Current ◽  
Macrocell Corrosion ◽  
Chloride Contaminated

Corrosion of reinforcement steel bars is a major threat to the durability of concrete structures exposed to chloride contaminated environment. Patch repairing is widely practiced in affected structures to avoid further damage due to corrosion. Macrocell formation within the patch repair is identified as one main reason for the failure of patch repairs. In the present study, a group of patch repairing materials is tested for their potential to form macrocell corrosion after repaired in a chloride contaminated environment. The influence of parameters such as level of chloride contamination, type of repair materials and the area of steel bar receiving repair are presented based on macrocell current measurements. The selected repair materials for study were cement based, GGBS based and polymer based in its composition. It is found that the severity of macrocell depends on the driving potential existing between the repair and substrate concrete. The quality of substrate concrete and repair material influences the macrocell formation. The surface area of the steel bar that receives the repair also affects the macrocell current. The study will be used for the evaluation of repair materials for macrocell corrosion formation potential before their field application in a chloride contaminated environment.

scholarly journals Meting van ultrasoniese pulssnelheid om die effektiwiteit van nabehandeling van kolherstel op beton te moniteer

2014 ◽  
Vol 33 (1) ◽  
Author(s):  
Johannes J. Bester ◽  
Deon Kruger
Keyword(s):  
Control Method ◽  
Ultrasonic Pulse Velocity ◽  
Pulse Velocity ◽  
Nondestructive Method ◽  
Patch Repair ◽  
Strength Development ◽  
Repair Material ◽  
Repair Work ◽  
Patch Repairs

Concrete patch repairing is a fairly new field in the concrete industry, so that there is only a limited number of standards available. Consequently there is also limited application of quality assurance for patch repairs. Curing has a major effect on the quality of the repair work; therefore the manufacturer of patch repair materials has very stringent guidelines with regards to curing methods. The question now is: How can it be ensured that the repair material was cured according to specification? So a need for a cost-effective, nondestructive test for the evaluation of the quality of patch repairing exists. This article presents the results of a research project on the use of ultrasonic pulse velocity to evaluate the quality of curing on concrete patch repairs. As part of the experimental work, three sets of four 1200 mm x 235 mm x 140 mm concrete test specimens were prepared in three concrete strengths (30 MPa, 40 MPa and 50 MPa). The results clearly indicate that there is a decline in the pulse velocities when inadequate curing is performed. This is due to the lower densities and poor strength development of the inadequately cured concrete patch material. This conclusion is supported by the corresponding pull-off tests that were done to determine the bond strength between the in situ concrete and concrete repair material. The measuring of the pulse velocities therefore proved an effective and fast nondestructive method to estimate the quality of concrete patch repairs, and can be used as a quality control method at the early stages of disrepair.

scholarly journals Alternative patch repair materials for rebar corrosion damage

2018 ◽  
Vol 199 ◽  
pp. 07017
Author(s):  
Primesh Jassa ◽  
Hans Beushausen ◽  
Ines Tchetgnia Ngassam
Keyword(s):  
Drying Shrinkage ◽  
Corrosion Damage ◽  
Point Of View ◽  
Patch Repair ◽  
Common Belief ◽  
Cement Concrete ◽  
Premature Failure ◽  
Repair Materials ◽  
Repair Procedure ◽  
Patch Repairs

One of the most common methods adopted in the rehabilitation of corrosion-damaged concrete is the patch repair procedure. However, in practice this method has shown to often be unreliable as a consequence of the widespread occurrence of shrinkage induced cracking and poor substrate-patch adhesion leading to debonding of the patch repair. From a practical point of view, such failed repair systems essentially restore the repaired concrete back to a deteriorated state. There is a common belief that repairing concrete with specialised proprietary repair materials would guarantee durability. However, the widespread premature failure of patch repairs conducted using such materials has proven the contrary. This paper presents an understanding of the materials and issues concerning the durability and serviceability of concrete patch repairs, with the aim of identifying alternative non-structural patch repair materials for the effective repair of corrosion-damaged concrete structures. The potential patch repair materials researched were polymer-cement concrete (copolymer of vinyl acetate and ethylene with 5% cement replacement) and 60%, 80% and 100% fly ash (FA) mortar. Patch repairs were conducted on substrate moulds to test application and observe cracking/debonding occurrence. Furthermore, compressive strength, durability index, accelerated drying shrinkage, restrained shrinkage, workability and scanning electron microscopy (SEM) tests were conducted to determine the properties of the materials developed with reference to performance requirements of durable concrete repairs. It was concluded that the 60% FA and polymer-cement concrete repair materials had the best overall performance. This research established that innovative alternative repair materials such as a 60% FA or polymer-cement concrete material, can be developed for non-structural patch repairs with improved long-term performance relative to conventional materials.

Influence Parameters Analysis of Forming Quality and System Dynamics Simulation of Vertical Steel Bar Benting

2013 ◽  
Vol 483 ◽  
pp. 280-284
Author(s):  
Xi Jian Zheng ◽  
Xin Zhuo Wang ◽  
Jin Meng Zhang ◽  
Yu Fei Zhu
Keyword(s):  
Simulation Analysis ◽  
Reference Value ◽  
Dynamics Simulation ◽  
Forming Quality ◽  
Steel Bar ◽  
New Process ◽  
Cutting Length ◽  
Bending Radius ◽  
The Relationship

The vertical steel bar bending forming is a kind of new process of bending method. The bending speed, bending radius and clamping length H which is the parameters of vertical steel bar bending machine , is directly affect the quality of bending forming parts. This paper calculated the length of reinforcement before being incised and the springback angle of bending steel bar which obtained the reasonable cutting length and bending Angle; Then based on rigid-flexible virtual prototype technology to build the dynamics model of vertical steel bar bending system. Through simulation analysis ,it obtained the relationship between bending speed, bending radius , clamping length H and forming quality of bending steel bar. In this paper, the analysis method have reference value to the design of similar steel bar bending machines.

Evaluation on the Addition of Inhibitor and Surface Treatment to Corrosion Behavior of the Reinforced Steel Bar Embedded in Mortar Specimen

2017 ◽  
Vol 744 ◽  
pp. 114-120
Author(s):  
Kyung Man Moon ◽  
Sung Yul Lee ◽  
Jae Hyun Jeong ◽  
Myeong Hoon Lee
Keyword(s):  
Current Density ◽  
Test Specimen ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Corrosion Properties ◽  
Mortar Specimen ◽  
Steel Bar ◽  
Steel Bars ◽  
Reinforced Steel ◽  
One Year

In this study, seven types of mortar test specimens were manufactured with parameters, that is, the surface of the reinforced steel bar was treated with hot dip galvanizing (Zn) and the surface of the test specimen was coated with underwater paint, and four types of inhibitors (DAW, MCI, DCI, and Silcon) were added in mortars respectively. And, the seven types of mortar test specimens were immersed in seawater for 4 years. The corrosion properties of the reinforced steel bars embedded in mortar test specimens were investigated using electrochemical methods. The corrosion potentials of the test specimens with painting on the surface of the specimen and Zn coating on the surface of the steel bar exhibited the noblest and lowest values respectively after one year, however, after 4 years, the specimens of underwater painting and of addition of Silcon inhibitor indicated the noblest and lowest values of corrosion potentials respectively. Furthermore, the painting specimen exhibited the smallest values of corrosion probability as welll as of the corrosion current density, while, addition of MCI inhibitor showed the highest values of both corrosion probability and corrosion current density. Moreover, the painting specimen showed the smallest value of neutralization degree among all the specimens, and the largest value of neutralization degree was observed at the specimen of natural condition (no adding of inhibitor, no painting and no Zn coating). As a result, it is considered that the addition of inhibitors, coating with hot dip galvanizing (Zn), and painting on the surface have the effects not only to inhibit the neutralization degree but also to increase the corrosion resistance of the embedded steel bar.

Pitting corrosion of reinforcing steel bars in chloride contaminated concrete

2019 ◽  
Vol 199 ◽  
pp. 359-368 ◽  
Author(s):  
Dawang Li ◽  
Ren Wei ◽  
L. Li ◽  
Xiaotao Guan ◽  
Xuming Mi
Keyword(s):  
Pitting Corrosion ◽  
Reinforcing Steel ◽  
Steel Bars ◽  
Chloride Contaminated

scholarly journals Non-Destructive Investigation of a 44-Year-Old RC Structure Exposed to Actual Marine Tidal Environments Using Electrochemical Methods

2021 ◽  
Vol 13 (3) ◽  
Author(s):  
Pinta Astuti ◽  
◽  
Khalilah Kamarulzaman ◽  
Hidenori Hamada ◽  
◽  
...  
Keyword(s):  
Visual Observation ◽  
Concrete Cover ◽  
Patch Repair ◽  
Cell Potential ◽  
Corrosion Condition ◽  
Electrochemical Tests ◽  
Rc Structure ◽  
Steel Bars ◽  
Potential Mapping ◽  
Non Destructive

Investigation of deterioration progress in marine structures without destroying them is crucial as early detection of damage before applying the suitable remedial measures. This study presents a series of non-destructive assessment on a 44-year-old naturally corroded RC structure exposed to marine tidal environments using observation of defective appearances and electrochemical tests. The visual observation was conducted by inspecting the corrosion condition of steel bars, crack patterns, and the spalling of concrete cover. The electrochemical investigations carried out in this research consisted of the half-cell potential mapping, the electrical resistivity of concrete, and the corrosion rate of steel bars. The results revealed that electrochemical test results conducted in this research were in good agreement with the actual deterioration degree checked by defective appearances. The RC structure was categorized as Grade II-1 (first half of the acceleration stage). Based on the deterioration degree, both applications of small direct current to control the potential of steel bars in immunity condition and patch repair method by removing the chloride contaminated concrete were recommended as appropriate repairing strategies, and they could extend the service life the of structure.

scholarly journals Effect of Nitrite Inhibitor on the Macrocell Corrosion Behavior of Reinforcing Steel

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Zhonglu Cao ◽  
Makoto Hibino ◽  
Hiroki Goda
Keyword(s):  
Corrosion Behavior ◽  
Current Density ◽  
Polarization Resistance ◽  
Cement Mortar ◽  
Corrosion Current ◽  
Potential Difference ◽  
Reinforcing Steel ◽  
Macrocell Current ◽  
The Relationship ◽  
Macrocell Corrosion

The effect of nitrite ions on the macrocell corrosion behavior of reinforcing steel embedded in cement mortar was investigated by comparing and analyzing the macrocell corrosion current, macrocell polarization ratios, and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was analyzed, and the mechanism of macrocell corrosion affected by nitrite ions was proposed. The results indicated that nitrite ions had significant impact on the macrocell polarization ratios of cathode and anode. The presence of nitrite could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the anode.

scholarly journals A High Precision Quality Inspection System for Steel Bars Based on Machine Vision

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2732 ◽  
Author(s):  
Xinman Zhang ◽  
Jiayu Zhang ◽  
Mei Ma ◽  
Zhiqi Chen ◽  
Shuangling Yue ◽  
...  
Keyword(s):  
Machine Vision ◽  
High Precision ◽  
Absolute Error ◽  
Detection Methods ◽  
Inspection System ◽  
Quality Inspection ◽  
Construction Site ◽  
High Definition ◽  
Steel Bar ◽  
Steel Bars

Steel bars play an important role in modern construction projects and their quality enormously affects the safety of buildings. It is urgent to detect whether steel bars meet the specifications or not. However, the existing manual detection methods are costly, slow and offer poor precision. In order to solve these problems, a high precision quality inspection system for steel bars based on machine vision is developed. We propose two algorithms: the sub-pixel boundary location method (SPBLM) and fast stitch method (FSM). A total of five sensors, including a CMOS, a level sensor, a proximity switch, a voltage sensor, and a current sensor have been used to detect the device conditions and capture image or video. The device could capture abundant and high-definition images and video taken by a uniform and stable smartphone at the construction site. Then data could be processed in real-time on a smartphone. Furthermore, the detection results, including steel bar diameter, spacing, and quantity would be given by a practical APP. The system has a rather high accuracy (as low as 0.04 mm (absolute error) and 0.002% (relative error) of calculating diameter and spacing; zero error in counting numbers of steel bars) when doing inspection tasks, and three parameters can be detected at the same time. None of these features are available in existing systems and the device and method can be widely used to steel bar quality inspection at the construction site.

scholarly journals Research on Compression Behavior of Square Thin-Walled CFST Columns with Steel-Bar Stiffeners

2018 ◽  
Vol 8 (9) ◽  
pp. 1602 ◽  
Author(s):  
Zhao Yang ◽  
Chengxiang Xu
Keyword(s):  
Bearing Capacity ◽  
Local Buckling ◽  
Steel Tube ◽  
Steel Tubes ◽  
Compression Behavior ◽  
Steel Bar ◽  
Steel Bars ◽  
Thin Walled ◽  
Structural Measure ◽  
Cfst Columns

Local buckling in steel tubes was observed to be capable of reducing the ultimate loads of thin-walled concrete-filled steel-tube (CFST) columns under axial compression. To strengthen the steel tubes, steel bars were proposed in this paper to be used as stiffeners fixed onto the tubes. Static-loading tests were conducted to study the compression behavior of square thin-walled CFST columns with steel bar stiffeners placed inside or outside the tube. The effect and feasibility of steel bar stiffeners were studied through the analysis of failure mode, load–displacement relationship, ultimate load, ductility, and local buckling. Different setting methods of steel bars were compared as well. The results showed that steel-bar stiffeners proposed in this paper can be effective in delaying local buckling as well as increasing the bearing capacity of the columns, but will decrease the ductility of the columns. In order to obtain a higher bearing capacity of columns, steel bars with low stiffness should be placed inside and steel bars with high stiffness should be placed outside of the steel tubes. The study is helpful in providing reference to the popularization and application of this new structural measure to avoid or delay the local buckling of thin-walled CFST columns.

Bond Strength Characteristic of Concrete Patch Repair Material Made from Unsaturated Polyester Resin (UPR)-Mortar

2015 ◽  
Vol 754-755 ◽  
pp. 442-446 ◽  
Author(s):  
Stefanus Adi Kristiawan ◽  
Ageng Bekti Prakoso
Keyword(s):  
Bond Strength ◽  
Strength Characteristic ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
High Strength ◽  
Unsaturated Polyester Resin ◽  
Test Method ◽  
Patch Repair ◽  
Repair Materials ◽  
Bond Plane

Patch repair materials made from unsaturated polyester resin (UPR)-mortar have been investigated to determine their bond strength characteristic by slant shear test method. The relative mechanical properties of UPR-mortar and substrate concrete for composing the specimens are: lower modular and high strength ratio. The experimental results show that the combination of materials causes the observed bond strength are dictated by failure of substrate concrete. The actual bond strength could be higher as most of the specimens fail without separation of the UPR-mortar and substrate concrete at the bond plane.

Sign in / Sign up

Export Citation Format

Share Document