Effect of Curing Temperature and Silicate Concentration on Fly-Ash-Based Geopolymerization

Sindhunata,; Deventer, J.S.J. van; Lukey, and G. C.; Xu, Haijing

doi:10.1021/ie051251p

Cited by 309 publications

(121 citation statements)

References 40 publications

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“…Some researches which utilize low calcium fly ash [44,46] indicates that the reaction of geopolymerization would not start without elevated temperature curing and did not harden for at least one day. On the other side, a work conducted by Somna et al [47] shows that curing in the room temperature is possible when utilizing the high calcium fly ash with a high concentration of alkaline activator.…”

Section: Fresh State Behaviorsmentioning

confidence: 99%

A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer

Wattimena¹,

Antoni²,

Hardjito³

2017

AIP Conference Proceedings

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Abstract. There are more than four decades since the last 1970s where geopolymers concrete was first introduced and developed to use as a replacement to conventional concrete material which uses cement as a binder. And since the last two decades, geopolymers which utilized fly ash as aluminosilicate source material, i.e. fly ash based geopolymers, have been investigated. Many researchers present how to produce the best fly ash based geopolymer with a various source of constituent material as well as mixing formula to achieve exceptional concrete performance. Although there is a similar trend towards factors affecting the result of fly ash based geopolymer synthesis, there is still remain a wide range in mixture proportion. The considerable variation in fly ash characteristics as source material in the synthesis can very likely be one of the causes of this problem. This paper attempts to identify the effect of source material variation of geopolymer concrete, particularly which use fly ash as source material and focuses on the variation of its characteristics and the effects to properties of concrete. From the reviews it concluded that different sources (and even the same source, but different batch) of fly ash materials will give some different characteristics of the fly ash, where it would affect the synthesis process of the fly ash based geopolymer concretes.

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Section: Fresh State Behaviorsmentioning

confidence: 99%

A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer

Wattimena¹,

Antoni²,

Hardjito³

2017

AIP Conference Proceedings

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“…fast hardening, high and early compressive strength, optimal acid resistance and long term durability (9)(10)(11). However, the performance of the final product in these applications is heavily reliant on the physical properties of geopolymers and more specifically, the microstructure and porosity.…”

Section: Introductionmentioning

confidence: 99%

Contributions to the study of porosity in fly ash-based geopolymers. Relationship between degree of reaction, porosity and compressive strength

2016

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ABSTRACT:The main contribution of this paper relates to the development of a systematic study involving a set of parameters which could potentially have an impact on geopolymer properties: curing temperature, type of activating solution, alkali metal in solution, incorporation of slag (Ca source) and type of slag used. The microstructures, degrees of reaction, porosities and compressive strengths of geopolymers have been evaluated. Geopolymers prepared with soluble silicate presented a more compacted and closed structure, a larger amount of gel, lower porosity and greater compressive strength than those prepared with hydroxides. On the other hand, Na-geopolymers were more porous but more resistant than K-geopolymers. Although there is an inverse relation between degree of reaction and porosity, between compressive strength and porosity it is not always inversely proportional and could, in some cases, be masked by changes produced in other influencing parameters. RESUMEN: Contribuciones al estudio de la porosidad de geopolímeros basados en cenizas volantes. Relación entre grado de reacción, porosidad y resistencia a compresión.La principal contribución de este documento es el desarrollo de un estudio sistemático implicando una serie de parámetros que podrían afectar a las propiedades de los geopolímeros: temperatura de curado, solución activadora, metal alcalino de la solución, incorporación de escorias (fuente de calcio) y tipo de escorias. Se han evaluado: microestructura, grado de reacción, porosidad y resistencia a compresión. Los geopolímeros preparados con silicatos presentaron un microestructura más densa y compacta, una mayor cantidad del gel geopolimérico, menor porosidad y mejores propiedades mecánicas que los preparados con hidróxidos. Los geopolímeros preparados con sales de sodio fueron más porosos pero más resistentes que los preparados con sales potasio. Aunque existe una relación inversa entre el grado de reacción y la porosidad, en algunos casos, la relación entre resistencia y porosidad es inexistente ya que puede estar enmascarada por cambios producidos por otros parámetros que afecten a la reacción.

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“…The curing temperature affects the structural transition from the amorphous to the crystalline state during polycondensation [38] and thus for synthesis carried out at higher temperatures it is possible to achieve better results in terms of the strength until a threshold value [29,39]. The curing temperature also affects the reaction kinetics [2,8,20] due to an increase in the dissolution and polycondensation rates [40] and this is an important factor in the optimization of polymerization reactions [1]. However, after 28 days the degrees of geopolymerization of the different mixtures were similar, so the quality of the reaction product is the predominant factor rather than the curing temperature.…”

Section: Effect Of Naoh Concentration and Curing Regime On Geopolymermentioning

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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Effect of Curing Temperature and Silicate Concentration on Fly-Ash-Based Geopolymerization

Cited by 309 publications

References 40 publications

A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer

A review on the effect of fly ash characteristics and their variations on the synthesis of fly ash based geopolymer

Contributions to the study of porosity in fly ash-based geopolymers. Relationship between degree of reaction, porosity and compressive strength

Effect of NaOH concentration and curing regime on geopolymer

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