Thermodynamic data of belite polymorphs. (February 2022)

• Record Type: Journal Article
• Authors: Grevel, K.-D.; Bellmann, F.; Majzlan, J.; Dachs, E.; Benisek, A.; Ludwig, H.-M.
• Is Part Of: Cement and concrete research. Volume 152(2022)
• Publication Date: 2022-02
• Subjects: Belite -- Calorimetry -- Enthalpy -- Entropy -- Heat capacity; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2021.106621
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: One major component of Portland cement clinker is Ca2 SiO4 (C2 S, belite). Synthetic samples of three polymorphs, β-C2 S (larnite), γ-C2 S (calcio olivine), and x-C2 S 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 C2 S phases were recorded by relaxation calorimetry using a PPMS. Supplementary DSC data of β- and γ-C2 S were obtained to verify their heat capacity evolution to 400 °C. The recommended values for β-C2 S and γ-C2 S are: Δ f H 0 298 γ − C 2 S = −2316.0 ± 4.5 kJ mol −1, S 0 298 γ − C 2 S = 119.7 ± 0.9 J mol −1 K −1, C P (γ-C2 S) = (249.098 − 1949.5 T –0.5 – 1.60822 ∙ 10 6 T −2 + 2.77532 ∙ 10 8 T −3 ) J K −1 mol −1, [ T ] = K, Δ f H 0 298 β − C 2 S = −2307.6 ± 4.5 kJ mol −1, S 0 298 β − C 2 S = 122.2 ± 0.9 J mol −1 K −1, and C P (β-C2 S) = (259.721 − 2466.09 T –0.5 + 2.62687 ∙ 10 6 T −2 – 4.77891 ∙ 10 8 T −3 ) J K −1 mol −1, [ T ] = K.