Morphological and mineralogical insights into acetic acid modifying and hydraulic process on steel slag for enhanced reactivity

Enhancing the hydraulic reactivity of steel slag (SS) powder as supplementary cementitious material by surface modification is a promising approach to promote its utilization and environment protection. Aiming to explore the intrinsic mineral reaction in the modifying and hydraulic process, a flat and dense SS surface at microscale was prepared innovatively for surface investigation, the roughness, morphology and minerals of the surface in the acetic acid solution modifying process were comprehensively investigated coupling with multi approaches. It is found that the reactions of acetic acid with SS significantly slows down after 30 s, crisscross cracks with width of about 0.98 μm appear on the surface of most calcium silicates, other minerals, e.g. calcium aluminate, amorphous phase and quartz dissociate with each other. In the hydration process, spherical hydrates appear on unmodified SS surface at about 12 h hydration, while spherical and lamellar hydrates have precipitated on the acetic acid modified SS surface after hydration for 2 h. The findings help explain the enhanced hydration reactivity of acetic acid modified SS and provide a new SS sample preparation approach for surface investigation.