Strength development properties of geopolymer paste and mortar with respect to amorphous Si/Al ratio of fly ash

Lee, Bokyeong; Kim, Gyu-Yong; Kim, Raehwan; Cho, Bongsuk; Lee, Sujeong; Chon, Chul-Min

doi:10.1016/j.conbuildmat.2017.06.078

Cited by 58 publications

(27 citation statements)

References 36 publications

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“…In general, a well-defined elastic regime is noted for all samples, although the failure yielding is not well-defined. There is higher early strength development with increase in fly ash content and/or The quartz and mullite, which were present in the raw fly ash, do not appear to lose much of their peak intensities upon activation of the aluminosilicates, which has also been reported in previous studies using pure or virgin products and red mud/coal gangue based geopolymers [25,40]. Mullite, an aluminosilicate mineral, is predominantly unreactive in alkaline medium as seen in FA8, the specimen with the highest fly ash content, by its visible peak at 26.2 • .…”

Section: Parametric Influences On Mechanical Propertiessupporting

confidence: 76%

“…For 28 days' strength, straight line fits with positive and negative slopes are obtained for Si/Al and Na/Al plots, respectively. However, further curing may have different patterns of strength as in the case of pure geopolymers where a gradual rise in Si/Al and a sudden subsequent fall has been reported [40]. The trends of the variation of Young's modulus with Si/Al and Na/Al ratios are similar to those of UCS.…”

Section: Parametric Influences On Mechanical Propertiessupporting

confidence: 56%

“…There are no observable humps in the diffractograms of the end products unlike the characteristic amorphous silica (glassy phase) humps in raw fly ash around 25°. This could be due to several reasons: (i) the glassy phase of silica participates in the chemical reactions and hence its hump reduces, (ii) the amorphous humps of red mud and geopolymers are very broad [27,40], and (iii) there is an increased proportion of other crystalline and amorphous phases contributed by the red mud and also by the geopolymeric reactions. As the reaction progresses, the fly ash particles get etched due to the strong alkaline environment (Figure 3b,c) and the silica and alumina dissolve into the matrix and form geopolymers, silicate hydrates, or zeolites [36,38].…”

Section: Microstructural and Mineralogical Characteristicsmentioning

confidence: 99%

“…There are no observable humps in the diffractograms of the end products unlike the characteristic amorphous silica (glassy phase) humps in raw fly ash around 25 • . This could be due to several reasons: (i) the glassy phase of silica participates in the chemical reactions and hence its hump reduces, (ii) the amorphous humps of red mud and geopolymers are very broad [27,40], and (iii) there The quartz and mullite, which were present in the raw fly ash, do not appear to lose much of their peak intensities upon activation of the aluminosilicates, which has also been reported in previous studies using pure or virgin products and red mud/coal gangue based geopolymers [25,40]. Mullite, an aluminosilicate mineral, is predominantly unreactive in alkaline medium as seen in FA8, the specimen with the highest fly ash content, by its visible peak at 26.2°.…”

Section: Microstructural and Mineralogical Characteristicsmentioning

confidence: 99%

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Mechanical Properties of Geopolymers Synthesized from Fly Ash and Red Mud under Ambient Conditions

Koshy

Dondrob

et al. 2019

Crystals

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Aluminosilicate gels form geopolymers and nanocrystalline zeolites which have comparable strength properties, making them a potential replacement for ordinary Portland cement. The study explores the use of two untreated industrial wastes, Class-F fly ash and red mud, for synthesizing geopolymeric material at ambient synthesis conditions. The high alkalinity present in the red mud was exploited for the dissolution of silica in the fly ash and red mud. The mechanical, mineralogical, microstructural, and pore characteristics were analyzed and the contributions of curing period, Si/Al, Na/Al, and liquid-to-solid (L/S) ratios on the compressive strength of the end products were also investigated. The alkalinity of the system due to the red mud was adequate for the dissolution of raw fly ash and the subsequent formation of aluminosilicate gels. The strength of the end product was directly proportional to the initial Si/Al ratio and the specimens with highest fly ash content exhibited highest compressive strength values after 28 days of curing. Furthermore, fly ash contributed to the formation and distribution of interstitial and capillary pores in the aluminosilicate matrix. The lowest L/S ratio of the initial mix resulted in the end product with the highest unconfined compressive strength.

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Section: Parametric Influences On Mechanical Propertiessupporting

confidence: 76%

Section: Parametric Influences On Mechanical Propertiessupporting

confidence: 56%

Section: Microstructural and Mineralogical Characteristicsmentioning

confidence: 99%

Section: Microstructural and Mineralogical Characteristicsmentioning

confidence: 99%

See 2 more Smart Citations

Mechanical Properties of Geopolymers Synthesized from Fly Ash and Red Mud under Ambient Conditions

Koshy

Dondrob

et al. 2019

Crystals

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“…Patterns of geopolymers show similar sharp peaks from raw precursors. A broad amorphous hump is observed in GP and SGP mixes; however, there is a slight shift in the range This suggests that the mechanisms of geopolymerization of mixes have considerable differences [55]. An average profile is provided by the inbuilt software, which helps in the identification of hump.…”

Section: Morphology and Reaction Mechanism Analysismentioning

confidence: 99%

Properties of fly ash geopolymer modified with red mud and silica fume: a comparative study

2020

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Alkali-activated geopolymer has emerged as a sustainable alternative to highly polluting conventional cement. The present paper investigates the activation of fly ash-based geopolymer paste modified by red mud and silica fume. Three geopolymer mixes are considered: (1) fly ash; (2) fly ash-red mud; and (3) fly ash-silica fume. Mass proportions of modifiers in the respected mixes varied by 0, 5%, 10%, 15%, 20%, and 25% of total binder. Heat curing (60 °C) provided for 24 h just after casting. Alkaline activator consists of sodium hydroxide and sodium silicate solutions. Workability results reveal that both red mud and silica fume triggered the reduction in workability with the later one had a greater impact. A flash set was obtained with the silica fume content of more than 15%. Both the modifiers cause a decrease in the setting time at ambient temperature, and silica fume proved to be more productive with the reduction of more than 65% of setting time. Mixes containing red mud exhibit slightly higher density. Water absorption of fly ash geopolymer increases with red mud. Compressive strength increases with the addition of modifiers, and geopolymer containing silica fume possesses the highest compressive strength among the three mixes considered. Compressive strength exhibited a linear correlation with molar ratios (Si/Al and Na/Si) of source materials. XRD and SEM methods showed that the geopolymerization reaction is affected by the red mud and silica fume. It is recommended that the flash set and setting time at higher contents of modifiers must be examined for the design of a modified geopolymer mix.

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Effect of addition diatomite powder on mechanical strength, elevated temperature resistance and microstructural properties of industrial waste fly ash-based geopolymer

Özsoy

Örklemez

İlkentapar

2023

J Mater Cycles Waste Manag

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Strength development properties of geopolymer paste and mortar with respect to amorphous Si/Al ratio of fly ash

Cited by 58 publications

References 36 publications

Mechanical Properties of Geopolymers Synthesized from Fly Ash and Red Mud under Ambient Conditions

Mechanical Properties of Geopolymers Synthesized from Fly Ash and Red Mud under Ambient Conditions

Properties of fly ash geopolymer modified with red mud and silica fume: a comparative study

Effect of addition diatomite powder on mechanical strength, elevated temperature resistance and microstructural properties of industrial waste fly ash-based geopolymer

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