Characterisation of asbestos-containing wastes by thermal analysis

Abstract

The study examined building materials containing asbestos, which have been considered hazardous waste for several years. Samples were taken from various places in Poland. The chemical composition was examined using chemical analysis, the mineralogical phases were identified using X-ray diffraction, and the structure was identified using scanning electron microscopy, taking into account energy-dispersive spectroscopy. Thermal tests of the samples were performed using thermal analysis, thermogravimetric measurements and high-temperature microscopy. Additionally, changes that occurred in the microstructure were determined using mercury porosimetry and infrared spectroscopy. All the above research methods were used to characterise the properties of cement–asbestos materials, which were also subjected to isothermal thermal treatment at a temperature of 1100 °C for 4 h. The results proved that the material after thermal treatment undergoes significant structural changes. The thermal decomposition process of cement–asbestos involves dehydration, dehydroxylation and then recrystallisation to new stable crystalline phases but in the context of asbestos, we are dealing here with the so-called phenomenon of pseudomorphosis. Knowledge about the thermal properties of asbestos materials can provide us with data on how the material undergoes significant structural changes, thanks to which it will be possible to use neutralised cement–asbestos waste as possible safe materials.