Characterization of chemosynthetic Al2O3–2SiO2 geopolymers

Cui, Xuemin; Liu, Leping; Zheng, Guangjian; Wang, Ruiping; Lu, Jianping

doi:10.1016/j.jnoncrysol.2009.10.008

Cited by 53 publications

(13 citation statements)

References 15 publications

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“…It is likely that during calcination these samples have undergone spinodal decomposition into a highly polymerised Si-rich phase and a phase containing mullite-like structures which, according to the literature, are expected to contribute resonances to the overall spectra at approximately -87, -90, -94 and -106 ppm [34,53,54]. The broad nature of the spectra presented here is similar to that observed for aluminosilicate powders synthesised via a sol-gel method [55].…”

Section: Si Mas Nmrsupporting

confidence: 75%

Synthesis of stoichiometrically controlled reactive aluminosilicate and calcium-aluminosilicate powders

et al. 2016

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Section: Si Mas Nmrsupporting

confidence: 75%

Synthesis of stoichiometrically controlled reactive aluminosilicate and calcium-aluminosilicate powders

et al. 2016

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“…The powder was then submitted to a chemical activation for the geopolymerization process using a sodium hydroxide solution. The characteristics of the synthetic powders and the geopolymers produced from these powders were studied by means of XRD, SEM and NMR 2,15,[20][21][22][23][24][25][26] . NMR spectra are generally considered the most important test for characterization of raw materials for the production of geopolymer, specifically the 27 Al spectrum.…”

Section: Introductionmentioning

confidence: 99%

Synthetic Aluminosilicates for Geopolymer Production

Pereira

Vasconcelos

2019

Mat. Res.

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The use of geopolymer has been studied as a potential substitute for Portland cement due to lower CO 2 emission and improvements on structural properties. Some of the major raw materials used in the manufacture of the geopolymer are: steel slag, fly ash and metakaolinite. Due to the impurities contained in these raw materials, the present study uses high purity synthetic aluminosilicates made from the sol gel process for production of geopolymers. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). The results showed that the synthetic aluminosilicates have similar behavior to metakaolinite (reference). It was found that the coordination of Al in the synthetic aluminosilicate changed from VI to IV and V from 300 °C, with the highest intensity at 900 °C. Temperature at which the highest mechanical strength of the geopolymer was also observed.

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“…A limited number of studies detailing the synthesis and characterisation of phases simulating those found in geopolymer binders can be found in the literature. [11][12][13][14][15][16][17][18][19][20] Most of these studies described the reaction of nitrate solutions containing silicon and aluminium, via a sol-gel procedure, to form alkali aluminosilicate or calcium-alkali-aluminosilicate gels. These studies generally investigate the effect of alkali cations, alkaline earth cations or aluminium on CaO-…”

Section: Introductionmentioning

confidence: 99%

Phase evolution of Na₂O–Al₂O₃–SiO₂–H₂O gels in synthetic aluminosilicate binders

et al. 2016

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This study demonstrates the production of stoichiometrically controlled alkali-aluminosilicate gels ('geopolymers') via alkali-activation of high-purity synthetic amorphous aluminosilicate powders. This method provides for the first time a process by which the chemistry of aluminosilicate-based cementitious materials may be accurately simulated by pure synthetic systems, allowing elucidation of physicochemical phenomena controlling alkali-aluminosilicate gel formation which has until now been impeded by the inability to isolate and control key variables. Phase evolution and nanostructural development of these materials are examined using advanced characterisation techniques, including solid state MAS NMR spectroscopy probing (29)Si, (27)Al and (23)Na nuclei. Gel stoichiometry and the reaction kinetics which control phase evolution are shown to be strongly dependent on the chemical composition of the reaction mix, while the main reaction product is a Na2O-Al2O3-SiO2-H2O type gel comprised of aluminium and silicon tetrahedra linked via oxygen bridges, with sodium taking on a charge balancing function. The alkali-aluminosilicate gels produced in this study constitute a chemically simplified model system which provides a novel research tool for the study of phase evolution and microstructural development in these systems. Novel insight of physicochemical phenomena governing geopolymer gel formation suggests that intricate control over time-dependent geopolymer physical properties can be attained through a careful precursor mix design. Chemical composition of the main N-A-S-H type gel reaction product as well as the reaction kinetics governing its formation are closely related to the Si/Al ratio of the precursor, with increased Al content leading to an increased rate of reaction and a decreased Si/Al ratio in the N-A-S-H type gel. This has significant implications for geopolymer mix design for industrial applications.

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Characterization of chemosynthetic Al2O3–2SiO2 geopolymers

Cited by 53 publications

References 15 publications

Synthesis of stoichiometrically controlled reactive aluminosilicate and calcium-aluminosilicate powders

Synthesis of stoichiometrically controlled reactive aluminosilicate and calcium-aluminosilicate powders

Synthetic Aluminosilicates for Geopolymer Production

Phase evolution of Na₂O–Al₂O₃–SiO₂–H₂O gels in synthetic aluminosilicate binders

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Characterization of chemosynthetic Al2O3–2SiO2 geopolymers

Cited by 53 publications

References 15 publications

Synthesis of stoichiometrically controlled reactive aluminosilicate and calcium-aluminosilicate powders

Synthesis of stoichiometrically controlled reactive aluminosilicate and calcium-aluminosilicate powders

Synthetic Aluminosilicates for Geopolymer Production

Phase evolution of Na2O–Al2O3–SiO2–H2O gels in synthetic aluminosilicate binders

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Phase evolution of Na₂O–Al₂O₃–SiO₂–H₂O gels in synthetic aluminosilicate binders