Aggregates & Materials
Gradation
// Definition
The distribution of particle sizes in an aggregate sample, determined by sieve analysis. Well-graded aggregates pack densely with minimum voids.
Good gradation reduces cement paste demand, improves workability, and increases strength and durability. Gap-graded or single-sized aggregates are used for special applications like pervious concrete.
// Related Indian Standards
IS 2386IS 383
// Cross-references
Coarse Aggregate
Aggregate retained on the 4.75 mm IS sieve. Forms the bulk of concrete volume (60-75%) and provides dimensional stability.
Fine Aggregate
Aggregate passing the 4.75 mm IS sieve — sand. Fills voids between coarse aggregates and contributes to workability.
Fineness Modulus
A single number describing the average particle size of an aggregate, calculated from cumulative percentages retained on standard sieves.
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