29Si, 27Al, 31P and 11B magic angle spinning nuclear magnetic resonance study of the structural evolutions induced by the use of phosphor- and boron–based additives in geopolymer mixtures

Dupuy, C.; Gharzouni, Ameni; Sobrados, Isabel; Texier-Mandoki, Nathalie; Bourbon, Xavier; Rossignol, Sylvie

doi:10.1016/j.jnoncrysol.2019.119541

Cited by 29 publications

(14 citation statements)

References 51 publications

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“…MAS-NMR spectroscopic studies conducted on the 27 Al and 29 Si nuclei have been essential to defining the type of geopolymeric matrix obtained [ 64 , 65 ].…”

Section: Resultsmentioning

confidence: 99%

Novel Magnetic Inorganic Composites: Synthesis and Characterization

et al. 2021

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The addition of magnetic particles to inorganic matrices can produce new composites exhibiting intriguing properties for practical applications. It has been previously reported that the addition of magnetite to concrete improves its mechanical properties and durability in terms of water and chloride ions absorption. Here we describe the preparation of novel magnetic geopolymers based on two different matrices (G1 without inert aggregates and G2 with inert quartz aggregates) containing commercial SrFe12O19 particles with two weight concentrations, 6% and 11%. The composites’ characterization, including chemical, structural, morphological, and mechanical determinations together with magnetic and electrical measurements, was carried out. The magnetic study revealed that, on average, the SrFe12O19 magnetic particles can be relatively well dispersed in the inorganic matrix. A substantial increase in the composite samples’ remanent magnetization was obtained by embedding in the geopolymer SrFe12O19 anisotropic particles at a high concentration under the action of an external magnetic field during the solidification process. The new composites exhibit good mechanical properties (as compressive strength), higher than those reported for high weight concretes bearing a similar content of magnetite. The impedance measurements indicate that the electrical resistance is mainly controlled by the matrix’s chemical composition and can be used to evaluate the geopolymerization degree.

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“…MAS-NMR spectroscopic studies conducted on the 27 Al and 29 Si nuclei have been essential to defining the type of geopolymeric matrix obtained [ 64 , 65 ].…”

Section: Resultsmentioning

confidence: 99%

Novel Magnetic Inorganic Composites: Synthesis and Characterization

et al. 2021

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“…The authors attributed the higher resistance obtained by geopolymers with 5% palm oil to the most noticeable bands observed by this composition, which proves the efficiency of the alkaline activation reaction [86]. Another way of characterizing the products of the AA reaction is by nuclear magnetic resonance (NMR) spectrometry, which in the case of the geopolymers study, for example, the resonance of two types of isotopes is carried out: Al 27 e Si 29 [39], [88], [89].…”

Section: Characterizaion Of Gels Formed In the Aa Reactionmentioning

confidence: 87%

“…In the isotope Si 29 resonance, the reference is made using tetramethylsilane, whose frequency is -94 ppm [88]. The analysis is carried out in the same way as for the Al 27 isotope, with the difference that the connections between silicon and aluminum, or between silicon and silicon can be studied [89]. Unlike aluminum, which can be tetravalent, pentavalent, or hexavalent, silicon has tetracoordination, which is why the Si 4 Q n symbology is not widely used.…”

Section: Characterizaion Of Gels Formed In the Aa Reactionmentioning

confidence: 99%

Reaction mechanisms of alkali-activated materials

Marvila

Azevedo

Vieira

2021

Rev. IBRACON Estrut. Mater.

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The Alkali-Activated Materials (AAM) are defined as materials obtained through the reaction between precursors and activators, and are separated into two classes depending on the products formed in the reaction, those rich in calcium, as the blast furnace slag, whose Ca/(Si+Al) ratio is higher than 1; and poor in calcium, which is the geopolymers subclass. In this review article, some bibliographical aspects were discussed regarding the discovery of these materials, through research conducted by Victor Glukhovsky and through the characterization of historical monuments by Davidovits, which began in the 50s and 60s and persist to the present day. The main products obtained in the alkaline activation reaction were also addressed, using the definition of polysialates and zeolites, in the case of geopolymers, and the tobermorite structure, in the case of materials rich in calcium. The main steps of the alkali-activated reaction, such as dissolution, condensation, polycondensation, crystallization, and hardening, were discussed. Some techniques for characterizing the AA reaction products were also examined, such as X-ray diffraction (XRD), nuclear magnetic resonance spectrometry (NMR), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Finally, the main factors that interfere in the kinetics of AA reactions were explored, in which the type of cure and the activating solution used in the alkali-activated materials production stands out.

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“…The resulting aluminium can react with silicate species leading to the formation of different networks. Similarly to glasses and geopolymers [29,57] , the boron from lithium tetraborate (asymmetric B III ) leads to the appearance of non bridging oxygens, resulting in charge defects in the structure. So, boron interacts with the alkali cation in the silicate gel to compensate this charge defects.…”

Section: Stability Of Silicate Gelsmentioning

confidence: 99%

Structural study of the effect of mineral additives on the transparency, stability, and aging of silicate gels

Felss

Gharzouni

Colas

et al. 2020

J Sol-Gel Sci Technol

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The objective of this work is to evaluate to structural evolution of silicate gel in function of time and mineral additives. A comparison between fresh and aged silicate gel synthesized by silica and potassium hydroxide was carried out using FTIR, Raman and 29 Si MAS-NMR spectroscopies. Then, different additives such as NaOH, AlOOH, Li2B4O7 and HCl were incorporated in the silica solution. Their effect on the aspect, transparency, Q n polymerization and stability of silicate gels was studied. The structural study has shown that the quantification of Q n species is difficult using FTIR and Raman spectroscopy because of the existence of several contributions in the same spectral region of silicate species. More precise informations were given by 29 Si NMR spectroscopy which has demonstrated the increase of Q 3 species in the detriment of Q 4 revealing the depolymerization of the structure over time. The study of effect of additives reveals that HCl, AlOOH and Li2B4O7 do not permit to improve the stability of the gel due to the formation of several networks. However, promising results of stability and transparency were obtained using NaOH with a molar ratio of former to modifier of 2.52.

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29Si, 27Al, 31P and 11B magic angle spinning nuclear magnetic resonance study of the structural evolutions induced by the use of phosphor- and boron–based additives in geopolymer mixtures

Cited by 29 publications

References 51 publications

Novel Magnetic Inorganic Composites: Synthesis and Characterization

Novel Magnetic Inorganic Composites: Synthesis and Characterization

Reaction mechanisms of alkali-activated materials

Structural study of the effect of mineral additives on the transparency, stability, and aging of silicate gels

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