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

Abstract

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.%more » 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.« less

Authors:
 [1];  [2];  [1];  [3];  [4]
  1. Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain)
  2. (Morocco)
  3. L.P.C.M. Departement de Chimie, Faculte des Sciences, Universite Chouaib Doukkali, El Jadida 24000 (Morocco)
  4. Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain). E-mail: g_aranda@uma.es
Publication Date:
OSTI Identifier:
20995380
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 37; Journal Issue: 5; Other Information: DOI: 10.1016/j.cemconres.2007.01.012; PII: S0008-8846(07)00023-3; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Morsli, Khadija, L.P.C.M. Departement de Chimie, Faculte des Sciences, Universite Chouaib Doukkali, El Jadida 24000, Torre, Angeles G. de la, Zahir, Mohammed, and Aranda, Miguel A.G. Mineralogical phase analysis of alkali and sulfate bearing belite rich laboratory clinkers. United States: N. p., 2007. Web. doi:10.1016/j.cemconres.2007.01.012.
Morsli, Khadija, L.P.C.M. Departement de Chimie, Faculte des Sciences, Universite Chouaib Doukkali, El Jadida 24000, Torre, Angeles G. de la, Zahir, Mohammed, & Aranda, Miguel A.G. Mineralogical phase analysis of alkali and sulfate bearing belite rich laboratory clinkers. United States. doi:10.1016/j.cemconres.2007.01.012.
Morsli, Khadija, L.P.C.M. Departement de Chimie, Faculte des Sciences, Universite Chouaib Doukkali, El Jadida 24000, Torre, Angeles G. de la, Zahir, Mohammed, and Aranda, Miguel A.G. Tue . "Mineralogical phase analysis of alkali and sulfate bearing belite rich laboratory clinkers". United States. doi:10.1016/j.cemconres.2007.01.012.
@article{osti_20995380,
title = {Mineralogical phase analysis of alkali and sulfate bearing belite rich laboratory clinkers},
author = {Morsli, Khadija and L.P.C.M. Departement de Chimie, Faculte des Sciences, Universite Chouaib Doukkali, El Jadida 24000 and Torre, Angeles G. de la and Zahir, Mohammed and Aranda, Miguel A.G.},
abstractNote = {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.},
doi = {10.1016/j.cemconres.2007.01.012},
journal = {Cement and Concrete Research},
number = 5,
volume = 37,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • This work describes the formulation of new belite-based (CR2) and lime-based (CR3) cementitious materials derived from industrial wastes, such as sludges (generated in the Al-anodising and surface coating industrial processes, potable water filtration/cleaning operations and in marble sawing processes) and foundry sand. Powder mixtures were prepared and fired at different temperatures. For comparison, similar formulations were prepared with pre-treated and commercially available natural raw materials and processed in similar conditions. The thermal process was followed by differential scanning calorimetry (DSC) and high-temperature powder X-ray diffraction (HT-XRD) studies. The CR2 clinker was found to contain belite as the main cementitious phase,more » the main polymorph being identified by NMR. The CR3 clinker contained common cementitious phases, such as C{sub 3}A and C{sub 3}S, but free lime and calcium aluminium oxide sulphates were also identified by high temperature XRD and NMR. Then the corresponding cement was prepared and the evolution of the mechanical strength with time was evaluated. The lime-based cement obtained from wastes shows a stronger hardening character than the standard material, which tends to show dusting phenomena due to the presence of a reasonable amount of free lime (as the result of its expansive reaction with ambient moisture). Some fluxing impurities (e.g. alkalis) present in the waste materials improve the overall reactivity of the mixture and induces the combination of the lime in CR3. Raman, XPS and FIB techniques were used to fully characterise the aged cements.« less
  • This research investigates various methods able to identify possible mineralogical, physical and chemical influences on the grindability of commercial clinkers with high MgO level. The aim of the study is to evaluate the hardness and elastic modulus of the clinker mineral phases and their fracture strength during the comminution processes, comparing samples from clinkers with low MgO level (0.5%) and clinkers with elevated MgO levels (> 5.0%). The study of the influence of mineralogical, chemical and physical properties was carried out using several analytical techniques, such as: optical microscopy, X-ray diffraction with Rietveld refinement (XRD) and X-ray fluorescence (XRF). Thesemore » techniques were useful in qualifying the different clinker samples. The drop weight test (DWT) and the Bond ball mill grindability test were performed to characterize the mechanical properties of clinkers. Nanoindentation tests were also carried out. Results from the Bond ball mill grindability test were found to be related to the hardness of the mineral phase and to mineralogical characteristics, such as type and amount of inclusions in silicates, belite and alite crystals shape, or microcracked alites. In contrast, the results obtained by the DWT were associated to the macro characteristics of clinkers, such as porosity, as well as to the hardness and mineralogical characteristics of belite crystals in clusters. Hardness instrumented tests helped to determine the Vickers hardness and elastic modulus from the mineral phases in commercial clinkers and produced different values for the pure phases compared to previous publications.« less
  • High belite cements may be an alternative to reduce CO{sub 2} emissions. Although CO{sub 2} emissions may be depleted up to 10%, unfortunately, the hydration reactivity of belite phases is slow which leads to low mechanical strengths at early ages. In order to enhance their hydraulic reactivity, the activation of these cements by doping with alkaline oxides has been proposed. Here, we have synthesised a laboratory belite clinker without activation (47 wt.% of {beta}-C{sub 2}S and 19 wt.% of {alpha}{sub H}'-C{sub 2}S) and two alkaline oxide activated clinkers (one with 13 wt.% of {beta}-C{sub 2}S, 24 wt.% of {alpha}{sub H}'-C{submore » 2}S and 19 wt.% of {alpha}-C{sub 2}S; and the second with 12 wt.% of {beta}-C{sub 2}S, 42 wt.% of {alpha}{sub H}'-C{sub 2}S and 5 wt.% of {alpha}-C{sub 2}S). We have also developed a methodology to analyse quantitatively the phase evolution of cement pastes and we have applied it to these high belite cements. Rietveld quantitative phase analysis of synchrotron X-ray powder diffraction data, together with chemical constraints, is used to determine the phase development up to 1 year of hydration in the belite cement pastes. {beta}-C{sub 2}S almost does not react during the first 3 months, meanwhile {alpha}{sub H}'-C{sub 2}S reacts on average more than 50% in the same period. Moreover, the degree of reaction of {alpha}-C{sub 2}S is slightly larger (on average about 70% after three months) than that of {alpha}{sub H}'-C{sub 2}S. Full phase analyses are reported and discussed including the time evolution of amorphous phases and free water.« less
  • Sulfate can occur in Portland cement clinkers as alkali sulfates, potassium calcium sulfate (calcium langbeinite), anhydrite, and as a substituent in the major phases, especially alite and belite. Data for the contents in alit and belite are reviewed and relations to bulk clinker composition are discussed. Evidence on sulfate distribution from extraction procedures is similarly considered. A procedure for predicting sulfate distribution from bulk composition is described and tested and potential sources of error in such calculations are discussed. The evidence does not support suggests that, in concrete made with present-day cements and not subjected to an elevated temperature, damagemore » through delayed ettringite formation can occur for reasons connected with the SO{sub 3} present in the clinker.« less
  • Belite-rich cements hold promise for reduced energy consumption and CO{sub 2} emissions, but their use is hindered by the slow hydration rates of ordinary belites. This drawback may be overcome by activation of belite by doping. Here, the doping mechanism of B and Na/B in belites is reported. For B-doping, three solid solutions have been tested: Ca{sub 2-x/2{open_square}x/2}(SiO{sub 4}){sub 1-x}(BO{sub 3}){sub x}, Ca{sub 2}(SiO{sub 4}){sub 1-x}(BO{sub 3}){sub x}O{sub x/2} and Ca{sub 2-x}B{sub x}(SiO{sub 4}){sub 1-x}(BO{sub 4}){sub x}. The experimental results support the substitution of silicate groups by tetrahedral borate groups with the concomitant substitution of calcium by boron for chargemore » compensation, Ca{sub 2-x}B{sub x}(SiO{sub 4}){sub 1-x}(BO{sub 4}){sub x}. Otherwise, the coupled Na/B-doping of belite has also been investigated and Ca{sub 2-x}Na{sub x}(SiO{sub 4}){sub 1-x}(BO{sub 3}){sub x} series is confirmed to exist for a large range of x values. Along this series, {alpha}'{sub H}-C{sub 2}S is the main phase (for x {>=} 0.10) and is single phase for x = 0.25. Finally, a new structural description for borax doping in belite has been developed for {alpha}'{sub H}-Ca{sub 1.85}Na{sub 0.15}(SiO{sub 4}){sub 0.85}(BO{sub 3}){sub 0.15}, which fits better borax activated belite cements in Rietveld mineralogical analysis.« less