What is the primary benefit of silica fume as a supplementary cementitious material?

Silica fume is a byproduct of producing silicon metal or ferrosilicon alloys, and it is known for its high pozzolanic activity. When utilized as a supplementary cementitious material, its primary benefit lies in enhancing the strength and durability of concrete.

The fine particles of silica fume have a high surface area, which allows for a more effective reaction with calcium hydroxide in the presence of water, leading to the formation of additional calcium silicate hydrate (C-S-H). This reaction not only contributes to higher compressive strength but also improves the overall durability of concrete, including its resistance to chemical attacks, permeability, and shrinkage.

This increased durability and strength make silica fume an excellent choice in high-performance concrete applications, such as in bridge decks, parking structures, and other high-stress environments. Thus, the main advantage of incorporating silica fume into concrete mixes is the significant enhancement of both strength and durability, making it a valuable addition to modern construction materials.