Class F Fly Ash
A pozzolan that makes concrete stronger, denser, and cheaper per yard.
Class F fly ash is the most widely used supplementary cementitious material in North American concrete. Its spherical particles improve workability at lower water content, and its pozzolanic reaction with calcium hydroxide densifies the paste over time — giving you lower permeability, better sulfate resistance, and controlled heat of hydration in mass pours.
Typical Specifications
What you're buying.
| Property | Value |
|---|---|
| Classification | ASTM C618 Class FPER STANDARD |
| SiO₂ + Al₂O₃ + Fe₂O₃ | 70.0% minimumPER STANDARD |
| Loss on ignition (LOI) | 6.0% maximumPER STANDARD |
| Fineness, retained on 45 µm sieve | 34% maximumPER STANDARD |
| Appearance | Fine gray powderTYPICAL — CONFIRM |
| Specific gravity | 2.1 – 2.6 typicalTYPICAL — CONFIRM |
Per standard values are requirements of the cited specification. Typical values reflect commercial norms and should be confirmed against the certificate of analysis for your specific shipment.
Principal Industrial Uses
Where it's used, and why.
Ready-Mix & Precast Concrete
Replaces 15–30% of portland cement by mass, improving workability and finishability while reducing permeability and long-term cost per yard.
Oilwell Cementing
Extends slurry yield and improves the durability of set cement in casing and squeeze operations, particularly where sulfate exposure is a concern.
Mass & Structural Pours
Controls heat of hydration in thick sections, reducing thermal cracking risk in foundations, mats, and large placements.
Related Minerals
Often ordered alongside Class F Fly Ash.
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