Thermal decomposition of hydrated alumina cement (CAH(10))

Abstract

It is known that the initial product of hydration of high-alumina cement at low temperatures, often labeled "CAH(10)," contains both crystalline and amorphous portions. The thermal decomposition of this product was studied in several samples. This study was carried out by two different methods: derivative thermogravimetric analysis (DTG) and x-ray diffraction (XRD) combined with temperature. The DTG signal of the compound was decomposed in four different kinetic processes. The nature of the water liberated in each process was characterized by the shape parameters of the process. The x-ray diffractograms at different temperatures showed two volume variations of the CAH(x) compound, related to contractions in the c parameter before the collapse of the structure to yield an amorphous phase. Two of the four observed processes are related to the dehydration of the crystalline portion and the other two to the amorphous dehydration.