硅粉的颗粒极小. 一般, 粒子大约是 0.1 千分尺 (100 纳米) 直径. 为了正确看待这一点, if a typical silica fume particle was the size of a football, then a single grain of cement would be about the size of a car.

The small particle size is a key reason why silica fume is so effective as a pozzolan in concrete. It fills in the gaps between larger particles, reducing the porosity and increasing the strength and durability of the finished product.