The characterization of hardened alkali-activated blast-furnace slag pastes and the nature of the calcium silicate hydrate (C-S-H) phase

Richardson, Ian; Brough, Adrian R.; Groves, G. W.; Dobson, Christopher M.

doi:10.1016/0008-8846(94)90002-7

Cited by 354 publications

(240 citation statements)

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“…As the N-A-S-H gel releases aluminium, less polymerised structures such as C-A-S-H gels form. At the same time, the C-A-S-H gel that formed in preceding stages is able to take up more silicon and aluminium ions in bridge positions (68). The 1-year hybrid cements studied here would be in this stage of the reaction (Stage E).…”

Section: Activation Modelsmentioning

confidence: 87%

“…Given the similar ionic radius and electronegative potential between sodium and calcium ions, calcium replaces the sodium ions via ion exchange reminiscent of the mechanisms observed in clay and zeolites, maintaining the three-dimensional structure of the (N,C)-A-S-H-type gel (97). Similarly, the C-S-H gel forming from the silicates in cement takes aluminium into its composition (preferably) in bridge positions (65)(66)(67)(68)(69), yielding C-(A)-S-H or C-A-S-H gels as the aluminium content rises. The presence of tetrahedral aluminium in the bridge position may favour chain cross-linking, generating twodimensional structures.…”

Section: Activation Modelsmentioning

confidence: 99%

“…The aluminium uptake was shown to depend on the concentration of alkalis and to be greater at high temperature and humidity. Richardson et al (65,67,68) also explored Al uptake in C-(A)-S-H gels in tetrahedral bridging positions and proposed a series of equations to calculate mean silicon chain length and the Si/Al ratio in the gel formed from NMR data.…”

Section: Fundamentals Of Alkaline Activation In Calcium-rich Systems:mentioning

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: Activation Modelsmentioning

confidence: 87%

Section: Activation Modelsmentioning

confidence: 99%

Section: Fundamentals Of Alkaline Activation In Calcium-rich Systems:mentioning

confidence: 99%

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A review on alkaline activation: new analytical perspectives

et al. 2014

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“…What can be said unambiguously is that C S H has a layered structure with similarities to the 1. 4 11 However, compared to 1.4-nm tobermorite and jennite, C S H is mainly amorphous, its C/S ratio is more variable and its silicate anion chains are very short (primarily dimers with a lesser amount of pentamers and octamers). 12 Ground-granulated blast furnace slag (GGBFS) is an amorphous by-product of the steel industry.…”

Section: Introductionmentioning

confidence: 99%

“…The main reaction product generally cited for alkali-activated slag is C S H gel similar to that found in PC but with lower Ca/Si ratios (around 0.7). [2][3][4][5] Some authors have also mentioned the presence of a Mg Al rich phase similar to hydrotalcite [Mg 6 Al 2 CO 3 (OH) 16 ·4H 2 O] or a tetracalcium aluminate hydrate phase (C,M) 4 AH 13 . 6,7 Alkali-activation of aluminosilicates, such as metakaolin or calcined clays, can also produce inorganic binders with excellent physical and chemical properties suitable for building purposes.…”

Section: Introductionmentioning

confidence: 99%