Aggregate gradation: how to read sieve results

Read the table before interpreting the curve

Aggregate gradation describes how sample mass is distributed among particle sizes. Individual retained percentage, cumulative retained percentage and percent passing are different quantities. With a consistent mass basis, percent passing is calculated from cumulative retention, not merely the material retained on one sieve. Representative sampling comes first: accurate weighing cannot make a selectively collected sample representative. This guide explains sieve order, mass balance, chart axes and hypothetical calculations, including a weighted blend of two components. A grading curve is interpreted against the approved requirements of its intended application; one preferred curve does not suit every concrete, pavement, drainage or ballast product. Passing a grading envelope does not establish strength, shape or durability, and a foreign teaching reference is not automatically an Iranian project requirement. The full Persian guide also addresses segregation, transport changes, fine particles and readable publication of real test documents.