Influence of the characteristic of input materials on formation and properties of sintered fly ash body

Artificial aggregate from sintered fly ash is an example of material, which can be used solely on the basis of fly ash without any additions. However, to ensure optimal progress of firing and high quality aggregate, it is necessary to study influence of the characteristic of fly ash on properties of fly ash body. The aim of the research work is evaluation of influence of characteristic of fly ash on formation, structure and properties of sintered fly ash body using laboratory firings of testing samples and also using the heating microscopy. The main difference as regards behavior is between fly ash originating from high temperature and fluidized bed combustion. While the first type of fly ash contains mainly mullite and other high temperature minerals, fluidized bed combustion fly ash contains mainly anhydrite and free lime. These increase for example manipulation strength of fly ash mix, but they also increase the amount of mixing water, emissions, content of extractable sulphur and weaken the sintered fly ash body.