The effects of Na2O/SiO2molar ratio, curing temperature and age on compressive strength, morphology and microstructure of alkali-activated fly ash-based geopolymers

Vargas, Alexandre Silva de; Molin, Denise Carpena Coitinho Dal; Vilela, Antônio Cezar Faria; Silva, Felipe José da; Pavão, Bruno; Veit, Hugo Marcelo

doi:10.1016/j.cemconcomp.2011.03.006

Cited by 301 publications

(102 citation statements)

References 13 publications

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“…For example, trace content in the order of ppm of certain elements such as Fe and Mg can greatly affect the chemical stability of the polymeric chains, resulting in partial depolymerization, shrinkage and multiple cracking of the microstructure 1 . Davidovits 2 insists on addressing the difference between the geopolymer and the alkali-activated matrices.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical Characterization of Pulverized Phyllite Rock for Geopolymer Resin Synthesis

et al. 2017

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Geopolymeric materials have some unique properties such as early-high compressive strength, durability, resistance to acids and sulfates, ability to immobilize toxic and radioactive compounds, low porosity and high temperature resistance. These materials are strategic for sustainable development and are a suitable alternative to Portland cement. The use of phyllite as a geopolymer precursor is encouraged by its abundance, low cost, and the fact that it is already applied in ceramic industries as a kaolin substitute. The objective of this paper is the physicochemical characterization of geopolymeric resin using two pulverized phyllite rocks as precursors with STEM, XRD and XRF techniques. It was found that both phyllite rocks studied have a high quartz content of approximately 50% (weight), which have a "filler" function in the microstructure of the resin helping stabilize residual tensions after curing. Kaolinite and muscovite minerals are present in up to 40% (weight) and are responsible for the high compressive strength of the geopolymer resins.

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Section: Introductionmentioning

confidence: 99%

Physicochemical Characterization of Pulverized Phyllite Rock for Geopolymer Resin Synthesis

et al. 2017

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“…Once there is a relationship between compressive strength and degree of reaction, it could be assumed that the geopolymerization reaction was incomplete, since a higher curing temperature is required for more efficient alkaline activation [34] and therefore to produce a better oriented molecular structure [35]. Nevertheless, on comparing the pastes prepared with the 8 M NaOH solution, it was noted that samples with a curing temperature of 85 °C had lower compressive strength than those obtained at 65 °C.…”

Section: Figurementioning

confidence: 99%

Effect of NaOH concentration and curing regime on geopolymer

Livi

Repette

2017

Rev. IBRACON Estrut. Mater.

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ResumoThe effect of alkali concentration and curing temperature regime on fly ash-based geopolymer pastes was investigated in this study by using NaOH solutions. Prismatic specimens were molded, cured at 65 °C and 85 °C and submitted to flexural and compressive strength tests. Unreacted fly ash and geopolymers were characterized by X-ray diffraction and thermogravimetric analysis. In general, the mechanical strength was enhanced by increasing the molar concentration and the curing temperature. This trend was confirmed by thermogravimetric data. However, for a lower amount of NaOH there were no significant differences between the strength results. The mixture with the highest strength was obtained with the 16 M NaOH solution and curing temperature of 85 °C, which resulted in flexural strength of 4.20 MPa, compressive strength of 21.35 MPa and also the highest weight loss of 9.89%.

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“…However previous research shows that one of challenges in the application of low calcium fly ash based geopolymer as binder is its setting process needs relatively high curing temperature 60°C-120°C for 6 -24 hours [2][3][4][5][6][7]. This conditions limit the application of geopolymer for precast purposes whilst for normal concrete, the binder should be able to set in room temperature.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Lime Addition on the Setting Time and Strength of Ambient Cured Fly Ash Based Geopolymer Binder

Adam

Amiri

Suarnita

et al. 2016

MATEC Web of Conferences

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Abstract.One of the limitations of geopolymer as the alternative binders in concrete is the necessity of heat curing. This study aimed to produce fly ash geopolymer binder subjected to ambient curing by adding a small proportion of lime and varying the activator dosage. The Class F fly ash from Mpanau coal-fired power plant was mixed with alkaline solution consists of sodium silicate and sodium hydroxide with Na2O dosage of 5%, 7%, and 9%. To achieve ambient cured paste, 8%, 9%, and 10% slaked lime was added as the substitute for the fly ash. The setting time test was conducted for each mix and the compressive strength was performed at age of 7, 14 and 28 days. The test result shows that the setting time of the fly ash based geopolymer paste can be controlled by adding a small proportion of slaked lime. The addition of lime increased strength but decreased the setting time.

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The effects of Na2O/SiO2molar ratio, curing temperature and age on compressive strength, morphology and microstructure of alkali-activated fly ash-based geopolymers

Cited by 301 publications

References 13 publications

Physicochemical Characterization of Pulverized Phyllite Rock for Geopolymer Resin Synthesis

Physicochemical Characterization of Pulverized Phyllite Rock for Geopolymer Resin Synthesis

Effect of NaOH concentration and curing regime on geopolymer

The Effect of Lime Addition on the Setting Time and Strength of Ambient Cured Fly Ash Based Geopolymer Binder

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