Thermodynamic data of belite polymorphs
One major component of Portland cement clinker is Ca2SiO4 (C2S, belite). Synthetic samples of three polymorphs, β-C2S (larnite), γ-C2S (calcio olivine), and x-C2S were investigated by high-temperature oxide melt solution calorimetry at 700 °C to obtain their enthalpies of formation. A natural sample...
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Veröffentlicht in: | Cement and concrete research 2022-02, Vol.152, p.106621, Article 106621 |
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Sprache: | eng |
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Zusammenfassung: | One major component of Portland cement clinker is Ca2SiO4 (C2S, belite). Synthetic samples of three polymorphs, β-C2S (larnite), γ-C2S (calcio olivine), and x-C2S were investigated by high-temperature oxide melt solution calorimetry at 700 °C to obtain their enthalpies of formation. A natural sample of wollastonite (CaSiO3) was measured for comparison. Low-temperature heat capacity data of the C2S phases were recorded by relaxation calorimetry using a PPMS. Supplementary DSC data of β- and γ-C2S were obtained to verify their heat capacity evolution to 400 °C.
The recommended values for β-C2S and γ-C2S are:
ΔfH0298γ−C2S = −2316.0 ± 4.5 kJ mol−1, S0298γ−C2S = 119.7 ± 0.9 J mol−1 K−1,
CP(γ-C2S) = (249.098 − 1949.5 T–0.5 – 1.60822 ∙ 106 T−2 + 2.77532 ∙ 108 T−3) J K−1 mol−1, [T] = K,
ΔfH0298β−C2S = −2307.6 ± 4.5 kJ mol−1, S0298β−C2S = 122.2 ± 0.9 J mol−1 K−1, and
CP(β-C2S) = (259.721 − 2466.09 T–0.5 + 2.62687 ∙ 106 T−2 – 4.77891 ∙ 108 T−3) J K−1 mol−1, [T] = K. |
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ISSN: | 0008-8846 1873-3948 |
DOI: | 10.1016/j.cemconres.2021.106621 |