Hydration studies of calcium sulfoaluminate cements blended with fly ash

García-Maté, Marta; Torre, Ángeles G. De la; León‐Reina, Laura; Aranda, Miguel A. G.; Santacruz, Isabel

doi:10.1016/j.cemconres.2013.07.010

Cited by 171 publications

(80 citation statements)

References 38 publications

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“…The hydration of the pastes was stopped prior to LXRPD characterisation. The experimental procedure to stop the hydration consists of filtration with acetone and ether, as is reported by García-Maté et al (2013). Furthermore, the ground powder, prepared by (b) procedure, was characterised with and without stopping hydration, named hereafter (b) and (b′) methodologies, respectively.…”

Section: Methodsmentioning

confidence: 99%

Structure of stratlingite and effect of hydration methodology on microstructure

Santacruz

Torre

Álvarez-Pinazo

et al. 2016

Advances in Cement Research

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Stratlingite, Ca 4 Al 2 (OH) 12 [AlSi(OH) 8 ] 2 ·2H 2 O, is an AFm phase which appears as a hydration product of aluminium-rich cements. These binders may be calcium aluminate cements, calcium sulfoaluminate cements and also belite calcium sulfo-aluminate (BCSA) cements. The structure of stratlingite is known from single-crystal studies of tiny minerals but their bulk formation, crystal structure and microstructure of powders is poorly understood. This paper reports on the synthesis of stratlingite and a complete structural and microstructural characterisation by synchrotron X-ray powder diffraction, nuclear magnetic resonance, scanning electron microscopy and thermal analyses. The structural and microstructural models have important implications for a correct quantitative phase analysis of stratlingite in cement pastes (for instance, in pastes of BCSA cements). The microstructure of stratlingite formed in cement pastes is highly dependent on the hydration conditions. In BCSA pastes, the (003) line position of stratlingite appears slightly shifted towards higher diffracting angles (lower inter-layered distance) after stopping hydration compared to that of a similar phase present in a paste analysed without stopping hydration. This is related to dehydration and disorder. This shift and peak broadening is even larger when the paste has suffered partial dehydration during curing (apart from stopping hydration). A microstructural study is presented.

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Section: Methodsmentioning

confidence: 99%

Structure of stratlingite and effect of hydration methodology on microstructure

Santacruz

Torre

Álvarez-Pinazo

et al. 2016

Advances in Cement Research

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“…Whatman filter with a pore size of 2.5 μm and a Teflon support) [12,31,32]. The obtained powder was kept into a desiccator to avoid any hydration or carbonation.…”

Section: Stopping Cement Hydrationmentioning

confidence: 99%

Tailored setting times with high compressive strengths in bassanite calcium sulfoaluminate eco-cements

García-Maté

Londoño-Zuluaga

Torre

et al. 2016

Cement and Concrete Composites

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This work deals with the hydration of a calcium sulfoaluminate (CSA) eco-cement prepared with bassanite and different additives (type and content) at a fixed water/CSA ratio of 0.5. Pastes prepared with bassanite show high water demands, high viscosity values and short initial setting times which are related to the fast dissolution rate of bassanite and the subsequent precipitation of gypsum. These facts have a dramatic effect onto the mechanical strength values, and make necessary the addition of additives.Here, the addition of different amounts of specific retarders (polycarboxylate, tartaric acid and phosphonic acid) not only improved the workability of pastes and mortars, but also delayed the setting time, by modifying the dissolution rates of the phase(s), and improved mechanical strengths.Finally, mortars with high compressive strengths (46 and 84 MPa at 1 and 7 days of hydration, respectively) and, chiefly, tailored setting times with high strengths have been prepared.

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“…At this stage, the pastes were milled to fine powder in an agate mortar. To remove the excess of water, samples were filtered in a Whatman system (90 mm diameter Whatman filter with a pore size of 2.5 µm on a Teflon support), and washed twice with isopropanol, and finally with ether [41].…”

Section: Sample Preparationmentioning

confidence: 99%

Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

et al. 2017

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Abstract:The analysis of atomic ordering in a nanocrystalline phase with small particle sizes, below ≈5 nm, is intrinsically complicated because of the lack of long-range order. Furthermore, the presence of additional crystalline phase(s) may exacerbate the problem, as is the case in cement pastes. Here, we use the synchrotron pair distribution function (PDF) chiefly to characterize the local atomic order of the nanocrystalline phases, gels, in cement pastes. We have used a multi r-range analysis approach, where the~4-7 nm r-range allows determining the crystalline phase contents; the~1-2.5 nm r-range is used to characterize the atomic ordering in the nanocrystalline component; and the~0.2-1.0 nm r-range gives insights about additional amorphous components. Specifically, we have prepared four alite pastes with variable water contents, and the analyses showed that a defective tobermorite, Ca 11 Si 9 O 28 (OH) 2 ·8.5H 2 O, gave the best fit. Furthermore, the PDF analyses suggest that the calcium silicate hydrate gel is composed of this tobermorite and amorphous calcium hydroxide. Finally, this approach has been used to study alternative cements. The hydration of monocalcium aluminate and ye'elimite pastes yield aluminum hydroxide gels. PDF analyses show that these gels are constituted of nanocrystalline gibbsite, and the particle size can be as small as 2.5 nm.

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Hydration studies of calcium sulfoaluminate cements blended with fly ash

Cited by 171 publications

References 38 publications

Structure of stratlingite and effect of hydration methodology on microstructure

Structure of stratlingite and effect of hydration methodology on microstructure

Tailored setting times with high compressive strengths in bassanite calcium sulfoaluminate eco-cements

Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

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