Hydration of belite–ye'elimite–ferrite cements with different calcium sulfate sources

Álvarez-Pinazo, Gema; Santacruz, Isabel; Aranda, Miguel A. G.; Torre, Ángeles G. De la

doi:10.1680/jadcr.16.00030

Cited by 53 publications

(46 citation statements)

References 47 publications

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“…Alkali-activated materials (AAMs) are binders obtained when aluminosilicate materials ("precursors") react chemically with an alkaline activator (normally an alkaline hydroxide or alkaline silicate solution) [1][2][3][4][5][6]. As materials with a low environmental impact, AAMs are attracting considerable research as cements for the future, along with limestone calcined clay (LC3) [7,8] and belite-ye'elimite-ferrite (BYF) cements [9,10].…”

Section: Introductionmentioning

confidence: 99%

Effect of Alkali Concentration on the Activation of Carbonate-High Illite Clay

et al. 2020

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The present study explores the effect of activating solution concentration (4, 6 and 8 M NaOH) on mechanically and thermally pre-treated carbonate-high illite clay (LCR). Pastes were prepared with an alkaline solution/clay (S/B) ratio of 0.55, which were cured at room temperature and relative humidity > 90% in a climatic chamber. At two and 28 days, compressive mechanical strength was determined, and the reaction products were characterised by X-ray Powder Diffraction analysis (XRPD), Fourier-transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy - Energy Dispersive X-ray spectroscopy (SEM/EDX). Results obtained showed that the presence of reactive calcium in the starting clay induces co-precipitation of a mix of gels: An aluminium-enriched C-S-H gel (C-A-S-H) and a N-A-S-H gel, in which sodium is partially replaced by calcium (N,C)-A-S-H. Pastes prepared with higher (6 or 8 M) activator concentrations exhibit a more compact matrix than the ones prepared with 4 M NaOH. The findings show that the use of a 6 M NaOH solution yields a binder with two days compressive strength >20 MPa and 28 days strength of over 30 MPa.

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Section: Introductionmentioning

confidence: 99%

Effect of Alkali Concentration on the Activation of Carbonate-High Illite Clay

et al. 2020

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“…On the other hand, the preparation and scale-up of BAY and BAYZ clinkers with the coexistence of alite and ye'elimite phases [17] by adding CaF 2 and ZnO was a success. Mortars prepared with aBYF cement developed higher compressive strengths than BYF at any hydration age and BAY at early hydration time (up to 7 days), and higher strengths than BAY at 28 d, Figure 2, independently of the type and amount of sulphate source [6,18]. Standard BYF clinker contains β-C 2 S, as main phase and orthorhombic ye'elimite.…”

Section: Clinkering Of Byf and Bay: Activationmentioning

confidence: 99%

“…CSA or BYF with bassanite pastes showed high water demand, high viscosity values and short setting times with the consequent dramatic effect on the mechanical strength values of the corresponding mortars. This makes necessary the selection of a hydration retarder which also reduces the viscosity of the pastes [18,19], Figure 2. The effect of three additives (polycarboxylate, tartaric acid and phosphonic acid) on CSA pastes and mortars was studied [20].…”

Section: Role Of Type Of Setting Regulator: Gypsum Bassanite or Anhymentioning

confidence: 99%

X-ray diffraction, cements and environment, three worlds in one.

et al. 2018

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Abstract. This keynote lecture will be focused on the strategies for reducing CO 2 emissions in the cement production. Concretely, the production of ecocements with optimised formulations that yield reductions in CO 2 emissions of up to 25%, when compared to OPC production. Phase assemblage has to be carefully optimised to be competitive and these new ecocements should develop compressive strengths of at least 50 MPa at 28 days of hydration. Optimised compositions of several ecocements will be discussed, but all of them are ye'elimite or calcium sulphoaluminate containing ones: belite-ye'elimite-ferrite (BYF), belite-alite-ye'elimite (BAY) and ye'elimite rich ones (CSA). The clinkering temperature of BYF and BAY has to be established to obtain the targeted phase assemblages. Moreover, the stabilisation of alpha-forms of belite is needed to develop high mechanical strengths at early ages. The benefits of the use of waste materials (such as fly ash or slag) as additions to ecocements are three-fold: lower CO 2 emissions due to clinker replacement; valorisation of "useless" products that need a lot of landscape and the consequent efficient consumption of raw materials; and to enhance mechanical properties of the corresponding mortars. The design of appropriate CSA, BYF and BAY mortars, with the final aim of knowing and controlling the hydration mechanisms, will be presented. Particularly, the role of i) type and amount of set regulator (gypsum, anhydrite, etc.), ii) water/cement ratio (w/c); iii) superplasticiser; and iv) pozzolanic additions will be discussed. The role of these parameters in the microstructure and hydraulic behaviour has been investigated through traditional techniques as well as advanced synchrotron characterisation. The formers include laboratory/synchrotron X-ray powder diffraction combined with Rietveld methodology (to obtain phase assemblage), electron microscopy techniques for paste microstructure determination, rheological studies (to control the effect of the different additives, w/c ratio and setting time retarders) and mechanical tests (setting times, compressive strengths and dimensional stability).

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“…Mortars prepared with aBYF cement developed higher compressive strengths than BYF at any hydration age and BAY at early hydration time (up to 7 days), and higher strengths than BAY at 28 d, Figure 2, independently of the type and amount of sulphate source [6,18]. Standard BYF clinker contains β-C 2 S, as main phase and orthorhombic ye'elimite.…”

Section: Role Of Activation Of Ye'elimite Bearing Cementsmentioning

confidence: 99%

X-ray diffraction, cements and environment, three worlds in one.

et al. 2018

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View full text Add to dashboard Cite

This keynote lecture will be focused on the strategies for reducing CO2 emissions in the cement production. Concretely, the production of ecocements with optimised formulations that yield reductions in CO2 emissions of up to 25%, when compared to OPC production. Phase assemblage has to be carefully optimised to be competitive and these new ecocements should develop compressive strengths of at least 50 MPa at 28 days of hydration. Optimised compositions of several ecocements will be discussed, but all of them are ye'elimite or calcium sulphoaluminate containing ones: belite-ye'elimite-ferrite (BYF), belite-alite-ye'elimite (BAY) and ye'elimite rich ones (CSA). The clinkering temperature of BYF and BAY has to be established to obtain the targeted phase assemblages. Moreover, the stabilisation of alpha-forms of belite is needed to develop high mechanical strengths at early ages. The benefits of the use of waste materials (such as fly ash or slag) as additions to ecocements are three-fold: lower CO2 emissions due to clinker replacement; valorisation of “useless” products that need a lot of landscape and the consequent efficient consumption of raw materials; and to enhance mechanical properties of the corresponding mortars. The design of appropriate CSA, BYF and BAY mortars, with the final aim of knowing and controlling the hydration mechanisms, will be presented. Particularly, the role of i) type and amount of set regulator (gypsum, anhydrite, etc.), ii) water/cement ratio (w/c); iii) superplasticiser; and iv) pozzolanic additions will be discussed. The role of these parameters in the microstructure and hydraulic behaviour has been investigated through traditional techniques as well as advanced synchrotron characterisation. The formers include laboratory/synchrotron X-ray powder diffraction combined with Rietveld methodology (to obtain phase assemblage), electron microscopy techniques for paste microstructure determination, rheological studies (to control the effect of the different additives, w/c ratio and setting time retarders) and mechanical tests (setting times, compressive strengths and dimensional stability). The latters comprise a group of techniques available at synchrotrons such as: i) high temperature x-ray diffraction for clinkering studies and ii) total scattering data to be analysed by pair distribution function, PDF.

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Hydration of belite–ye'elimite–ferrite cements with different calcium sulfate sources

Cited by 53 publications

References 47 publications

Effect of Alkali Concentration on the Activation of Carbonate-High Illite Clay

Effect of Alkali Concentration on the Activation of Carbonate-High Illite Clay

X-ray diffraction, cements and environment, three worlds in one.

X-ray diffraction, cements and environment, three worlds in one.

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