Thermodynamics and kinetics of calcium sulphoaluminate

Abstract

The formation process of calcium suphoaluminate(C₄A₃S) was investigated by the X-ray diffraction technique and then the thermodynamics was analyzed, finally the kinetics of which was studied by SC-132. XRD results show that the formation of C₄A₃S is accomplished in three different kinds of ways: one is by solid reaction of Ca (OH)₂/CaO, Al₂O₃ and CaSO₄, other two ways are through such interstitial products as CaO·Al₂O₃ and CaO·₂Al₂O₃. The formation thermodynamics shows that C₄A₃S begins to form at 900 °C–1 000 °C and increases as temperature rising; the quantity of reaches the highest at 1 300 °C–1 350 °C and then falls at >1350°C. Kinetics study shows that the formation rate of C₄A₃S can be described as first-order kinetics at high temperature, and it belongs to the random nucleation growth mechanism. The apparent activation energy is 456.37 kJ·mol⁻¹ and pre-exponential factor is 1.545×10¹².

Keywords

thermal decomposition / mechanism / kinetics / calcium sulphoaluminate

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