Abstract
This article presents the results of a study on the structural and chemical properties of silica fume and fly ash from local plants, focusing on their potential as mineral additives in self-compacting concrete. Scanning electron microscopy (SEM) and X-ray fluorescence (XRF) analysis were used to investigate particle morphology, microstructure, and elemental composition. Silica fume was characterized by a high SiO₂ content (>75%), spherical particle morphology, and a smooth surface, which promotes the formation of a dense cement matrix. Fly ash exhibited a complex chemical composition dominated by SiO₂ and Al₂O₃ oxides, with spherical particles and surface roughness enhancing adhesion to the cement paste. The results demonstrated that the combined use of silica fume and fly ash has the potential to improve concrete workability, increase strength, reduce the water-cement ratio, and enhance durability due to microstructure densification. Partial cement replacement with these additives may not only optimize concrete performance but also reduce the environmental footprint of cement production. The findings highlight the efficiency of silica fume and fly ash as pozzolanic components for developing high-performance and sustainable self-compacting concrete.