Hydration reaction and hardening of calcined clays and related minerals V. Extension of the research and general conclusions

Ambroise, J.; Murât, Michel; Péra, J.

doi:10.1016/0008-8846(85)90037-7

Cited by 141 publications

(68 citation statements)

References 6 publications

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“…Calcination implied the modification of a wet process rotary kiln -regularly used for clinker production-in order to calcine the material on dry conditions (Figure 2). The clay was fed to the kiln and then heated to 750 °C; temperature chosen as optimal for calcination of the material (16,23,24).…”

Section: Proof Of Concept: Industrial Trial For the Manufacture Of Lomentioning

confidence: 99%

Industrial trial to produce a low clinker, low carbon cement

et al. 2015

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A preliminary assessment of conditions for the industrial manufacture of a new cementitious system based on clinker-calcined clay and limestone, developed by the authors, referred as "low carbon cement" is presented. The new cement enables the substitution of more than 50% of the mass of clinker without compromising performance. The paper presents the follow-up of an industrial trial carried out in Cuba to produce 130 tonnes of the new cement at a cement plant. The new material proved to fulfill national standards in applications such as the manufacture of hollow concrete blocks and precast concrete. No major differences either in the rheological or mechanical properties were found when compared with Portland cement. Environmental assessment of the ternary cement was made, which included comparison with other blended cements produced industrially in Cuba. The new cement has proven to contribute to the reduction of above 30% of carbon emissions on cement manufacture. RESUMEN:Impacto del uso de un cemento de bajo carbono en la mejora de la sostenibilidad de la producción de cemento. Se presenta la evaluación preliminar de las condiciones de fabricación industrial de un nuevo sistema cementicio a partir del empleo de clínquer; arcillas calcinadas y piedra caliza; desarrollado por los autores; denominado "cemento de bajo carbono". El nuevo cemento posibilita la reducción de más de un 50% de la masa de clínquer; sin comprometer el comportamiento del material. El presente trabajo presenta el monitoreo de la producción industrial en una planta en Cuba; de 130 t del nuevo cemento. El cemento obtenido cumple con las regulaciones nacionales de calidad y su empleo tiene similar rendimiento que el cemento Pórtland para la producción de bloques y hormigón de 25 MPa. Se realiza el análisis de impacto ambiental del cemento ternario mediante la comparación con otros cementos producidos industrialmente. El nuevo cemento puede contribuir a la reducción de más del 30% de las emisiones de CO 2 asociadas a la manufactura de cemento.

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Section: Proof Of Concept: Industrial Trial For the Manufacture Of Lomentioning

confidence: 99%

Industrial trial to produce a low clinker, low carbon cement

et al. 2015

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“…Los contenidos de C 3 S, C 2 S, C 3 A The thermal transformation of kaolinite has been widely researched. Dehydroxylation has been reported to be significantly impacted by calcination parameters such as temperature, heat ramping and time, as well as postcalcination cooling conditions (6)(7)(8). According to the literature, in the pozzolanic reaction calcium hydroxide from Portland cement hydration is taken up to form more C-S-H gel as well as crystalline products that serve as micro-fill, with the concomitant refinement of the matrix pore structure (9)(10).…”

Section: Materialesmentioning

confidence: 99%

“…In other words, calcination ruptures the long-range order of the alumina and silica layers, yielding metakaolin (MK), an amorphous pozzolan with certain latent hydraulic properties that make it suitable for use as a cementitious material. La transformación térmica de la caolinita ha sido objeto de gran número de estudios, en los que se afirma que los parámetros del tratamiento térmico como la temperatura, la velocidad y tiempo de calentamiento, así como los pará-metros del enfriamiento al final del ciclo de producción, influyen de manera significativa en el proceso de deshidroxilación (6)(7)(8). En la literatura se describen reacciones puzolánicas en las que el hidróxido cálcico procedente de la hidratación del cemento Portland se consume en la formación del gel C-S-H y de productos cristalinos, produciendo un efecto de microllenado y provocando el refinamiento de la estructura porosa de la matriz (9)(10).…”

Section: Introductionunclassified

Propiedades y durabilidad de los cementos adicionados con metacaolín

Abo-El-Enein¹,

Abbas²,

Ezzat³

2010

Mater. construcc.

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RESUMENEl presente trabajo evalúa el comportamiento puzolánico de metacaolín (MK), producto de la calcinación a distintas temperaturas de dos tipos de caolín local de composiciones químicas diferentes, al incorporarse al cemento en diferentes proporciones. Se preparó un cemento adicionado mediante la mezcla en seco de cemento Portland ordinario (OPC) y metacaolín (MK), a los que se añadió la cantidad óptima de agua para obtener una pasta de la consistencia deseada. Las probetas se curaron a una HR del 100% durante 24 horas, sumergiéndose posteriormente en agua durante 3, 7, 28, 90 o 180 días. A cada tiempo de ensayo se controló el grado de hidratación de las pastas endurecidas y se comprobó la resistencia a la compresión de las probetas cúbicas a las edades de curado establecidas. Los resultados obtenidos indican que la temperatura más adecuada para la calcinación del caolín es de 700°C y que el porcentaje óptimo de éste en la mezcla se encuentra entre el 25 y el 30%. Las fases que componen los productos resultantes de la hidratación se identificaron mediante ATD a distintas edades de curado. Se estableció la durabilidad del OPC puro y de las mezclas de OPC-MK en disoluciones de NaCl al 3% y MgSO 4 al 5% tras 30, 90 y 180 días de inmersión. Se concluyó que las pastas de OPC-MK muestran una elevada resistencia al ataque del ion cloruro.Palabras clave: cemento con adiciones, metacaolín, resistencia, durabilidad, microestructura. SUMMARYThis paper evaluates the optimal calcination temperature and replacement ratio to ensure high metakaolin (MK) pozzolanicity in blended cement. The MK used was prepared by firing two types of local at temperatures ranging from 700 to 850 ºC. Dry blends of ordinary Portland cement (OPC) and varying proportions of MK were mixed with the amount of water required to ensure optimal consistency of the resulting pastes. The specimens were cured at 100% RH for 24 h and then immersed in water for 3, 7, 28, 90 or 180 days. At each test time, the degree of hydration and compressive strength of the hardened cement pastes were measured The findings showed that the most suitable calcination temperature to obtain metakaolin is 700 ºC, while the optimal replacement ratio ranges from 25 to 30%. DTA was used to determine the phases comprising the hydration products forming at the ages studied. Pure OPC and OPC-MK specimens were immersed in 3% NaCl and 5% MgSO 4 solutions for 30, 90 and 180 days to measure their durability. The OPC-MK pastes immersed in the 3% NaCl solution were observed to be highly resistant to chloride attack. Persona de contacto/Corresponding author: rafikaa65@yahoo.com INTRODUCCIÓNExisten varios tipos de cemento Portland con caracterís-ticas distintas, que se clasifican principalmente en función de la evolución del calor (es decir, la temperatura que alcanzan y la velocidad a la que lo hacen) durante la hidratación, así como de la resistencia de la pasta ante los ataques químicos. Las características de cada mezcla de cemento dependen de las propiedades de sus principales fases, d...

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“…The investigation of thermal activation, within the ranges of between 650 and 750˝C with kaolinite-containing waste, resulted in products with a high latent pozzolanicity [12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

The Transformation of Coal-Mining Waste Minerals in the Pozzolanic Reactions of Cements

et al. 2016

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Abstract:The cement industry has the potential to become a major consumer of recycled waste materials that are transformed and recycled in various forms as aggregates and pozzolanic materials. These recycled waste materials would otherwise have been dumped in landfill sites, leaving hazardous elements to break down and contaminate the environment. There are several approaches for the reuse of these waste products, especially in relation to clay minerals that can induce pozzolanic reactions of special interest in the cement industry. In the present paper, scientific aspects are discussed in relation to several inert coal-mining wastes and their recycling as alternative sources of future eco-efficient pozzolans, based on activated phyllosilicates. The presence of kaolinite in this waste indicates that thermal treatment at 600˝C for 2 h transformed these minerals into a highly reactive metakaolinite over the first seven days of the pozzolanic reaction. Moreover, high contents of metakaolinite, together with silica and alumina sheet structures, assisted the appearance of layered double hydroxides through metastable phases, forming stratlingite throughout the main phase of the pozzolanic reaction after 28 days (as recommended by the European Standard) as the reaction proceeded.

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Hydration reaction and hardening of calcined clays and related minerals V. Extension of the research and general conclusions

Cited by 141 publications

References 6 publications

Industrial trial to produce a low clinker, low carbon cement

Industrial trial to produce a low clinker, low carbon cement

Propiedades y durabilidad de los cementos adicionados con metacaolín

The Transformation of Coal-Mining Waste Minerals in the Pozzolanic Reactions of Cements

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