Alkali-activated limestone/metakaolin cements exposed to high temperatures: Structural changes

Perez-Cortes, Pedro; Cabrera-Luna, K.; Escalante-Garcı́a, J.I.

doi:10.1016/j.cemconcomp.2021.104147

Cited by 23 publications

(7 citation statements)

References 86 publications

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“…The deconvolutions of spectra were carried out using the OriginPro software with Gaussian peak shapes and following the Levenberg-Marquardt (L-M) algorithm. The procedure of deconvolution spectra is similar to a previous report by [45]. Figure 6 illustrates that the deconvoluted spectra consist of five bands corresponding to the specific components.…”

Section: Atr-ftir Analysis and Effect Of Curing Temperature On Geopol...mentioning

confidence: 84%

“…The crystalline phase in fly ash gives a sharp rather than a broad peak, as shown by amorphous geopolymer [44]. The broadening phenomenon on Si-O-T asymmetric bands indicates multiple overlapping components [45].…”

Section: Atr-ftir Analysis and Effect Of Curing Temperature On Geopol...mentioning

confidence: 99%

“…Figure 6 illustrates that the deconvoluted spectra consist of five bands corresponding to the specific components. The bands at 877-897 cm −1 are associated with the OH bending in Si-OH groups, which can be assumed from unreacted activating solutions [45]. The absorption bands at 953-969 cm −1 are due to non-bridging oxygen (NBO) stretching in the Si-O-Na structure, associated with immature aluminosilicate bonds [45].…”

Section: Atr-ftir Analysis and Effect Of Curing Temperature On Geopol...mentioning

confidence: 99%

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Circular Economy of Coal Fly Ash and Silica Geothermal for Green Geopolymer: Characteristic and Kinetic Study

Petrus

Olvianas

Shafiyurrahman

et al. 2022

Gels

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The study of geopolymers has become an interesting concern for many scientists, especially in the infrastructure sector, due to having inherently environmentally friendly properties and fewer energy requirements in production processes. Geopolymer attracts many scientists to develop practical synthesis methods, useful in industrial-scale applications as supplementary material for concrete. This study investigates the geopolymerization of fly ash and geothermal silica-based dry activator. The dry activator was synthesized between NaOH and silica geothermal sludge through the calcination process. Then, the geopolymer mortar was produced by mixing the fly ash and dry activator with a 4:1 (wt./wt.) ratio. After mixing homogeneously and forming a paste, the casted paste moved on to the drying process, with temperature variations of 30, 60, and 90 °C and curing times of 1, 3, 5, 7, 14, 21, 28 days. The compressive strength test was carried out at each curing time to determine the geopolymer’s strength evolution and simulate the reaction’s kinetics. In addition, ATR-FTIR spectroscopy was also used to observe aluminosilicate bonds’ formation. The higher the temperature, the higher the compressive strength value, reaching 22.7 MPa at 90 °C. A Third-order model was found to have the highest R2 value of 0.92, with the collision frequency and activation energy values of 1.1171 day−1 and 3.8336 kJ/mol, respectively. The utilization of coal fly ash and silica geothermal sludge as a dry activator is, indeed, an approach to realize the circular economy in electrical power generations.

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Section: Atr-ftir Analysis and Effect Of Curing Temperature On Geopol...mentioning

confidence: 84%

Section: Atr-ftir Analysis and Effect Of Curing Temperature On Geopol...mentioning

confidence: 99%

Section: Atr-ftir Analysis and Effect Of Curing Temperature On Geopol...mentioning

confidence: 99%

See 1 more Smart Citation

Circular Economy of Coal Fly Ash and Silica Geothermal for Green Geopolymer: Characteristic and Kinetic Study

Petrus

Olvianas

Shafiyurrahman

et al. 2022

Gels

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“…Perez‐Cortes et al 26 . reported that sodium alumina silicate hydrate (N–A–S–H) structure presented thermal resistance of up to 700°C−900°C, resulting in the high thermal stability of geopolymers.…”

Section: Introductionmentioning

confidence: 99%

“…Barbosa et al reported that geopolymers with potassium polysialate (K-PS) show little sign of melting up to 1400 • C, its amorphous structure being replaced by the crystalline feldspars leucite and kalsilite at 1000 • C. 23 He et al 24 found that cesiumsubstituted K-geopolymers underwent a four-stage shrinking process including structural resilience, dehydration, dihydroxylation, and viscous sintering, which ultimately resulting in a 19% shrinkage at 1200 • C. Compared to the K-based geopolymer ceramics, Na-based geopolymer ceramics generally show lower thermal stability due to the pyrolysis reaction at high temperature, which produce the free sodium, silicon, aluminum and produce Na-feldspars, and lead to a lower melting point and structural breakdown owing to the higher diffusion coefficient of Na than K in the matrix upon firing. 25 Perez-Cortes et al 26 reported that sodium alumina silicate hydrate (N-A-S-H) structure presented thermal resistance of up to 700 • C−900 • C, resulting in the high thermal stability of geopolymers. Liu et al 27 reported the thermal stability of metakaolin-based geopolymer, which obtained a lower sintering temperature from 870 • C to 780 • C due to the high chemical activity of RHA.…”

Section: Introductionmentioning

confidence: 99%

Phase transition and thermal stability of ceramics from Na‐based geopolymers

Gao,

Li,

Son

et al. 2024

Int J Applied Ceramic Tech

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Geopolymer ceramics undergo a series of thermal phase transitions, progressing from an amorphous geopolymer gel to a crystalline phase, and eventually to an amorphous glass phase as the temperature increases. However, there is a lack of mechanism understanding regarding to the crystallization process and the subsequent thermal degradation. Here, we fundamentally investigated the kinetics of nepheline formation in Na‐based geopolymer systems and its thermal stability up to 1400°C. Nepheline crystallization is controlled by bulk nucleation and three‐dimensional crystal growth based on the Avrami factor of 4.64, where the activation energy of nepheline formation is 350.59 kJ/mol. High thermal stability of geopolymer ceramics is achieved due to the appearance of nepheline up to 1400°C with the Si/Al ratio ranging from 1.40 to 1.94, while melting and amorphous structure are formed above a higher Si/Al ratio of 2.22. The nature of sintering for geopolymer ceramics consists of shrinkage, expansion and shrinkage corresponding to dehydroxylation, crystallization, and densification, leading to a thermal shrinkage of 21% at 1400°C.

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Effect of the Limestone Content on the Durability of Alkali-Activated Limestone-Metakaolin Subjected to Acidic and Sulfate Environments

Perez-Cortes

Escalante-Garcı́a

2023

RILEM Bookseries

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Alkali-activated limestone/metakaolin cements exposed to high temperatures: Structural changes

Cited by 23 publications

References 86 publications

Circular Economy of Coal Fly Ash and Silica Geothermal for Green Geopolymer: Characteristic and Kinetic Study

Circular Economy of Coal Fly Ash and Silica Geothermal for Green Geopolymer: Characteristic and Kinetic Study

Phase transition and thermal stability of ceramics from Na‐based geopolymers

Effect of the Limestone Content on the Durability of Alkali-Activated Limestone-Metakaolin Subjected to Acidic and Sulfate Environments

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