Effects of Silica Fume and Fly Ash on compressive strength and durability of concrete

Enhancing the durability and resistance of concrete in aggressive environments is considered one of the major challenges in civil engineering. The penetration of harmful ions such as chloride and sulfate can deteriorate the microstructure of concrete and gradually reduce the mechanical strength of concrete structures. In recent years, the use of supplementary cementitious materials as partial replacements for Portland cement has attracted significant attention as an effective approach to improve the mechanical properties and durability of concrete. Among these materials, fly ash and silica fume play an important role in refining the microstructure of concrete and reducing its permeability due to their pozzolanic properties and high specific surface area. In this study, the optimal consumption levels of these supplementary materials are investigated through an analytical review of previously published research on their effects on compressive strength and the performance of concrete in aggressive environments. Considering the diversity of mix designs reported in different studies, the comparison of results was conducted relative to the control specimens of each study. Comparative analysis reveals that silica fume is more effective than fly ash in increasing compressive strength, with optimal incorporation rates of ۵-۱۰ wt.% and ۱۰-۲۰ wt.%, respectively. Regarding chemical durability, fly ash exhibited superior performance in ۶۰% of investigated acidic environments. In contrast, the effectiveness of both mineral admixtures in chloride environments is sensitive to the water-to-binder ratio and overall mix design, leading to varying results were either material may outperform the other depending on the context.

کلیدواژه ها:

Concrete ، Silica fume ، Fly ash ، Environment effects ، Compressive strength ، durability