The composition range of aluminosilicate geopolymers

Fletcher, Ross A.; MacKenzie, Kenneth J.D.; Nicholson, Catherine L.; Shimada, Shiro

doi:10.1016/j.jeurceramsoc.2004.06.001

Cited by 315 publications

(182 citation statements)

References 3 publications

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“…29 Si MAS NMR experiments were performed on a Bruker DMX 400 spectrometer with a wide bore magnet (9.4 T) using a 7-mm triple-resonance probe with a sample spinning frequency of 6.5 kHz. The spectra were recorded at room temperature with a 90°pulse of 7.7 ls and at least 144 scans were accumulated.…”

Section: Xrd and Nmr Analysesmentioning

confidence: 99%

“…The recycle delay was 400 s for the silica and the geopolymer with the lowest SiO 2 / Al 2 O 3 ratio; a recycle delay of 1200 s was used for the 123 other geopolymers because of long relaxation times of Q 4 species (see ''Results'' section). The 29 Si MAS NMR shift was referenced using kaolinite as secondary chemical shift standard with -91.5 ppm for the upfield peak. Two-pulse phase modulation sequence [21] was used for high-power proton decoupling.…”

Section: Xrd and Nmr Analysesmentioning

confidence: 99%

“…The phase content of the cured geopolymers was investigated by means of XRD, 29 Si and 27 Al MAS NMR, and the degree of reaction of the silica materials in the geopolymers was measured using two different methods: chemical attack with HCl to dissolve the reaction products and evaluation of peak areas of 29 Si MAS NMR spectra, using the fact that the intensity of each peak corresponds to the abundance of the Si-sites in the different compounds. The resulting degrees of reaction were compared and related to the phase content of the geopolymers, thus giving new insights into the behaviour of the silica and the composition of the hardened geopolymers.…”

Section: Introductionmentioning

confidence: 99%

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Degree of reaction and phase content of silica-based one-part geopolymers investigated using chemical and NMR spectroscopic methods

et al. 2015

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One-part geopolymers were synthesized from two different silica materials (a silica-rich residue from chlorosilane production and a commercial microsilica) and sodium aluminate at three different SiO 2 /Al 2 O 3 ratios and a nominal water/solids ratio of 0.5. The degree of reaction of the silica in the cured geopolymers (i.e. the fraction of silica dissolved to form aluminosilicates and minor products) was determined using two different methods: chemical attack with HCl to dissolve the reaction products and evaluation of peak areas of 29 Si MAS NMR spectra. It was found that the degree of reaction of the silica decreases with increasing the silica content of the starting mix, and that it is almost constant after 1 day of curing and almost independent from the kind of starting silica. From the results of the NMR-based method, the mean SiO 2 /Al 2 O 3 ratio of the reaction products (aluminosilicates and minor products) can be estimated to be ca. 2.0, nearly independent of the starting composition of the geopolymers. The dissolution method is biased, but of sufficient precision to be useful for following changes of the degree of reaction. Major crystalline phases in the cured geopolymers are zeolite A and/or hydrosodalite. Depending on the starting composition, the relative amounts of these zeolites vary; additionally, sodalite (only for the residue from chlorosilane production with [1 wt% Cl -), faujasite, and zeolite EMT can appear in the geopolymers. The 29 Si and 27 Al MAS NMR results indicate mainly Si(4Al) and Al(4Si) sites, in line with the presence of zeolite A, hydrosodalite, sodalite, and geopolymeric gel of comparatively low SiO 2 /Al 2 O 3 ratio.

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Section: Xrd and Nmr Analysesmentioning

confidence: 99%

Section: Xrd and Nmr Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Degree of reaction and phase content of silica-based one-part geopolymers investigated using chemical and NMR spectroscopic methods

et al. 2015

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“…The SEM image analysis of kaolin and white clay based geopolymer coating (Figure 2 (b) and Figure 3 (b)) obviously shows the raw particles has been stimulated by the alkaline activator solution with alters at the edges of the plate-like particles and became more compact [28,29]. The microstructure of silica sand based geopolymer coating showed more homogeneous structure with more intervening materials was examined (Figure 4 (b)).…”

Section: Scanning Electron Microscopymentioning

confidence: 98%

Morphology and Properties of Geopolymer Coatings on Glass Fibre-Reinforced Epoxy (GRE) pipe

et al. 2016

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Abstract. Geopolymer coatings were coated on glass fibre-reinforced epoxy (GRE) pipe by using kaolin, white clay and silica sand as source materials and sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) as alkaline solution. The microstructure and mechanical property of geopolymer coating on GRE pipe were methodically investigated through morphology analysis, and flexural strength test. The result indicates the microstructure and interfacial layer between geopolymer coating and GRE pipe significantly influence the mechanical property of geopolymer coating. However, different source materials gave different microstructure and property in geopolymer coating.

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“…In fact, the formation of geopolymers from natural minerals [5,6], calcined clays [7,8], industrial by-products [9][10][11][12] or a combination of them [13][14][15] has been widely explored. In the last decades, due to the increasing The formation of a geopolymer is a result of several chemical reactions, which starting from an amorphous silico-aluminate source, lead to a 3D-structure ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Geopolymerization Ability of Natural and Secondary Raw Materials by Solubility Test in Alkaline Media

Liguori¹,

Capasso²,

Pertis

et al. 2017

Environments

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Abstract:The extent of the dissolution of aluminosilicate compounds is crucial, since the amount of Si and Al initially dissolved is essential for the following polycondensation and can strongly influence physical and mechanical performances of the final product. In order to set up a method to test the ability of a material to react in alkaline media, different aluminosilicate sources have been selected: a mineral resource (a zeolitized tuff), an industrial by product (silt from washing process of construction and demolition wastes), a heat treated clay sediment and a calcined clay (metakaolin). Two test methods, static and dynamic, have been applied to evaluate the attitude of a silicoaluminate precursor to give a geopolymerization reaction. In particular, a fixed amount of precursor was put into contact with a alkaline solution under continuous stirring or in static conditions at 60 • C for fixed times. The dynamic test method seems to be more suitable, since it is faster and requires lower amounts of reactants (solution). Moreover, the dynamic test provides a reactivity sequence (ordered from the more to the less reactive precursor) metakaolin > treated clay sediment > zeolitized tuff ≈ silt both for Si and Al release, which is coherent with the performances of geopolymers obtained by using the above precursors.

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The composition range of aluminosilicate geopolymers

Cited by 315 publications

References 3 publications

Degree of reaction and phase content of silica-based one-part geopolymers investigated using chemical and NMR spectroscopic methods

Degree of reaction and phase content of silica-based one-part geopolymers investigated using chemical and NMR spectroscopic methods

Morphology and Properties of Geopolymer Coatings on Glass Fibre-Reinforced Epoxy (GRE) pipe

Geopolymerization Ability of Natural and Secondary Raw Materials by Solubility Test in Alkaline Media

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