Abstract

Ladle slag, a by-product of steelmaking process, has shown potential to be used as a cementitious material in construction. However, the stability of the hydration products has not been investigated, and has been found to depend on available water. This paper presents the investigation of ladle slag hydration at different water-to-binder ratios. Hydrates of ladle slag converts from metastable to a stable reaction product over a period of time, thus affecting the mechanical and microstructural properties of the hydrated slag. These hydration products were analyzed using TGA, XRD, ²⁷Al NMR, FTIR and SEM techniques. The water-to-binder ratio primarily contributes to the rate at which the conversion process occurs in the system which consequently has a direct effect on the strength derived over a period of time. Through analytical characterization of the microstructure, these hydrates and the conversion process were confirmed, revealing the initial hydrate product of ladle slag to be a metastable dicalcium aluminate octahydrate (C₂AH₈) which converts to a stable tricalcium aluminate hexahydrate (C₃AH₆) over a period of time.