Rebar Corrosion Resistance of Ultra High-Strength Concrete by Existing Chlorides

Ishinaka, Masato; Kimura, Shunta; Nakayama, Hideaki; Naruse, Hajime

doi:10.14250/cement.65.435

Cited by 3 publications

(2 citation statements)

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“…Various accelerated corrosion tests have been proposed for reinforcing steel: electrolytic corrosion test, 6,7) wet-dry cycle corrosion test, 810) autoclave test, 11,12) etc. The electrolytic corrosion test accelerates reinforcing steel corrosion by applying relatively high anodic current to the steel.…”

Section: Introductionmentioning

confidence: 99%

Hyperbaric-Oxygen Accelerated Corrosion Test for Iron in Cement Paste and Mortar

2018

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A novel accelerated corrosion test method which enhances oxygen supply has been proposed for reinforcing steel in concrete in this study. Oxygen reduction current density (ORCD) was measured by means of potentiodynamic polarization test for an iron specimen embedded in cement paste or mortar in a saturated Ca(OH) 2 solution in ambient air. The ORCD decreased with an increase in cover thickness and the current density was reciprocally proportional to the cover thickness from 1 mm to 10 mm, suggesting that diffusion limited oxygen reduction can be accelerated by reducing the cover thickness below 10 mm. The oxygen supply to iron surface in cement paste or mortar was enhanced by pressurized oxygen gas using a newly developed hyperbaric-oxygen accelerated corrosion test container. Iron specimens with 5 mm cement paste and mortar covers showed almost 25 times higher ORCD in 0.5 MPa oxygen gas than that in ambient air, respectively. The iron specimens covered with 5 mm of cement paste or mortar containing chloride ion were immersed in a saline solution and exposed to 0.5 MPa oxygen gas in the container for 30 days. The thickness of the rust layer formed for 30-days was in good agreement with that estimated from the ORCD obtained in 0.5 MPa oxygen gas, indicating that the corrosion was accelerated in proportion to the oxygen (partial) pressure. Furthermore, the rust formed in pressurized oxygen gas showed similar characteristics to that formed in a practical service environment. Thus, the hyperbaric-oxygen is beneficial and effective to validly accelerate the corrosion of reinforcing steel in concrete.

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Section: Introductionmentioning

confidence: 99%

Hyperbaric-Oxygen Accelerated Corrosion Test for Iron in Cement Paste and Mortar

2018

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“…Several accelerated corrosion tests for steel rebar in concrete have been proposed. [8][9][10] However, most of the conventional accelerated corrosion tests do not reproduce the corrosion product formed in the practical service environment. Many of the previous researchers have applied galvanostatic electrolysis with current densities from 1 to 100 A/m 2 to steel rebar in concrete from 24 to a few thousand hours.…”

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confidence: 99%

Effects of Oxygen Pressure and Chloride Ion Concentration on Corrosion of Iron in Mortar Exposed to Pressurized Humid Oxygen Gas

Doi

Hiromoto

Katayama

et al. 2018

J. Electrochem. Soc.

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The effects of oxygen pressure on the corrosion of iron embedded in mortar with various Cl − contents were examined by using a novel hyperbaric-oxygen accelerated corrosion test (HOACT). Exposure and electrochemical tests of a pure iron sample embedded in mortar with a cover thickness of 5 mm were performed in HOACT condition with pressurized 100% oxygen gas and with relative humidity of 95%. For comparison, these tests were also performed in ambient air with the same relative humidity. Oxygen reduction current density of iron embedded in mortar increased with an increase in oxygen pressure, suggesting that the corrosion of the embedded iron is expected to be accelerated with oxygen gas pressure assuming an oxygen reduction limited corrosion current density. Iron corrosion in mortar without Cl − was minimal regardless of oxygen gas pressure. In contrast, the corrosion of iron in mortar with Cl − was accelerated with increasing the oxygen gas pressure up to a certain pressure as expected, and the thickness of the rust formed on the iron surface increased with Cl − concentration under each oxygen gas pressure, indicating that Cl − is necessary to initiate corrosion which is enhanced in the pressurized oxygen gas. However, when the oxygen pressure exceeded a certain level, the corrosion was suppressed. Electrochemical impedance spectroscopy measurement using a sensor consisting of a pair of carbon steel electrodes in mortar showed that the charge transfer resistance of the carbon steel under excessively high oxygen gas pressure became high in comparison to that at lower oxygen pressure, indicating the suppression of corrosion initiation is due to formation of a protective passive film under the excessive supply of oxygen. Consequently, the pressurized oxygen gas accelerates the corrosion of iron in mortar with Cl − ; however, excess oxygen suppresses corrosion. The optimum condition to efficiently accelerate corrosion of iron in mortar was evaluated.

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Durability of ultra-high performance concrete in tension under cold weather conditions

Zhou

Qiao

2018

Cement and Concrete Composites

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Rebar Corrosion Resistance of Ultra High-Strength Concrete by Existing Chlorides

Cited by 3 publications

References 0 publications

Hyperbaric-Oxygen Accelerated Corrosion Test for Iron in Cement Paste and Mortar

Hyperbaric-Oxygen Accelerated Corrosion Test for Iron in Cement Paste and Mortar

Effects of Oxygen Pressure and Chloride Ion Concentration on Corrosion of Iron in Mortar Exposed to Pressurized Humid Oxygen Gas

Durability of ultra-high performance concrete in tension under cold weather conditions

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