Silica fume is a byproduct of producing silicon metal or ferrosilicon alloys. It consists of very fine particles of silicon dioxide, which are about 100 times smaller than a grain of sand. This material is often used in construction and concrete production to enhance strength and durability. When added to concrete, silica fume improves its resistance to chemical attacks and reduces permeability. This makes the concrete less susceptible to damage from water and other harmful substances. Additionally, it can help reduce the overall amount of cement needed, making concrete production more environmentally friendly.