Microfume 106 UM is an undensified silica fume that improves the mechanical properties (compressive strength) and durability (via permeability decrease). Microfume 106 UM can be an extender for lightweight cements and a compressive strength enhancer for low-temperature, lightweight cements. Lower water content and improved flowability with a higher PAI (Pozzolonic Activity Index) for improved compressive strength development in light weight slurries is a key feature of Microfume 106.