Study on corrosion mechanism of alkali-activated concrete with biogenic sulfuric acid

Xie, Yudong; Lin, Xiaoyan; Pan, Weijie; Ji, Tao; Liang, Yongning; Zhang, Hongru

doi:10.1016/j.conbuildmat.2018.08.105

Cited by 29 publications

(8 citation statements)

References 18 publications

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“…However, the fundamental mechanism of Portland cement sulfate attack, with expansive processes involving the monosulfate-AFm phase, is not possible in most AAMs as this phase is absent from the hydrate products. Sulfuric acid attack on AAMs is, however, a relevant mechanism related to use in sewer infrastructure and other highly aggressive environments [240,241], and the performance of AAMs (particularly those with low Ca content [242,243]) under such conditions has been observed to significantly exceed that of most other cementitious binders [242,244]. Organic acid resistance has also been reported to be a strength of low-calcium AAMs, as small organic acids damage calcium-rich binders through complexation and removal of Ca 2+ ions, but this mechanism is much less significant for AAMs that do not rely on calcium as a key binder constituent [245,246].…”

Section: Durabilitymentioning

confidence: 99%

Recent progress in low-carbon binders

Shi

Provis

2019

Cement and Concrete Research

493

131

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The development of low-carbon binders has been recognized as a means of reducing the carbon footprint of the Portland cement industry, in response to growing global concerns over CO2 emissions from the construction sector. This paper reviews recent progress in the three most attractive low-carbon binders: alkali-activated, carbonate, and belite-ye'elimite-based binders. Alkali-activated binders/materials were reviewed at the past two ICCC congresses, so this paper focuses on some key developments of alkali-activated binders/materials since the last keynote paper was published in 2015. Recent progress on carbonate and belite-ye'elimite-based binders are also reviewed and discussed, as they are attracting more and more attention as essential alternative low-carbon cementitious materials. These classes of binders have a clear role to play in providing a sustainable future for global construction, as part of the available toolkit of cements.

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Section: Durabilitymentioning

confidence: 99%

Recent progress in low-carbon binders

Shi

Provis

2019

Cement and Concrete Research

493

131

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“…Xie et al [16] studied the corrosion resistance of ordinary Portland concrete and alkali-activated concrete subjected to biogenic sulfuric acid attack, and found that the latter had better performance in terms of appearance, mass loss, and strength deterioration. Furthermore, biological sulfuric acid was more corrosive to geopolymer concrete than chemical sulfuric acid, however, their corrosion mechanisms were the same and the main products of both were gypsum [17]. Bernal et al [18] found that the appearance of alkali-activated slag mortar had almost no change after exposure to acetic acid, while the strength and pore structure of the cement mortar were seriously degraded.…”

Section: Introductionmentioning

confidence: 99%

Characterization and Comparison of Corrosion Layer Microstructure between Cement Mortar and Alkali-Activated Fly Ash/Slag Mortar Exposed to Sulfuric Acid and Acetic Acid

Zhao

Fan

et al. 2022

Materials

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In this study, we investigated the formation and evolution of the corrosion layers in alkali-activated mortar and ordinary Portland cement mortar exposed to sulfuric acid and acetic acid environments with different pH values, and explored the differences in the deterioration mechanisms. The experimental results indicated that ordinary Portland cement (OPC) mortars experienced more severe deterioration in terms of appearance, mass loss, and strength loss as compared with alkali-activated mortars exposed to an acetic acid environment, but their neutralization depths were smaller. Alkali-activated fly ash (AAF) mortar had a the relatively intact appearance but the greatest neutralization depth, which was due to its stable three-dimensional network but highly porous structure. To sum up, alkali-activated fly ash/slag (AFS) mortar had the best resistance to acid attack. In addition, the mortars exposed to acetic acid suffered greater deterioration than those exposed to sulfuric acid with the same pH values, which was mainly due to the highly porous corrosion layer formed in acetic acid, whereas crystallization of gypsum in sulfuric acid had a pore filling effect. However, for alkali-activated slag (AAS) and OPC mortars exposed to a sulfuric acid environment, extensive gypsum resulted in the formation of micro-cracks, and the corrosion layer of OPC mortar was more prone to fall off. OPC mortar also had the greatest resistance difference values of the continuously connected micro-pores before and after acid corrosion, followed by AAS, AAF, and AFS mortars, and these values for all the specimens were smaller in sulfuric acid. Furthermore, the gaps between acetic and sulfuric acid attacks increased with increased calcium content in binders, which were 7%, 13%, 21%, and 29% for AAF, AFS, AAS, and OPC mortars, respectively. Thus, it can be inferred that an appropriate amount of gypsum existed in the corrosion layer which could act as a barrier to some extent ina sulfuric acid environment.

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“…This trend is expected since the H 2 SO 4 attack is more intense on Ca‐rich binders whereby Ca‐based products are decomposed and transformed in to gypsum. It is reported that acidification of alkali‐activated concrete mainly involves exchange of cations in following order, such as Ca 2+ , Na + , K + , and H + followed by Al and Si 24 . A gradual decrease in the pH of the pore solution and its buffering capacity is reported to occur due to the diffusion of OH − and H + as well as alkali and Ca 2+.…”

Section: Resultsmentioning

confidence: 99%

Sulfuric acid resistance of alkali/slag activated silico‐manganese fume‐based mortars

Nasir

Johari

Maslehuddin

et al. 2020

Structural Concrete

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The resistance of alkaline‐activated silico‐manganese fume (SMF) and blast furnace slag (BSF)‐based mortar, prepared by varying BFS and NaOHaq composition, during 20 weeks of exposure to 5% sulfuric acid (H2SO4aq) of initial pH = 0.24 and pure water (controlled) was studied. The deterioration was monitored by visual, alkalinity, mass, compressive strength and microstructural tests. The set of specimens synthesized included: (a) BFS‐free high alkaline, (b) SMF‐BFS blended high alkaline, and (c) SMF‐BFS blended mild alkaline system. Their residual strengths after 20 weeks of acid exposure were 20.1, 18.6, and 16%, respectively. BFS‐free specimens exhibited high resistance to acid attack due to the dearth of Ca in SMF. BFS‐admixed mild alkali system resulted formation of more gypsum and dealumination attributed to incomplete dissolution of Ca grains leading to severe spalling. BFS‐admixed high alkaline system underwent moderate resistance due to dense microstructure formed by additional C‐S‐H, K‐A‐S‐H, and C‐Mn‐H gel which enhanced retention of the polymerized framework.

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Study on corrosion mechanism of alkali-activated concrete with biogenic sulfuric acid

Cited by 29 publications

References 18 publications

Recent progress in low-carbon binders

Recent progress in low-carbon binders

Characterization and Comparison of Corrosion Layer Microstructure between Cement Mortar and Alkali-Activated Fly Ash/Slag Mortar Exposed to Sulfuric Acid and Acetic Acid

Sulfuric acid resistance of alkali/slag activated silico‐manganese fume‐based mortars

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