Effects of varying grades of silicomanganese fume on hydration attributes of cementitious composites

The viability of silicomanganese fume (SMF) as a supplementary cementitious material (20% binder replacement) in blended cement pastes was evaluated through setting time, flowability, isothermal calorimetry, compressive strength (7, 28, and 90 days), and microstructural analyses. Three SMF grades with varying fineness and composition were studied at a water-to-binder ratio of 0.30. SMF incorporation increased setting time but showed minimal effect on flowability due to its spherical morphology. While early-age (7-day) strength was slightly lower, SMF-modified mixes exhibited substantial gains at later ages, with SMF1, SMF2, and SMF3 showing total strength increases of 42.2%, 30.4%, and 51.5%, compared to 20.0% in the control. XRD, TGA/DTG, and SEM analyses at 28 days confirmed enhanced hydration, additional C–S–H formation, and a denser matrix. Finer SMF grades promoted higher pozzolanic reactivity, reduced porosity, and improved long-term performance, highlighting SMF’s potential as a sustainable cementitious material.