Fine Aggregate Upper Size – IS practice In standard concrete and mortar grading, the maximum size that still classifies as fine aggregate (sand) is taken as not exceeding which sieve size?

Introduction / Context:
Aggregates are broadly classified into fine and coarse fractions for proportioning and quality control. The upper sieve size defining fine aggregate is a standard reference that determines which grading limits apply and how mix designs are computed.

Given Data / Assumptions:

• Sieve series used in common IS/metric practice.
• “Fine aggregate” refers to material commonly called sand.
• Ordinary concrete and mortar specifications.

Concept / Approach:

Fine aggregate comprises particles that pass the 4.75 mm sieve. Material retained on larger sieves belongs to coarse aggregate fractions for proportioning and grading purposes. This boundary ensures a clear separation of roles: fines influence workability and paste demand, while coarse particles contribute to skeleton and economy.

Step-by-Step Solution:

Verification / Alternative check:

Mix design tables and grading specifications consistently use the 4.75 mm sieve as the cutoff between fine and coarse aggregates.

Why Other Options Are Wrong:

Other sieve sizes listed do not correspond to the standard fine/coarse boundary and would misclassify aggregate fractions for design.

Common Pitfalls:

Confusing nominal maximum size with the fine/coarse boundary; ignoring that well-graded sands still must comply with limits across multiple sieves below 4.75 mm.

Final Answer:

4.75 mm