Comparative study on the characteristics of fly ash and bottom ash geopolymers

Chindaprasirt, Prinya; Jaturapitakkul, Chai; Chalee, Wichian; Rattanasak, Ubolluk

doi:10.1016/j.wasman.2008.06.023

Cited by 622 publications

(253 citation statements)

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“…Bottom ash is pulverized fuel ash collected from the bottom of thermal power station boilers differs from fly ash in containing a range of particle sizes, including coarser particles (8). Although geopolymers are more commonly synthesized from fly ash, they may also be prepared from bottom ash (9)(10)(11)(12). Depending on the composition of the coal source, both fly ash and bottom ash can contain heavy metals, and in the dry state this dust can constitute a health hazard; for this reason it is often stored under water in ponds or lagoons.…”

Section: Introductionmentioning

confidence: 99%

Properties of geopolymer binders prepared from milled pond ash

et al. 2017

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Alkali-activated materials were prepared from pond ash from the Darkhan city (Mongolia) thermal power station. This ash contains about 60 wt % X-ray amorphous material in addition to quartz, mullite, hematite and magnesioferrite, and presents significant storage problems since it is accumulating in large amounts and is a hazardous waste, containing 90-100 ppm of the heavy metals As, Pb and Cr, and about 800 ppm Sr. Alkali-activated materials synthesized from the as-received pond ash achieved compressive strengths of only 3.25 MPa. Reduction of the particle size by mechanical milling for up to 30 min progressively increases the compressive strength of the resulting alkali-activated geopolymer up to 15.4 MPa. Leaching tests indicate that the combination of milling and alkali treatment does not cause the release of the hazardous heavy metals from the product, making it suitable for construction applications. RESUMEN: Propiedades de geopolímeros preparados a partir de cenizas de estanque.Se prepararon materiales activados alcalinamente a partir de cenizas de charca de la central térmica de Darkhan (Mongolia). Esta ceniza contiene alrededor de un 60% en peso de material amorfo además de mullita, hematita, cuarzo y magnesioferrite. Presenta además importantes problemas de almacenamiento ya que se acumula en grandes cantidades y es un desecho peligroso, que contiene entre 90-100 ppm de metales pesados como Pb y Cr, y alrededor de 800 ppm de Sr. Los materiales sintetizados a partir de las cenizas de estanque presentaron resistencias a compresión de tan sólo 3,25 MPa. La reducción del tamaño de partícula por fresado mecánico hasta 30 min aumentó las resistencias mecánicas hasta valores de 15.4 MPa. Las pruebas de lixiviación indican que la combinación de molienda y activación alcalina no causan la liberación de los metales pesados peligrosos del producto, por lo que resulta adecuado para aplicaciones en construcción.PALABRAS CLAVE: Cenizas de estanque; Molienda; Cementos activados alcalinamente; Resistencias a compresión; Microstructura ORCID ID: J. Temuujin

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Section: Introductionmentioning

confidence: 99%

Properties of geopolymer binders prepared from milled pond ash

et al. 2017

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“…It offers good strength, improved mechanical properties, and reduced CO 2 emission 6,7 . Although FBC-FA can be used to produce geopolymer, the strength is low compared to that of the PCC-FA geopolymer 8,9 . The blending of FBC-FA with a high glassy phase material such as PCC-FA is recommended to improve the strength of FBC-FA geopolymer 5 .…”

Section: Introductionmentioning

confidence: 99%

Microstructure and strength of blended FBC-PCC fly ash geopolymer containing gypsum as an additive

Boonserm¹,

Sata²,

Pimraksa³

et al. 2012

ScienceAsia

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This study focused on the microstructure and strength of blended fluidized bed coal combustion fly ash (FBC-FA) and pulverized coal combustion fly ash (PCC-FA) geopolymers containing gypsum as an additive. The source materials consisted of 100% FBC-FA and a blend of 75% FBC-FA and 25% PCC-FA. Gypsum was used as an additive at the dosage levels of 0, 5, and 10%wt of the source materials. NaOH and Na 2 SiO 3 were used to activate aluminosilicate sources and temperature curing to accelerate the geopolymer reaction. The microstructures of the geopolymer pastes were examined using XRD, FTIR, MIP and SEM tests. The compressive strengths of the geopolymer mortars were also tested. Test results showed that the blending of FBC-FA and PCC-FA improved the geopolymerization and resulted in a dense matrix with reduced porosity and increased compressive strength as compared to those of the FBC-FA geopolymer. The improvement is due primarily to the high glassy phase content of PCC-FA. In addition, the use of 5% gypsum as an additive further improved the geopolymerization. The sulphate ions enhanced the leaching of alumina from the source materials forming additional aluminosilicate and increased calcium in the system which resulted in the formation of additional CSH.

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“…It is known that the alkali concentration determined by the molar concentration is an important factor in relation to geopolymerization since it is responsible for dissolving the glassy structure of the fly ash, activating the silicon and aluminum to form the precursor gel [29,30]. Higher leaching of silica and alumina [31] promotes better binding between the solid particles in the final structure of the system [32] and it contributes to the mechanical properties of the hardened geopolymer [33]. However, the compressive strength was mainly influenced by the curing regime parameter.…”

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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Comparative study on the characteristics of fly ash and bottom ash geopolymers

Cited by 622 publications

References 6 publications

Properties of geopolymer binders prepared from milled pond ash

Properties of geopolymer binders prepared from milled pond ash

Microstructure and strength of blended FBC-PCC fly ash geopolymer containing gypsum as an additive

Effect of NaOH concentration and curing regime on geopolymer

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