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Silica Fume (Microsilica) Pozzolanic Additive

CAS Number: 69012-64-2

Silica fume (microsilica) is an ultra-fine by-product of silicon metal production, consisting primarily of amorphous silicon dioxide with particle sizes 100x finer than cement. As a pozzolanic additive at 5–10% replacement of cement, it reacts with calcium hydroxide to form additional calcium silicate hydrate, dramatically densifying the concrete microstructure, increasing strength, and reducing permeability. It is essential in high-performance and ultra-high-performance concrete.

Technical Specifications

appearanceLight grey to dark grey ultra-fine powder
SiO2 content (%)≥85
moisture content (%)≤3
pozzolanic activity index (%)≥105
specific surface area (m²/kg)≥15000

Applications

  • High-strength and ultra-high-strength concrete (>80 MPa)
  • Marine and aggressive environment concrete
  • Bridge decks and infrastructure requiring low permeability
  • Shotcrete for tunnels and slope protection
  • Abrasion-resistant industrial floor overlays

Key Features

  • Ultra-fine particles fill cement paste pores for maximum densification
  • Pozzolanic reaction converts weak Ca(OH)2 to strong CSH
  • Dramatically reduces chloride ion diffusivity for corrosion protection
  • Compliant with ASTM C1240 and EN 13263 standards

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Silica Fume (Microsilica) Pozzolanic Additive chemical structure

CAS Number

69012-64-2

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