IS 3812 Part 1

: 2023

Pulverized fuel ash - Specification - Part 1: For use in cement, cement mortar and concrete

CurrentEssentialSpecificationMaterials Science · Green Building and Sustainability
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This standard specifies the physical and chemical requirements for pulverized fuel ash (fly ash) used as a pozzolana in cement, cement mortar, and concrete. It defines the limits for critical parameters like fineness, loss on ignition, and reactive silica to ensure proper strength development and long-term durability in concrete mixtures.

Specifies requirements for fly ash used as an admixture or ingredient in cement, mortar, and concrete for sustainable construction.

Quick Reference Values
Fineness (Specific Surface by Blaine's)Minimum 320 m2/kg
Loss on ignition (LOI)Maximum 5.0 percent
Moisture contentMaximum 2.0 percent
Soundness by autoclave test expansionMaximum 0.8 percent
Lime reactivityMinimum 4.5 N/mm2
Total SiO2, Al2O3 and Fe2O3 (Siliceous Fly Ash)Minimum 70.0 percent
Compressive strength at 28 daysMinimum 80 percent of control mix
Practical Notes
High Loss on Ignition (LOI) indicates unburnt carbon, which can increase water demand and absorb air-entraining or superplasticizing admixtures, reducing their effectiveness.
Fineness of fly ash significantly impacts its pozzolanic activity; coarser fly ash reduces the rate of strength development.
Siliceous fly ash and calcareous fly ash possess different reactive properties and must be correctly identified and tested before finalizing a concrete mix design.