The use of thermogravimetric analysis technique for the characterization of construction materials

The thermogravimetric analysis (TG) technique is widely used in the characterization of diverse types of construction materials related to binders, such as plasters, limes and cements. For calcium sulphate dihydrate (gypsum) two serial dehydration steps are very near in temperature decomposition and overlapping in the thermogravimetric events is observed. The goal of this research is to develop new thermogravimetric analysis procedures that allow obtaining more precise information in the characterization of plasters. The resolution of both dehydration events has been increased using two different strategies: on one hand, the production in the experience of a water vapour self-generated atmosphere by the use of sealed aluminium pan with a pinholed lid. On the other hand, the use of high resolution thermogravimetric analysis (HRTG), based on the variation of the heating rate as a function of the rate of mass loss observed at once. The results obtained for both strategies of improvement of the TG curves, showed that they are two procedures that let to obtain a total resolution of the two dehydration steps for gypsum.