Influence of degree of dehydroxylation on the pozzolanic activity of metakaolin

Bich, Ch.; Ambroise, J.; Péra, J.

doi:10.1016/j.clay.2009.01.014

Cited by 214 publications

(111 citation statements)

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“…The bands at wavenumbers 3620-3630 cm -1 are due to the -OH groups bonding into octahedral sheets, and it constitutes ¼ of the -OH groups in the mineral, while the bands of 3690-3698 cm -1 belong to the -OH groups bonding on the face of the octahedral sheets and constitutes ¾ of the -OH groups [40]. The water molecules in kaolin are detected by the presence of the H-O-H bending mode at approximately 1630 cm -1 [40][41][42][43]. The wavenumbers between 400 cm -1 and 1000 cm -1 indicate the presence of Al-O deformation vibration as well as Si-O bending vibration [40][41][42][43].…”

Section: Particle Size Analysismentioning

confidence: 99%

Synthesis of zeolite-A using kaolin samples from Darazo, Bauchi state and Ajebo, Ogun state in Nigeria

Mgbemere¹,

Lawal²,

Ekpe³

et al. 2018

Nig. J. Tech.

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Kaolin samples from Ajebo and Darazo in Nigeria were characterized and used to produce zeolite-A crystals. The thermal analysis indicates that both samples undergo de-hydroxylation from 450 o C to about 700 o C and are converted to metakaolin with a weight loss of about 11.39 and 10.43% for the Ajebo and Darazo samples respectively. Characteristic OH, Al-OH, Si-OH and Si-O-Al bands were confirmed in both samples with Infra-red spectroscopy studies. The X-ray diffraction patterns clearly show the presence of the characteristic peaks (12.35 and 24.88 o ) of kaolinite with little quartz impurities. X-ray diffraction measurements (2Ɵ peaks at 7-18 o and 21-35 o ) and scanning electron micrographs clearly show that zeolite-A crystals are produced. The microstructures of kaolin, metakaolin and zeolite-A crystals reveal the presence of platy crystals, amorphous spherical aggregates and cubic-shaped crystals with some amorphous gel respectively. The results show that both Ajebo and Darazo kaolin are suitable for zeolite-A synthesis.

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Section: Particle Size Analysismentioning

confidence: 99%

Synthesis of zeolite-A using kaolin samples from Darazo, Bauchi state and Ajebo, Ogun state in Nigeria

Mgbemere¹,

Lawal²,

Ekpe³

et al. 2018

Nig. J. Tech.

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“…Se secaron y se molieron hasta lograr una superficie específica de 800 m 2 /kg. Posteriormente se calcinaron a 750 °C durante 5 horas (15-16), siguiendo las recomendaciones recogidas en la literatura, según las cuales, el rango óptimo de temperaturas para la calcinación de caolín con el fin de obtener metacaolín se encuentra entre los 600 y los 900 °C (27)(28)(29). A continuación se retiró el producto del horno y se enfrió a temperatura ambiente en desecadores.…”

Section: Preparación Y Tratamiento Térmico De Los Lodosunclassified

“…Como puede verse en la Tabla 3, en todas las muestras que contenían lodos se redujo la concentración de CaO de la disolución de cal en aproximadamente el 78%, valor muy parecido al observado en la puzolana natural. La calcinación provocó la pérdida física de agua (deshidroxilación) y la formación de metacaolín (29,30). La estructura amorfa del metacaolín generado y detectado tanto por DRX como por MEB hacía que el material resultante del tratamiento térmico fuera más reactivo con la cal que la arcilla inicial (véase la Figura 3), ya que se trataba fundamentalmente de una reacción ácido-base.…”

Section: Puzolanicidad Del Lodo Calcinadounclassified

“…The burnt silt and the natural pozzolan exhibited very similar pozzolanicity. Calcination induced the physical loss of water (dehydroxylation) and the formation of metakaolin (29,30). The amorphous structure of the metakaolin generated, as revealed by XRD and SEM findings, rendered it more reactive with lime than the starting clay (see Figure 3), for what was essentially involved was an acid-base reaction.…”

Section: Burnt Silt Pozzolanicitymentioning

confidence: 99%

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Reología y potencial zeta de pastas de cemento con lodos de embalse calcinados y escorias granuladas de horno alto

Safi¹,

Benmounah²,

Saidi³

2011

Mater. construcc.

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“…During this thermal treatment, factors such as temperature, calcinations time, shape and size of particles influence metakaolin reactivity (MK) (Bich et al, 2009;Gonçalves et al, 2009;Samet et al, 2007).…”

Section: Pozzolans Made Out From Calcined Claysmentioning

confidence: 99%

Activación de arcillas de bajo grado a altas temperaturas

Castillo

Fernández²,

Antoni

et al. 2010

Rev. ing. constr.

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ResumenSe presenta una propuesta de producción de puzolanas artificiales a partir de activar arcillas de baja pureza, como alternativa de producción de Metacaolín.Se trabajó básicamente con tierra rica en minerales arcillosos, principalmente caolín. Este material fue sedimentado y luego calcinado a 900 grados Celsius.Igual proceso se realizó al material original sin sedimentar. Producto de la calcinación disminuyó considerablemente la superficie específica, y por ende la actividad puzolánica, que fue evaluada monitoreando el consumo de HC en pastas a varias edades, y la resistencia a compresión en morteros. El material calcinado, aparentemente inerte, fue molido hasta una alta finura. Se introdujo una serie experimental con ceniza de paja de caña, como referencia de puzolana anteriormente estudiada. Las arcillas calcinadas molidas incrementaron cuantiosamente su actividad puzolánica, caracterizado por un mayor consumo de HC en pastas, y una mayor resistencia a compresión en morteros. Aparentemente este cambio se debe al efecto del molido sobre la reactividad de los suelos arcillosos calcinados. Los mejores resultados se obtuvieron para las muestras sedimentadas antes de calcinar. La resistencia a compresión de morteros, sustituyendo un 30% del peso de cemento por dicho material, es similar al control (100% cemento) a 7 días, y mayor a 28 y 60 días. Aunque dicha sustitución no disminuye la porosidad total, se disminuye la sorptividad, principalmente en muestras producidas con material sedimentado calcinado y molido. Posiblemente este fenómeno ocurra por un proceso de refinación de poros capilares inducido por la precipitación de productos de la reacción puzolánica.Palabras Clave: Puzolanas, arcillas calcinadas, microestructura, porosidad, sorptividad Abstract This paper introduces a proposal to produce artificial pozzolans by means of activation of low grade clays, as an alternative to metakaolin production.Basically the work considered clay mineral enriched soils, mainly kaolin. Such material was sediment and later calcined at 900 Celsius degrees. The same process was conducted with non-sediment material. Due to calcinations, the specific surface decreased significantly, and therefore, its pozzolanic activity, which was assessed by monitoring the CH consumption in cement pastes of several ages, as well as compressive strength in cement mortars. Calcined material, apparently inert, was ground until achieving high finesse. An experimental series made of sugar cane straw ash was introduced, as a reference to the pozzolans previously studied. Ground calcined clays increased its pozzolanic activity at a huge extent, which is characterized by a higher consumption of CH in cement pastes and by a higher compressive strength in cement mortars. Apparently this change takes place due to grinding effect on the reactivity of calcined clayey soils. The best results were obtained from sediment samples before their calcinations. The compressive strength of cement mortars, replacing a 30% the cement weight by such material, is s...

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Influence of degree of dehydroxylation on the pozzolanic activity of metakaolin

Cited by 214 publications

References 10 publications

Synthesis of zeolite-A using kaolin samples from Darazo, Bauchi state and Ajebo, Ogun state in Nigeria

Synthesis of zeolite-A using kaolin samples from Darazo, Bauchi state and Ajebo, Ogun state in Nigeria

Reología y potencial zeta de pastas de cemento con lodos de embalse calcinados y escorias granuladas de horno alto

Activación de arcillas de bajo grado a altas temperaturas

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