Mineralogical phase analysis of alkali and sulfate bearing belite rich laboratory clinkers

Journal Article · Tue May 15 04:00:00 EDT 2007 · Cement and Concrete Research

DOI:https://doi.org/10.1016/j.cemconres.2007.01.012· OSTI ID:20995380

Morsli, Khadija ^[1]; Torre, Angeles G. de la ^[1]; Zahir, Mohammed ^[2]; Aranda, Miguel A.G. ^[1]

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1. Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain)
2. L.P.C.M. Departement de Chimie, Faculte des Sciences, Universite Chouaib Doukkali, El Jadida 24000 (Morocco)

The activation of laboratory belite clinkers has been carried out by adding variable amounts of alkaline salts (K{sub 2}CO{sub 3}, Na{sub 2}CO{sub 3}), and/or SO{sub 3} as gypsum in the raw materials but keeping almost constant the main elements ratios, Ca/Si/Al/Fe. Quantitative phase analyses by the Rietveld method using high resolution synchrotron and strictly monochromatic CuK{alpha}{sub 1} laboratory X-ray powder diffraction data has been performed. Quantitative phase analysis results have been compared to validate the protocol using laboratory X-ray data. The agreement in the results is noteworthy, which indicates that good quantitative phase analyses can be obtained from laboratory X-ray powder data. Qualitative studies have confirmed that the addition of alkaline salts to raw mixtures promotes the stabilization, at room temperature, of the highest temperature polymorphs: {alpha}'{sub H}-C{sub 2}S and {alpha}-C{sub 2}S. Quantitative studies gave the phase assemblage for ten different laboratory belite clinkers. As an example, an active belite clinker with 1.0 wt.% of K{sub 2}O and 1.0 wt.% of Na{sub 2}O (amounts added to the raw mixtures) contains 8.5(3) wt.% of {beta}-C{sub 2}S, 21.2(3) wt.% of {alpha}'{sub H}-C{sub 2}S, 24.1(2) wt.% of {alpha}-C{sub 2}S, 18.9(3) wt.% of total C{sub 3}S, 17.3(2) wt.% of C{sub 3}A and 10.0(2) wt.% of C{sub 4}AF. A belite clinker with 0.8 wt.% SO{sub 3} (nominal loading) contains 60.7(1) wt.% of {beta}-C{sub 2}S, 6.7(2) wt.% of {alpha}'{sub H}-C{sub 2}S, 12.3(7) wt.% of C{sub 3}S, 9.1(2) wt.% of C{sub 3}A and 11.2(2) wt.% of C{sub 4}AF. Overall, quantitative phase analyses have shown that alkaline oxides stabilize {alpha}'{sub H}-C{sub 2}S and {alpha}-C{sub 2}S, sulfur stabilizes {beta}-C{sub 2}S, with a large unit cell volume, and the joint presence of alkaline oxides and sulfur promotes mainly the stabilization of the {alpha}'{sub H}-C{sub 2}S polymorph.

• OSTI ID: 20995380
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Journal Issue: 5 Vol. 37; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CEMENTS
GYPSUM
MONOCHROMATIC RADIATION
PHASE STUDIES
POTASSIUM OXIDES
SODIUM CARBONATES
SODIUM OXIDES
STABILIZATION
SULFATES
SULFITES
TEMPERATURE RANGE 0273-0400 K
X RADIATION
X-RAY DIFFRACTION