Corrosion Behaviors of Reinforcing Steel in Concrete with Various Moisture Contents

2019 ◽  
Vol 805 ◽  
pp. 100-105 ◽  
Author(s):  
Zhong Lu Cao
Keyword(s):  
Reinforcing Steel ◽  
Half Cell ◽  
Cell Potential ◽  
Moisture Contents ◽  
Macro Cell ◽  
Saturated State ◽  
Cell Current ◽  
Corrosion Behaviors ◽  
Water Saturated ◽  
Kinetics Of

Moisture contents of concrete can affect the corrosion of reinforcing steel. In this paper, moisture contents of concrete were increased by filling the small holes with water or fully submerging in water. The effect of moisture contents on the corrosion behaviors of cathodic and anodic steel was investigated by comparing the half-cell potential, micro-cell and macro-cell current density. The results indicated that when only the concrete around cathodic steel was in water-saturated state, it could greatly weakened the kinetics of cathodic reaction and resulted in a considerable decrease in macro-cell current. When only the concrete around anodic steel was in water-saturated state, it could not effectively inhibit the macro-cell corrosion. When both the concrete around the cathodic steel and the anodic steel were in water-saturated state, the macro-cell current flowing between cathode and anode could be inhibited effectively, and the corrosion was little affected by chloride contents.

Effect of Water Conditions on Macro-Cell Corrosion Potential Difference and Current Density of Reinforcing Steel in Concrete

2020 ◽  
Vol 831 ◽  
pp. 87-94
Author(s):  
Zhong Lu Cao
Keyword(s):  
Water Content ◽  
Current Density ◽  
Corrosion Potential ◽  
Potential Difference ◽  
Limiting Factor ◽  
Reinforcing Steel ◽  
Effect Of Water ◽  
Macro Cell ◽  
Water Conditions ◽  
Cell Current

In marine concrete structure, corrosion behaviors of reinforcing steel in atmosphere, splash, water-level-fluctuating and underwater zone are significantly different. This paper investigated and analyzed the effect of water conditions on the macro-cell corrosion potential difference and macro-cell current density of steel in concrete free of chloride and concrete contaminated by chloride. Results indicated that in concrete that is free of chloride and with low water content, its resistance becomes the limiting factor for the formation of macro-cell current. The increase of water content of concrete could promote the flow of macro-cell current. In concrete contaminated with chloride, only the water-saturated state of anode was little helpful to inhibit the macro-cell current, but the increase of water content of concrete around the cathodic steel could weaken the macro-cell corrosion. The water condition of cathode and anode could play an important role in controlling the ratio of magnitude of macro-cell current to micro-cell current.

Passive corrosion control and active corrosion prevention of the reinforced concrete structures by electrochemical chloride removal and inhibitors

2013 ◽  
Vol 61 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Guofu Qiao ◽  
Yi Hong ◽  
Tiejun Liu ◽  
Jinping Ou
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Corrosion Control ◽  
Cell Potential ◽  
Content Type ◽  
Chloride Removal ◽  
Active Corrosion

Purpose – The aim of this paper was to investigate the passive corrosion control and active corrosion protective effect of the reinforced concrete structures by electrochemical chloride removal (ECR) method and inhibitors approach, respectively. Design/methodology/approach – The concentration of aggressive chloride ion distributed from the reinforcing steel to the surface of the concrete cover was analyzed during the ECR processes. Besides, the half-cell potential, the concrete resistance R c , the polarization resistance R p and the capacitance of double layer C dl of the steel/concrete system were used to characterize the electrochemical performance of the concrete prisms. Findings – The effectiveness of ECR could be enhanced by increasing the amplitude of potential or prolonging the time. Inhibitor SBT-ZX(I) could successfully prevent the corrosion development of the reinforcing steel in concrete. Originality/value – The research provides the scientific basis for the practical application of ECR and inhibitors in the field.

scholarly journals Experimental Study on the Softening Characteristics of Sandstone and Mudstone in Relation to Moisture Content

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Gui-chen Li ◽  
Chong-chong Qi ◽  
Yuan-tian Sun ◽  
Xiao-lin Tang ◽  
Bao-quan Hou
Keyword(s):  
Moisture Content ◽  
Vertical Displacement ◽  
Surface Porosity ◽  
Shear Tests ◽  
Moisture Contents ◽  
Dynamic Finite Element ◽  
Rock Types ◽  
Underground Roadway ◽  
The Stability ◽  
Kinetics Of

The kinetics of fluid-solid coupling during immersion is an important topic of investigation in rock engineering. Two rock types, sandstone and mudstone, are selected in this work to study the correlation between the softening characteristics of the rocks and moisture content. This is achieved through detailed studies using scanning electron microscopy, shear tests, and evaluation of rock index properties during exposure to different moisture contents. An underground roadway excavation is simulated by dynamic finite element modeling to analyze the effect of moisture content on the stability of the roadway. The results show that moisture content has a significant effect on shear properties reduction of both sandstone and mudstone, which must thus be considered in mining or excavation processes. Specifically, it is found that the number, area, and diameter of micropores, as well as surface porosity, increase with increasing moisture content. Additionally, stress concentration is negatively correlated with moisture content, while the influenced area and vertical displacement are positively correlated with moisture content. These findings may provide useful input for the design of underground roadways.

scholarly journals How nutrient rich are decaying cocoa pod husks? The kinetics of nutrient leaching

2021 ◽  
Author(s):  
D.-G. J. M. Hougni ◽  
A. G. T. Schut ◽  
L. S. Woittiez ◽  
B. Vanlauwe ◽  
K. E. Giller
Keyword(s):  
Nutrient Release ◽  
Nutrient Content ◽  
Nutrient Leaching ◽  
Intense Rainfall ◽  
Decomposition Rates ◽  
Rainfall Events ◽  
Rainfall Frequency ◽  
Water Saturated ◽  
Kinetics Of ◽  
Cocoa Pod Husks

Abstract Aim Recycling of cocoa pod husks has potential to contribute to mineral nutrition of cocoa. Yet little is known of the nutrient content and nutrient release patterns from the husks. The potassium (K) rich husks are usually left in heaps in cocoa plantations in Africa. We aimed to understand and quantify release patterns of K and other nutrients from husks under varying rainfall regimes and assessed the effects of partial decomposition and inundation on nutrient leaching rates. Methods We incubated chunks of cocoa pod husks to assess decomposition rates and we measured nutrient leaching rates from two sets of husk chunks: one set was placed in tubes that were submitted to simulated scheduled rainfall events while the second set was continuously inundated in beakers. Results Decomposition of husks followed a second-order exponential curve (k: 0.09 day−1; ageing constant: 0.43). Nutrient losses recorded within 25 days were larger and more variable for K (33%) than for other macronutrients released in this order: Mg > Ca ≈ P > N (less than 15%). Potassium leaching was mainly driven by rainfall frequency (P < 0.05) and reinforced by intense rainfall, especially at lower frequency. Under water-saturated conditions, 11% of K was leached out within 48 h from fresh husks compared with 92% from partially decayed husks. Conclusion Some initial decomposition of cocoa pod husks is required to expose K to intense leaching. As decomposition progresses, abundant K losses are to be expected under frequent and/or intense rainfall events.

Quantifying chloride-induced corrosion from half-cell potential

1993 ◽  
Vol 23 (6) ◽  
pp. 1443-1454 ◽  
Author(s):  
R.K. Dhir ◽  
M.R. Jones ◽  
M.J. McCarthy
Keyword(s):  
Half Cell ◽  
Cell Potential ◽  
Chloride Induced Corrosion
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