**3.3 Quartz flour**

Quartz flour, also referred to as crystalline silica, is a mineral used in UHPC and HPC mix development. Quartz flour is found in sand, granite, rocks, and some soil types. When these materials are cut, chipped, or drilled, dust evolves that contains the quartz flour particles. The diameter of quartz flour particles enables quartz flour to fill the voids within cement particles, which reduces the mix permeability and improves the resistivity of concrete to adverse environmental conditions. Quartz flour is used as a supplementary cementitious component in proprietary UHPC mixes produced by Lafarge and is commercially available in global markets under the name Ductal. Proprietary UHPC mix composition including quartz flour is shown in **Table 3**.
