Ceramics-Silikáty 70, (1) 128 - 137 (2026)

A 10% phosphorus slag was used as a silicate and calcium raw material to produce Portland clinker, but this caused delays. The study found that when the designed content of C₄A₃$ was 7.5% and the calcination temperature was 1350 °C, the clinker showed optimal performance. The XRD and petrographic analysis indicated excellent mineral development in the clinker, which could be due to the addition of sulfur and CaF₂, lowering the liquid phase formation temperature and promoting mineral-forming reactions. Furthermore, its mechanical properties improved compared to clinkers made from the same raw materials without C₄A₃$, even slightly exceeding those of ordinary Portland clinker (OPC). Most importantly, with a designed 7.5% C₄A₃$ in the mineral composition, the clinker’s setting time was shortened. This is because a large amount of ettringite (AFt) forms during the early hydration stage, which not only shortens the setting time, but also improves the early mechanical properties. The study also explained the formation mechanism of C₄A₃$-modified Portland clinker, providing a theoretical basis for the stable production of this clinker type using solid waste, particularly phosphorus slag.