Optimization and Characterization of Geopolymer Mortars using Response Surface Methodology

Dhakal, Milap; Kupwade‐Patil, Kunal; Allouche, Erez N.; Johnson, Charles Conner la Baume; Ham, Kyungmin

doi:10.1002/9781118807743.ch12

Cited by 2 publications

(2 citation statements)

References 11 publications

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“…The variation in setting times is influenced by calcium oxide content, LOI and particle size distribution of the precursor material (fly ash) [32]. Although, measurement of setting time via Vicat needle test as per ASTM C191 has been used for measuring setting times of Portland cements, it does not provide an insight into the chemical reactions taking place during hydration [33].…”

Section: Introductionmentioning

confidence: 99%

Investigation of activation kinetics in geopolymer paste using quasielastic neutron scattering

Kupwade‐Patil

Diallo

Hossain

et al. 2016

Construction and Building Materials

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h i g h l i g h t sQuasielastic neutron scattering analysis in geopolymer paste. Activation kinetics is affected by temperature and molarity of the activator. QENS is effective in studying the alkali-activation process in geopolymer cements. a b s t r a c tQuasielastic neutron scattering (QENS) has been used to investigate the binding process of water molecules in pastes of calcium geopolymer prepared with low and high calcium fly ash contents, and at two different NaOH molarities, 10 and 14 M. The in situ measurements were carried at ambient and elevated curing temperatures (60°C). By carefully monitoring the time evolution of the elastic peak intensity, we infer a gelation process, followed by polymerization and a hardening in the high calcium geopolymer paste at 60°C, in agreement with previously proposed geopolymerization model. This behavior was neither observed at ambient temperature in both low and high calcium geopolymer cement paste, within the precision of the neutron instrument. Our study clearly shows that a minimal amount of heat is necessary to form gelation and polymerization during the activation process. The activation of geopolymer paste with high NaOH molarity involves more chemically bound water molecules than that at lower activator concentration. This work shows that the QENS technique can be effectively used to characterize the alkali-activation kinetics in certain geopolymer pastes, and that temperature and molarity of the activator play a vital role in controlling the gel mechanism.

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Section: Introductionmentioning

confidence: 99%

Investigation of activation kinetics in geopolymer paste using quasielastic neutron scattering

Kupwade‐Patil

Diallo

Hossain

et al. 2016

Construction and Building Materials

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“…Recent studies have suggested that the amorphous silica to alumina ratio (SiO2/Al2O3) also plays a significant role on the early age properties [25]. The optimum SiO2/Al2O3 ratio however depends on the calcium content of the feedstock [26,27]. It therefore follows that a generalised mix formulation in these binders does not exist, thus necessitating the need to optimize the activator composition for every feedstock.…”

Section: Introductionmentioning

confidence: 99%

Effect of synthesis parameters on the performance of alkali-activated non-conformant EN 450 pulverised fuel ash

Adu-Amankwah

Khatib

Searle

et al. 2016

Construction and Building Materials

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The fly ash reported in this paper is coarser than conventional pulverised fuel ash (PFA), with loss on ignition (LOI) exceeding 10.8%. Consequently, it is precluded from being used as a supplementary cementitious material (SCM) according to EN 450 and disposed in landfills. Alkali-activation of such PFAs is considered here. Three concentrations of sodium hydroxide (NaOH) were separately blended with water glass at different ratios to modify the silica modulus. Heat of reaction, setting time, compressive strength and drying shrinkage were investigated as a function of activator composition. Specimens were either cured at room temperature or hydrothermally treated at 75°C for five hours. The results show that by optimizing the activator composition, a binder with a 28 day compressive strength of 25MPa can be synthesised from such PFAs even at room temperature. Among the activator parameters, the alkali content was observed to be most influential.

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Optimization and Characterization of Geopolymer Mortars using Response Surface Methodology

Cited by 2 publications

References 11 publications

Investigation of activation kinetics in geopolymer paste using quasielastic neutron scattering

Investigation of activation kinetics in geopolymer paste using quasielastic neutron scattering

Effect of synthesis parameters on the performance of alkali-activated non-conformant EN 450 pulverised fuel ash

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