China Nonferrous Metallurgy

Some studies suggest that TiO₂ can reduce the viscosity of the liquid phase and stabilize the β-C₂S phase during the calcination of cement clinker. Currently, there is a large amount of titanium-containing blast furnace slag stockpiled in China, which contains a significant amount of TiO₂ and cement raw material components. In this study, titanium-containing blast furnace slag and cement raw materials were taken as raw materials to preparebelite cement clinker with excellent dry shrinkage and chemical resistance properties, which was composed of largeamount β-C₂S and a small amount of C₃S. The study investigated the influence of titanium-containing blast furnace slag addition on the phase composition, microstructure, and hydration characteristics of the clinker, and conducted an in-depth study on the distribution pattern of Ti⁴⁺ in the clinker, leading to the following main conclusions. The addition of blast furnace slag enhanced the hydration activity of the clinker and increased compressive strength. The compressive strengths of blank cement mortar specimens cured for 3 days, 7 days, 28 days, and 90 days were 20.3MPa, 27.2MPa, 42.3MPa, and 53.8MPa, respectively. When 4% blast furnace slag was added, the compressive strengths increased to 34.6MPa, 40.5MPa, 57.6MPa, and 68.3MPa, respectively. The mechanism by which blast furnace slag enhanced the hydration activity of clinker was that the TiO₂ and MgO in the slag reduce and disrupt the silicon-oxygen network structure of the silica-rich liquid phase, thereby lowering the viscosity of the liquid phase. The results of the structural difference factor D and radius difference percentage C calculations indicated that, compared to other ions in the clinker, Ti⁴⁺ tends to replace Fe³⁺ and dissolve into the belite clinker phase, such as the intermediate phase C4AF. The solid solution of Ti⁴⁺ not only causes lattice distortion in the clinker phases, thereby enhancing hydration activity, but also inhibits the transformation of β-C₂S into γ-C₂S with no hydration activity, promoting the reaction between f-CaO and β-C₂S to form C₃S. This study provides a theoretical foundation for the efficient and clean utilization of titanium-containing blast furnace slag.