Activation energy of calcium sulfoaluminate cement-based materials

In this study, calcium sulfoaluminate (CSA) cement pastes were tested for heat of hydration and chemical shrinkage at temperatures of 20 °C, 30 °C and 40 °C. Apparent activation energy (Ea\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$E_{a}$$\end{document}) values were then calculated using both exponential and hyperbolic methods. The average Ea\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$E_{a}$$\end{document} of the CSA cements ranged from 42.24 to 80.22 kJ/mol, much higher than that of Type I Portland cement (38–45 kJ/mol). Ea\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${E}_{a}$$\end{document} increased slightly with the replacement of silica fume for cement. However, average Ea\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${E}_{a}$$\end{document} decreased by 18.4% when 20% Class C fly ash was used, but increased by 21.3% when 40% Class C fly ash was used. Ea\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$E_{a}$$\end{document} calculated from heat of hydration using the exponential method is 17% lower than that obtained using the hyperbolic method. When the exponential method was used, Ea\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${E}_{a}$$\end{document} values determined using heat of hydration were 30% higher than those obtained using chemical shrinkage.