Corrosion of Post-Tensioned Tendons with Deficient Grout, Part 1: Electrochemical Behavior of Steel in Alkaline Sulfate Solutions

CORROSION ◽  
10.5006/2541 ◽  
2017 ◽  
Vol 74 (3) ◽  
pp. 362-371 ◽  
Author(s):  
K.K. Krishna Vigneshwaran ◽  
S. Permeh ◽  
M. Echeverría ◽  
K. Lau ◽  
I. Lasa
Keyword(s):  
Passive Film ◽  
Alkaline Solutions ◽  
Corrosion Mechanism ◽  
Solution Ph ◽  
Steady State Condition ◽  
Sulfate Ions ◽  
Sulfate Solutions ◽  
Corrosion Of Steel ◽  
Post Tensioned

Severe corrosion recently documented in Florida post-tensioned bridges were related to grout segregation that created deficient grout with characteristics of having low chloride content, high sulfate concentration, high pore water pH, and high moisture content. The role of elevated sulfate concentrations in the development of steel corrosion in deficient grout has not been elucidated. As first approach to determine the corrosion mechanism of steel strand in deficient grout, the objective of the research, described here, was to evaluate the role of sulfate ions on the corrosion of steel in alkaline solutions. Steel coupons were exposed to two different alkaline solutions (SPS) simulating pore solutions with pH 12.6 (SPS1) or 13.3 (SPS2) with varying sodium sulfate levels (early fixed content and later increments). Electrochemical experiments included the steady-state condition and potentiodynamic polarization tests. Solution pH was found as an important parameter in the corrosion development of steel in sulfate SPS solutions. In the highly SPS2 solution (pH 13), sulfate ions did not impair passive film growth or stability. In the moderate SPS1 solution (pH 12.6), early fixed sulfate presence could be aggressive by impairing passive film development; however, even high levels of later increments of sulfates cannot depassivate steel. The instability of the passive film in alkaline sulfate solutions resulted in pitting corrosion of steel.

Characteristics of the Oxides Films formed on Alloy C-22

2002 ◽  
Vol 757 ◽  
Author(s):  
Alan W. Szmodis ◽  
Kelly L. Anderson ◽  
Joseph C. Farmer ◽  
Tiangan Lian ◽  
Christine A. Orme
Keyword(s):  
Corrosion Rate ◽  
Oxide Film ◽  
Aqueous Solutions ◽  
Passive Film ◽  
Electrochemical Potential ◽  
Solution Ph ◽  
Protective Oxide ◽  
Wide Range ◽  
Electrochemical Potentials

ABSTRACTThe passive corrosion rate of Alloy C-22 is exceptionally low in a wide range of aqueous solutions, temperatures and electrochemical potentials. Alloy C-22 contains approximately 22% chromium (Cr) by weight; thus, it forms a Cr-rich passive film in most environments. A study of the composition, thickness and other properties of the passive film was undertaken to better understand the role of the protective oxide in preventing corrosion. In general the oxide film is expected to be a function of solution pH, temperature and applied electrochemical potential. In this work we focus on the oxide films that form at pH=8.

scholarly journals Mechanisms of passivation and chloride-induced corrosion of mild steel in sulfide-containing alkaline solutions

2021 ◽  
Author(s):  
Shishir Mundra ◽  
John L. Provis
Keyword(s):  
Mild Steel ◽  
Surface Film ◽  
Critical Role ◽  
Chloride Concentration ◽  
Alkaline Solutions ◽  
Sulfide Concentration ◽  
Chloride Induced Corrosion ◽  
Alkaline Sulfide ◽  
High Sulfide

AbstractThe pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on the surface film formed on steel reinforcement is poorly understood. This study investigates the critical role of HS− in defining mild steel passivation chemistry. The surface film formed on the steel in alkaline-sulfide solutions contains Fe(OH)2 and Fe–S complexes, and the critical chloride concentration to induce corrosion increases at high sulfide concentration. However, this behavior is dependent on the duration of exposure of the steel to the electrolyte, and the nature of the sulfidic surface layer.

Breakdown of Passive Film on Copper in Bicarbonate Solutions Containing Sulfate Ions

1992 ◽  
Vol 139 (9) ◽  
pp. 2409-2418 ◽  
Author(s):  
I. Milošev ◽  
M. Metikoš‐Huković ◽  
M. Drogowska ◽  
H. Ménard ◽  
L. Brassard
Keyword(s):  
Passive Film ◽  
Sulfate Ions ◽  
Bicarbonate Solutions

The Study about Environmentally-Friendly Passivation Technology Process and Performance on Brass Surface

2011 ◽  
Vol 399-401 ◽  
pp. 1967-1971
Author(s):  
Hong Yin Xu ◽  
Li Li
Keyword(s):  
Corrosion Resistance ◽  
Phytic Acid ◽  
Passive Film ◽  
Ph Value ◽  
Sodium Molybdate ◽  
Solution Ph ◽  
Sulfosalicylic Acid ◽  
Passivation Film ◽  
Brass Surface ◽  
And Performance

The paper through the synergy before mixed Phytic acid and Sodium molybdate, Sulfosalicylic acid, Organic silane, and add the active substances PEG, Optimize the Passivation liquid formula of Brass surface, Phytic acid is the main ingredient, study the affection of Phytic acid Passive film Corrosion resistance on the three main Passivation conditions: Passivation temperature, time and Passivation solution PH value. The results show that，Phytic acid passivation film process recipes as follows：Phytic acid (quality score 50%) 2~5ml/L, sodium molybdate 4~8g/L, organic material 10~30ml/L, sulfosalicylic acid 3~7g/L, polyethylene glycol 2~6g/L, deactivated temperature 30~35°C, pH value 5, deactivated time 60s. The test showed that，the phytic acid passive film can obviously enhance the anti-corrosive performance on the brass surface, its corrosion resistance proportion chromates passive film is fairly good.

Experimental Study on the Interaction Effect of Sulfate Ions and Chloride Ions on Reinforcement Corrosion in Marine Environment

2017 ◽  
Author(s):  
Yi Huang ◽  
Yunze Xu ◽  
Xiaona Wang ◽  
Shide Song ◽  
Lujia Yang
Keyword(s):  
Passive Film ◽  
Pore Solution ◽  
Construction Materials ◽  
Chloride Ions ◽  
Localized Corrosion ◽  
Test Results ◽  
Reinforcement Corrosion ◽  
Marine Structures ◽  
Sulfate Ions ◽  
Corrosion Risk

Reinforced concrete is one of the most widely used construction materials for marine structures. Due to the abundance of the aggressive ions such as chloride ions and sulfate ions in the seawater, the reinforcement exposed to the marine and costal environment are exposed to a high corrosion risk. Localized corrosion will occur once the passive film on the rebar is damaged. In this work, the corrosion behavior of the steel in the simulated pore solution containing with both sulfate ions and chloride ions are studied by using cyclic potentialdynamic polarization methods and the corrosion morphologies observed using scanning electron microscope (SEM). The test results show that the initial rebar corrosion is caused by the absorption of the chloride ions in the passive film. The sulfate ions nearly had no effect on the corrosion of the rebar in pore solution and it can further mitigate the pitting corrosion in chloride containing pore solution.

scholarly journals THE ROLE OF ALKALINE PHOSPHATASE IN OSTEOGENESIS

1951 ◽  
Vol 93 (5) ◽  
pp. 415-426 ◽  
Author(s):  
Robert S. Siffert
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Bone Matrix ◽  
Living Cells ◽  
Alkaline Solutions ◽  
Human Beings ◽  
Acid Media ◽  
Weakly Acid

The role of alkaline phosphatase in osteogenesis has been investigated by histochemical techniques with particular attention to its relationship to phosphate metabolism and matrix elaboration. The upper tibial epiphysis mainly, and other epiphyses as well of growing rabbits, and the costochondral junctions of newborn human beings were studied, as were bone grafts in growing rabbits. The findings in the newborn human beings were identical with those in the rabbits. Phosphatase activity and free phosphate localization do not universally coincide. The enzyme appears to be intimately related to preosseous cellular metabolism and to the elaboration of a bone matrix that is chemically calcifiable. It remains possible, however, that phosphatase may be in some way involved in making inorganic salts available to the calcifiable matrix. If this function does exist it is a secondary one, since the elaboration of bone matrix, which is always associated with phosphatase activity, can and does occur in the absence of calcification. Calcification may occur later, in the absence of the enzyme. There is evidence to suggest that cartilage matrix is utilized in the formation of bone matrix. Phosphatase is physiologically active only in the presence of living cells. Where it is demonstrable in the absence of living cells, as in the cartilage remnants of the metaphysis, it appears to be physiologically inactive. Since phosphatase is temporarily inactivated in weakly acid media, and readily reactivated by alkaline solutions it is possible that the enzyme might survive in a physiologically inactive state in weakly acid tissues, and yet remain capable of histochemical demonstration in vitro in an alkaline medium. Phosphatase is not related to the disappearance of chondroitin sulfate.

scholarly journals Boosting alkaline hydrogen evolution: the dominating role of interior modification in surface electrocatalysis

2020 ◽  
Vol 13 (9) ◽  
pp. 3110-3118 ◽  
Author(s):  
Zhao Li ◽  
Wenhan Niu ◽  
Zhenzhong Yang ◽  
Abdelkader Kara ◽  
Qi Wang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Water Dissociation ◽  
Alkaline Solutions ◽  
Great Promise ◽  
Hydrogen Fuel ◽  
Practical Utilization

The alkaline hydrogen evolution reaction (A-HER) holds great promise for clean hydrogen fuel generation but its practical utilization is severely hindered by the sluggish kinetics for water dissociation in alkaline solutions.

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