Kinetics of geopolymerization: Role of Al2O3 and SiO2

Silva, P. De; Sagoe-Crenstil, Kwesi; Sirivivatnanon, V.

doi:10.1016/j.cemconres.2007.01.003

Cited by 738 publications

(298 citation statements)

References 12 publications

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“…Previous research comparing different Al:Si ratios has shown that a ratio of 2 results in relatively high strength geopolymers [24][25][26][27]. The water content of 8 moles per mole of Al gave adequate paste workability and good geopolymer strength development [28][29][30].…”

Section: Preparation Of Geopolymer Mortar Samplesmentioning

confidence: 99%

“…Geopolymers have improved acid and fire resistance compared to most cementitious matrixes, and unlike concrete containing Portland cement, the maximum strength is achieved significantly before 28 days [4, [7][8][9][10]. Several potential applications have been proposed for geopolymer concrete including use in fire resistant panels, insulation materials and geopolymer concrete precast construction products [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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Production of nepheline/quartz ceramics from geopolymer mortars

Kuenzel

Grover

Vandeperre

et al. 2013

Journal of the European Ceramic Society

132

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This research has investigated the mechanical properties and microstructure of metakaolin derived geopolymer mortars containing 50% by weight of silica sand, after exposure to temperatures up to 1200 °C. The compressive strength, porosity and microstructure of the geopolymer mortar samples were not significantly affected by temperatures up to 800 °C.Nepheline (NaAlSiO 4 ) and carnegieite (NaAlSiO 4 ) form at 900 ºC in the geopolymer phase and after exposure to 1000 °C the mortar samples were transformed into polycrystalline nepheline/quartz ceramics with relatively high compressive strength (~275 MPa) and high Vickers hardness (~350 HV). Between 1000 and 1200 °C the samples soften with gas evolution causing the formation of closed porosity that reduced sample density and limited the mechanical properties.2

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Section: Preparation Of Geopolymer Mortar Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Production of nepheline/quartz ceramics from geopolymer mortars

Kuenzel

Grover

Vandeperre

et al. 2013

Journal of the European Ceramic Society

132

View full text Add to dashboard Cite

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“…Those spherical particles which were covered by the reaction products slowed down the degree of reaction. Energy dispersive X-ray spectra (EDS) analysis of gel showed majority of the phases containing Na-Si-Al in the bulk region suggesting the formation of silicate-activated gel by polymerization throughout the inter particles volume (De Silva et al 2007;Lloyd et al 2009). The properties of AAB systems depend not only on the composition and reactivity of the fly ash used, but also on the initial SiO 2 /Al 2 O 3 ratio in the mixture.…”

Section: Introductionmentioning

confidence: 99%

Characterizations and Quantitative Estimation of Alkali-Activated Binder Paste from Microstructures

Kar

Ray

Halabe

et al. 2014

Int J Concr Struct Mater

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Alkali-activated binder (AAB) is recently being considered as a sustainable alternative to portland cement (PC) due to its low carbon dioxide emission and diversion of industrial wastes and by-products such as fly ash and slag from landfills. In order to comprehend the behavior of AAB, detailed knowledge on relations between microstructure and mechanical properties are important. To address the issue, a new approach to characterize hardened pastes of AAB containing fly ash as well as those containing fly ash and slag was adopted using scanning electron microscopy (SEM) and energy dispersive X-ray spectra microanalyses. The volume stoichiometries of the alkali activation reactions were used to estimate the quantities of the sodium aluminosilicate (N-A-S-H) and calcium silicate hydrate (CSH) produced by these reactions. The 3D plots of Si/Al, Na/Al and Ca/Si atom ratios given by the microanalyses were compared with the estimated quantities of CSH(S) to successfully determine the unique chemical compositions of the N-A-S-H and CSH(S) for ten different AAB at three different curing temperatures using a constrained nonlinear least squares optimization formulation by general algebraic modeling system. The results show that the theoretical and experimental quantities of N-A-S-H and CSH(S) were in close agreement with each other. The R 2 values were 0.99 for both alkali-activated fly ash and alkali-activated slag binders.

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“…Higher loading of RHA will result in higher silica content which consequently leads to high Si/Al ratio. Therefore, high compressive strength can be achieved as proved by Komnitsas et al [5] and Silva et al [6]. Although high Si/Al ratio proved to provide higher compressive strength, further increase in Si/Al ratio has a tendency to reduce the compressive strength as studied by Songpirijakij et al [7].…”

Section: Introductionmentioning

confidence: 86%

Correlation between Compressive Strength and Fire Resistant Performance of Rice Husk Ash-Based Geopolymer Binder for Panel Applications

et al. 2017

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Abstract. Panel structures which are mainly used as insulation materials should possess high fire resistance characteristic. In addition, their mechanical requisites for walls and doors such as compressive strength must not be unduly compromised. Rice husk ash (RHA) was used as an aluminosilicate source and two factors namely RHA/AA ratio and NaOH concentration were analyzed using statistical tool to study the effect of both factors on the compressive strength. Surface morphology and fire resistant behavior of four selected samples based on their compressive strength (brittle, semi-brittle, ductile, and semi-ductile samples) were studied to determine the correlation between compressive strength and fire resistant performance of those selected samples. Results showed that RHAbased geopolymer sample recorded high compressive strength above 28 MPa when its RHA/AA ratio and NaOH concentration were high ranging from 0.7 to 0.8 and 12M to 14M, respectively. Brittle geopolymer sample (GS) with low Si/Al ratio shows high compressive strength together with high degree of geopolymerization. Ductile GS in comparison, shows low compressive strength irrespective of its degree of geopolymerization. Semi-ductile GS showed the best fire resistant properties with a maximum non-exposed surface temperature of only 50°C after 50 minutes (after it was exposed to a direct fire with temperature of 900°C) followed by semibrittle and brittle GS.

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Kinetics of geopolymerization: Role of Al2O3 and SiO2

Cited by 738 publications

References 12 publications

Production of nepheline/quartz ceramics from geopolymer mortars

Production of nepheline/quartz ceramics from geopolymer mortars

Characterizations and Quantitative Estimation of Alkali-Activated Binder Paste from Microstructures

Correlation between Compressive Strength and Fire Resistant Performance of Rice Husk Ash-Based Geopolymer Binder for Panel Applications

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