29Si and 27Al high-resolution NMR characterization of calcium silicate hydrate phases in activated blast-furnace slag pastes

Schneider, José Fabián; Cincotto, Maria Alba; Panepucci, Horácio Carlos

doi:10.1016/s0008-8846(01)00530-0

Cited by 190 publications

(108 citation statements)

References 9 publications

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“…Small reflections for akermanite (Ca 2 Mg(Si 2 O 7 )), gehlenite (Ca 2 Al(AlSiO 7 )) and merwinite (Ca 3 Mg(SiO 4 ) 2 ) were identified. [28,40,43,44,[60][61][62][63][64][65][66]. Akermanite was again present.…”

Section: Crystalline Phasesmentioning

confidence: 99%

Hydration and properties of sodium sulfate activated slag

Rashad

Bai

Basheer

et al. 2013

Cement and Concrete Composites

246

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Section: Crystalline Phasesmentioning

confidence: 99%

Hydration and properties of sodium sulfate activated slag

Rashad

Bai

Basheer

et al. 2013

Cement and Concrete Composites

246

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“…It is assumed that the C-(A)-S-H phases of the same system will have the same peak position and shape. A similar approach was described in [36,37].…”

Section: Nuclear Magnetic Resonance Spectroscopymentioning

confidence: 99%

Effect of slag chemistry on the hydration of alkali-activated blast-furnace slag

2014

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This paper presents results of detailed investigations about the alkaline activation of ground granulated blast furnace slags whose chemical composition were modified. Sodium hydroxide and potassium silicates were used as alkaline activators. The influence of the CaO/SiO 2 ratio, the Al 2 O 3 and TiO 2 content of the slag composition on the hydration reaction was analyzed utilizing isothermal heat flow calorimetry, compressive strength development of binder samples, 29 Si MAS NMR spectroscopy and molybdate method. It could be shown that the TiO 2 content of the slag has only minor influence on the hydraulic reactivity and compressive strength of the alkaline activated binders.The variation of the Al 2 O 3 content of the slag leads to different results. A rise in Al 2 O 3 content enhanced the strength if activating with NaOH but resulted in a lower strength if activating with potassium silicate. The results of the 29 Si MAS NMR spectroscopy verify the decrease in the reaction degree with increase of Al 2 O 3 content. This is associated with the rise of the chain length of the C-(A)-S-H phases by incorporation of Al-O tetrahedrons resulting in a lower Si/Al-ratio. A decrease in the C/S-ratio yielded to a lower heat evolution, whereas the reaction was delayed if activated with potassium silicate with higher silicate content. The increase of the C/S-ratio caused in less condensed slag glass and therefore an enhancement of the reaction degree with a simultaneous decrease of silicate chain length, as seen by 29 Si NMR. These outcomes fit well with the results measured by the molybdate method.

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“…These have been previously assigned, respectively, to SiQ 2 and SiQ 2 (1Al) units by a lot of authors who published similar spectra for alkaliactivated slags. 2,3,5,7,26 So, most of the silicate tetrahedra are chain mid-members and important Al substitution for Si occurs in the silicate chains. The general characteristic of the AAS sample spectrum compared to the PC sample is a shift towards more negative chemical shifts, which reflects significantly longer aluminosilicate chains than in Portland cement.…”

Section: Si and 27 Al Mas-nmr Analysismentioning

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%