Structure analysis of geopolymers synthesized from clay originated from Serbia

Nenadović, Snežana; Kljajević, Ljiljana; Nešić, Maja D.; Petković, Marijana; Trivunac, Katarina; Pavlović, Vladimir B.

doi:10.1007/s12665-016-6360-4

Cited by 23 publications

(22 citation statements)

References 32 publications

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“…Furthermore, the shifting of the wavenumber of the Si-O-Si stretching to the right (to a lower wavenumber) is indicative of the breaking of Si-O bonds and the formation of new Si bonds in the process of geopolymerization. 16 In addition, new vibration band appear at 1478 cm -1 . There are no registered vibration bands in the area 770-800 cm -1 .…”

Section: Ftir Analysismentioning

confidence: 98%

Characterization of red mud/metakaolin-based geopolymers as modified by Ca(OH)2

Bošković¹,

Vukčević²,

Nenadović³

et al. 2019

Mater. Tehnol.

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Geopolymers are an emerging class of materials that offer an alternative to the Portland cement as the binder of structural concrete. One of the advantages is that the primary source of their production is waste alumosilicate materials from different industries. One of the key issues in geopolymer synthesis is the low level of mechanical properties due to porosity as well as the high activity of conductivity carriers. It can often lead to limited application possibilities, so the objective is to obtain an enhanced strength as well as decreased cracking tendency through microstructure modification. The introduction of Ca(OH)2, under certain pH conditions could lead to the filling-the-pores process and improving the mechanical properties. The aim was to understand the role that calcium plays in the geopolymer synthesis, and to define which reaction prevails under the synthesis conditions: formation of geopolymer gel or calcium silicate hydrate that contains aluminum substitution (CASH). The synthesis was performed with different raw materials (with or without red mud) and different alkalinity conditions. Ca(OH)2 was the obligatory supplement to both of the mixtures. Different techniques were performed for the testing of reaction products, as well as to define the microstructural changes as the generator of improved mechanical properties and changed electrical conductivity. The characteristics of the geopolymer's macrostructure were defined by means of an SEM analysis. Compressive strength and electrical conductivity are among the investigated product's properties. X-ray diffraction (XRD) and Fourier transform infra-red spectroscopy (FTIR) were used for the identification of various crystalline phases and an amorphous phase.

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Section: Ftir Analysismentioning

confidence: 98%

Characterization of red mud/metakaolin-based geopolymers as modified by Ca(OH)2

Bošković¹,

Vukčević²,

Nenadović³

et al. 2019

Mater. Tehnol.

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“…The new standard introduces a quality control system for fly ash, consisting of an internal quality control by the producer and an audit testing by a certification body which is notified by the building authorities. The European Union has approved the use of fly-ash derived from the co-combustion of coal with wood, straw, olive husks, green wood, cultivated biomass, animal meal, municipal solid waste and paper sludge as a cement admixture, as long as the fly-ash contains less than 5 wt % carbon, 5 wt % total alkali, and 0.1 wt % chloride [7][8][9][10][11][12][13][14][15]. Finding means of utilizing waste products is a very important and actual field of research.…”

Section: Introductionmentioning

confidence: 99%

“…Finding means of utilizing waste products is a very important and actual field of research. Fly ashes, obtained as waste products, from different sources (wood and lignite) were used as a basic ingredient of the new geopolymeric materials [9]. The technology of geopolymerisation is gaining commercial interest because it has been demonstrated that, in certain cases, the properties of geopolymeric materials are superior to existing cementations systems [10].…”

Section: Introductionmentioning

confidence: 99%

Alkali activation of different type of ash as a production of combustion process

et al. 2021

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Presented study deals with the final structure and radiological properties of different fly ash-based geopolymers. lignite fly-ash (lignite Kolubara - Serbia) and wood fly ash were obtained in combustion process together with commercial fly ash. Synthesis of the geopolymers was conducted by mixing fly ash, sodium silicate solution, NaOH and water. The samples were cured at 60?C for 48h after staying at room temperature in covering mold for 24 h. X - ray diffraction, Fourier transform infra - red and Scanning electron microscope measurements were conducted on the samples after 28 days of geopolymerization process. X-ray diffraction measurements of lignite fly ash samples show anhydrite as the main constituent, while wood fly ash samples consist of calcite, albite and gypsum minerals. Beside of determination of physical-chemical properties, the aim of this study was radiological characterization of lignite fly ash, wood fly ash and the obtained geopolymer products. Activity concentration of 40K and radionuclides from the 238U and 232Th decay series in ash samples and fly ash-based geopolymers were determined by means of gamma-ray spectrometry, and the absorbed dose rate rate (D) and the annual effective dose rate (E) were calculated in accordance with the UNSCEAR 2000 report.

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“…Finally, the mixtures were kept in a sample drying oven for two days at 60 °C. The alkaline solution was prepared from sodium silicate (volume ratio Na2SiO3/NaOH = 1.5) and an aqueous solution of NaOH, cNaOH = 2mol/dm 3 -2M NaOH (analytical grade), in accordance with our previous research [23][24][25]. After this reaction step, all samples were aged for 28 days.…”

Section: Methodsmentioning

confidence: 99%

Structural and electrical properties of geopolymer materials based on different precursors (kaolin, bentonite and diatomite)

Kljajević

Melichová

Stojmenović

et al. 2019

Maced. J. Chem. Chem. Eng.

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Geopolymers (GP) were successfully synthesized from metabentonite (MB), metadiatomite (MD) and metakaolinite (MK). Characterization of their phase structure and microstructure was performed by XRD, FTIR, SEM/EDX methods. A SEM micrograph of GPMD shows a homogeneous surface with some longitudinal cavities in the gel, and it is significantly different from the micrographs of the other two geopolymer samples, GPMB and GPMK. A considerable amount of unreacted particles, as well as the presence of pores in the geopolymer matrix of GPMK and GPMD, indicate an incomplete reaction in the system. Aluminosilicate inorganic polymers, geopolymers, are quasi solid electrolytes which possess a high electrical conductivity at room temperature in relation to materials of similar chemical composition. The highest conductivity was found for the sample obtained from GPMK, amounting to 2.14 × 10 -2 Ω -1 cm -1 at 700 ºC. The corresponding activation energies of conductivity for this sample amounted to 0.33 eV in the temperature range of 500-700 ºC. The geopolymer synthesized from metakaolin has good ionic conductivity values, which recommends it for use as an alternative material for an SOFC (Solid Oxide Fuel Cell). СТРУКТУРНИ И ЕЛЕКТРИЧНИ СВОЈСТВА НА ГЕОПОЛИМЕРНИ МАТЕРИЈАЛИ БАЗИРАНИ НА РАЗЛИЧНИ ПРЕКУРЗОРИ (КАЛОЛИН, БЕНТОНИТ И ДИАТОМИТ)Успешно беа синтетизирани геополимери (GP) од метабентонит (MB), метадиатомит (MD) и метакаолинит (MK). Карактеризацијата на нивните фазни структури беше определена со методите на XRD, FTIR и SEM/EDX. Mикрографот SEM на GPMD покажува хомогена површина со лонгитудинални празнини во гелот и значајно се разликува од микрографите на двата други примероци на геополимери, GPMB и GPMK. Значителна количина на неизреагирани честички, како и присуство на пори во геополимерната матрица на GPMK и GPMD укажуваат на нецелосна реакција на системите. Алумосиликатните неоргански полимери, геополимери, се квазицврсти електролити што имаат висока електрична спроводливост на собна температура во однос на материјалите со сличен хемиски состав. Највисока спроводливост е најдена кај примерокот од GPMK и изнесува 2,14 × 10 -2 Ω -1 cm -1 на 700 ºC. Соодветните активациони енергии на кондуктивноста за овој примерок изнесуваат до 0,33 eV во температурниот опсег од 500-700 ºC. 284Геополимерот синтетизиран од метакаолин има добри вредности на јонска спроводливост, што го прави погоден за употреба како алтернативен материјал на SOFC (Горивна ќелија од цврст оксид).

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Structure analysis of geopolymers synthesized from clay originated from Serbia

Cited by 23 publications

References 32 publications

Characterization of red mud/metakaolin-based geopolymers as modified by Ca(OH)2

Characterization of red mud/metakaolin-based geopolymers as modified by Ca(OH)2

Alkali activation of different type of ash as a production of combustion process

Structural and electrical properties of geopolymer materials based on different precursors (kaolin, bentonite and diatomite)

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