scholarly journals Corrosion Risk of Reinforced Concrete Structure Arising from Internal and External Chloride

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
M. J. Kim ◽  
K. Y. Ann
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Concrete Structure ◽  
Threshold Level ◽  
Exposure Condition ◽  
Reinforced Concrete Structure ◽  
Galvanic Current ◽  
Corrosion Risk ◽  
Wet Condition ◽  
Cathode Metal

The corrosion risk of internal chloride and external chloride from three different exposure conditions was evaluated. The initiation of corrosion was detected by monitoring the galvanic current between cathode metal and embedded steel. The chloride threshold was determined by measuring the corrosion rate of steel by the polarization technique for internal chloride and the chloride profiling test for external chloride. As the result, the initiation of corrosion was accelerated with a cyclic wet/dry condition, compared to the totally wet condition. In addition, it was found that an increase of the drying ratio in the exposure condition resulted in an increase of corrosion rate after initiation. The threshold level of external chloride ranged from 0.2 to 0.3% weight by cement and internal chloride shows higher range, equated to 1.59–3.10%. Based on these data, the chloride penetration with exposure condition was predicted to determine the service life of reinforced concrete structure.

Test and Study on Impact of Corrosion on Bond Force between Steel and Concrete

2010 ◽  
Vol 36 ◽  
pp. 176-181
Author(s):  
Xian Feng He ◽  
Shou Gang Zhao ◽  
Yuan Bao Leng
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Concrete Structure ◽  
Steel Corrosion ◽  
Reinforced Concrete Structure ◽  
Bond Force ◽  
Steel Bars ◽  
Protection Layer ◽  
Corrosion Of Steel ◽  
The Impact

The corrosion of steel will have a bad impact on the safety of reinforced concrete structure. In severe cases, it may even be disastrous. In order to understand the impact of steel corrosion on the structure, tests are carried out to study corrosion and expansion rules of steel bars as well as the impact rules of corrosion on bond force between steel and concrete. The results show that wet and salty environment will result in steel corrosion; relatively minor corrosion will not cause expansion cracks of protection layers; when steel rust to a certain extent, it will cause cracks along the protection layer; when there exists minor corrosion in steel and the protection layer does not have expansion cracks, the bond force is still large and rapidly decreases as the corrosion rate increases.

Effect of Interrupting Electricity Period on Electrochemical Chloride Extraction of Reinforced Concrete

2015 ◽  
Vol 754-755 ◽  
pp. 342-347
Author(s):  
Mien Van Tran ◽  
Dong Viet Phuong Tran ◽  
Mohd Mustafa Al Bakri Abdullah
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Current Density ◽  
Concrete Structure ◽  
Chloride Concentration ◽  
Steel Reinforcement ◽  
Reinforced Concrete Structure ◽  
Half Cell ◽  
Cell Potential ◽  
Electrochemical Chloride Extraction

Electrochemical chloride extraction – ECE is an effective method to rehabilitate reinforced concrete structure, which has been corroded. This study investigated concentration of chloride remained in concrete and half-cell potential of the steel reinforcement after ECE using interrupting period of electricity current. Efficiency of ECE using Ca (OH)2was surveyed with two current density of 0.5 and 1A/m2. In this study, ECE treatment was proceeded intermittently in approximately 8 weeks. Results pointed out that chloride concentration decreased to 30 – 60% significantly, especially at in the vicinity of reinforcing steel. Simultaneously, half-cell potential of the steel reinforcement after 4 weeks halted treatment stabilizes in low-corrosion rate.

scholarly journals Alternative methodology for linear polarization resistance assessment of reinforced concrete structure

2018 ◽  
Vol 199 ◽  
pp. 06009 ◽  
Author(s):  
Gabriel Samson ◽  
Fabrice Deby ◽  
Jean-Luc Garciaz ◽  
Jean-Louis Perrin
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Current Density ◽  
Linear Polarization ◽  
Concrete Structure ◽  
Polarization Resistance ◽  
Concrete Cover ◽  
Reinforced Concrete Structure ◽  
Linear Polarization Resistance ◽  
Steel Rebar

For reinforced concrete structures, several corrosion detection methods exist: concrete resistivity, half-cell potential or linear polarization resistance (LPR) measurement. The LPR value can be linked to the corrosion rate thanks the Stern-Geary equation if strong hypotheses are made. Existing commercial devices use a guard ring to canalize the current on specific steel rebar area and assume that the steel rebar is uniformly polarized. However, recent works reveal that the top part of the steel rebar, right under the counter electrode, is the most polarized point. The particular point is referred as the point of interest (PI). This works belongs to the DIAMOND project which aims to produce a new corrosion rate measurement device. Comsol® software was used to model the influence of concrete cover, resistivity and injected current on the current density at the PI. Moreover, a significant influence of the steel rebars diameter was also demonstrated. Two types of abacus are built. The first one links to polarization measured on the surface to the polarization on the rebar at the PI. The second links the ratio between the current density at the PI and the density of injected current to concrete cover and steel rebar diameter. The Stern-Geary equation can now be used at the PI without using the approximation of a uniformly polarized rebar. The corrosion state of reinforced concrete structure can be controlled more precisely. The methodology is then applied on two concrete slabs in which three metal bars are embedded at different concrete covers. The first slab is prepared with ordinary concrete while the second contain chloride to artificially activate the corrosion process. The results reveal that the rebars embedded on the first slab are not corroding (icorr ≤0.2 μΑ/cm2) while the second rebar are corroding (icorr>0.2 μΑ/cm2).

scholarly journals PENGARUH DENSITAS ARUS TERHADAP PERILAKU RETAK BETON BERTULANG YANG MENGALAMI KOROSI TULANGAN

Teras Jurnal ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 351
Author(s):  
Zahra Amalia ◽  
Taufiq Saidi ◽  
Taufiq Saidi ◽  
Teuku Budi Aulia ◽  
Teuku Budi Aulia ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Current Density ◽  
Concrete Structure ◽  
Corrosion Products ◽  
Reinforced Concrete Structure ◽  
Accelerated Corrosion ◽  
Cracking Behavior ◽  
Cross Section Area ◽  
Lower Corrosion Rate

<p align="center"><strong>Abstrak</strong></p><p class="11daftarpustaka"> </p><p>Korosi pada struktur beton betulang dapat mengurangi kinerja struktur dan umur layannya karena volume tulangan yang berkurang. Besarnya jumlah korosi yang dipengaruhi oleh laju korosi dapat digambarkan melalui besarnya densitas arus yang terjadi. Jumlah korosi yang terjadi mempengaruhi perilaku retak pada beton bertulang, oleh karen itu, pada studi ini dilakukan uji eksperimental untuk mengevaluasi pengaruh densitas arus terhadap perilaku retak permukaan beton dari struktur beton bertulang yang mengalami korosi tulangan. Pengujian dilakukan dengan mengaplikasikan variasi densitas arus yaitu 900 µA/cm<sup>2</sup>, 500 µA/cm<sup>2</sup>, 200 µA/cm<sup>2</sup> and 100 µA/cm<sup>2</sup> pada pengujian korosi secara elektrik menggunakan larutan NaCl sebagai elektrolit untuk menghasilkan ion Cl<sup>-</sup>. Benda uji yang digunakan adalah balok dengan luas penampang 150x150 mm<sup>2</sup> dan panjang benda uji 300 mm. Tulangan baja diameter 19 mm digunakan pada tengah penampang. Hasil pengujian menunjukkan bahwa perilaku retak dari beton bertulang yang mengalami korosi pada tulangannya memiliki kurva yang bilinear. Selain itu, hasil pengujian menunjukkan bahwa densitas arus yang rendah memiliki kecepatan retak permukaan beton yang lebih tinggi jika dibandingkan dengan benda uji dengan menggunakan densitas arus yang tinggi.</p><p> </p><p>Kata kunci<em>: korosi, beton bertulang, produk korosi, retak, densitas arus</em></p><p align="center"><strong> </strong></p><p align="center"><strong>Abstract</strong></p><p class="Abstract"> </p><p>Corrosion in reinforced concrete structure can reduce structure performance and its service life due to rebar mass loss. Corrosion amount influenced by corrosion rate can be figured out by using current density. Corrosion amount influences the crack behavior of reinforced concrete, therefore, in this study, experimental study was performed to evaluate the effect of current density to surface concrete cracking behavior of corroded reinforced concrete structure. Accelerated corrosion test tests were conducted with various current density. It was 900 µA/cm2, 500 µA/cm2, 200 µA/cm2 and 100 µA/cm2. NaCl solution was used as electrolyte to produce ion Cl<sup>-</sup>. The specimens were beam with cross section area 150x150 mm<sup>2</sup> and 300 mm in length. Rebar with diameter 19 mm was applied in the center of specimen. The results showed that cracking behavior of corroded rebar has bilinear curve that shows the effect of corrosion products movement through cracks. Furthermore, lower corrosion rate has higher cracking speed than higher corrosion rate.</p><p> </p><p>Keywords: <em>corrosion, reinforced concrete, corrosion products, cracking, current density</em></p>

Assessment of the aftertreatment quality of concrete

2021 ◽  
Author(s):  
Lisa Ptacek ◽  
Alfred Strauss ◽  
Clémence Bos ◽  
Martin Peyerl
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structure ◽  
Test Methods ◽  
Reinforced Concrete Structure ◽  
Process Step ◽  
Simple Tool ◽  
Lack Of Control ◽  
Complex Construction

<p>The curing of concrete is extremely important for the durability of a reinforced concrete structure. In practice, due to the complex construction processes, the very limited phases and the lack of control, aftertreatment is often neglected by executing companies. Hence infrastructure operators are therefore very interested in having a robust, simple tool that enables aftertreatment to be easily checked and, as a result, to convey the importance of this process step to the client. In the project presented here, classic and novel test methods are presented and discussed, as well as their suitability for the detection of the aftertreatment quality on laboratory samples and subsequently on some real structures.</p>

scholarly journals Numerical Analysis of a Moderate Fire inside a Segment of a Subway Station

2018 ◽  
Vol 8 (11) ◽  
pp. 2116 ◽  
Author(s):  
Rodrigo Díaz ◽  
Hui Wang ◽  
Herbert Mang ◽  
Yong Yuan ◽  
Bernhard Pichler
Keyword(s):  
Reinforced Concrete ◽  
Surface Temperature ◽  
Concrete Structure ◽  
Fire Test ◽  
Material Behavior ◽  
Sensitivity Analyses ◽  
Subway Station ◽  
Elastic Model ◽  
Reinforced Concrete Structure ◽  
Actual Distribution

A 1:4 scaled fire test of a segment of a subway station is analyzed by means of three-dimensional Finite Element simulations. The first 30 min of the test are considered to be representative of a moderate fire. Numerical sensitivity analyses are performed. As regards the thermal boundary conditions, a spatially uniform surface temperature history and three different piecewise uniform surface temperature histories are used. As regards the material behavior of concrete, a temperature-independent linear-elastic model and a temperature-dependent elasto-plastic model are used. Heat transfer within the reinforced concrete structure is simulated first. The computed temperature evolutions serve as input for thermomechanical simulations of the fire test. Numerical results are compared with experimental measurements. It is concluded that three sources of uncertainties render the numerical simulation of fire tests challenging: possible damage of the structure prior to testing, the actual distribution of the surface temperature during the test and the time-dependent high-temperature behavior of concrete. In addition, the simulations underline that even a moderate fire represents a severe load case, threatening the integrity of the reinforced concrete structure. Tensile cracking is likely to happen at the inaccessible outer surface of the underground structure. Thus, careful inspection is recommended even after non-catastrophic fires.

Sign in / Sign up

Export Citation Format

Share Document