Effect of silica fume on efflorescence formation and alkali leaching of alkali-activated slag

Saludung, Apriany; Azeyanagi, Takumu; Ogawa, Yuko; Kawai, Kenji

doi:10.1016/j.jclepro.2021.128210

Cited by 54 publications

(20 citation statements)

References 29 publications

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“…In terms of the effect of mineral additives on efflorescence, ref. [16] put forward that the addition of silica fume could reduce the efflorescence of Portland cement-based materials, which is consistent with our findings. In general, the following conditions contribute to the inhibition of efflorescence: (a) decreasing the number of water-soluble substances and (b) fining pore structure, preventing water from transporting to the surface [27].…”

Section: Discussionsupporting

confidence: 92%

Influence of Mineral Additives on the Efflorescence of Ettringite-Rich Systems

Liu

Wang

et al. 2021

Materials

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Efflorescence is aesthetically undesirable to all cementitious materials products and mainly results from the carbonation of hydrates and salt precipitation. Alternative binders without portlandite formation theoretically have much lower efflorescence risk, but in practice, the efflorescence of ettringite-rich systems is still serious. This study reports the impacts of mineral additives on the efflorescence of ettringite-rich systems and the corresponding microstructural evolution. The effects of silica fume, limestone powder, and diatomite on efflorescence and the capillary pore structure of mortars were investigated from a multi-scale analysis. The composition and microstructure of efflorescent phases were revealed by optical microscope (O.M.), in-situ Raman spectroscopy, and Scanning Electron Microscopy (SEM). Results indicate that the addition of mineral additives can efficiently inhibit the efflorescence of reference, especially with silica fume. Similar to the ettringite-rich system, the efflorescence substances of all modifies are composed of ettringite and CaCO3, indicating that the addition of mineral admixture does not lead to chemical reactions, lower capillary absorption coefficient of mineral additives modified specimen, the denser pore structure and the lower efflorescence degree.

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Section: Discussionsupporting

confidence: 92%

Influence of Mineral Additives on the Efflorescence of Ettringite-Rich Systems

Liu

Wang

et al. 2021

Materials

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“…For samples subjected to accelerated aging by simulated rain (Figure 4b), from 0 • to 2 • cycles, a significant decrease in FS values was observed only in the Na 2 SiO 3 -activated sample. Such behavior must be related to the leaching of soluble silica [45]. From the 2 • to 6 • cycles, the FS values decreased for all samples, regardless of the activator used, obtaining a subtle increase in the 12 • cycle.…”

Section: Durability Of Activated Samplesmentioning

confidence: 89%

Durability of Sustainable Ceramics Produced by Alkaline Activation of Clay Brick Residue

et al. 2021

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Alkali-activated materials (AAMs) were produced using residues from the red ceramic industry as a precursor, and sodium hydroxide (NaOH), potassium hydroxide (KOH), and sodium silicate (Na2SiO3) as alkaline activators. The effect of activators and curing conditions on physical-mechanical properties and durability were evaluated. The processing parameters (amount of water and consistency index) and the activation conditions (the activator contents and curing temperature) were defined based on an experimental design getting the flexural rupture module as the response. The durability behavior was evaluated by natural aging, accelerated aging (simulated rain test), exposure to the marine environment (salt fog), and acidic environments (HCl and H2SO4). The results showed that the NaOH- and KOH-activated samples exhibited inferior mechanical behavior than those activated with Na2SiO3. In the durability studies, due to leaching, there was a decrease in mechanical strength when samples are subjected to aggressive exposure conditions. However, the strength values are still higher than the minimum indicated for traditional ceramic applications.

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“…So that, the excess alkali ions become residue in the material. Over time, the weak alkaline bonds in the N-A-S-H gel structure released the excessive unreacted alkaline substances, migrated to the surface of the specimen and reacted with CO2 caused the appearance of white salt-like deposits on the surface of the specimen, which in the long run can cause microcrack (Saludung et al, 2021;Singh & Subramaniam, 2017;Wang et al, 2020).…”

Section: Visual Observationsmentioning

confidence: 99%

The Effect of Sodium Hydroxide Molarity on The Compressive and Splitting Tensile Strength of Ferronickel Slag-Based Alkali-Activated Mortar

Kuncoro

Djayaprabha

2021

MKTS

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The use of cement as the main binding agent in construction contributes approximately 7-10% in total of carbon dioxide gas emissions worldwide. In this study, the replacement of Portland cement using ground granulated ferronickel slag (GFNS) activated by the combination of sodium hydroxide (NaOH) dan sodium silicate (Na2SiO3) was utilized for producing alkali-activated mortar (AAM) as construction material. Four different mortar mixtures were prepared in this experimental work. There were three mixtures of ferronickel slag-based alkali activated mortar (FAM) with the variations of NaOH molarity of 6, 8, and 10M and cement-based mortar mixture (PCM) with water-to-cement ratio (w/c) of 0.5 was used as the control specimens. Overall, the flow and workability of the FAM specimen was lower than the PCM specimen due to the presence of silicate caused a sticky characteristic on the paste. On the other hand, the unit weight of FAM mortar was higher than the PCM specimen. Among all FAM mixtures, the most effective compressive strength and splitting tensile strength results were achieved by the FAM8 mixture, with a compressive strength at 28 days of 33.72 MPa and the splitting tensile strength at 28 days of 2.65 MPa, which had both good workability and chemical reaction of the material.

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Effect of silica fume on efflorescence formation and alkali leaching of alkali-activated slag

Cited by 54 publications

References 29 publications

Influence of Mineral Additives on the Efflorescence of Ettringite-Rich Systems

Influence of Mineral Additives on the Efflorescence of Ettringite-Rich Systems

Durability of Sustainable Ceramics Produced by Alkaline Activation of Clay Brick Residue

The Effect of Sodium Hydroxide Molarity on The Compressive and Splitting Tensile Strength of Ferronickel Slag-Based Alkali-Activated Mortar

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