Mechanical behavior and leaching characteristics of cementitious composites incorporating silicomanganese fume

This study investigates the feasibility of incorporating silicomanganese fume (SMF) into concrete by replacing varying percentages of cement with SMF (0, 10, 20, and 30%). The leaching behavior, mechanical properties, and microstructural characteristics were studied in detail. The leaching of manganese (Mn), a potentially hazardous element, and Calcium (Ca) was evaluated using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) analysis over 90 days. Mn leaching was observed in the first two days, with a maximum leaching of about 0.002 mg/L in the specimen with 30% SMF, which is below the limits set by standards, and no leaching of Mn was detected after 2 days. Significant Ca leaching was detected at maximum in all specimens. Control (C) specimen showed maximum Ca leaching at 90 days, with about 234 mg/L. Mechanical properties revealed that replacing up to 20% cement with SMF resulted in an 8% gain compared to the control specimen. However, beyond the 20% replacement level, the impact was negative. Microstructural investigations by SEM/EDS, XRD, and TGA further confirmed that SMF is a cement substitute, enhancing microstructure when used within specified limits. Reduced portlandite content and increased chemically bound water indicated a higher degree of hydration, resulting in a denser, less porous microstructure.