Calcium sulfoaluminate (C$A) cement is a binder of increasing interest to the cement industry and as such is undergoing rapid development. Current formulations do not contain alite; however, it can be shown that hybrid C$A-alite cements can combine the favourable characteristics of Portland cement with those of C$A cement while also having a lower carbon footprint than the current generation of Portland cement clinkers. This paper presents two results on the formation of alite calcium sulfoaluminate (a-C$A) clinkers. The first is a thermodynamic study which demonstrates that the production of a-C$A clinker is possible without the use of mineralizers such as CaF 2 , doping with foreign elements such as barium and strontium, or using multiple stages of heating to produce ye'elimite. It is established that a-C$A clinker can be readily produced in a standard process by controlling the oxygen and sulfur dioxide fugacity in the atmosphere. This allows for the stabilization of ye'elimite to the higher temperatures required for alite stability. The second result establishes that when using fluorine to mineralise a-C$A clinker production at 1250°C, the iron content in the clinker is also an important variable. Although the exact mechanism of alite stabilisation is not known, it is shown that alite formation increases with the combination of CaF 2 and Fe 2 O 3 in the mix.

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