STUDIES ON THE FORMATION KINETICS OF CALCIUM SULFOALUMINATE

Calcium sulphoaluminate, C4A3SBAR, is an important mineral phase for rapid hardening sulphoaluminate cement. Its formation from molar mixes of the oxides of calcium aluminum and sulphur derived from synthetic pure chemicals and commercial grade natural minerals, such as limestone, bauxite and gypsum have been studied. The degree of formation of calcium sulphoaluminate phase in the temperature range of 1100 - 1325-degrees-C is comparatively higher from pure chemicals. This is due to increased solid state reaction between oxides. The formation obeys the rate law equation 1-(1-x)1/3 = Kt where x is the fraction of C4A3SBAR formed at time t. The activation energy of the formation has been found to be about 90 kcal mole-1.