Densified and undensified silica fume are chemically identical but behave very differently in handling, shipping, and concrete mixing. The choice between the two grades affects freight cost per container, workability in the mixer, dust control at the batching plant, and suitability for UHPC formulations. Densified silica fume, at 500–700 kg/m³ bulk density, loads twice as much payload per 20-foot container as undensified material and integrates easily into automated pneumatic batching systems — making it the default choice for international buyers in Europe, the Middle East, and the Americas. Undensified silica fume, at 200–350 kg/m³, is preferred for ultra-high-performance concrete and oilwell cementing where full dispersion at low water-to-binder ratios is critical. Both grades comply with ASTM C1240 and EN 13263. This guide covers bulk density, shipping economics, plant handling, concrete performance, dosage, and a decision framework for procurement teams sourcing microsilica internationally.