Effect of raw mix design and of clinkering process on the formation and mineralogical composition of (ternesite) belite calcium sulphoaluminate ferrite clinker

The effect of the clinkering process on mineral formation in calcium sulphoaluminate clinker and its reactivity has been investigated using a multi-method approach. Industrial by-products were used as main raw materials for clinker production. Under the given conditions, clinker burning processes lead to variable clinker reactivity and sometimes to an uncontrollable early hydration. The rapid early age hydration seems to result from a simultaneous incorporation of iron in yeʹelimite, which stabilises its cubic polymorph at the expense of the orthorhombic one. Yeʹelimite has demonstrated as well a high capacity to substitute aluminium with iron. This study proves the possibility to adjust the performance of calcium sulphoaluminate ferrite based systems by applying specific clinkering and cooling processes, and by optimizing the raw mix design accordingly. Additionally, ternesite is formed. Ternesite, which is usually assumed to be inert, has shown reactivity potential when it is a part of belite calcium sulphoaluminate ferrite clinker.