THERMOANALYTICAL EVENTS AND ENTHALPIES OF SELECTED PHASES AND SYSTEMS OF THE CHEMISTRY AND TECHNOLOGY OF CONCRETE PART I. CALCIUM-SILICATE-ALUMINATE-SULFATE HYDRATES

Abstract

Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions - (delta)H, of natural minerals of calcium-silicate-sulfate-aluminate hydrates. The thermoanalytical curves of thaumasite and ettringite are fully in line with that reported in reference sources. The values of (delta)H calculated from DSC curves in the intervals of key decomposition steps ranging from 50 to 250 C, achieve (1215 +/- 60) J g-1 for thaumasite and (930 +/- 40) J g-1 for ettringite. The differing values of decomposition enthalpies (delta)H, as presented by various research groups, are indicated and critically discussed in the paper.

Keywords

• Calcium-silicate-sulfate-aluminate hydrates
• Thaumasite
• Ettringite
• Thermal analysis
• Decomposition enthalpy