Macrocell corrosion mechanisms of prestressing strands in various concretes

Corrosion of concrete reinforcement at a patch repair is a complex problem, and current knowledge of its mechanism is quite limited. This review examined the correlation between two corrosion mechanisms, macrocell and microcell corrosion, from fundamental electrochemical principles. It was found that both mechanisms could play significant roles in inducing corrosion damage, contrary to the prevailing opinion that macrocell corrosion is the main deterioration mechanism in patch repair. This has practical implications that need to be considered for an effective and durable repair. A review of the studies done to date also enabled the identification of the key factors in patch repair controlling the corrosion characteristics. Corrosion could occur at different locations in the vicinity of the patch — substrate, interface, or patch area — depending on the respective electrochemical environments induced by the repair material properties and treatments, as well as the in-service exposure and mechanical loading. The review indicates that much of the needed research should focus on identification of corrosion mechanisms to effect successful patch repair in reinforced concrete structures.Key words: patch repair, substrate, corrosion, macrocell corrosion, microcell corrosion.

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Corrosion Characteristics and Corrosion Current Distribution of Steel Bar in Carbonated Concrete

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.239-242.3371 ◽

2011 ◽

Vol 239-242 ◽

pp. 3371-3376 ◽

Cited By ~ 1

Author(s):

Yong Sheng Ji ◽

Jian Li Shen ◽

Lei Wang ◽

Cong Yu Xu

Keyword(s):

Current Distribution ◽

Experimental Verification ◽

Corrosion Current ◽

General Assumption ◽

Concrete Cover ◽

Corrosion Mechanism ◽

General Corrosion ◽

Steel Bar ◽

Corrosion Mechanisms ◽

Macrocell Corrosion

The corrosion characteristics of steel bar in concrete are decided by the corrosion current distribution along the circumference of the steel bar. It is a general assumption that carbonation lead to a general corrosion on the rebar. However, the destruction of a large number of specimens indicated that before corrosion cracking, the carbonation-induced corrosion mainly distributes on the surface of the steel bar facing the concrete cover. This paper examined the corrosion mechanism from fundamental electrochemical principles and experimental verification. It was illustrated that the macrocell corrosion must co-exist with microcell corrosion, both macrocell and microcell corrosion mechanisms could play significant roles, and the total corrosion could be underestimated if each of two is overlooked.

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Theoretical study of the prestressing strand's stress by computer modeling methods

Ferrous Metallurgy Bulletin of Scientific Technical and Economic Information ◽

10.32339/0135-5910-2020-111-1139-1148 ◽

2020 ◽

Vol 76 (11) ◽

pp. 1139-1148

Author(s):

A. G. Korchunov ◽

E. M. Medvedeva ◽

E. M. Golubchik

Keyword(s):

Residual Stresses ◽

High Strength ◽

Pearlitic Steel ◽

Internal Stresses ◽

Steel Microstructure ◽

Compressive Stresses ◽

Wide Range ◽

Prestressing Strands ◽

Increasing Temperature ◽

Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

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Formation of Iron Sulfides on Carbon Steel in a Specific Cement Grout Designed for Radioactive Waste Repository and Associated Corrosion Mechanisms

Materials ◽

10.3390/ma14133563 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3563

Author(s):

Mathieu Robineau ◽

Valérie Deydier ◽

Didier Crusset ◽

Alexandre Bellefleur ◽

Delphine Neff ◽

...

Keyword(s):

Carbon Steel ◽

Radioactive Waste ◽

Corrosion Product ◽

Product Layer ◽

Cement Grout ◽

Radioactive Waste Disposal ◽

Sulfide Concentration ◽

Iron Sulfides ◽

Corrosion Mechanisms ◽

A Minor

Carbon steel coupons were buried in a specific low-pH cement grout designed for radioactive waste disposal and left 6 months in anoxic conditions at 80 °C. The corrosion product layers were analyzed by µ-Raman spectroscopy, XRD, and SEM. They proved to be mainly composed of iron sulfides, with magnetite as a minor phase, mixed with components of the grout. Average corrosion rates were estimated by weight loss measurements between 3 and 6 µm yr−1. Corrosion profiles revealed local degradations with a depth up to 10 µm. It is assumed that the heterogeneity of the corrosion product layer, mainly composed of conductive compounds (FeS, Fe3S4, and Fe3O4), promotes the persistence of corrosion cells that may lead to locally aggravated degradations of the metal. New cement grouts, characterized by a slightly higher pH and a lower sulfide concentration, should then be designed for the considered application.

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Recent progress on the corrosion behavior of metallic materials in HF solution

Corrosion Reviews ◽

10.1515/corrrev-2020-0101 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Hailong Dai ◽

Shouwen Shi ◽

Lin Yang ◽

Can Guo ◽

Xu Chen

Keyword(s):

Environmental Factors ◽

Stainless Steels ◽

Hydrofluoric Acid ◽

Recent Progress ◽

Future Research ◽

Fluoride Ion ◽

Metallic Materials ◽

Chemical Coupling ◽

Corrosion Behaviors ◽

Corrosion Mechanisms

Abstract Hydrofluoric acid (HF) or fluoride ion corrosion issues are often encountered in many fields, which have attracted extensive research due to its strong corrosiveness. In this paper, a critical review is presented based on recent progress on HF corrosion. In view of the discrepancy of fluoride ion compared with other ions, the special attack characteristics of fluoride ion are firstly discussed. Afterwards, the corrosion mechanisms of stainless steels, nickel-based alloys, and titanium alloys in HF solution or fluoride ion-containing environment are reviewed, and three typical corrosion behaviors are summarized, which are essentially weakening process of passivation of metallic materials. The effects of influencing factors (e.g. alloying elements, environmental factors, and stress, etc.) on HF corrosion are also discussed, which involve changes in passivation mechanism, the influence of HF attack mode and multiple damage mechanisms due to mechanical–chemical coupling. Finally, future research works on HF corrosion are proposed.

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Microstructure and Corrosion Behavior of Ni-Alloy/CrN Nanolayered Coatings

Journal of Nanomaterials ◽

10.1155/2011/137498 ◽

2011 ◽

Vol 2011 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Hao-Hsiang Huang ◽

Fan-Bean Wu ◽

Jyh-Wei Lee ◽

Li-Chun Chang

Keyword(s):

Corrosion Behavior ◽

Single Layer ◽

Phase Identification ◽

Bilayer Thickness ◽

Ni Alloy ◽

Nitride Coatings ◽

Superior Corrosion Resistance ◽

Corrosion Mechanisms ◽

Steel Substrates ◽

Crn Coatings

The Ni-alloy/CrN nanolayered coatings, Ni-Al/CrN and Ni-P/CrN, were deposited on (100) silicon wafer and AISI 420 stainless steel substrates by dual-gun sputtering technique. The influences of the layer microstructure on corrosion behavior of the nanolayered thin films were investigated. The bilayer thickness was controlled approximately 10 nm with a total coating thickness of . The single-layer Ni-alloy and CrN coatings deposited at were also evaluated for comparison. Through phase identification, phases of Ni-P and Ni-Al compounds were observed in the single Ni-alloy layers. On the other hand, the nanolayered Ni-P/CrN and Ni-Al/CrN coatings showed an amorphous/nanocrystalline microstructure. The precipitation of Ni-Al and Ni-P intermetallic compounds was suppressed by the nanolayered configuration of Ni-alloy/CrN coatings. Through Tafel analysis, the and values ranged from –0.64 to –0.33 V and to A/, respectively, were deduced for various coating assemblies. The corrosion mechanisms and related behaviors of the coatings were compared. The coatings with a nanolayered Ni-alloy/CrN configuration exhibited a superior corrosion resistance to single-layer alloy or nitride coatings.

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Electrochemical reactivity, surface composition and corrosion mechanisms of the complex metallic alloy Al3Mg2

Corrosion Science ◽

10.1016/j.corsci.2009.10.015 ◽

2010 ◽

Vol 52 (2) ◽

pp. 562-578 ◽

Cited By ~ 52

Author(s):

Ming Liu ◽

Patrik Schmutz ◽

Sandrine Zanna ◽

Antoine Seyeux ◽

Helene Ardelean ◽

...

Keyword(s):

Surface Composition ◽

Metallic Alloy ◽

Electrochemical Reactivity ◽

Corrosion Mechanisms

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Corrosion Mechanisms for Copper and Silver Objects in Near-Surface Environments

Journal of the American Institute for Conservation ◽

10.1179/019713692806066574 ◽

1992 ◽

Vol 31 (3) ◽

pp. 355-366 ◽

Cited By ~ 12

Author(s):

Michael B. Mcneil ◽

Brenda J. Little

Keyword(s):

Near Surface ◽

Corrosion Mechanisms

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Computational and Experimental Insights into the Role of Acidic Molecules on the Corrosion Behavior on 7A46 Aluminum Alloy

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19087 ◽

2021 ◽

Vol 21 (4) ◽

pp. 2221-2233

Author(s):

Yaru Liu ◽

Qinglin Pan ◽

Xiangdong Wang ◽

Ye Ji ◽

Qicheng Liu ◽

...

Keyword(s):

Corrosion Resistance ◽

Aluminum Alloy ◽

Corrosion Behavior ◽

First Principles ◽

First Principles Calculations ◽

Corrosive Media ◽

Corrosion Depth ◽

Corrosion Mechanisms ◽

Nanoscale Level

The corrosion mechanisms for different corrosive media on the aged 7A46 aluminum alloy were systematically investigated at nanoscale level. The combination of empirical intergranular and exfoliation corrosion behavior was employed, and coupled with first-principles calculations. Results revealed that the dispersed distribution of matrix precipitates (MPs) leads to the enhancement of the corrosion resistance pre-ageing (PA) followed by double-ageing (PA-DA) alloy. The deepest corrosion depth of PA-DA alloy was in hydrochloric acid, and the calculation result demonstrates that the passivation effect in combination with the accumulation of corrosion products in nitric acid protect the PA-DA alloy from further corrosion.

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