Engineered Fly Ash

• Normal raw fly ash, classified ASTM C618 Class F fly ash and BS EN 450-1 Category S compliant fly ash are generally specified based on 45 µm sieve residue, rather than a mandatory BET specific surface area requirement. As a result, the actual fineness and performance can vary depending on the source, collection system and classification process.
• Typical raw fly ash usually has a Blaine fineness of around 250–350 m²/kg, which may broadly correspond to a BET specific surface area of approximately 400–600 m²/kg, depending on particle characteristics.
• Classified fly ash is generally finer, with Blaine fineness typically in the range of 350–600 m²/kg, and a typical BET specific surface area of approximately 400–1,000 m²/kg, depending on the level of classification and product grade.
• In contrast, Ultrafine Fly Ash (UFFA) is an engineered fly ash designed for significantly higher fineness, controlled particle size distribution and improved performance. HITEPOZZO® UFFA is manufactured with a minimum BET specific surface area of around 1,500 m²/kg, making it suitable for advanced cementitious systems, high-performance concrete, construction chemicals and other performance-driven applications.