Effect of an Early-Age Exposure on the Degradation Mechanisms of Cement Paste under External Sulfate Attack

Metalssi, Othman Omikrine; Ragoug, Rim; Barberon, Fabien; Lacaillerie, Jean-Baptiste d’Espinose de; Roussel, Nicolas; Divet, Loïc; Torrenti, Jean-Michel

doi:10.3390/ma16176013

Cited by 9 publications

(6 citation statements)

References 37 publications

(62 reference statements)

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“…As microcracks multiply, more corrosive ions from the external environment infiltrate the specimen, causing an increase in internal stress and resulting in severe deterioration. When the internal stress exceeds the tensile strength, the specimen will undergo destruction and failure [ 51 , 52 ]. Combining changes in the physical and mechanical properties of the D-M and S-M specimens, the premixed magnesium salt primarily affects the strength rather than causing expansion in the early stage.…”

Section: Discussionmentioning

confidence: 99%

Durability Performance of Basalt Fiber-Reinforced Concrete Subjected to Sulfate–Magnesium Combined Attack

Fan,

Wang,

et al. 2024

Materials

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In salt lake areas, cast-in situ concrete structures are subjected to long-term corrosion by sulfate and magnesium ions. The properties of concrete can be improved by adding materials like basalt fiber (BF). To investigate the degradation process and mechanism of cast-in situ concrete with premixed BF under the dual corrosion of sulfate and magnesium salts, concrete with a content of BF ranging from 0 to 0.5% was prepared. Specimens were subjected to different internal and external corrosion conditions and immersed for 180 days. Dimension, mass, and appearance changes at different immersion times were recorded. The compressive and flexural strength of the specimens were tested and continually observed throughout the immersion time. Mineral and microstructural changes at different immersion times were determined by the XRD, TG, and SEM analysis methods. Results indicated that external sulfate–internal magnesium combined attack had a significant negative effect on the early strength. The compressive and flexural strength of the corroded specimens decreased by 17.2% and 14.1%, respectively, compared to the control group at 28 days. The premixed magnesium ions caused the decomposition of the C-S-H gel, resulting in severe spalling and lower mechanical properties after immersing for a long time. As the BF can inhibit crack development, the properties of the concrete premixed with BF were improved. Specimens exhibited superior performance at a BF content of 0.5%, resulting in a 16.2% increase in flexural strength. This paper serves as a valuable reference for the application of basalt fiber-reinforced concrete under the challenging conditions of sulfate–magnesium combined attack.

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Section: Discussionmentioning

confidence: 99%

Durability Performance of Basalt Fiber-Reinforced Concrete Subjected to Sulfate–Magnesium Combined Attack

Fan,

Wang,

et al. 2024

Materials

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“…After each increase in the expansion rates, a period of stability is observed, followed by a subsequent increase. This pattern is likely attributed to the formation of ettringite and/or gypsum in the pores, leading to internal stresses and causing cracking [20,40] (resulting in an increase in expansion). Subsequently, these products begin to fill the formed cracks (resulting in the stability of the expansion) until they recreate internal stresses and induce new cracks (leading to an increase in expansion).…”

Section: Expansionmentioning

confidence: 99%

“…In addition, if not prefabricated, on-site cast concrete is directly exposed to the surrounding environment from an early age [20,21]. A recent investigation compared the resistance of prefabricated and cast-in-site concrete against ESA, revealing that prefabricated concrete demonstrates greater resistance to ESA [22].…”

Section: Introductionmentioning

confidence: 99%

“…Most studies and standards focus on cured samples, typically after 28 or 90 days of curing before attacking the samples, leaving unanswered questions about the impact of ESA on RC structures during their early stages. A recent study [20] investigated the degradation mechanisms induced by ESA on both cured and uncured cement pastes. Surprisingly, pre-cured cement pastes exhibited rapid degradation, although sulfate ion ingress did not show significant differences when comparing pre-cured samples to the uncured ones.…”

Section: Introductionmentioning

confidence: 99%

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Long-Term Effects of External Sulfate Attack on Low-Carbon Cementitious Materials at Early Age

El Inaty,

Aydin,

Houhou

et al. 2024

Applied Sciences

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Placed in a sulfate-rich environment, concrete reacts with sulfate ions, influencing the long-term durability of reinforced concrete (RC) structures. This external sulfate attack (ESA) degrades the cement paste through complex and coupled physicochemical mechanisms that can lead to severe mechanical damage. In common practice, RC structures are generally exposed to sulfate at an early age. This early exposition can affect ESA mechanisms that are generally studied on pre-cured specimens. Moreover, current efforts for sustainable concrete construction focus on replacing clinker with supplementary cementitious materials, requiring a 90-day curing period, which contradicts real-life scenarios. Considering all these factors, the objective of this study is to explore ESA effects at an early age on cement-blended paste samples using various low-carbon formulations. The characterization techniques used demonstrated that the reference mix (100% CEM I) exhibits the weakest resistance to sulfate, leading to complete deterioration after 90 weeks of exposure. This is evident through the highest mass gain, expansion, cracking, formation of ettringite and gypsum, and sulfate consumption from the attacking solution. Conversely, the ternary mix, consisting of CEM I, slag, and metakaolin, demonstrates the highest resistance throughout the entire 120 weeks of exposure. All the blended pastes performed well in the sulfate environment despite being exposed at an early age. It can be recommended to substitute clinker with a limited quantity of metakaolin, along with blast furnace slag, as it is the most effective substitute for clinker, outperforming other combinations.

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“…These products are primarily responsible for concrete expansion and cracking. The formation of these chemical compounds induces internal pressure within the concrete matrix, leading to structural deterioration and compromising its long-term integrity [12][13][14]. Nevertheless, unbound chloride ions within the cement matrix, such as Friedel's salt, remain free and contribute to the corrosion of steel reinforcing bars (rebars).…”

Section: Literature Review and Research Significancementioning

confidence: 99%

Chemical Mechanisms Involved in the Coupled Attack of Sulfate and Chloride Ions on Low-Carbon Cementitious Materials: An In-Depth Study

El Inaty,

Marchetti,

Quiertant

et al. 2023

Applied Sciences

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This study aims to analyze the individual and combined chemical attacks of sulfate and chloride ions on cementitious materials and assess the efficiency of some selected additives (fly ash, blast furnace slag, and metakaolin) in countering this combined attack. This research is conducted in the context of construction in marine environments, where reinforced concrete structures are often subject to significant challenges due to early exposure to sulfate and chloride ions. This early exposure results in concrete expansion, cracking, and, ultimately, the corrosion of steel reinforcements. Nevertheless, the interaction between sulfate ions, chloride ions, and the cementitious matrix remains poorly understood. Previous research has drawn conflicting conclusions, with some suggesting that sulfate ions mitigate chloride attacks, while others have come to the opposite conclusion. During this study, experimental investigations were conducted by immersing powders obtained from crushed ordinary Portland cement (CEM I) paste specimens, as well as binary, ternary, and quaternary blends, in sulfate, chloride, and sulfate–chloride solutions over the course of 25 days at an early age. Results from different characterization techniques (thermogravimetric analysis, Fourier Transform Infrared spectroscopy, Raman spectroscopy, etc.) indicate that chloride ions delay the formation of ettringite, while the presence of sulfate ions accelerates the chloride attack by limiting the formation of Friedel’s salt. The Mercury Intrusion Porosimetry test confirmed these results by showing a pronounced increase in specimens’ porosity after exposure to solely sulfate after 25 days, compared to the ones exposed to both sulfate and chloride ions. Furthermore, the incorporation of multiple additives, particularly in ternary and quaternary blends, demonstrates the enhanced durability of the studied samples. This was confirmed by a Fourier Transform Infrared spectroscopy analysis, which indicated a delayed ettringite formation in these mixtures. This delay was further affirmed by the complete depletion of sulfate ions in the sulfate solutions upon contact with powders derived from the 100% CEM I paste.

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Effect of an Early-Age Exposure on the Degradation Mechanisms of Cement Paste under External Sulfate Attack

Cited by 9 publications

References 37 publications

Durability Performance of Basalt Fiber-Reinforced Concrete Subjected to Sulfate–Magnesium Combined Attack

Durability Performance of Basalt Fiber-Reinforced Concrete Subjected to Sulfate–Magnesium Combined Attack

Long-Term Effects of External Sulfate Attack on Low-Carbon Cementitious Materials at Early Age

Chemical Mechanisms Involved in the Coupled Attack of Sulfate and Chloride Ions on Low-Carbon Cementitious Materials: An In-Depth Study

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