scholarly journals Study on the Durability of the T-Beam Based on Chloride Ion Erosion

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1504
Author(s):  
Lifeng Gu ◽  
Guowen Yao ◽  
Xuanrui Yu ◽  
Qiaoyi Li
Keyword(s):  
Crack Width ◽  
Failure Modes ◽  
Crack Depth ◽  
Chloride Ion ◽  
Shear Capacity ◽  
Chloride Ions ◽  
Beam Model ◽  
Bending Capacity ◽  
T Beam ◽  
Ion Erosion

Based on analyzing the bearing capacity of existing T-beam bridges in service, the factors that affect the T-beams cracked by chloride ions mainly include the width and the depth of cracks. Combined with practical engineering examples, a single-piece T-beam model is established to explore the influence of factors such as crack width and crack depth on the T-beams affected by chloride ion erosion through numerical simulation in this paper. In addition, the attenuation models of bending capacity and shear capacity of the T-beam are obtained to analyze the possible failure modes of T-beams with cracks. All of which provides a reference for exploring the effect of crack width and depth on the durability of reinforced concrete members under chloride ion field.

Chloride Diffusivity in Cracked Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 113-117 ◽  
Author(s):  
Shi Ping Zhang ◽  
Lan Zong ◽  
Jia Ping Liu
Keyword(s):  
Crack Width ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Chloride Permeability ◽  
Chloride Diffusivity ◽  
Analysis Technique ◽  
Average Crack ◽  
Splitting Tensile Test ◽  
Penetration Profile ◽  
Cracked Specimens

A detailed observation on the penetration profile of chloride ions through a crack in concrete structures was carried out. Cracks were induced using a splitting tensile test, and average crack width was measured using an image analysis technique. Chemical analysis tests were conducted on cracked specimens, which were exposed to NaCl solution at a temperature of 20°C, after being cured for 28d. The results showed that the concrete specimens having cracks showed rapid penetration of chloride ion. The diffusion coefficient calculated according to Fick’s law also indicated that the chloride permeability increased with the increasing crack width.

scholarly journals Experimental Research on Joint Mechanical Behavior of Container Structures

2015 ◽  
pp. 215-222
Author(s):  
Ye Lu ◽  
GuoQiang Li ◽  
Lei Mao
Keyword(s):  
Failure Modes ◽  
High Efficiency ◽  
Low Cost ◽  
Tall Buildings ◽  
Shear Capacity ◽  
Modular System ◽  
Building Industry ◽  
Flexural Stiffness ◽  
Structural System ◽  
Bending Capacity

In recent years, building industry in China is experiencing upgrade and industrialization becomes popular. Container building has many advantages including low cost, high efficiency and clean construction. Therefore it is the most promising kind of industrialized building. The joint of boxes in container buildings is one of the main bottlenecks in restricting box-type architecture in multi-story and tall buildings. To solve this problem in box-type buildings, this paper present a new joint of boxes applied to a specific structural system named as column-bearing box-type modular system. The tensile capacity, shear capacity and corresponding failure modes of vertical two-box joint are obtained through experimental study. Meanwhile the flexural bending capacity and flexural stiffness of the vertical two-box joint are studied.

Chloride Ion Erosion in Concrete under Sustained Axial Pressure

2016 ◽  
Vol 680 ◽  
pp. 402-405
Author(s):  
Zong Ming Yang ◽  
Wei Hong Li ◽  
Yi Han Wang
Keyword(s):  
Axial Compression ◽  
Concrete Structure ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Reinforcement Corrosion ◽  
Compression Load ◽  
Durability Design ◽  
Chloride Ion Penetration ◽  
Chloride Environment ◽  
Ion Erosion

As one of the leading causes of influencing the durability of concrete structure, reinforcement corrosion has been a central issue. Erosion of chloride ions on the concrete structure is influenced by many factors. This is not only concerned with its own structural properties, but also to its environment, to withstand the load and other factors. This article has carried on an experiment which researches on the rules of chloride ion penetration in the sustained axial compression after different corrosive time, when the concrete is corroded under the joint action of axial compression load and chlorine salt circulation. The results prove that, with the increase of Intensity of load and the cycle time of chlorine salt, the number of Chloride ion ingress in concrete continues to increase. The experimental results may provide a reference to the durability design of concrete in chloride environment.

scholarly journals Effects of Transverse Crack on Chloride Ions Diffusion and Steel Bars Corrosion Behavior in Concrete under Electric Acceleration

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2481 ◽  
Author(s):  
Fengyin Du ◽  
Zuquan Jin ◽  
Chuansheng Xiong ◽  
Yong Yu ◽  
Junfeng Fan
Keyword(s):  
Transmission Coefficient ◽  
Corrosion Behavior ◽  
Crack Width ◽  
Steel Corrosion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Transverse Cracks ◽  
Steel Bars ◽  
Ion Transmission

Cracks greatly impact the durability of concrete structures due to their influence on the migration of chloride ions and the corrosion process of steel bars. This study investigates the effects of transverse cracks on chloride diffusion and the corrosion behavior of two types of steel bars (low carbon steel and corrosion resistant steel) in fly ash concrete with 1 kg/m3 solution-polymerized super absorbent polymer. Electrochemical impedance spectroscopy was used to monitor the chloride-induced corrosion behavior of steel bars in concrete. The chloride profile around cracks was tested via chemical titration. The corrosion products diffusion area was photographed and measured to evaluate the influences of cracks on the corrosion degree of steel bars. Transverse cracks greatly influence the chloride ion transport. When their width is less than 0.15 mm, cracks exert little influence on both chloride diffusion and steel corrosion. When the crack width exceeds 0.15 mm, the chloride ion transmission coefficient is significantly improved and steel corrosion is accelerated. However, when the crack width exceeds 0.20 mm, this effect is gradually weakened. Based on the experimental data, a quantitative relationship between the crack width and the chloride ion transmission coefficient in electric acceleration was established.

Experimental Research on Ultimate Bending Capacity of Reinforced Concrete Poles in Service Period

2011 ◽  
Vol 368-373 ◽  
pp. 2468-2472
Author(s):  
Kai Quan Xia ◽  
Ni Wang ◽  
Zong Ping Chen ◽  
Ming Zhong
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Failure Modes ◽  
Design Method ◽  
Limit State ◽  
Bending Test ◽  
Experiment Data ◽  
Reinforced Beams ◽  
Service Period ◽  
Bending Capacity

In order to evaluate safety performance of reinforced concrete poles accurately, 6 reinforced concrete pole specimens were selected randomly for the bending test. The mechanical behavior and failure mechanism of all specimens were studied, failure modes were revealed, and important experiment data were also obtained, such as cracking loading, ultimate loading, crack development shape, crack width and so on. Based on the experiment data, moment-crack width relationship curve and moment-deflection relationship curve were obtained. Research results showed that failure modes of specimens were similar to “less-reinforced beams”, based on limit state design method in normal use, security surplus factor is 1.27 before collapse damage.

scholarly journals Effect of Steel Fiber Content on Shear Behavior of Reinforced Expanded-Shale Lightweight Concrete Beams with Stirrups

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1107
Author(s):  
Changyong Li ◽  
Minglei Zhao ◽  
Xiaoyan Zhang ◽  
Jie Li ◽  
Xiaoke Li ◽  
...  
Keyword(s):  
Crack Width ◽  
Failure Modes ◽  
Steel Fiber ◽  
Lightweight Concrete ◽  
Volume Fraction ◽  
Shear Crack ◽  
Shear Capacity ◽  
Shear Cracks ◽  
Shear Cracking ◽  
Expanded Shale

To determine the validity of steel fiber reinforced expanded-shale lightweight concrete (SFRELC) applied in structures, the shear behavior of SFRELC structural components needs to be understood. In this paper, four-point bending tests were carried out on reinforced SFRELC beams with stirrups and a varying volume fraction of steel fiber from 0.4% to 1.6%. The shear cracking force, shear crack width and distribution pattern, mid-span deflection, and failure modes of test beams were recorded. Results indicate that the shear failure modes of reinforced SFRELC beams with stirrups were modified from brittle to ductile and could be transferred to the flexure mode with the increasing volume fraction of steel fiber. The coupling of steel fibers with stirrups contributed to the shear cracking force and the shear capacity provided by the SFRELC, and it improved the distribution of shear cracks. At the limit loading level of beams in building structures at serviceability, the maximum width of shear cracks could be controlled within 0.3 mm and 0.2 mm with the volume fraction of steel fiber increased from 0.4% to 0.8%. Finally, the formulas are proposed for the prediction of shear-cracking force, shear crack width, and shear capacity of reinforced SFRELC beams with stirrups.

Bending Capacity of Reinforced Concrete Box-Girders Strengthened with SMPM Laminates

2011 ◽  
Vol 368-373 ◽  
pp. 2235-2240
Author(s):  
Tong Guo ◽  
Wen Hai Chen ◽  
Yong Sheng Song
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Shear Capacity ◽  
Wire Mesh ◽  
Test Results ◽  
Box Girders ◽  
Bending Tests ◽  
Bending Capacity ◽  
Polymer Mortar ◽  
Bending Failure

Steel stranded wire mesh and polymer mortar (SMPM) is a novel technique recently developed for structural strengthening. To investigate the feasibility of strengthening reinforced concrete (RC) bridge box-girders with SMPM, bending tests on three scaled RC box-girders were made, based on which formulas for predicting the bending and debonding capacities of the strengthened RC box-girders are proposed. First, the box section is represented by the T section using the effective width factor in the elastoplastic stage. Then, based on the equivalent height of compressive region, bending failure modes of the strengthened girders are classified, and equations regarding the ultimate bending capacity corresponding to each failure mode are established respectively. To account for the debonding failure observed in the tests, a shear-capacity-based model is proposed. Comparison was made between the analytical and existing test results.

scholarly journals A Research About One-dimensional Chloride Ion Erosion In Concrete Under Drying-wetting Cycles

2021 ◽  
Vol 272 ◽  
pp. 01020
Author(s):  
Hang Shen ◽  
Jinyuan Li ◽  
Changyuan Chen ◽  
Yongli Li ◽  
Wenjun Ji
Keyword(s):  
Concrete Structures ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Marine Resources ◽  
One Dimensional ◽  
Service Environment ◽  
Tidal Stream ◽  
Saturated Concrete ◽  
The One ◽  
Ion Erosion

Reinforced concrete structures are now widely used in China, and with the exploitation of marine resources, many concrete structures are in a relatively harsh service environment. Concrete in wave and tidal stream areas is in a dry and wet cycle state. When unsaturated concrete is in a dry and wet cycle state, chloride ions will invade the concrete by diffusion and convection, which accelerates the erosion of the reinforcement within the concrete and degrades the concrete performance. Therefore, the study of chloride ion erosion in concrete under dry and wet cycles is particularly important. Fick’s law is a good predictor of the diffusion of chloride ions in saturated concrete with stable boundaries, but it is difficult to obtain satisfactory results for concrete under dry and wet cycles. There are many difficult parameters in the microscopic model that make programming the calculations more difficult. In this paper, we propose to use the radial basis function matching point method to solve the problem. It is found that the error is within acceptable limits and can be used to calculate the one-dimensional erosion of chloride ions under dry and wet cycles through solving the validation algorithm.

scholarly journals Experimental Study and Simulation Calculation of the Chloride Resistance of Concrete under Multiple Factors

2021 ◽  
Vol 11 (12) ◽  
pp. 5322
Author(s):  
Yang Ding ◽  
Tong-Lin Yang ◽  
Hui Liu ◽  
Zhen Han ◽  
Shuang-Xi Zhou ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Penetration Depth ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Chloride Ions ◽  
Finite Element Software ◽  
Chloride Resistance ◽  
Simulation Calculation ◽  
Marine Concrete ◽  
Resistance Performance

Cement is widely used in marine concrete, and its resistance to chloride ion corrosion has been widely considered. In this paper, based on a laboratory test, the influence of different hydrostatic pressures, coarse aggregate contents and w/c ratios on the chloride resistance performance is analyzed. Based on COMSOL finite element software, a two-dimensional cementitious materials model is established, and the simulation results are compared with the experimental results. The results show that the penetration depth of chloride ions in cement increases with the increase of the w/c ratio. Under the hydrostatic pressure of 0 MPa, when the w/c ratio is 0.35, the penetration depth of chloride ions is 7.4 mm, and the simulation result is 8.0 mm. When the w/c ratio is 0.45, the penetration depth of chloride ions is 9.3 mm, and the simulation result is 9.9 mm. When the w/c ratio is 0.55, the penetration depth of chloride ions is 12.9 mm, and the simulation result is 12.1 mm. Under different hydrostatic pressures, the penetration depth of chloride ions obviously changes, and with the increase in hydrostatic pressure, the penetration depth of chloride ions deepens. Under the w/c ratio of 0.35, when the hydrostatic pressure is 0.5 MPa, the penetration depth of chloride ions is 11.3 mm, and the simulation result is 12.1 mm. When the hydrostatic pressure is 1.0 MPa, the penetration depth of chloride ions is 16.2 mm, and the simulation result is 17.5 mm.

scholarly journals Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec ◽  
Patryk Włodarczyk
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Spectroscopy ◽  
Low Frequency ◽  
Chloride Ion ◽  
Ion Source ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Broadband Dielectric Spectroscopy ◽  
Free Chloride ◽  
Structure Rebuilding

AbstractThe dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [Bi2O2]2+ layers and their growth, which increased the intensity of the (101) diffraction peak. The electrical conductivity and dielectric permittivity were related to the movement of chloride ions between plates (in the low-frequency region), the interplanar motion of Cl− ions at higher frequencies, vibrations of these ions, and charge carrier hopping at frequencies above 10 kHz. The influence of the free chloride ion concentration on the electrical conductivity was also described. Structure rebuilding was associated with a lower concentration of free chloride ions, which significantly decreased the conductivity. According to the analysis, the BiOCl plate conductivity was related to the movement of Cl− ions, not electrons.

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