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

Bernal, Susan A.; Gutiérrez, Ruby Mejía de; Ruiz, Franklin; Quiñones, Héctor Jesús Contreras; Provis, John L.

doi:10.3989/mc.2012.01712

Cited by 37 publications

(11 citation statements)

References 38 publications

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“…Prior studies have shown that the co-precipitation of these two gels in hybrid cements is possible (38)(39)(40)(41)(42)(43)(44)(45)(46), although recent research has revealed that the two products do not develop singly as two separate gels, but that they interact, undergoing structural and compositional change in the process (104).…”

Section: Co-precipitation Of Cementitious Gels: C-s-h + N-a-s-hmentioning

confidence: 99%

“…Procedure 3: today, a mixed alkaline activation procedure, a combination of the preceding two, can also be described. The product in this case is a new type of binder known as a hybrid alkaline cement, formed as the result of the alkaline activation of materials with CaO, SiO 2 and Al 2 O 3 contents >20% (38)(39)(40)(41)(42)(43)(44)(45)(46).…”

Section: Alkali-activated Cementsmentioning

confidence: 99%

“…Examples are cement+slag, cement+fly ash, cement+slag+fly ash (38)(39)(40)(41)(42). Group B comprises blends containing no portland cement: blast furnace slag+fly ash, phosphorous slag+blast furnace slag+fly ash and similar (43)(44)(45)(46).…”

Section: Alkali-activated Cementsmentioning

confidence: 99%

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A review on alkaline activation: new analytical perspectives

et al. 2014

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For many years now the idea of including alkalis in a Portland cement matrix has been regarded as a daft or inexcusably erroneous proposition: despite its absurdity, that opinion has been widely accepted as a basic premise by the scientific and technical community working in the area of the chemistry of cement. In 1957 Glukhovsky proposed a working hypothesis in which he established a close relationship between alkalis and cementitious materials. That hypothesis has become consolidated and has served as a basis for developing a new type of binders, initially called "alkaline cements". The present paper reviews the most significant theoretical interpretations of the role played by alkalis in the formation of the "stony" structure of cement. It ends with a broad overview of the versatility of this type of materials for industrial applications and a discussion of the possibility of building on the existing legislation to meet the need for the future regulation of alkaline cement and concrete manufacture. RESUMEN: Activación alcalina: Revisión y nuevas perspectivas de análisis.Hace algunos años, la sola idea de la presencia de álcalis en una matriz de cemento Portland se consideraba casi como una aberración, o como un error imperdonable; convirtiéndose en un postulado básico (absurdo) ampliamente aceptado por la comunidad científica y técnica vinculada a la química de los cementos. En 1957 Glukhovsky propuso una hipótesis en la que se establecía una estrecha relación entre los álcalis y los materiales cementantes. Hoy día nadie duda de que dicha hipótesis ha servido de base para el desarrollo de una nueva clase de materiales cementantes: "cementos alcalinos". En el presente trabajo se hace una revisión sobre los aspectos teóricos más relevantes del papel de los álcalis en la formación de estos conglomerantes. También se da una visión genérica de su versatilidad, desarrollo industrial y estado de la normativa actual para regular en el futuro la fabricación de cementos y hormigones alcalinos.

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Section: Co-precipitation Of Cementitious Gels: C-s-h + N-a-s-hmentioning

confidence: 99%

Section: Alkali-activated Cementsmentioning

confidence: 99%

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A review on alkaline activation: new analytical perspectives

et al. 2014

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“…This implies that alkaliactivated materials derived from different sources can develop different properties based on the specific conditions of production, curing and testing. However, there is a good consensus that these materials can exhibit advantageous properties such as higher structural and dimensional stablity when exposed to high temperatures, when compared with Portland cement based materials (10)(11)(12)(13)(14)(15)(16).…”

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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“…Previous research reports that use SCMs, such as FA and MK, not only contributes to the reduction of environmental pollution, but also makes a positive contribution to the sustainability and durability of concrete and mortars [52][53][54]. Following from that, the purpose of this investigation was to examine the effects of partially replacing OPC with massive-generated materials from different production sources that would create a cementitious composite material with similar properties to the currently marketed binder, but without all of the detrimental effect to the environment.…”

Section: Discussionmentioning

confidence: 99%

Synthesis and Characterization of a Hybrid Cement Based on Fly Ash, Metakaolin and Portland Cement Clinker

2020

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Hybrid cement has become one of the most viable options in the reduction of CO 2 emissions to the environment that are generated by the cement industry. This could be explained by the reduction of the content of clinker in the final mixture and substitution of the remaining percentage with supplementary cementitious materials with the help of an alkaline activation. Following that, properties that are provided by an Ordinary Portland Cement and of a geopolymer are mixed in this type of hybrid material and could be achieved at room temperature. Thereafter, the main objective of this research was to synthesize hybrid cements reducing the clinker content of Portland Cement up to 20% and use metakaolin and fly ash as supplementary cementitious materials in different proportions. The mixtures were alkaline activated with a mixture of sodium silicate and sodium hydroxide, calculating the amounts according to the percentage of Na 2 O that is present in each of the activators. The samples were then characterized using Compressive strength, X-ray diffraction, Fourier Transform Infrared Spectroscopy, and Scanning Electron Microscopy with energy-dispersive X-ray spectroscopy. The results indicated that the hybrid cements have similar mechanical properties than an Ordinary Portland Cement, and they resulted in a dense matrix of hydration products similar to those that are generated by cements and geopolymers.Materials 2020, 13, 1084 2 of 15 that serve as partial or total substitutes are called supplementary cementitious materials (SCMs) [4], of which the best known are ground granulated blast furnace slag (GGBFS), fly ash (FA), silica fume (SF), and calcined clays. The use of these materials can be a viable solution for the reduction of CO 2 emissions [5]. Current cement consumption is projected to be double by 2050, and the use of these materials could highly reduce CO 2 emissions to the environment [4]. Following that, a model of binders is currently being studied, which consists of adding to the mix of supplementary materials a very low portion of CaO in the form of clinker, to obtain a setting at room temperature [1]. During the past decades, alkali-activated and blended cement have attracted strong interest worldwide, due to their advantages of low energy cost, high strength, good durability, and sustainability. A major incentive for the further development of such cements is generated by the great quantity of annual generation of wastes, which cause a need to find new uses for them. The main raw materials used for this proposal are FA, GGBFS, and metakaolin (MK), in which activators, like water glass and sodium hydroxide, are used. Among the alkaline cements, two large groups are known: (a) calcium and silicon-rich activated materials (Me 2 O-MeO-Al 2 O 3 -SiO 2 -H 2 O system); here, the activation of GGBFS (SiO 2 + CaO > 70%) corresponds, under relatively mild alkalinity conditions [6]. A hydrated calcium aluminosilicate gel (C-A-S-H) is the main hydration product generated, similar to the gel generated in the hydrati...

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

Cited by 37 publications

References 38 publications

A review on alkaline activation: new analytical perspectives

A review on alkaline activation: new analytical perspectives

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

Synthesis and Characterization of a Hybrid Cement Based on Fly Ash, Metakaolin and Portland Cement Clinker

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