ABSTRACT
Two ternary compounds exist in the system C-S-A-S: calcium sulfoaluminate and calcium sulfosilicate.
Calcium sulfoaluminate [tetracalcium trialuminate sulfate (4CaO.3Al2O3.SO3 or Ca4(Al6O12)(SO4), abbreviation C4A3S], also called also "kleinite" or "Klein's compound," may be produced from a starting blend of an appropriate oxide composition by burning it at a temperature of about 1250-1300 °C (Santoro et al., 1986; Havlica and Sahu, 1992; Zhang et al, 1992; Sharp, 1999):
The compound is stable up to about 1350-1400 °C. The second compound of the system, calcium sulfosilicate [5CaO.2SiO2.SO3
or Ca5(SiO4)2.(SO4), abbreviation C5S2S, also sometimes called sulfospurrite] is stable only in a narrow temperature range, 1100-1180 °C, and is of little significance for cement chemistry.
