The Effect of Different Particle Sizes of SiO2 in Sintering on the Formation of Ternesite

Ternesite is synthesized through sintering a mixture of CaCO3, SiO2, and CaSO4 in a molar ratio of 4:2:1. Ternesite has a hydration rate between ye’elimite and belite in an aluminum-containing environment, and is considered to be a new material that can be used to enhance the performance of calcium sulphoaluminate cements. This experiment investigated the influence of different particle sizes of SiO2 on ternesite formation. Controlled partial pressure sintering was employed within the temperature range from 1100 °C to 1200 °C, with a 72 h incubation period. The highest purity of ternesite in the samples reached 99.47% (500 nm SiO2 sample). The analysis results from scanning electron microscopy and an energy dispersive spectrometer indicated that the particle size of SiO2 exerted a significant influence on the formation of ternesite. In the preparation of ternesite from 10 μm particle size SiO2, traces of calcium silicate were found in the product. The results of a thermal analysis further demonstrated significant distinctions in the thermal stability of ternesite prepared with SiO2 of different particle sizes. Additionally, the crystallinity of ternesite was influenced by the particle size of SiO2, consequently impacting the hydration performance of ternesite–calcium sulphoaluminate cement.