Reactivity and mechanical performance of geopolymer binders from metakaolin/meta-halloysite blends

Kaze, Cyriaque Rodrigue; Jiofack, Séverin Bidias Keumeka; Cengiz, Özgür; Alomayri, Thamer; Adesina, Adeyemi; Rahier, Hubert

doi:10.1016/j.conbuildmat.2022.127546

Cited by 17 publications

(9 citation statements)

References 53 publications

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“…The decrease in compressive strength from 64.12 to 29.43 MPa could be attributed to the non-gelatinisation of amylopectin due to its higher content in the structure of geopolymer composites. The maximum compressive strength value obtained in this work (64.12 MPa) is comparable to that (65.2 MPa) obtained by Kaze et al [29] in which the metakaolin was replaced by 50 wt% calcined halloysite. The micrographs of the geopolymer composites before the addition of starch (GB0) and after the addition of starch (GB15 and GB30) were made with the scales at 50 and 100 µm and are shown in Figure 8.…”

Section: Compressive Strengthssupporting

confidence: 87%

Influence of Starch Powder on Compressive Strength and Microstructural Properties of Geopolymer Composite Materials Based on Metakaolin

Dieuhou,

Tchakoute,

Kamlo

et al. 2024

Engineering Science & Technology

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The main objective of the present study is the investigation of the behaviour of starch powder incorporated at different levels (0, 5, 10, 15, 20, 25, and 30 wt%) on the compressive strength and microstructural properties of metakaolin-based geopolymers. Sodium silicate with a molar ratio of SiO2/Na2O of 1.6 was used as the hardener and standard metakaolin was used as the aluminosilicate source. The results showed that when metakaolin was replaced by starch from 0 to 15 wt%, the compressive strength increased from 36.50 to 64.12 MPa. When metakaolin was replaced by starch above 15 wt%, the compressive strength decreased from 64.12 to 29.43 MPa. That of the reference geopolymer material is 36.50 MPa.The infrared spectra of the geopolymer composites indicate that the Si-O-C bonds are formed. The thermal behaviour of geopolymer composites containing starch shows a mass loss at around 100 and 278 °C. The geopolymer material without starch only shows a loss of mass at around 100 °C. The micrographs of the geopolymer composite with 15% by weight of starch show that the matrix is more compact, more homogeneous, and denser than the one without starch. On the contrary, possibly due to a large amount of unreacted starch in its network, the micrographs of the geopolymer composite obtained after the incorporation of 30 wt% starch show a heterogeneous microstructure. It can be concluded that suitable starch content for the synthesis of geopolymer composites would be around 15% by weight.

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Section: Compressive Strengthssupporting

confidence: 87%

Influence of Starch Powder on Compressive Strength and Microstructural Properties of Geopolymer Composite Materials Based on Metakaolin

Dieuhou,

Tchakoute,

Kamlo

et al. 2024

Engineering Science & Technology

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“…Natomiast ilość prac dotyczących geopolimerów zawierających naturalne pucolany inne niż metakaolinit jest bardzo ograniczona. W ostatnim czasie ukazały się także prace omawiające zastosowanie metahaloizytu jako prekursora w materiałach geopolimerowych (19)(20)(21)(22)(23)(24)(25)(26).…”

Section: Discussionunclassified

“…However, the number of works on geopolymers that contain natural pozzolans other than metakaolin is very limited. In recent times, there have also been publications discussing the application of meta-halloysite as a precursor in geopolymers (19)(20)(21)(22)(23)(24)(25)(26).…”

Section: Introductionmentioning

confidence: 99%

Physical and mechanical properties of meta-halloysite-based geopolymer mortars

Owsiak,

Szczykutowicz

2024

Cement Wapno Beton

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Geopolymers are amorphous materials produced by the polymerisation reaction between an aluminosilicate precursor and an alkaline reagent or by activation with phosphoric acid. The aluminosilicate raw material used in the manufacture of geopolymers an be industrial waste, such as fly ash or volcanic ash, blastfurnace slag, or it can be obtained from natural raw materials, such as metakaolin and meta-halloysite. The work aimed to select the composition of an activator for the production of meta-halloysite geopolymers with optimum physico-mechanical properties such as specific and bulk density, porosity, weight, and bulk absorption, as well as flexural and compressive strength. A two-factor experimental design was employed to determine the composition of the alkaline activator for geopolymer mortars, with sodium hydroxide solution molar concentration and sodium silicate to NaOH ratio as variables. Research has shown that increasing the amount of sodium silicate relative to the mass of a 12M NaOH solution in the activator solution improves the compressive strength of geopolymers by 36.8%, while an increase in flexural strength of 14.2% was achieved. As the molar concentration of caustic soda in the activator solution increases from 19.0 to 24.5%, the porosity of geopolymer mortars decreases. The reduction in the ratio of water glass to sodium hydroxide and the reduction in the molar concentration of NaOH increases the mass and volume water absorption of the mortar. Further studies is necessary to determine the optimal mixture of metahalloysite geopolymer, taking into account its functional properties and durability.

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“…Three alkaline solutions were prepared by mixing 8, 10, and 12 M of aqueous NaOH with commercial sodium silicate (composed of 14.37 wt.% Na 2 O, 29.54 wt.% SiO 2 , and 56.09 wt.% H 2 O). To prepare the activating solution for the geopolymer mortars, the mass ratio of sodium silicate to each concentrated NaOH (8, 10, and 12 M) solution was xed at 2, according to a previous study [22,23]. Each activating solution was maintained at room temperature for 24 h before use.…”

Section: Methodsmentioning

confidence: 99%

Mechanical and Microstructural Properties of Meta-Halloysite-Based Geopolymer Mortars Cured at Room Temperature

Kaze

Cengiz

Jiofack

et al. 2022

Preprint

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In this study, meta-halloysite (MH) mixed with an alkaline solution(8, 10, and 12 M) was used as a binder phase to produce geopolymer mortars with alkaline solution/MH ratios of 0.6, 0.7, and 0.8. The flow slump behaviour, setting time, and mechanical properties of the end products were studied at room temperature. The microstructural properties of the geopolymer mortars were evaluated using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The results indicated that the cohesion between the geopolymer binder and quartz sand aggregates improved with an increase in the molarity and alkaline solution/meta-halloysite ratio from 0.6 to 0.8. The corresponding slump and flow values increased from 25 to 118 mm, 14 to 115 mm, and 12 to 102 mm, whereas the setting time increased from 77 to 163 min, 54 to 140 min, and 35to 121 min,respectively, with an increase in the alkaline solution concentration. Increasing the alkaline solution/MH ratio (from 0.6 to 0.8) improved the dissolution of the solid precursor and produced a sufficient amount of geopolymer,ensuring the formation of a dense and compact structure with few accessible voids, thus justifying the reduction in water absorption and porosity. A similar trend was observed in the compressive, flexural, and tensile strengths, which increased with the alkaline activator/solid precursor and curing time (7 and 28 days). The geopolymer mortar samples prepared using 0.8 and 12 M NaOH developed high compressive strength (65 MPa), lower porosity, and lower water absorption.

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Reactivity and mechanical performance of geopolymer binders from metakaolin/meta-halloysite blends

Cited by 17 publications

References 53 publications

Influence of Starch Powder on Compressive Strength and Microstructural Properties of Geopolymer Composite Materials Based on Metakaolin

Influence of Starch Powder on Compressive Strength and Microstructural Properties of Geopolymer Composite Materials Based on Metakaolin

Physical and mechanical properties of meta-halloysite-based geopolymer mortars

Mechanical and Microstructural Properties of Meta-Halloysite-Based Geopolymer Mortars Cured at Room Temperature

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