TG/DTG-DSC and high temperature in-situ XRD analysis of natural thaumasite

This paper investigated thermal properties of natural thaumasite, such as phase composition and reaction mechanism decomposition using simultaneous TG/DTG-DSC in Ar Air medium up to 1673 K, coupled with masspectrometer for analysis evolving gases, in-situ powder X-ray diffraction measurements. The transitional solid phases, grown increasing temperature at thaumasite decomposition, are calcium hydrogen carbonate (Ca(HCO3)2) sulphate (Ca(HSO4)2), calcite, anhydrite, silicates (wolastonite larnite), silico-carbonate (spurrite), silico-sulphate (ternesite). both gaseous media includes the stages dehydration, dehydroxylation, dacarbonation desulphuration obtaining a residue varying degrees crystallinity. main phase, highest temperatures, is larnite. Based on obtained results it was proposed scheme chemical reactions, which presents decomposition. defined has fundamental importance by adding new details reference data, practical application identification archaeology, chemistry cement cement-based materials.