Utilizing silica fume for development of concrete strength

Abstract

Corresponding to the introduction of silica fume in concrete improves both the mechanical and durability characteristics of the concrete. This thesis presents the results of research effort conducted at different percentage of silica fume in concrete. The program investigated various characteristics of silica-fume concrete. It emphasized the effect of silica fume on workability level and its maintenance of fresh concrete; strength development and strength optimization and of hardened concrete. The experimental program comprised four levels of silica-fume contents (as partial replacement of cement by weight) at 0% (control mix), 5%, 10%, and 15% without superplasticizer. Concrete mixture been designed by respecting to American Concrete Institute (ACI) method. Concrete cube specimens were tested using compression machine for curing age of 3, 7, and 28 days. It was found that there was an optimal value of silica-fume content at which concrete strength improved significantly. All data had been analyzed using mean statistical method and regression method. Due to the slow development of pozzolanic effect, there was a drop in early strength up to seven days and late significant gains up to 28 days upon introducing silica fume to concrete. As per design requirement, the control mixture batch achieved the targeted 28-day compressive strength of 35 MPa. Result of modified concrete designation indicates that 10 and 15 percent addition of silica fume batches stated the 28-day average compressive strength of 38.28 MPa and 40.66 MPa, significantly higher compared to control mix. However, the 5% added silica fume concrete batch showed unobvious increase in compressive strength with 35.62 MPa