A Comparative Study on the Degradation of Alkali-Activated Slag/Fly Ash and Cement-Based Mortars in Phosphoric Acid

Ren, Jie; Zhang, Lihai; Zhu, Yingcan; Li, Zhenming; Nicolas, Rackel San

doi:10.3389/fmats.2022.845349

Cited by 6 publications

(4 citation statements)

References 56 publications

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“…The resistance of AAMs to sulfate [145] and phosphoric acid [146] seems to be superior compared to PC. However, the information on the freeze and thaw resistance of AAMs seems controversial.…”

Section: Other Issuesmentioning

confidence: 99%

Recycling of Aluminosilicate-Based Solid Wastes through Alkali-Activation: Preparation, Characterization, and Challenges

Feng,

Yi,

Zhao

et al. 2024

Buildings

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Recycling aluminosilicate-based solid wastes is imperative to realize the sustainable development of constructions. By using alkali activation technology, aluminosilicate-based solid wastes, such as furnace slag, fly ash, red mud, and most of the bio-ashes, can be turned into alternative binder materials to Portland cement to reduce the carbon footprint of the construction and maintenance activities of concrete structures. In this paper, the chemistry involved in the formation of alkali-activated materials (AAMs) and the influential factors of their properties are briefly reviewed. The commonly used methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), nuclear magnetic resonance spectroscopy (NMR), and X-ray pair distribution function technology, to characterize the microstructure of AAMs are introduced. Typical characterization results of AAMs are shown and the limitations of each method are discussed. The main challenges, such as shrinkage, creep, efflorescence, carbonation, alkali–silica reaction, and chloride ingress, to conquer for a wider application of AAMs are reviewed. It is shown that several performances of AAMs under certain circumstances seem to be less satisfactory than traditional portland cement systems. Existing strategies to improve these performances are reviewed, and recommendations for future studies are given.

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Section: Other Issuesmentioning

confidence: 99%

Recycling of Aluminosilicate-Based Solid Wastes through Alkali-Activation: Preparation, Characterization, and Challenges

Feng,

Yi,

Zhao

et al. 2024

Buildings

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“…Combined with the FTIR analysis results, this discussion implies that when Na 2 O interacts with metakaolin, Na 2 O promotes the dissolution of metakaolin, and metakaolin provides large amounts of A1 3+ and Si 4+ . OH − and Na + react with A1 3+ and Si 4+ in the solution, and the proportion of the formed hydration product (N-A-S-H) increases, thus significantly reducing the structural compactness of the AASM; this decreases the compressive strength but coarsens the pore structure and increases volume stability (Li et al, 2017b;Ren et al, 2022b).…”

Section: Mip Analysismentioning

confidence: 99%

Composition design and characterization of alkali-activated Slag–Metakaolin materials

Zhan

Li³

et al. 2022

Front. Built Environ.

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This study explores the effects of the interactions among Na2O content, metakaolin content and activator modulus on the compressive strength and autogenous shrinkage of alkali-activated slag–metakaolin (AASM) materials. The Box–Behnken RSM design was used to create an experimental scheme, establish a model, and optimize the mix proportions. Fourier transform infrared spectroscopy, scanning electron microscopy, and Mercury intrusion experiments were used to analyze the compositions, microstructures, and pore structures of the hydration products of the AASM, respectively. Results showed that the interactions between the activator modulus and metakaolin content, as well as Na2O content and metakaolin content, are the key factors affecting the compressive strength and autogenous shrinkage, respectively, of the AASM. Under the optimal conditions of Na2O content of 6%, sodium silicate modulus of 1.5, and metakaolin/slag ratio of 1: 3, the relative errors in the model verification test for compressive strength and autogenous shrinkage are 0% and 0.18%, respectively. In the water glass modulus and metakaolin content interaction, Ca2+, A13+, and Si4+ ions in the composite system react with several [SiO4]4− groups to form C-A-S-H and N-A-S-H gels, which fill each other to make the composite structure denser. When Na2O interacts with metakaolin, the OH− and Na+ in the solution react with A13+ and Si4+ to generate additional N-A-S-H, thereby reducing the compressive strength of the composite system, mitigating autogenous shrinkage, and increasing volume stability.

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“…Similar to ordinary Portland cement, alkali-activated ground granulated blast furnace slag (GGBS) also has hydraulic reaction characteristics so that hardened alkali-activated GGBS mortars have the mechanical characteristics of high strength at early and long-term ages, and are known to exhibit advantages such as a high resistance to chemical attack and freeze-thaw as well as a low carbonation rate [5][6][7]. In the construction industries, ordinary concrete has many advantages as one of most widely used materials.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Alkali-Activated Slag Fiber Composites Varying with Fiber Volume Fractions

et al. 2022

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The mechanical properties of alkali-activated slag fiber composites (ASFC) were investigated with varying volume fractions of PVA (Polyvinyl alcohol) fibers. Ground granulated blast furnace slag (GGBS) and alkali-activators were used as the main binders instead of cement, which emits a large amount of carbon dioxide during the manufacturing process. The measured slump flow of ASFC showed a high fluidity at a fiber content of 1.5 vol.% or less. The tensile, flexural, and shear strength of ASFC showed higher values as the amount of fiber increased. Compared to the existing high ductility fiber composites showing strain hardening behaviors with a fiber content of 2.0 vol.%, ASFC proved that it could exhibit high ductility characteristics due to multi-microcracks even at low fiber mixing rates of 1.0% and 1.25%. ASFC could be expected to lower the manufacturing cost with a low fiber content and provide improved workability with high fluidity. In addition, when manufacturing structural components using the developed ASFC, it is expected that the amount of fiber could be selected and used according to the required performance.

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A Comparative Study on the Degradation of Alkali-Activated Slag/Fly Ash and Cement-Based Mortars in Phosphoric Acid

Cited by 6 publications

References 56 publications

Recycling of Aluminosilicate-Based Solid Wastes through Alkali-Activation: Preparation, Characterization, and Challenges

Recycling of Aluminosilicate-Based Solid Wastes through Alkali-Activation: Preparation, Characterization, and Challenges

Composition design and characterization of alkali-activated Slag–Metakaolin materials

Mechanical Properties of Alkali-Activated Slag Fiber Composites Varying with Fiber Volume Fractions

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