scholarly journals Combined Effect of Stray Current and Sustained Compressive Loading on Chloride Transport in Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yuancheng Ni ◽  
Eryu Zhu
Keyword(s):  
Transport Properties ◽  
Chloride Transport ◽  
Surrounding Medium ◽  
Compressive Loading ◽  
Steel Corrosion ◽  
Concrete Specimen ◽  
Experimental Results ◽  
Combined Effect ◽  
Stray Current ◽  
Cover Cracking

As with the leakage of stray current in the surrounding medium, the chloride transport in concrete is influenced by the stray current and loading of the subway structure. This paper presents the results of the experimental study on the chloride transport properties of concrete under the combined action of stray current and sustained compressive loading. First, an experiment was setup to explore the chloride transport in the subway structure as the concrete specimen embedded with steel under test current and study the influence of the existence of steel on the chloride transport profiles in concrete under stray current. Then, to investigate the combined effect of stray current and loading on the chloride transport properties, an improved experiment was designed with stray current and sustained compressive loading. The chloride transport profiles were measured, respectively, subjected to different stray currents and compressive stress levels. The experimental results indicated that stray current and sustained compressive loading have a significant influence on the chloride transport properties of concrete, and the loading threshold existed as the turning point of the chloride transport rate. Based on the experimental data and migration theory, the prediction model of chloride transport in concrete under stray current and sustained compressive loading was established and verified by the experimental measurements, and the steel corrosion-induced cover cracking was studied, and the comparison indicated that the numerical results were consistent with the experimental results.

The Combined Effect of Wages and Firm Profit on Employee Effort

2005 ◽  
Vol 80 (1) ◽  
pp. 167-188 ◽  
Author(s):  
R. Lynn Hannan
Keyword(s):  
Gift Exchange ◽  
Experimental Results ◽  
Combined Effect ◽  
Financial Reward ◽  
Ex Post ◽  
Employee Effort ◽  
Profit Maximizing ◽  
Firm Profit ◽  
As If

This study investigates whether paying higher wages motivates employees to provide higher effort and whether firm profit moderates this relation. Consistent with gift exchange (Akerlof 1982) and reciprocity (Rabin 1993) models, my experimental results show that workers provided more effort when they were paid higher wages even though there was no ex post financial reward for doing so. Moreover, firm profit influenced the relation between wages and effort. Workers provided higher effort when firm profit decreased compared to when it increased. This suggests that the degree of reciprocity is affected by firm profit. However, workers' responded asymmetrically to firm profit, in that they behaved as if they expected to share in firm profit increases but not decreases. Although firms were fairly adept at predicting the profit-maximizing wage strategy, they apparently did not anticipate workers' reluctance to share in firm profit decreases.

scholarly journals Investigation of Corrosion Rate and Rust Expansion Form of Segment Reinforcement for Shield Tunnel by Combined Action of Soil Loading, Chloride Ion and Stray Current

2021 ◽  
Vol 13 (6) ◽  
pp. 3444
Author(s):  
Zheng Li ◽  
Hao Jin ◽  
Shuo Yu
Keyword(s):  
Corrosion Rate ◽  
Steel Corrosion ◽  
Chloride Ion ◽  
Shield Tunnel ◽  
Uniform Corrosion ◽  
Stray Current ◽  
Soil Loading ◽  
Capacity Degradation ◽  
Expansion Form ◽  
Combined Action

Segment reinforcement corrosion can cause bearing-capacity degradation of shield tunnel, which is unsafe for the metro operation. Therefore, a three-dimensional computational model was proposed in this paper to study the corrosion rate and rust expansion form of segment reinforcement by the combined action of soil loading, chloride ion and stray current. The results show that the arch waist segment steel corrosion rate in the middle is larger than the ends. The rust expansion form of segment reinforcement appears be an eccentric circle. The radius size and circular center are related to the non-uniform corrosion coefficient and the maximum corrosion current density.

scholarly journals On the Structural Performance of Recycled Aggregate Concrete Columns with Glass Fiber-Reinforced Composite Bars and Hoops

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1508
Author(s):  
Ali Raza ◽  
Ahmad Rashedi ◽  
Umer Rafique ◽  
Nazia Hossain ◽  
Banjo Akinyemi ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Compressive Loading ◽  
Reinforcement Ratio ◽  
Recycled Aggregate Concrete ◽  
Experimental Results ◽  
Recycled Aggregate ◽  
Fiber Reinforced ◽  
Aggregate Concrete ◽  
Gfrp Bars ◽  
Glass Fiber Reinforced

Structural members comprising geopolymer recycled aggregate concrete (RAC) reinforced with glass fiber-reinforced polymer (GFRP) bars have not been investigated appropriately for axial compressive loading cases. The present study addresses this knowledge gap by evaluating the structural efficiency of GFRP-reinforced geopolymer recycled aggregate concrete (GGRAC)-based members subjected to axial compressive loading. A total of nine compressive members (250 mm in cross-section and 1150 mm in height) were constructed to examine the effect of the number of longitudinal GFRP bars and the vertical spacing of transverse GFRP hoops/ties. The experimental results portrayed that the ductility of GGRAC compressive members improved with the reduction in the pitch of GFRP hoops. The axial load-carrying capacity (LCC) of GGRAC compressive members increased by increasing the number of GFRP bars up to eight (corresponding to a reinforcement ratio of 2.11%) while it decreased by using ten longitudinal GFRP bars (corresponding to a reinforcement ratio of 2.65%). Additionally, an empirical model was suggested to predict the axial LCC of GGRAC compressive members based on a large amount of experimental data of similar members. The experimental results and related theoretical predictions substantially prove the applicability and accuracy of the proposed model. The proposed column represents a feasible structural member in terms of material availability and environmental sustainability.

Discussion on Micro-Structure and Transport Properties of Carbon Micro-Coil

2011 ◽  
Vol 399-401 ◽  
pp. 573-576
Author(s):  
Fa Yu Wu ◽  
Yi Yong Wang ◽  
Wei Juan Li ◽  
Yan Wen Zhou ◽  
Jun Wei Zhang
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
Experimental Results ◽  
Helical Conformation ◽  
Micro Structure ◽  
Electrical Transport Properties ◽  
Relationship Of

The micro-structure, the thermal and electrical transport properties, and their corresponding relationship of carbon micro-coils were discussed, based on the experimental results. The disordered micro-structure and the helical conformation of carbon micro-coils were responsible for the characteristic of their transport properties.

scholarly journals Practical and Theoretical Study on the Inhibitory Influences of New Azomethine Derivatives Containing an 8-Hydroxyquinoline Moiety for the Corrosion of Carbon Steel in 1 M HCl

2018 ◽  
Vol 34 (6) ◽  
pp. 3016-3029 ◽  
Author(s):  
A. El-Yaktini ◽  
A. Lachiri ◽  
M. El-Faydy ◽  
F. Benhiba ◽  
H. Zarrok ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Density Functional ◽  
Electrochemical Impedance ◽  
Density Functional Theory Method ◽  
Steel Corrosion ◽  
Experimental Results ◽  
Chemical Parameters ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Inhibition Ability

The inhibition ability of a new Azomethine derivatives containing the 8-hydroxyquinoline (BDHQ and MDHQ) towards carbon steel corrosion in HCl solution was studied at various concentrations and temperatures using weight loss, polarization curves and electrochemical impedance spectroscopy (EIS) methods. The experimental results reveal that BDHQ and MDHQ are efficient mixed type corrosion inhibitors, and their inhibition efficiencies increase with increasing concentration. The adsorption of these inhibitors on mild steel surface obeys Langmuir isotherm. Quantum chemical parameters are calculated using the Density Functional Theory method (DFT) and Monte Carlo simulations. Correlation between theoretical and experimental results is discussed.

Full-Field Displacement and Strain Measurement: Application of Digital Image Correlation to Reinforcement Corrosion Induced Concrete Fracture and Cover Cracking

2015 ◽  
Vol 738-739 ◽  
pp. 889-892
Author(s):  
Qiang Li ◽  
Hong Fa Yu ◽  
Jing Tong
Keyword(s):  
Reinforced Concrete ◽  
Steel Corrosion ◽  
Test Method ◽  
Image Correlation ◽  
Concrete Fracture ◽  
Reinforcement Corrosion ◽  
Full Field ◽  
Rc Structures ◽  
Whole Process ◽  
Cover Cracking

Cracking of the cover concrete due to steel corrosion is considered as one of the major issues of durability of reinforced concrete (RC) structures. This paper tentatively studies the feasibility of DIC to reinforcement corrosion induced concrete fracture and cover cracking measurement. Advantages and limitations of DIC-based non-contact full-field measurement for corrosion induced concrete fracture and cover cracking are discussed. Drawbacks in this test need improvement are pointed out and test method for further study of whole process of simulating the real reinforced concrete cracking is put forward.

scholarly journals Chloride Distribution and Steel Corrosion in a Concrete Bridge after Long-Term Exposure to Natural Marine Environment

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3900 ◽  
Author(s):  
Jun Liu ◽  
Zhilu Jiang ◽  
Yulong Zhao ◽  
Hao Zhou ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Marine Environment ◽  
Chloride Transport ◽  
Steel Corrosion ◽  
Concrete Bridge ◽  
Reinforced Concrete Structure ◽  
X Ray Diffraction ◽  
Tidal Zone ◽  
X Ray

Chloride-induced steel corrosion is the most concerning issue for the durability of concrete structures. Concrete and steel samples were obtained from a 30-year-old reinforced concrete bridge. The chloride content was measured by a potentiometric titration method and the microstructure of concrete was obtained by scanning electron microscopy and mercury intrusion porosimetry. The rust phases of the steel were detected by X-ray diffraction and Raman analysis. It was found that the convection depth for chloride transport in cracked concrete was significantly larger than that in uncracked concrete. The concrete in a pier column facing upstream had greater porosity due to the water impact and calcium leaching. The coefficients of variability of chloride diffusivity of concrete for the bridge deck and the pier column were significantly different. Rust phases including lepidocrocite, goethite, akaganeite, magnetite, and maghemite were detected using Raman spectroscopy and X-ray diffraction. The major phases of steel rust in the atmospheric zone were lepidocrocite and goethite, while they were lepidocrocite and maghemite in the tidal zone. The results of this study would provide information concerning the chloride-induced steel corrosion under a marine environment in order to predict long-term behaviors of a reinforced concrete structure.

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