Microstructural and 29Si and 27Al MAS NMR spectroscopic evaluations of alkali cation and curing effects on Class C fly ash-based geopolymer

Moutaoukil, Ghizlane; Alehyen, Saliha; Sobrados, Isabel; Taïbi, M.

doi:10.1016/j.cdc.2022.100898

Cited by 19 publications

(2 citation statements)

References 40 publications

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“…In this study, three common foaming agents were used: aluminum powder [26,27,31,32], zinc powder [28,33,34], and hydrogen peroxide [28,32,[35][36][37]. Aluminum powder is favored for its ability to release hydrogen gas upon reacting with alkaline solutions, contributing to lightweight foam with interconnected voids.…”

Section: Methodsmentioning

confidence: 99%

“…The formulation selection was based on extensive research conducted in our previous studies. In these studies, we focused on optimizing various parameters, including the initial ratios of fly ash (FA) to alkaline solution, and the ratio of sodium silicate to sodium hydroxide [33], as well as the type of alkaline solution and curing conditions [34,35]. Through systematic experimentation and analysis, we identified the optimum formula that yielded the desired properties for geopolymer foam production, encompassing mechanical, microstructural, and thermal aspects [36].…”

Section: Methodsmentioning

confidence: 99%

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Monitoring the Geopolymerization Reaction of Geopolymer Foams Using 29Si and 27Al MAS NMR

Moutaoukil,

Sobrados,

Alehyen

et al. 2024

Minerals

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This study aims to investigate the geopolymerization reaction of geopolymer foams produced with three different foaming agents: aluminum powder, zinc powder, and hydrogen peroxide. The geopolymerization reaction of geopolymer foam was monitored using the 27Al and 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy technique. 27Al MAS-NMR was used to monitor the reaction at an early stage, while 29Si and 27Al MAS-NMR analyses were employed at specific time intervals of 3, 6, 10, 15, and 28 days to examine the changes that occurred in the formed gel over time. We discussed in detail how the type of foaming agent used and the duration of the reaction both influence the quantity of gel formed and the amount of remnant fly ash. Our findings indicate that the type of foaming agent used affects the formation and structure of the gel, with aluminum powder leading to the highest gel formation. Additionally, the duration of the reaction plays a significant role in determining the quantity of remnant fly ash, with longer reaction times resulting in decreased fly ash content. This study sheds light on the relevance of understanding the role of foaming agents in the geopolymerization reactions of geopolymer foams and the influence of reaction time on the formed gel properties.

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