Sintering is performed for the pure alpha-cristobalite, with TiO2 additive, and with CaO additive powder compacts. The sintering temperatures were 1500, 1515, and 1525 A degrees C for different dwell times. The master sintering curve theory is applied to the densification data and the activation energies are obtained. The splitting strength is measured for the sintered specimens. It is found that CaO decreases the activation energy due to the formation of liquid phase at the used sintering temperatures. The TiO2 increases the activation energy because it exists as solid particles at the used sintering temperatures. The measured splitting strengths of the sintered specimens are shown to be best expressed by a sigmoid function of the work of sintering.