The Hydration Activity Enhancement Method of Mayenite in Ladle Slag: A Review

Abstract

As a byproduct of the steelmaking process, ladle slag has the potential to be used as an auxiliary cement material in the construction field. However, ladle slag generated after secondary refining is typically handled by air cooling and stacking, leading to the presence of the typical mineral phase mayenite (Ca₁₂Al₁₄O₃₃, abbreviated as C₁₂A₇) in a crystalline form within the slag. This reduces its early hydration activity, which adversely affects the compressive strength of concrete and consequently lowers the resource utilization rate of ladle slag. Based on this, this article provides a comprehensive review of the generation process and composition of ladle slag. By discussing the hydration process and hydration products of the typical mineral phase C₁₂A₇ in ladle slag, as well as the mutual transformation of hydration products, it is shown that hydration products undergo transformation with increasing temperature. Compared to crystalline C₁₂A₇, amorphous, C₁₂A₇ exhibits excellent hydration activity. Building upon this, methods for amorphizing C₁₂A₇ are elucidated, wherein thermal activation or chemical activation is employed to alter the ordered arrangement of atoms within the crystal structure, thereby reducing the stability of the crystal structure to achieve amorphization of C₁₂A₇.