The Effect of Silica Fume Pozzolan Percentage as a Partial Cement Substitution on Concrete Compressive Strength

This research aims to investigate the effect of varying percentages of pozzolanic silica fume on the compressive strength of normal concrete at the age of 28 days. Cube specimens with dimensions of 15 cm × 15 cm × 15 cm were tested using a compression testing machine with a capacity of 2000 kN. The variations of silica fume addition used were 0.05%, 0.10%, and 0.15% by cement weight, and the results were compared to control concrete without any silica fume. The findings indicate that the addition of silica fume significantly affects the compressive strength of concrete. Concrete with 0.05% silica fume achieved an average compressive strength of 56.319 MPa, higher than that of the control concrete. The optimum result was obtained at 0.10% addition, reaching 56.744 MPa, which marked the highest strength in this study. However, the addition of 0.15% silica fume resulted in a lower compressive strength of 55.559 MPa, likely due to poor homogeneity in the mixture and the formation of clumps of silica fume. It can be concluded that the use of silica fume as an additive improves the quality of concrete when applied in the proper proportion, with 0.10% being the most effective dosage. This study highlights the importance of mix proportioning and homogeneity in maximizing the benefits of silica fume to enhance concrete compressive strength.