Alkali-activated aluminosilicate composite with heat-resistant lightweight aggregates exposed to high temperatures: Mechanical and water transport properties

Zuda, Lucie; Drchalová, J.; Rovnanı́k, Pavel; Bayer, Patrik; Keršner, Zbyněk; Černý, Robert

doi:10.1016/j.cemconcomp.2009.11.009

Cited by 63 publications

(36 citation statements)

References 22 publications

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“…This performance was attributed to the higher thermal shrinkage experienced by the alkali-activated slag binder compared with Portland cement, and the differences in the thermal expansion coefficient of the aggregates used in that study (basalt) and the cementitious matrix. Zuda et al (20,21) evaluated the influence of the type of aggregate in the performance of alkali-activated slag materials, and identified lower reductions in the strength at temperatures above 800 °C when adding porcelain and quartz aggregate, as a consequence of the thermal stability of these aggregates.…”

Section: Introductionmentioning

confidence: 99%

Performance at high temperature of alkali-activated slag pastes produced with silica fume and rice husk ash based activators

Bernal¹,

Rodríguez²,

Gutiérrez³

et al. 2015

Mater. construcc.

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This study assessed the mechanical properties, and structural changes induced by high temperature exposure, of alkali-silicate activated slag cements produced with sodium silicates derived from silica fume (SF) and rice husk ash (RHA). Similar reaction products were identified, independent of the type of silicate used, but with subtle differences in the composition of the C-S-H gels, leading to different strength losses after elevated temperature exposure. Cements produced with the alternative activators developed higher compressive strengths than those produced with commercial silicate. All samples retained strengths of more than 50 MPa after exposure to 600 °C, however, after exposure to 800 °C only the specimens produced with the RHA-based activator retained measurable strength. This study elucidated that silicate-activated slag binders, either activated with commercial silicate solutions or with sodium silicates based on SF or RHA, are stable up to 600 °C.

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Section: Introductionmentioning

confidence: 99%

Performance at high temperature of alkali-activated slag pastes produced with silica fume and rice husk ash based activators

Bernal¹,

Rodríguez²,

Gutiérrez³

et al. 2015

Mater. construcc.

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“…Sin embargo, hay aún muchas interrogantes respecto de su desempeño y estabilidad cuando son expuestos a medios agresivos, siendo esto una de las principales limitantes para su estandarización y comercialización (8). Estudios de materiales de activación alcalina elaborados con metacaolín (9)(10)(11)(12)(13)(14) o escoria siderúrgica (15)(16)(17)(18)(19) han mostrado, que independientemente del precursor usado, generalmente estos cementantes reportan una mejorada estabilidad cuando son expuestos a temperaturas altas, comparado con el cemento Portland ordinario. Esto es más significativo en cementos alcalinos con bajos o ningún contenido de calcio, lo cual se atribuye a la formación de un gel cementante altamente polimerizado del tipo aluminosilicato sódico hidratado (4) y un contenido reducido de agua químicamente enlazada en los productos de reacción (20).…”

Section: Introductionunclassified

“…However, there are still questions regarding the performance and stability of these materials when exposed to aggressive service environments, and this is one of the main limitations facing standardisation and commercialisation of alkaliactivated materials (8). Studies of alkali-activated materials based on metakaolin (9)(10)(11)(12)(13)(14) or slag (15)(16)(17)(18)(19) have shown that independent of the precursor used, alkaliactivated cements generally show greater stability when exposed to high temperatures, compared with ordinary Portland cement. This is more remarkable in alkaliactivated cements with low calcium contents, which is attributed to the formation of a highly crosslinked sodium aluminosilicate type gel (4), and a reduced content of chemically-bonded water in the reaction products (20).…”

Section: Introductionmentioning

confidence: 99%

Desempeño a temperaturas altas de morteros y hormigones basados en mezclas de escoria/metacaolín activadas alcalinamente

Bernal

Gutiérrez²,

Ruiz³

et al. 2012

Mater. construcc.

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RESUMENEste artículo evalúa el desempeño de morteros y hormigones basados en mezclas de escoria siderúrgica (GBFS)/metacaolín (MK), activadas alcalinamente expuestos a temperaturas altas. Se identifica una elevada estabilidad en morteros con contenidos de MK de hasta un 60% cuando se exponen a temperaturas de 600 ºC, con una resistencia residual de 20 MPa posterior a la exposición a esta temperatura. Por otra parte, la exposición a temperaturas más elevadas conduce al agrietamiento de los hormigones como consecuencia de una elevada contracción de la matriz cementante y las restricciones por efecto de los áridos, especialmente en aquellos especímenes con cementantes que contienen altos contenidos de MK. Se identifican diferencias significativas en las propiedades de absorción de agua de morteros y hormigones, y esto se relaciona con las divergencias en el desempeño de estos materiales posterior a la exposición a temperaturas altas. Esto indica que el desempeño a temperaturas elevadas de morteros de activación alcalina no es completamente transferible a hormigones, ya que los sistemas difieren en permeabilidad. Las diferencias en los coeficientes de expansión térmica entre matriz cementante y los áridos gruesos contribuyen al macrofisuramiento del material y su consecuente reducción de propiedades mecánicas.Palabras claves: cementos alcalinos, altas temperaturas, escoria siderúrgica, metacaolín, propiedades mecánicas. SUMMARYThis paper assesses the performance of mortars and concretes based on alkali activated granulated blastfurnace slag (GBFS)/metakaolin (MK) blends when exposed to high temperatures. High stability of mortars with contents of MK up to 60 wt.% when exposed to 600°C is identified, with residual strengths of 20 MPa following exposure to this temperature. On the other hand, exposure to higher temperatures leads to cracking of the concretes, as a consequence of the high shrinkage of the binder matrix and the restraining effects of the aggregate, especially in those specimens with binders containing high MK content. A significant difference is identified between the water absorption properties of mortars and concretes, and this is able to be correlated with divergences in their performance after exposure to high temperatures. This indicates that the performance at high temperatures of alkali-activated mortars is not completely transferable to concrete, because the systems differ in permeability. The differences in the thermal expansion coefficients between the binder matrix and the coarse aggregates contribute to the macrocracking of the material, and the consequent reduction of mechanical properties. . La principal diferencia entre estas dos clases de cementantes es la presencia de calcio en la escoria lo que promueve la formación de una estructura compuesta fundamentalmente por geles de silicatos cál-cicos hidratados (C-(A)-S-H) (2), mientras que en los geopolímeros se forman geles del tipo aluminosilicato sódi-co hidratado (N-A-S-H) (4). KeywordsEl uso tanto de metacaolín como de escoria activada a...

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“…A number of studies have been reported in literature on their use and production. [Zuda et al, 2010;Green, 2006 and references therein; Palomo et al, 1999;Roy, 1999].…”

Section: Alkali Activated Cements (Aac)mentioning

confidence: 99%

An Overview of Cement production: How “green” and sustainable is the industry?

Potgieter

2012

EMSD

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Problem statement: This paper tries to answer the question: Is cement production still a sustainable industry in the 21 st century? Approach: It starts off by considering the current status quo and potential alternatives for the production process, right from the raw meal composition stage through to the final application of cement in concrete. Results: In the process alternative raw meal components and energy sources are reviewed in detail. The changes that could and should be made to cement plants and equipment to produce cement more sustainably, as well as different types of other binders that can be used for construction, are discussed. The suitability of the cement production process to destroy wastes and utilize byproducts from other industrial processes, are highlighted and analysed. Alternative methods and equipment to manufacture cement, are summarized and ways to get rid off or convert the released carbon dioxide from the cement manufacturing, are discussed. Conclusions:In the final instance the conclusion is reached that the cement industry, despite proven new technology, equipment and concepts, can do more to respond fast enough and to a sufficient extent to improve the sustainability of their operations substantially and to an acceptable level for the 21 st century.

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Alkali-activated aluminosilicate composite with heat-resistant lightweight aggregates exposed to high temperatures: Mechanical and water transport properties

Cited by 63 publications

References 22 publications

Performance at high temperature of alkali-activated slag pastes produced with silica fume and rice husk ash based activators

Performance at high temperature of alkali-activated slag pastes produced with silica fume and rice husk ash based activators

Desempeño a temperaturas altas de morteros y hormigones basados en mezclas de escoria/metacaolín activadas alcalinamente

An Overview of Cement production: How “green” and sustainable is the industry?

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