Fly ash is a fine, glass-like powder recovered from gases created by coal-fired electric power generation. Fly ash material is solidified while suspended in the exhaust gases and is collected by electrostatic precipitators or filter bags.
Fly ash is a pozzolan. When mixed with lime (calcium hydroxide), pozzolans combine to form cementitious compounds. Concrete containing fly ash becomes stronger, more durable, and more resistant to chemical attack. Fly ash particles are hard and round, giving a "ball bearing" effect that allows concrete to be produced using less water — improving both workability and durability.
Our fly ash is sourced from state-of-the-art government-run coal-fired thermal power plants in the State of Gujarat, India, under one-source long-term contracts for quality coal fly ash procurement. The in-built classification system in the power plant enables extraction of a specific fineness, consistently.
Fly ash is packed in 1.4 MT jumbo bags especially for exports, with liners. Since jumbo bags are critical during handling of fly ash, we use only high-grade jumbo bags to ensure the material reaches its destination in export-ready condition.
Two classes of fly ash are defined by ASTM C618: Class F and Class C. The chief difference between these classes is the amount of calcium, silica, alumina and iron content in the ash, largely influenced by the type of coal burned (anthracite, bituminous or lignite).
Not all fly ashes meet ASTM C618 requirements, though depending on the application this may not be necessary. Ash used as a cement replacement must meet strict construction standards: 75% of the ash must have a fineness of 45 μm or less, with a carbon content (loss on ignition, LOI) of less than 4%. Ongoing quality verification is essential — expressed through quality control seals like the Indian ISI mark or the DCL mark of the Dubai Municipality.
Class F fly ash — produced by burning harder, older anthracite and bituminous coal. It is pozzolanic in nature and contains less than 10% lime (CaO). The glassy silica and alumina requires a cementing agent such as Portland cement, quicklime, or hydrated lime in the presence of water to produce cementitious compounds. The addition of a chemical activator such as sodium silicate can also lead to the formation of a geopolymer.
M.L. Fly Ash has in-house laboratories for continuous quality testing on every batch of material dispatched, and complies with all major international standards: IS 3812:2003 Part 1, ASTM C618 Class-F, BS EN 450, and BS 3892.
| Properties | Unit | Typical Performance | IS 3812 Part 1 | ASTM C618 Class F | BS 3892 | BS EN 450 Cat. N |
|---|---|---|---|---|---|---|
| Loss on Ignition (LOI) | % | 1.5–3 | 5 max | 6 max | 7 max | 5 max |
| Chloride as Cl | % | 0.01 | 0.05 max | — | 0.1 max | 0.1 max |
| SO₃ | % | 0.5–1.0 | 3 max | 5 max | 2 max | 3 max |
| Free CaO | % | 0.0–0.5 | — | — | 1.5 max | 1.5 max |
Full technical specification available on request — send an inquiry for the complete test-report data sheet.
