Particle Size & Application:

• Particle Size: 5–100 nanometers (nm)

• Application in Cementitious Systems:

• • Enhances strength and durability by promoting calcium-silicate-hydrate (C-S-H) formation.

  • Improves rheology and cohesion in high-performance concrete.

Processing Method:

• Sol-Gel Process:

  • Silica precursors (e.g., sodium silicate) are mixed in a liquid medium.

  • A controlled chemical reaction forms nano-sized silica particles, which remain suspended in solution.

• Precipitated Silica:

  • Acid is added to sodium silicate, causing silica to precipitate out as a fine powder.

• Pyrolysis:

  • Silicon tetrachloride (SiCl₄) is burned in an oxygen-hydrogen flame, forming amorphous silica nanoparticles.

Benefits in Cementitious Systems:

✔ Enhances early strength development by accelerating hydration.
✔ Improves cement paste cohesion, reducing segregation and bleeding.
✔ Fills voids between cement particles, lowering porosity and permeability.
✔ Increases durability and resistance to chemical attack.